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TZ350
20th November 2008, 18:38
.

This is Thomas a Vietnamese race mechanic, you know that place where they have all those hot 50's and 125's are big bikes.

Thomas, ESE's Race Team's Tuner is fettling number 9. adjusting the port timing for Taupo.

Its hard to see but he has taped a degree wheel to the magneto flywheel so he can mark out the exhaust port height he wants.

None of this raise the port 3.5mm for a gazillion HP nonsense. He knows what timing he needs and sets the crank position there before marking the port and then doing the hells death port job that we all dream of.

You should see him setting up a carb. Talk about pain staking, he starts with a main jet so big the bike floods at about half throttle (apparently this proves the oriface of the needle/needle jet combo is big enough) and then he slowly step by step works back until it runs clean.

Most people start at the bottom with a carb and work up, He starts at the top and works backwards.

Never seen him blow one up. But then he is intelligent with the throttle and does not ring its neck when the engine is in distress.

Boy o Boy am I Looking forward to Taupo.

.

R6_kid
20th November 2008, 18:57
You imported a Vietnamese dude to tune you're bike...

You must really want to win!

Rick 52
20th November 2008, 19:42
Bloody hell that thing is quick already it will be a rocket ship when you have finnished
Good luck

Pumba
20th November 2008, 21:02
I hope he has all his visas sorted, as imigration may be about to get a tip off:shutup:

F5 Dave
21st November 2008, 09:26
Just add another nut to the end of flywheel, then you can add a bolt that secures the degree wheel. Pointer must be secure (I use a clamped on scriber) & degree wheel should be as big as possible. Barrel must be bolted down well or gives incorrect readings, this can be a problem if engine has thru bolts & a few gaskets used. Use feeler gauge to determine if port is closed by piston, doing it by eye is imprecise.

When starting with another carb just pull the mainjet out, no point putting a big one in. If the engine doesn’t bog past ½ way then the needle is too fat.

Bert
22nd November 2008, 06:25
You should see him setting up a carb. Talk about pain staking, he starts with a main jet so big the bike floods at about half throttle (apparently this proves the oriface of the needle/needle jet combo is big enough)



When starting with another carb just pull the mainjet out, no point putting a big one in. If the engine doesn’t bog past ½ way then the needle is too fat.

Interesting.
A few stupid Questions:
right what do you guys think is the largest carb that could be run on a ported tf100?
I've ended up with a small issue with my stupid engine placement where my standard carb is sloping downwards (i.e. float bowl is not sitting flat), I will looking at mounting one of my RGV carbs (34mm?) which would mean the float bowl was flat again... Would this work with the right jetting or will it just be too lean?

Cheers
Bert.

speedpro
22nd November 2008, 09:08
Interesting.
A few stupid Questions:
right what do you guys think is the largest carb that could be run on a ported tf100?
I've ended up with a small issue with my stupid engine placement where my standard carb is sloping downwards (i.e. float bowl is not sitting flat), I will looking at mounting one of my RGV carbs (34mm?) which would mean the float bowl was flat again... Would this work with the right jetting or will it just be too lean?

Cheers
Bert.

I reckon 34mm is just on the too big side of things. I've run a 32mm mikuni round slide on a "ported" TF and it worked good but bigger would definitely have been a mistake. I've had some work done more recently and have ended up requiring a 34mm carb on a 100cc. 32mm was going to be fine right towards the end but final calculations said 34mm was required. Those calculations were being done by someone who makes a living building and modifying leading edge 2-strokes. Have you tried to find the similar smaller carb from the earlier model?

Bert
22nd November 2008, 09:53
I reckon 34mm is just on the too big side of things. I've run a 32mm mikuni round slide on a "ported" TF and it worked good but bigger would definitely have been a mistake. I've had some work done more recently and have ended up requiring a 34mm carb on a 100cc. 32mm was going to be fine right towards the end but final calculations said 34mm was required. Those calculations were being done by someone who makes a living building and modifying leading edge 2-strokes. Have you tried to find the similar smaller carb from the earlier model?

Cheers Speedpro.

I had a funny feeling that maybe the case. I'll have a look around for a slightly smaller sloping carb, or modify the current setup.

TZ350
23rd November 2008, 07:00
Thomas is working on the ports. Rear port angles up 55 degrees, secondaries 45 and mains are angled flat across the bore. All the transfer ports were made to open at the same time, 114 degrees ATDC, duration 132.

The max possible width of the exhaust port is considered to be 75% with thin/deep steel rings and 70% is considered reliable. I got greedy and we went for 73%, opening at 81 degrees ATDC, duration 198.

Thomas assures me we can get away with 73% with careful shaping of the port. The problem is that the compression causes the ring to bulge into the exhaust port as its closing and the top edge of the port has to be shaped in an arc that gently pushes the ring back into its grove.

Thomas said life expectancy is going to be short and as I was greedy I am not to go boohooing :crybaby: to him if it all turns to custard at Taupo.

I got three seasons out of my barrel with the standard exhaust port shape, the new port job is expected to last a season at best between re-bores. Is it worth it for two more horse power? I think I have just shot myself in the wallet again. :2guns:

Thomas reckons it will be the fastest thing to the first corner. :woohoo: but if it chucks up :puke: it will be spectacular.

Its Death or Glory at Taupo.

.

Skunk
23rd November 2008, 08:10
I got three seasons out of my barrel with the standard exhaust port shape, the new port job is expected to last a season at best between re-bores.Shit! I've got three seasons out of my modified motor and expect to get a few more. It's only been apart to check the tune (underside of the piston) and fix a crankcase leak. Mind you the exhaust is only at 189° duration.

Buckets4Me
23rd November 2008, 09:44
Shit! I've got three seasons out of my modified motor and expect to get a few more. It's only been apart to check the tune (underside of the piston) and fix a crankcase leak. Mind you the exhaust is only at 189° duration.

#9 is still running and running well it was wheelspinning at the 2 hour and lifting thew wheel in the air out of corners no real nead to do all this work there
but you know old guys just cant help fixing things that arn't broke

I think this bike only ever failed to finish 1 race in all that time and that was my fault
the bike often finished in better condition that the rider :Playnice:

TZ350
23rd November 2008, 10:06
Shit! I've got three seasons out of my modified motor and expect to get a few more. It's only been apart to check the tune (underside of the piston) and fix a crankcase leak. Mind you the exhaust is only at 189° duration.


Its the width of the port thats the reliability problem. I think I should have left it well alone, or at least kept it < = 70% of the bore diameter, as Buckets4me says, don't fix whats not broke.

Now that I want to attack the inlet port Thomas can't understand me and now only speaks in Vietnamese, I think he is saying "stick to the plan!". :girlfight:


“Experience is what you get when you don't get what you want.”


Thomas recomends these books on Two Stroke Tuning.
(Some of these are PDF's that can be down loaded, read them then get yourself a copy of the book)

Graham Bell

http://www.kreidler.nl/artikelen/performance-tuning-graham-bell/performance-tuning-graham-bell.pdf

Gordon Jennings

http://www.vintagesleds.com/library/manuals/misc/Two-stroke%20Tuner's%20Handbook.pdf


http://toostroke.blogspot.com/2007/12/two-stroke-tuners-handbook.html

Engine Formulas

http://members.bellatlantic.net/~vze2p5sj/modelengines/engine1.htm

Reading Plugs.

http://www.dragstuff.com/techarticles/reading-spark-plugs.html

Rate of fuel burn and how it affects power output

http://www.factorypro.com/tech_tuning_procedures/tuning_fuel_octane_vs_power.html

F5 Dave
24th November 2008, 08:27
Hey Bert, long time, hope make it to Taupo. You're hijacking thread a bit, but no mind. Don't use the later RGV 34mm carb. They have a strange set up because of the solenoid & are reputably a pig to use if you aren't using it. Yes earlier model is 32mm & still downdraft. To be fair a 28mm flatslide Mikuni semi-downdraft such as from first TZR etc wouldn't be a bad place to start either.

TZ350
24th November 2008, 18:48
.

Thomas is working with the Mota engine simulation software to develop inlet porting ideas and checking out expansion pipe designs.

The inlet timing looks best at opening 145 BTDC closing 85 ATDC..145/85.. 230 Duration. A TZ350 inlet is 95/95 190 Duration.

He has been simulating all sorts of pipes and the RM125 pipe found in Graham Bells book looks the best. He has found that part of the front pipe from a RG250 can be used to make the front section of the RM pipe and he only needs to make some basic cones for the mid and rear section. Using the front pipe from an RG250 saves a shit load of work and makes the rest of the job easy-peesy.

He reckons the front pipe is pretty good as it tapers neatly and is very close to the RM125 specs. He intends to make the rest of the chamber out of the same heavy material as the original (1.25mm) and mount the whole thing rigidly, to handle the rough and tumble of Bucket racing. You only need springs and flexy mounting for light thin walled pipes that will crack if they are not free to vibrate.

As the metal is quite thick and easy to work with it can be gas welded, hammerd and the welds ground to make them a smooth flowing shape inside.

For the RM125 pipe specs see Page 76..........http://www.kreidler.nl/artikelen/performance-tuning-graham-bell/performance-tuning-graham-bell.pdf

I was pretty excited to see Mota predicting 32HP but Thomas said it won't be that high, probably low 20's at best. As there is a thermal barrier that prevents a air cooled 125 engine going over about 26HP.

It is the shape of the torqe curve that is important. Mota is predicting a flat torqe (dotted line in the picture) curve from 9,500 to 12,000rpm. If this works in real life the bike should drive very well.

Thomas reckons the more area under the torque curve the better and if we can get the shape seen in the simulation we will be doing well, whatever the final HP achieved.

When we have made all of the changes I hope to get the bike on a dyno, if we can we will get a printed graph and put it up here for comparison.

.

TZ350
25th November 2008, 19:13
.

Thomas at work on the cylinder head, because the exhaust port has been raised the effective compression ratio has been lowered.

Thomas is skimming about 0.15mm off at a time to bring the trapped compression ratio back up to 8:1

After about five cuts the compresion ratio was checking out close to what we wanted.

A final check with a compression tester and it reads 160 psi. We have found the bikes run great at 160 but 180 psi gets a bit borderline.

Thomas says that as the pipe design/build gets better at supercharging the cylinder you need less effective compression and maybe a little ignition retard.

.

bucketracer
25th November 2008, 19:28
Fawk me does this guy know what he's doing or what! :shit:

speedpro
25th November 2008, 21:03
For the RM125 pipe specs see Page 76..........http://www.kreidler.nl/artikelen/performance-tuning-graham-bell/performance-tuning-graham-bell.pdf



Note the method used on page 15 to calculate compression ratio.

It is correct to adjust compression ratio down if it has previously been optimised for a less than ideal engine configuration which is now corrected resulting in improved pumping through optimised porting, pipe resonance, etc. What is regularly overlooked is the crankcase volume which may also need to be increased to supply the volume of gas to the transfer ports in the optimised engine.

Bert
25th November 2008, 21:19
Nice Work TZ. Thanks for sharing all this useful bits and pieces, keep it up (It would make a useful web page or addition to some of the other ones around the place).
I could only wish that i had access to all that equipment & labour to make my bucket sing.

So it should go well then,,, see you on the track at taupo as you go past me.

Bert

Skunk
25th November 2008, 21:34
Nice Work TZ. Thanks for sharing all this useful bits and pieces, keep it up (It would make a useful web page or addition to some of the other ones around the place).
There's room at http://www.bucketracing.co.nz

TZ350
25th November 2008, 22:11
What is regularly overlooked is the crankcase volume which may also need to be increased to supply the volume of gas to the transfer ports in the optimised engine.

.
Hi Speedpro, I remember you explaining to me how crank case volumes had become to small and how its easier to get a cylinder full of air/fuel from a larger crankcase volume than a smaller one. Your advice made sense, check out the 12mm cylinder spacer under the barrel. I rememberd that fitting the longer RD400 rods to a TZ was the trick setup years ago.
.

F5 Dave
26th November 2008, 08:40
Fawk me does this guy know what he's doing or what! :shit:
I'd say 'or what', but only to be controversial.

Measuring compression with a gauge is a rough stick. Far more accurate to measure the actual combustion volume with liquid (fork oil works well). Maybe he did.

I’d only ever use a gauge to check the engine after a rebuild & take that as a point to compare later to. If you were too lazy to take the engine apart.

One of my bikes I measured it as 196psi with fresh piston & ring & a base gasket removed. I then machined the head & got . . . 196psi. Same german gauge, same technique (kick it an awful lot of times with throttle wide open till it stops moving) but a very real difference in combustion size.

Oh & the high number? Just peachy for the bike’s application, watercooled trail bike with a wide spread pipe.

The correct compression ratio is the one that best matches the bike, there are other compromises that in isolation may appear best, stinger size (or steep baffle), general pipe, ignition, head shape to name a few.

Primary compression is another compromise & which way it is approached has different benefits, the Honda or the Yamaha route (some way back) was high crankcase compression for more pumping efficiency (the crankcase is afterall just a pump) or more volume & let the pipe do the work.

TZ350
26th November 2008, 11:07
.

So some one does read this.

.

speedpro
26th November 2008, 15:45
only for a laugh :laugh:

TZ350
26th November 2008, 19:10
Note the method used on page 15 to calculate compression ratio.


Translated for Thomas.


Thats a good point Speedpro. Using the total swept volume of 125cc uncorrected compression ratio is 15:1 using the volume above the exhaust port for the corrected ratio is 8:1 different approaches.

For those who want to know:- R = (CV+SV)/CV
Where R=Ratio, the compression ratio.
CV=ClearanceVolume, the bit in the cylinder head.
SV= SweptVolume, the cc's of the whole cylinder or the bit above the exhaust port, however you want to do it.

If you know the compression Ratio you want and the SweptVolume you have (total or corrected) then by transposition.

R = (CV+SV)/CV
R = CV/CV + SV/CV
R = 1+SV/CV
R-1 = SV/CV
(R-1)/SV = 1/CV
SV/(R-1) = CV

CV = SV/(R-1)

So there you have it.

CV The ClearanceVolume is the bit you need in the cylinder head and it needs to be equal to the SweptVolume divided by the compression Ratio you want minus One.

So now you can chose a compression Ratio and work out the CC's for the ClearanceVolume required.

Speedpro knows all this.

F5 Dave you caught me, I think your comments are spot on, now ask me about the Science and Philosophy behind getting the compression ratio right, using a compression tester.

I dare you!!! :laugh:

Please

.

TZ350
27th November 2008, 22:10
.

Thomas wants to measure the compression ratio accurately and see how it compares to my compression tester method.

See page 16 of Graham Bells book for a discription of corrected and un-corrected compresion ratio.

http://www.kreidler.nl/artikelen/performance-tuning-graham-bell/performance-tuning-graham-bell.pdf

Basic dimensions are:- rod length 110mm between centers, -2mm piston pin offset, 56mm bore, 50mm stroke, 125cc.

Ex opens ATDC.....height.....Volume...8:1 CR...7.5:1 CR.....15:1 CR
......81...............23.8mm.....58.6cc....8.4cc. ...9.0cc.........8.9cc.........Race
......83...............24.7mm.....60.8cc....8.7cc. ...9.4cc.........8.9cc
......86...............26.0mm.....64.0cc....9.1cc. ...9.8cc.........8.9cc.........MotoX
......91...............28.2mm.....69.5cc....9.9cc. ..10.7cc.........8.9cc
......96...............30.5mm.....75.0cc...10.7cc. ..11.5cc........8.9cc.........Road...Enduro..and.. early.MotoX

At Ex opens 81 ATDC (road race) the clearance volume for the corrected and un-uncorrected compresion ratios are close but for Ex opens 96 ATDC (road or motoX) they are quite different.

It looks like Graham Bell at 15:1 uncorrected was talking more about the race end than road, even if your using AvGas.

Thomas says there is no right way, just better ways and CC'ing the combustion chamber is a better way.

He is real keen to see if my quick and dirty way is anywhere close to the more accepted CC'ing way for establishing a working compression ratio.

The design parameters are 125cc, Ex opens 81 degrees ATDC, and the ClearanceVolume should be 8.4cc for a corrected compression ratio of 8:1.

When we get a chance we will measure it to see how close to 8.4cc's it actually is and publish the results.

.

F5 Dave
28th November 2008, 09:49
Corrected cr is probably relevant if you don't run an expansion chamber. If you do & the engine is running in the tuned frequency then all bets are off, but the real compression ratio & the full ratio are likely the same or close enough that you can use it to gauge where you're at vs fuel you use.

If it is 8.4cc then I'd say hmm 15.9:1 on an aircooled 125:(. Better retard that ignition quite somewhat if you want it to survive. I was nowhere near that high on my 125. I've run higher on my watercooled 40mm bore 50, but not these days, probably a tickle less.

When I measure with fluid I count 2 threads from bottom of spark plug to account for the sparkplug extra volume (about 0.2cc from foggy memory, but I measured it). A burrette makes it much easier to get consistent measurements.

TZ350
28th November 2008, 13:02
.

Ex opens ATDC.....height.....Volume...8:1 CR...7.5:1 CR.....15:1 CR
......81...............23.8mm.....58.6cc....8.4cc. ...9.0cc.........8.9cc

From F5...."If it is 8.4cc then I'd say hmm 15.9:1 on an aircooled 125. Better retard that ignition quite somewhat."


Yes F5, I see what you mean.

.

F5 Dave
28th November 2008, 13:32
What would be nice is a fast burning fuel with a high octane & high calorific value. (kind of like the old red leaded super we used to get a decade ago). Then if you are keen running a high compression ratio then & esp with an engine perhaps a bit shy of too many revs for the crank assembly you could build a midrange monster suitable for kart tracks. With a reasonably large squish area hence small flame lead & thus a fairly high MSV figure + a matching supercross style pipe (with steep baffle to suppress over rev) then high comp is still a good idea.

My old H100 was built with this in mind. Not so flash on the longer ccts, but good fun everywhere else. Still was good enough to get a 3rd in old cct Taupo GP many moons ago even with a crash (almost a 2nd but that damn Diprose chap got me on his MB when I got run off the track ~ 2 laps from the end).

TZ350
28th November 2008, 18:44
Have CC'd the engine.

Thomas is really keen to CC the engine. The best way would be to take the engine out of the bike so it can be levelled up and CC’d through the sparkplug hole but we are to pressed for time to do this.

With the engine in the frame the spark plug hole is a bit inaccessible and the cylinder slopes forward. Taking the motor out is a bit more work than we wanted to do and because the engine is fitted with a flat piston with a small dish in it.

We figured we could get a fairly good result by CC’ing the bore with the piston at TDC, then the head and then adding the two results together. Working with what we could find.

We cut the top of a takeaway container to shape and put a small hole in it. Liquids because of their surface tension tend to bulge up.

So using the flat piece of plastic and pouring brake fluid through the small hole with a syringe would flatten the fluid bulge and allow us to measure more accurately how many CC’s it takes to fill the cylinder.

Piston at TDC, a light smear of grease to seal the rings. Another smear of grease to stick the plastic to the barrel. Inject the brake fluid and count the CC’s. Now the same for the head.

Results:-

Barrel/Piston = 5.3
Head&Plug = 5.7
Total ClearanceVolume = 11cc’s
Corrected Compresion Ratio = 6.3
Uncorrected Compression Ratio = 12.4

So we were safe.

Until Thomas reminded me that when we had 0.5mm static squish the piston was just touching the head at 10,000rpm and that we had added another 0.5mm giving a static squish of 1mm and a dynamic squish of 0.5mm.

0.5mm of squish in our engine is equal to 1cc.

So the total dynamic ClearanceVolume is now 10cc’s at 10,000rpm
Dynamic Corrected Compresion Ratio = 6.8
Dynamic Uncorrected Compression Ratio = 13.5

Our aim was for a bit more than this.

So a couple of skims and re-measures later we had:-

The total dynamic ClearanceVolume is now 9.4cc’s
Dynamic Corrected Compresion Ratio = 7.3
Dynamic Uncorrected Compression Ratio = 14.3

Close enough for us. We will be starting out with the ignition timing retarded and then incrementaly advance looking for the optimum. We will be doing many plug checks along the way looking for the change in colouration of the plugs earth strap. The colouration should end just before the bend of the earth strap for best results. See all those, reading plugs, posts earlier.

One symptom of over compression in a bike that ran well before, is that it now goes flat up top. This is the same for slightly over advanced ignition timing. This makes sense when you think about it.

As the piston is going up there is a negative pressure working on it. We want the maximum cylinder pressure to occur sometime (15 degrees approx) ATDC. If the maximum pressure has not quite reached detonation point but has moved closer to TDC then there is more negative pressure before TDC trying to push the piston back and we experience this as the engine going flat.

So as F5 Dave says, a faster burning fuel would allow maximum pressure after TDC with less negative pressure buildup (slowing us down) before TDC.

Its all about BMEP brake mean effective pressure, and how to achieve it.

So if we are careful we can test our handy work and dial it in without blowing it up.

The final compression test read lower than before we increased the compression ratio.

Yes I got away with it this time but using a compression tester to check the compression ratio, is not only quick and dirty but also lazy and very likely to bite one on the bum.

As I can find them I will put up details about other bikes compression ratios and ignition timing like the Honda RS125, Suzuki RM125 etc.

My next move is to build a programmable ignition, or at least one that can be setup advanced and then retards to the correct setting as the engine comes onto the pipe.

Water injection into the expansion chamber when the engine is running below peak torque.

.

Buckets4Me
29th November 2008, 05:29
get Thomas onto my bike next please
you know the one the rs powed rs125 for the Slipway
and make sure he hase put puke gearing on it please
11 fround 54 rear thanks
<_< :laugh: :Police: :jerry::eek::doh::chase: :no:

TZ350
29th November 2008, 12:15
The correct compression ratio is the one that best matches the bike, there are other compromises that in isolation may appear best, stinger size (or steep baffle), general pipe, ignition, head shape to name a few.

Primary compression is another compromise & which way it is approached has different benefits, the Honda or the Yamaha route (some way back) was high crankcase compression for more pumping efficiency (the crankcase is afterall just a pump) or more volume & let the pipe do the work.


Yes! I agree its the compression ratio that best matches the bike thats needed, and its the Black-Art fitting it in with all the other compromises.

It could be said the "Black-Art" is the tuner who compromises best, wins!

From what I've read. The high crankcase compression bikes have high but peaky power and the more volume & let the pipe do the work bikes have lower but wider power bands.

My bike is of the " more volume & let the pipe do the work" approach/compromise for the gear box it has and Kart tracks.

After Taupo and when we have got it going properly we are thinking of taking it to a Pukekohe Track Day. Ride in the slow novice class and see if we can crack 100MPH.

If we can pull that off, the plan is to then fit a fairing and run it in the GP125 class with the aim of a fast start and coming around mid field on the first lap. I know I can make real fast starts and wouldn't that give them the shits. A bucket running mid pack (at least for the first lap), once would be enough twice would be excellent.

Should be fun.

Does any one have times and top speeds for the GP125 class, especially mid field times/speeds?

k14
29th November 2008, 13:06
FYI: RS125's running leaded have head cc of anywhere from 10.6cc to 9.8cc. Although to go that low you need some super duper $8 a litre race gas. For avgas the optimal is about 10.6-10.5cc.

Ignition curve is here (http://www.sp125racing.com/BPS%20162.jpg)


Does any one have times and top speeds for the GP125 class, especially mid field times/speeds?
Top speed at puke earlier this year for me on datalogger was 215kph, fastest lap 1:05. Standing lap 1:10.

Sorry to tell you but you'd be left for dead even off the start. I can do 0-100 in 3.9s and even if you did make it onto the back straight leading you'd be dead last before the kink. Good luck though :beer:

TZ350
29th November 2008, 13:32
I enjoyed reading your Bucket race report http://www.kirkpritchard.com/extras/2008_report7.php

Thanks for the info, ignition map and encouragement.

I had the idea that mid field Honda RS125's did about 110mph.

I did try a while ago and managed mid field from the start to about 1/3 down the back straight then the engine shit itself. Had't up jetted from Mt Wellington. The fast bucket start helped in cutting through the traffic around the s'es to the back straight as typically the mid fielders were waiting for a clear run before getting into it.

Later, did manage to get it to survive lap after lap but top speed was a little less than 100MPh.

Lap times, 1:27 to 1:32

Yes it could just be a small boys dream and a step to far.

Might have to settle for just cracking the Ton and a sub 1:20 lap time if thats possible.

But for the moment any more info on the GP125 class especially mid field would be appreciated.

Bren_chch
29th November 2008, 13:38
exciting project... i am enjoying the reading and information you have provided... thanks! :2thumbsup

k14
29th November 2008, 14:04
But for the moment any more info on the GP125 class especially mid field would be appreciated.
Ask away, but mid field isn't really applicable at puke. In march top 10 were separated by around 1-1.5s and all very much of a muchness. Then the slowest 2 or 3 back markers doing approx 1:10s laps. Even the slowest modern 125 will do 190kph at Puke. For me I am hitting 200kph at all tracks in NZ bar Manfeild. However my old 91 RS did only about 182 give or take. I could still manage 1:10s at puke on that though.

TZ350
29th November 2008, 14:35
Thanks for the reality check. I know how fast 1:05 and 1:10 is.

Looks like the after Taupo aim, is cracking the Ton and/or sub 1:20 and embarising a few novic big bike riders on a Track Day in 09.

gav
29th November 2008, 17:56
Are you still running a 24mm carb on the GP125?

TZ350
29th November 2008, 18:43
.

Yes 24mm carb. They say a rotary valve engine with its asymmetrical and longer timing sucks more through a 24 than a piston porter does. I hope this is true.

There may not be much benifit in going to a bigger carb as we can get to the thermal limit of the air cooled 125 engine with a 24mm carb.

.

CM2005
29th November 2008, 20:20
tell you what robert, i dunno how you've managed this while fixing my bike too!! this thread's given me a headache lol.. came 7 out of 22 bikes in 6 hr mopedathon today

TZ350
29th November 2008, 20:26
Had your bike running today it's going great. I am ashamed to say the problem with it was all my own fault and pretty much what you predicted. Glad to hear you survived today.

TZ350
29th November 2008, 22:03
.

Thomas and I have been working on a programmable ignition, its actually three kits from J-Car. Programmable Ignition Kit, Coil Driver Kit and Hand Controller Kit for setting the parameters.

The ignition works by seeing a trigger point calculates the rev’s and waits 360 degrees plus or minus the advance/retard programmed into the parameters table by the hand controller. Then triggers the CDI.

We have run this on a bike already but found a problem with the signal coming from the trigger.

The problem is the trigger output is a full 360-degree sign wave and the trigger point varies as the rev’s go up. At first it’s very retarded then briefly correct then over advances.

Its all to do with the fact that the triggering takes place at a set voltage and as the rev’s go up the amplitude of the sign wave goes up triggering the ignition sooner and sooner.

I have drawn a picture to show how this happens. If any one has a circuit idea that triggers at a constant point like where the sign wave changes sign in the middle. I would be very interested. Can anyone help me?

Another solution might be to have a small trigger coil on the outside of the flywheel that gives a short blip then the trigger point can’t wander to far.

Any input would be welcome.

When we ran it, it was soggy to start (to retarded) then as the rev’s picked up it began to backfire as the over advanced ignition tried to spin the running motor backwards and the flywheel key sharing off probably saved the engine.

The plan is to insert the programmable ignition between the original stator and CDI box in such a way as to be able to quickly un-plug it if it becomes problematic and be able to quickly revert to the standard system.


.

CM2005
30th November 2008, 08:22
Had your bike running today it's going great. I am ashamed to say the problem with it was all my own fault and pretty much what you predicted. Glad to hear you survived today, was it the 6 hour race?

I only just survived to be honest, had a pretty bad crash at the 1 hr mark, which we lost 5laps on rebuilding the foot peg, re fueling and swapping riders.
banged my knee up and scuffed my leathers, and put a little scratch on my lid lol. i hit a tyre at about 40k's, bounched about 1.2m in the air then hit the track. i won a box of red bull for best crash.:Punk:
I love endurance racing!!
sorry for the thread hijack!

speedpro
30th November 2008, 09:14
I'd be going optical for the trigger. The LED/Trigger devices are cheap and then all you need is a chopper disc, easy. See this link for the sort of thing i'm thinking of. http://www.meccanisms.com/modules/xfsection/article.php?articleid=21

Skunk
30th November 2008, 10:25
This is great info... I'm looking at the ignition system on my F6 and wondering what to do.

k14
30th November 2008, 12:43
Yes, very interesting. Any chance you can let us know how you made the ignition?

speedpro
30th November 2008, 12:48
OR go to these guys http://www.twostrokeshop.com/index.htm and ask for one of these http://www.ignitech.cz/english/aindex.htm. Opps - you will need to click your way to the programmable DC powered CDI ignition. No more peak power to be had but I know from lots of dyno time and experimenting that you can boost the mid-range heaps.

You can actually get them from Wobbly here in NZ before he leaves for Oz and the TSS.

TZ350
30th November 2008, 21:51
.

Boosting the mid-range and a little over run past peak power is what I am after.

But Ooh the dilemma, make or buy? I did ask them if they could provide a unit for my KX80 ignition, they said "no" can do.

I can't see why not. I think something must have got lost in the translation.

I will ask them again but this time send photos of my ignition. The lack of a 12volt dc source (battery) might have been a problem.

The price is right.

Even if I eventually buy one, while I am looking into it, I am going to see if I can complete the J-Car programmable ignition.

Thanks for the tip and the pointers for making a better trigger, the trigger is my sticking point at the moment.

.

TZ350
30th November 2008, 22:14
I'd be going optical for the trigger. The LED/Trigger devices are cheap and then all you need is a chopper disc, easy. See this link for the sort of thing i'm thinking of. http://www.meccanisms.com/modules/xfsection/article.php?articleid=21


I would still like to see a circuit that works with a sign wave. I was hoping to use the out-put from the stator, becouse it's simpler.

But yes, this would give the 5volt sharp rising edge output signal that I need.

I will check Radio Spares and see what they have.

It shouldn't be hard to mount the sensor on the crank case and an interrupter blade on the flywheel.

Thanks.

.

Bert
1st December 2008, 18:01
You could always try a hall effect sensor, which would supply a 5volt signal. from Jaycar. Hall effect sensors are what they use on pitbikes, scooters and weedeaters etc (high reving).

As for your voltage issue, use a small 12v battery and run a 6-12 volt converter such as:
http://www.aaroncake.net/Circuits/6-12conv.asp.

thought this maybe of some use.

Cheers
Brent

TZ350
1st December 2008, 18:51
.

Thanks for the info Bert I will have a closer look at the Hall Effect sensor from J-Car.

Did not have time to get to Radio Spares today and I will be away for a week for work. But I remember seeing opto interrupters like Speedpro describes http://www.meccanisms.com/modules/xfsection/article.php?articleid=21 as end stops in older ink jet printers and floppy drives. I guess I will be hunting through the in organics when I get back.

The first picture shows one type of KX80 ignition with no pickup sensor. It must use the sign wave from the generator coil in some way as the timing point. Does anyone know how they do this. The next picture shows a different type of KX80 ignition with a pulser coil which probably would be ideal but the stator plate does not fit the GP easily. The third picture shows on the left some RGV250 pickup coils that probably would work and on the right some hall effect pickups from an old Mitzi L2000 distributor.

There should be something here to use. I am looking forward to getting onto it when I get back next week.

.

Bert
1st December 2008, 19:13
My setup for the TF100 is similer to that of the first photo. we made a backing plate that fitted between the stator plate and the engine mounts. I've also had a internal rotor RM stator which we also used the same backing plate (with more mods), so it has become quite useful over the years...
Good luck with the jaycar CDI; When I saw them, I though that it would be the best thing since sliced bread; so I was hopeing someone would sort them out.:innocent:

TZ350
12th December 2008, 19:29
.

The setup in the first photo virtually fits straight into a GP125 but does not have a separate trigger pulse. How the Japanese make it trigger at a set point without it advancing/retarding I don't know. If anyone has a circuit diagram of how this works I would love to see it.

We have been running a RM80 ignition in the RG50 with an internal rotor like Bert describes. It has quite an amount of retard built into it. The idea is to over advance it at low rpm to get some low end drive and let it retard back to the correct setting as it comes onto the power.

Then as the rev's go up and it retards further it heats the gas in the expansion chamber (retarded ignition means hotter exhaust and sound waves travel faster in the hotter gas) and it fools the engine into thinking the pipe is shorter so the usefull rev's carry on a bit further past peak power.

The reverse happens when water is injected into the pipe below the power peak, for a moment the engine thinks the pipe is longer and it pulls from lower rev's.

The header section of the RG50's chamber has turned blue with heat. My problem is that without a dyno I don't realy know the shape of the torque (BMEP) curve and could easily over advance the ignition at low rev's trying to get it spot on for when it comes onto the power.

Does the blue header mean its retarded to far up top or is this a sign of correct (retarded) timing?? and every thing working OK. The whole retard curve could be too steep and will never be ideal. I just don't know.

Thomas says, get it onto a dyno, its the only (easy) way to find out and set it up.

This advance/retard and water idea is what we want to get working on the GP125.

When we get the RG50 figured out we can get on with the GP125.

I am looking forward to getting back to working on the J-Car programmable ignition and then water injection for the 125. A broader power band and more drive out of the corners sounds good to me.

.

speedpro
12th December 2008, 21:03
Put it on a dyno, stop pissing round. You make a change, do a run, and see exactly what effect the change has had. No bullshit, no guessing, no theories, just cold hard data.

TZ350
12th December 2008, 22:14
.

Always theory and questions first, I do like to understand what I am trying to achieve, then hard data.

Reckon your right speedpro, time to get the RG50 on a dyno to setup it's RM80 ignition and run the GP with its stock ignition to check the compression mod's and get a base line for later.

The 125's Jaycar programmable ignition needs more work before it's worth while dynoing it. I want to see the timing actually retard/advance with a timing light and be able to control it before giving it any dyno time.

.

bucketracer
13th December 2008, 07:49
Yea, speedpro think :first: to be :first: otherwise it's :doh: screwed up!!! again. :crybaby:

koba
23rd December 2008, 21:13
I've built a jaycar kit too, Its for my Volkswagen but I was also going to experiment with it on the A100, but to do this I was going to graft a 12v RGV150 ignition system on to the A. I havn't looked into it too far as it is fairly down the list for me.

TZ350
24th December 2008, 05:45
Thats great koba, I was looking at using pickups from a RGV250 I guess they are like the RG150's. I will be getting back to mine after Taupo and would like to keep intouch with you about your progress.

koba
24th December 2008, 06:41
Sweet, dont expect much progress tho!
I have lots of other stuff on the go, as always and will probably get a loncin powered NSR up and running first.
I can let you know how it goes on the volkswagen tho, initially I have soldered it together to run on points, I will pull that out and try a more modern triggering system once I get it working ok. Type of system will probably be determined by what I can find and make work with VW dizzy drive easiest.
This is all so I have more accurate triggering for the EFI system I have sitting in a box!
to run a EFI is much longer down the track tho as I will need later, better twinport heads so will prob build a new engine for it.

TZ350
30th December 2008, 09:48
.

Well that was Taupo! a third in the GP :woohoo:

We learn't a thing or two, like the importance of keeping the momentum going and that corner speed is everything.

I could match Ricks (the GP winners) FXR for speed but he was the much better rider.

The CB125T ridden by Daniel Lancaster went past me in turn one near the end of the race in one of the smoothest displays of cornering that I have ever seen, we swapped places several times going up the hill and in the last lap but he had the drive out of the last corner to the line. :sick:

I got beaten in every race after a tussle by F5 Dave on his RG50, he was very good at keeping up the momentum and corner speed and that is one very fast 50 :gob: but he did have to work for it (I hope) :blink:

There was a very tidy looking GP125 from Wellington that took my 3rd place trophy in the Sundays racing. :crybaby:

But I have seen the promised land. The GP125 ran well, the motor would sound real sharp and make so much power the clutch would slip under full throttle in the first lap or two and then settle down as the engine heated up.

Man! that clutch can take a hiding, exited every corner like I was leaving the start line, 15 laps in the GP caning the clutch all the way and it all held together.

Many thanks to Thomas for his efforts in sorting the beast out.

Next year we need to find ways to keep the engine cool, Thomas has some ideas like ceramic coatings and water injection to suppress detonation.

Also Speedpro told me about how he had welded some extra heat sinks onto the cylinder head, and some other tricks (He is a clever basted). I wounder if this extra heatsink idea with some computer CPU fans that are thermostatically controlled would work.

To get a handle on the size of the problem we need to think about how much heat energy is involved. The rule of thumb is 1/3 is lost down the exhaust, 1/3 is dissipated in the cooling system and 1/3 does some usefull work.

So if you have a 16kW motor you have to dissipate 16kW in the cooling system, thats 16,000 watts or 8 big "two bar" heaters. Thats a lot of heat. These are very interesting ideas, but it would be a mistake to let them distract me from what I know I need to do.

Now that I have a half decent bike, to get any further I need to learn to keep up that momentum and corner speed. :scooter:

Roll on next year, Taupo's great racing with very very great people. It was so excellent to meet up with the other Bucketeers from Wellington and ChristChurch :sunny:

.

speedpro
30th December 2008, 17:26
Water cool the head, you know you want to. Don't worry about the barrell. The head is where most of the fire happens and the piston and barrell have the benefit of nice cold mixture swirling around and through them.

TZ350
30th December 2008, 17:48
Water cool the head, you know you want to. Don't worry about the barrell. The head is where most of the fire happens and the piston and barrell have the benefit of nice cold mixture swirling around and through them.


Water cool the head, yes I want to, but not allowed! 125 2 stroke! maybe a rule change to allow the old school 2 strokes to keep up with the new fangled FXR's!!!

Got to keep it fair you know. :soon:

bucketracer
30th December 2008, 18:10
My TF100's coming along fine, sounds like a water cooled head could be in order. Sent some money to some Dutch guys and they sent back detailed plans for pipe, cylinder, and head, 14,000rpm 32hp, total loss, programable ignition and hand made gears. These are the guys that convert 50cc Kreidlers to rotary valve and clock over the ton on them.

speedpro
30th December 2008, 22:20
Pity about the cranks and clutches

gav
30th December 2008, 22:26
My TF100's coming along fine, sounds like a water cooled head could be in order. Sent some money to some Dutch guys and they sent back detailed plans for pipe, cylinder, and head, 14,000rpm 32hp, total loss, programable ignition and hand made gears. These are the guys that convert 50cc Kreidlers to rotary valve and clock over the ton on them.
So they are competition parts then? Illegal?

bucketracer
30th December 2008, 22:28
Pity about the cranks and clutches

What!!!! Bugger. do you know something?

bucketracer
30th December 2008, 22:30
So they are competition parts then? Illegal?

No No they just work out a plan based on their experiance, you have to hand make the bits yourself. The final result depends on your own efforts.

diesel pig
30th December 2008, 23:43
The final result depends on your own efforts

F@&king A brother!

Buckets4Me
31st December 2008, 07:49
So they are competition parts then? Illegal?

everything is a dam competitive part
you race your's dont you

but these are hand made :girlfight:
dont you like that cool

so we have the Dutch entering this now
and some Asian dude building engines
next we will hear that you guys are sending your engines off to be built by others :zzzz:

TZ350
31st December 2008, 14:40
.

Striped the engine, everything looks in great condition. Right sort of color on the top and underside of the piston. Perfect wash marks in the combustion chamber showing the transfer streams are evenly matched. Good plug color and dry exhaust. Clutch in good condition in spite of the hiding I gave it. Dam those GP125's are good.

Wrote up the log book and made plans for next year.

Performance wise, the lack of effective cooling of the Cylinder and Head is the limiting issue with air cooled motors.

Some Temperatures

Exhaust Gas Temperature:- 1000F, 540C to 1200F, 650C

Air Cooled Head:- 350F, 175C to 375F, 190C

Water Cooled Head:- 180 to 200F, 80C to 95C

Water cooled heads/motors run 100C cooler more or less than air cooled.

The big performance enhancement this year will be to try and find more effective ways of controlling the head temperature.

It's all about cooling fin surface area, thermal transfer to the air, air flow and heat input into the cylinder/head.

Some options I can think off:-

Ducting of air flow.
Detonation control.
Ignition control.
Ceramic coatings
Water injection.
Increased cooling fin area.
Variable forced air cooling.

I can see the real issue is getting the heat away from the immediate combustion chamber area. Which is what, water cooling is so good at. Air cooled motors have a long thermal path from the combustion chamber roof to the cooling fin tips.

I would love to hear of other options and what others have done/tried.

.

speedpro
31st December 2008, 22:16
I have done myself or helped someone else to:
Add fin extensions on a AC50 head, they helped a bit.
Watercooled an AC50 barrell, helped a lot.
Added fin extensions on the head and barrell and ducted air around the engine on a Honda XL125S, possibly some help.
Big air scoop /shroud on a AC50, helped a fair bit but not as much as watercooling.
Built a 100cc engine using a watercooled barrell, disappointing but very consistent. It didn't fade with heat.
Had a sidecar with a MB100 with a watercooled barrell, Had problems with pistons but power was consistent. Added watrcooling to head and piston problems went away.(when I remembered to turn on the electric water pump)

TZ350
1st January 2009, 08:20
Thanks speedpro for the background. My problem is power fade, from your information it looks like I need to find a way to improve cooling the head. I am looking at using some CPU heat sinks and cooling fans.

I have done some research (of course) and that increasing the velocity of the cooling medium, increases the scrubbing action and transfers heat better. With low velocity's boundary layers build up blanketing the radiating surface from the cooling medium. Pretty easy to imagine/see how this could happen to an air cooled motor at low speed.

All this pretty much fits with what you have told me before. I am hoping the controlled airflow/scrubbing action of the CPU heat sink/fans will help. Good thing is that the energy needed for the extra cooling can be stored in battery's before a race.

speedpro
1st January 2009, 09:35
As you have said earlier, the problem is the heat getting into the fins. I've thought about a waterspray system but that "might" be considered watercooling though not in the typical sense. I don't think you'd need too much water as long as it was atomised before getting to the fins. Bit like the intercooler sprays on Subarus though even they don't atomise efficiently I think. You need to effectively wet the fins with the minimum amount of water.
A possibility would be an electric fuel pump for a bit of pressure and some very small jets to atomise the spray. You could always spray methanol which would be fantastic, till it caught fire

k14
1st January 2009, 09:51
As you have said earlier, the problem is the heat getting into the fins. I've thought about a waterspray system but that "might" be considered watercooling though not in the typical sense. I don't think you'd need too much water as long as it was atomised before getting to the fins. Bit like the intercooler sprays on Subarus though even they don't atomise efficiently I think. You need to effectively wet the fins with the minimum amount of water.
A possibility would be an electric fuel pump for a bit of pressure and some very small jets to atomise the spray. You could always spray methanol which would be fantastic, till it caught fire
And if you used methanol it wouldn't be water cooling would it :msn-wink:

TonyB
1st January 2009, 10:18
As you have said earlier, the problem is the heat getting into the fins. I've thought about a waterspray system but that "might" be considered watercooling though not in the typical sense. I don't think you'd need too much water as long as it was atomised before getting to the fins. Bit like the intercooler sprays on Subarus though even they don't atomise efficiently I think. You need to effectively wet the fins with the minimum amount of water.
A possibility would be an electric fuel pump for a bit of pressure and some very small jets to atomise the spray. You could always spray methanol which would be fantastic, till it caught fire Sounds like what you need is a small fogging unit. They use high pressure and special nozzles to create fog- you can get ultrasonic versions as well which use sound to do the same job. They are very effective at dropping air temperature (so long as the relative humidity isn't too high). Not sure if you could get a fogging unit small enough to run on a bucket though!

speedpro
1st January 2009, 10:31
And if you used methanol it wouldn't be water cooling would it :msn-wink:

It could end up being a pretty spectacular barbeque though.

speedpro
1st January 2009, 10:32
Not sure if you could get a fogging unit small enough to run on a bucket though!

The bigger the better I reckon

bucketracer
1st January 2009, 12:35
Thanks speedpro for the background. Good thing is that the energy needed for the extra cooling can be stored in battery's before a race.

Now this gives me an idea, there is nothing in the rules that say, a bucket must actually be powered during the race by a class legal motor. Your in so long as the power comes from a class legal motor. I could use my TF100 to wind up a dirty great rubber band the night before and then have the fastest slingshot from the flag to the first corner.

Think of the possibilities, compressed air, rubber bands, battery power, there must be other possibilities for using a class legal motor to store its energy the night before and release it more effectively during the actual race.

Now if a race is say 10 minutes long and you run your class legal 125 motor for 20 minutes storing its energy in whatever the night before. Are you effectively running a 250 during the race?

Am I being to simple? :baby: or could this work?

Buckets4Me
1st January 2009, 13:04
If it was a hill climb in a straight line I'm sure you would win
hand down

anyone up for drag racing

I pulled my mickymouse car apart and am now fitting the spring system to the bike lets see how it goes

:jerry: what a wind up

Pumba
1st January 2009, 13:41
anyone up for drag racing

Sure, as long as I can use my Triumph.

It seriously scares me the thought of this bike going any quicker

bucketracer
1st January 2009, 14:50
Think of the possibilities, compressed air, rubber bands, battery power, there must be other possibilities for using a class legal motor to store its energy the night before and release it more effectively during the actual race.




Bugger the class legal motor, thinking of the possibilities of, compressed air, rubber bands, battery power, and energy release the night before.

Oooooo the possibilities of energy release , I do like to wear nappys :baby: Spank me nurse :spanking: and other role plays like :doctor: and :Police: and leather.

TZ350
1st January 2009, 21:11
.

Off Topic, bucketracer your last comment realy belongs in some other forum!

.

TZ350
3rd January 2009, 18:18
Reliable cooling is the issue with the GP125. After much thought and input from Carl I think we will try ducting around the head and cylinder, small scoop at the front and a suck through fan at the back.

From researching the Internet, an air cooled head temperature is typically 250 degrees c and a water cooled head about 80 degrees c.

Increasing the velocity and scrubbing action of the air is required to reduce and stabilize the head temperature.

A small dual speed electric fan from a car radiator should do the job and can be automatically turned on by thermal sensors attached to the head.

Alternatively a grunter fan could be driven by a small chainsaw/minibike motor that's coupled to the bikes throttle and this could drive a larger fan.

Unusual, but there is nothing in the rules that say you can't have a second internal combustion motor for running the cooling system. Please tell me if I am wrong.

The rules restrict 125 2 strokes to Air Cooling so using the latent heat of evaporation of water sprayed onto the head for cooling would be very easy but to controversal.

stanko
3rd January 2009, 20:32
maybe a chainsaw motor running the fan might be pushing the rules, that would make it a 2 cylinder powerplant displacing 125 plus maybe 30 cc for the chainsaw motor, plus you would probably go over the 24mm carb equivelent rule. However if you used a model aeroplane motor say 5cc (guessing) and a really tiny carb , fitted with a aeroplane prop you could easy go under the capacity limit which is around 130cc allowing for overbores, they make a pretty mighty airstream. Just have it going flat out for the whole race.

TZ350
3rd January 2009, 21:46
Model areo engine, yep that might work. But I don't think they can count my chainsaw motor as powering the bike, its like using an electric motor for the fan except its a petrol motor.

Sketchy_Racer
3rd January 2009, 21:50
The extra power gain from running cooler won't overcome the defect from the extra weight you'll have to carry. Stick to the air duct, or turn it into a 100 and water cool it.

TZ350
3rd January 2009, 22:25
The extra power gain from running cooler won't overcome the defect from the extra weight you'll have to carry.

A water cooled 100, means 3l of water = 3kg, radiator, shroud, water pump and battery another 3-5kg. Total extra weight of water cooling 6 to 8kg.

After a lot of work I have finally got this 125 thing working. I don't want to spend several more seasons in the wilderness developing a 100 if I can avoid it.

I know its good to have a lighter bike but how will the extra weight on the 125 be a defect? It weighs around 90kg at the moment.

Skunk
3rd January 2009, 22:53
You don't NEED a water pump, or battery, nor fan and I'd think less than 3 litres of water should do. My AX100 is 80kgs with a splash of fuel ready to race for comparison.

speedpro
3rd January 2009, 23:32
Thermosyphon works a treat, been there, done that.

Waterjacket, couple of hoses, and a radiator. KISS.

TZ350
4th January 2009, 08:50
Thanks, I'v been thinking too complicated.

speedpro
4th January 2009, 09:27
Thermosyphon was good enough for a Morris Minor 850, it'll be good enough for your bucket, if it was a 100.

TZ350
4th January 2009, 09:37
Heat tubes, would you call them "Air Cooling" suitable for a 125?

TZ350
4th January 2009, 17:15
Thermosyphon works a treat, been there, done that.

Waterjacket, couple of hoses, and a radiator. KISS.

KISS, is the last "S" for stupid? what are you trying to say? :bleh:

Thanks for the tip's.

speedpro
4th January 2009, 22:15
The other thing is that the shroud should have diverging sides and the exit should be constructed such that the airflow around it extracts the air from within. In this way a pressure drop is created within further reducing the cooling air temp.

Plus it's a little known fact but if you pass an electric current through a bi-metallic junction in one direction heat will be created but if you pass the current in the other direction it will cool. They use this effect to cool electronic equipment. The cool junctions are attached to the bit to be cooled and the hot junctions are attached to a cool wall. The heat is just sucked out of the components. You could even make it variable to maintain a constant head temp. How trick would that be?

Skunk
4th January 2009, 22:18
Plus it's a little known fact but if you pass an electric current through a bi-metallic junction in one direction heat will be created but if you pass the current in the other direction it will cool. They use this effect to cool electronic equipment. The cool junctions are attached to the bit to be cooled and the hot junctions are attached to a cool wall. The heat is just sucked out of the components. You could even make it variable to maintain a constant head temp. How trick would that be?
Can you explain that a bit better for me? What's the technical name for it and I'll look it up.

k14
5th January 2009, 08:48
http://en.wikipedia.org/wiki/Thermoelectric_cooling They are usually referred to as peltiers.

You'd need one big mofo of a battery if you were running total loss. If you still had the generator then it may be feesible, depends how big a power drop off you get on your engine when it heats up. But seeing as its only 10% efficient at best you may be pushing shit up hill.

I think heat pipes may have a use. Pretty sure its some sort of oil in them so when is it classed as water cooled??

Skunk
5th January 2009, 09:09
Thanks for the link - I wasn't thinking of using it - just interested in it as I hadn't heard of it.

gav
6th January 2009, 23:07
I'd look at making up a radial finned head and adding a radiator type shroud/air scoop to try and divert air onto the cylinder head. Similiar to the setup used on the older air cooled MX bikes before they went to water cooling.

Radial head
http://www.mxworksbike.com/1981_RC250_2_750.jpg

TZ350
7th January 2009, 07:16
Thanks for the tip, we will look at the shroud you describe and the possibility of adding an electric fan.

That’s a great looking Honda MX bike there!

gav
7th January 2009, 17:55
Thanks for the tip, we will look at the shroud you describe and the possibility of adding an electric fan.

That’s a great looking Honda MX bike there!
I must admit I got seriously sidetracked looking for a photo for ya! :laugh:
Check these awesome sites for some great old MXers!
http://www.mxworksbike.com/bikes%20a.htm

http://www.thumpertalk.com/forum/archive/index.php/t-587186.html

Copy and paste each link into a seperate browser to view!

TZ350
7th January 2009, 18:44
I must admit I got seriously sidetracked looking for a photo for ya! :laugh:
Check these awesome sites for some great old MXers!
http://www.mxworksbike.com/bikes%20a.htm

http://www.thumpertalk.com/forum/archive/index.php/t-587186.html

Copy and paste each link into a seperate browser to view!

Realy great bikes, great stories, spent ages looking at them. I remember a lot of these people from reading about them at the time.

Thanks.

.

TZ350
9th January 2009, 08:18
.

Jan a very clever person, here at ESE sugested to me that I could use a garden leaf blower to fan the cylinder and head on the GP125.

I don't know if I will go this way but you do have to be impresed with his thinking.

As a bucketeer I feel humbled that I had not thought of it myself. :pinch:

And then Thomas sugested looking at a portable battery powered vacuum cleaner.

Ooooo the cleverness of it all.

.

speedpro
9th January 2009, 17:43
Battery powered vacuum cleaners don't shift enough air. YOU definitely need mains power for the vacuum cleaner.

bucketracer
9th January 2009, 20:00
Yep your right, just pulled a 12v car vac apart. It has impressive suck but doesn't shift all that much air.

TZ350
9th January 2009, 20:06
Battery powered vacuum cleaners don't shift enough air. YOU definitely need mains power for the vacuum cleaner.


Have been looking at petrol driven leaf blowers on trade-me, looks like it would take $100 to $200 to get one.

Bit much, but off to Bunnings tomorrow to look at the size of them.

Found some massive heat sinks at work from an old soft starter. They have radial finning like some old mx bikes did.

k14
9th January 2009, 21:09
I wouldn't bother with a vaccum cleaner. Get 2 or 3 high rpm 120mm or 200mm 12v computer cooling fans. Can get some pretty good airflow and will run of a smallish battery ok.

Buddha#81
9th January 2009, 23:32
I wouldn't bother with a vaccum cleaner. Get 2 or 3 high rpm 120mm or 200mm 12v computer cooling fans. Can get some pretty good airflow and will run of a smallish battery ok.

Why not try riding really fast and using the air flow to do all that?

Yow Ling
10th January 2009, 07:06
I wouldn't bother with a vaccum cleaner. Get 2 or 3 high rpm 120mm or 200mm 12v computer cooling fans. Can get some pretty good airflow and will run of a smallish battery ok.

I think that you guys are thinking cooling fans are good because they are used for cooling, they are great on computers for removing say 50w of heat. put your hand out the car window at 100kph, now put your hand behind one of these powerfull computer fans, see the difference? remember you are trying to remove about 7 or 8kW of heat from the head you need a mighty airstream to do this . Buddha is right onto it

Buddha#81
10th January 2009, 08:52
Buddha is right onto it


Thanks big guy......and at 12.30 last night when I was drunk.......go figure.:whistle:

TZ350
10th January 2009, 08:54
Why not try riding really fast and using the air flow to do all that?

:scooter: I have found the problem with riding really fast, its that there is always a corner at the end of the fast bit and corner bits are confusing. :blink:

A motorcycle pulling out of a slow corner is like an aircraft climbing out, they are both making max power and thats when they both need the most cooling. Because of the motorcycles slow speed and the aircrafts angle of attack their engines are getting the least airflow when they need it the most. I think supplementary cooling is required if I am going to make some real power.

Its just how to do it and stay air cooled?

koba
10th January 2009, 09:11
Just an idea for inspiration:

Look at a Volkswagen Beetle engine.
The cooling system is an amazing piece of engineering, tuners have been trying to improve it over the years and there is very little that can be done to make it better.

More oil cooling is the only way to do it But strangley if you take the oil cooler out of the fan shroud it cocks the whole thing up because it was so carefully designed.

These engines began life pumping out about 30 horsepower from 1100cc, the ones with the most advance cooling systems were good for 50 horse from 1600cc but the cooling system on it routinely puts up with 150+ hp on modified engines, the craze is centred in California so I guess they can probably handle it on a hot day too.

One reason for the fan and tin shrouding is that it is all jammed in the back of a car and way out of the airflow.
They cool better the slower you go!

There is some good infor here (http://www.offroadvw.net/tech/wes/fan.html)

They also have pics of the fan shrouds cut in half. (http://www.offroadvw.net/tech/brad/fanshroudtech.htm)

TZ350
10th January 2009, 09:21
Thanks Koba, for the the V-Dub info. That is a very informative article. I did not know it takes eight times the power to double the fan speed and the heat transfer is not linear with velocity but roughly 0.73 of the difference in velocity.

Its probably no surprise that linear air is better than turbulent air for cooling.

Forced air cooling and ducting for the bike in some way has got to be the go.

I have allways known about cavitation but did not know that:-

"The fan cavitates - wrong, cavitation is only a liquid phenomena, it is boiling of a liquid due to a localised pressure drop below the vapour pressure of the liquid, you cannot boil a gas.

The fan chokes - wrong, you need to be approaching blade tip speeds near the speed of sound for that one to happen, trust me the VW fan isn't going to mechanically survive speeds anywhere near that.

The fan stalls - This is an interesting one. People say it aerodynamically stalls and cannot pass anymore air, this is wrong and is basically the fan chokes argument. However the fan stalling is partly correct, but it is not aerodynamically stalling, it is the fan belt slipping and preventing the fan from spinning any faster. This has to do with the VW fan belt being very small and not capable of transmitting enough power to continue accelerating the fan forever."

Quoted from the artical in Koba's post.

TZ350
10th January 2009, 09:24
I think that you guys are thinking cooling fans are good because they are used for cooling, they are great on computers for removing say 50w of heat. put your hand out the car window at 100kph, now put your hand behind one of these powerfull computer fans, see the difference? remember you are trying to remove about 7 or 8kW of heat from the head you need a mighty airstream to do this . Buddha is right onto it

Thanks Yow Ling, its a good point you make, do you know the ratings in degrees C per watt of any CPU fan assisted heat sinks?

I am hoping there could be some scrubbing action by the small fans air stream shifting the hot boundary layer air from between the fins and then that hot air being swept away by the main air stream.

I measured the fin area of one I have and the small heat sink (80X80 fan) had 1/3 the fin area of my GP125 cylinder head.

I suspect although there is plenty of area the thin fins of the CPU cooler offer a higher thermal resistance to heat flow than the thicker fins on the GP125's head.

Or they are thick because the die cast metal used in the head is not so great a heat conductor as pure aluminum and well spaced so that when stationary or going slow there is some heat dissipation by convection.

Enlightenment about this would be welcome.

I am also concerned the plastic CPU fan will melt as from what I'v read typically an air cooled head runs at 250-350 degrees C and a water cooled head is about 80-100 degrees C. So the fan could easily melt on the air cooled head.

I tried a duct with an air scoop on the GP at Taupo but the results were inconclusive. Mainly because I had not done any before and after measurements.

I don't know a lot about cooling systems but now I have a reason to find out and being a bucket its affordable to apply to my bike. This is what I enjoy about buckets, the challenge and afford-ability.

speedpro
10th January 2009, 14:38
You need lots of heat sinking ability as close to the combustion chamber as possible. Water cooling is the obvious choice if you are allowed but if not then I reckon lots of thin(ish) fins bolted tightly to the combustion chamber with heat sink compound, and then a shroud/duct to make sure plenty of air goes through the fins. Years ago, Frank (Paul Francois) bolted a stack of thin aluminium pieces to his AC50 head and then bent the ends up progressive amounts to form his own radial fin head. Until I watercooled mine it was obvious that mine faded lots more than his in a race.

gav
10th January 2009, 14:58
One of the popular mods for a VFR800 is to use a computer cooling fan to cool the regulator/rectifier. Somehow I don't see the same unit able to cool a 125cc cylinder head.

TZ350
10th January 2009, 15:32
You need lots of heat sinking ability as close to the combustion chamber as possible. Water cooling is the obvious choice if you are allowed but if not then I reckon lots of thin(ish) fins bolted tightly to the combustion chamber with heat sink compound, and then a shroud/duct to make sure plenty of air goes through the fins. Years ago, Frank (Paul Francois) bolted a stack of thin aluminium pieces to his AC50 head and then bent the ends up progressive amounts to form his own radial fin head. Until I watercooled mine it was obvious that mine faded lots more than his in a race.

That's a really good idea. As pure copper is a much better thermal conductor than pure aluminum. Then the strength of an alloy block for the combustion chamber and the fins made from copper sheet could be the go.

TZ350
10th January 2009, 15:48
Look at a Volkswagen Beetle engine.

These engines began life pumping out about 30 horsepower from 1100cc, the ones with the most advance cooling systems were good for 50 horse from 1600cc but the cooling system on it routinely puts up with 150+ hp on modified engines, the craze is centred in California so I guess they can probably handle it on a hot day too. More oil cooling is the only way to do it.


Looking at a hot V-Dubs 150hp from 1600cc thats 94hp per liter.

If I can get 22hp from my GP125 then thats 176hp per liter.

A significantly greater cooling load, so increased oil cooling for the gear box might be an option too.

koba
10th January 2009, 17:11
If you want to fight about rules you could make an oil cooled head.
But then it would be oil cooled and I think the 125 rule specifically says "aircooled".

koba
10th January 2009, 17:12
Looking at a hot V-Dubs 150hp from 1600cc thats 94hp per liter.

If I can get 22hp from my GP125 then thats 176hp per liter.

A significantly greater cooling load, so increased oil cooling for the gear box might be an option too.

Plus it doesn't have the extra stroke to unload the heat from the piston...

TZ350
11th January 2009, 08:09
From Koba,s post, and Goggle I have found some interesting info on air cooled motors. Before the "War" in some circles water cooling was considered inefficient, unreliable and expensive. This is the era V-Dubs come from.

Before the "War" Hitler had the Autobahns built, this was before there were fast cars. Then he encouraged the car makers to build Autobahn cars. They were often air cooled and very aerodynamic. There was an air cooled 3.8l V8.

In the 80's when large wind tunnels became available some of these old cars were tested and their drag coefficients (and fuel consumption) were lower than modern cars.

A quick intro to Mackerle. Julius Mackerle was the chief engineer at Tatra motorworks for many years. Tatra make a lot of air cooled vehicles and trucks. Mackerle published a huge amount of interesting air cooled engine information in a book of his called Air-Cooled Engines.

The interesting thing is that the air cooling was effected in different ways.

There was the V-Dub style cooling fan

Another device like a turbo charger that was spun by the exhaust gas and the fan compressor sucked or blew the air through the cooling fin ducts.

And a ventuire ejector system that also used the energy of the exhaust gas to sucke the air through the cooling fin ducts.

I am not sure about the difference between a venturie and a venturie ejector. But I think a venturie is like a motorcycle carb's needle-jet/choke arrangement. Where a small pipe leads into the middle of the venturie's choke and a venturie ejector is more like the old vaccume cleaner spray paint gun?

A venturie ejector is used where shifting bulk is the aim.

Here is an abstract from a US Patent.

Venturi exhaust cooler Document Type and Number: United States Patent 3875745

"The kinetic energy of the exhaust gas from an internal combustion engine is utilized as a driving fluid to aspirate a large volume of quiescent ambient air as a driven fluid for cooling the exhaust gas quickly in a very short path of travel. This mode of operation is to be distinguished from conventional injector and ejector devices utilizing a current of air as the driving fluid. The present device utilizes the Coanda effect to introduce the exhaust gas around a lip on one end of a venturi tube, causing the gas to flow in a high velocity film adherent to the inner surface of the tube. This laminar flow draws in a large volume flow of air through the center of the venturi, cooling 1000°F. exhaust gas down almost to ambient temperature in a distance of a few inches."

I have seen on some modern expansion chamber designs, that the stinger has changed to a restricter that looks like a venture with a tail pipe, makes me think this could be made into a venture ejector.

The good thing about using the energy in the exhaust gas to do some work, is that it quietens it like a muffler does.

A ventuire ejector might have possibilities.

.

Yow Ling
11th January 2009, 16:53
the norton rotary race bikes used a venturi ejector to draw cooling air through the rotor internals, the road bike version drew fuel air mixture through the engine to cool it, which wouldnt be helpfull on the race bike as it would reduce the charge density. this vid shows the ejector input at the start of the muffler http://video.google.com/videoplay?docid=4795455775237376823 Maybe worth a google

TZ350
11th January 2009, 17:47
the norton rotary race bikes used a venturi ejector to draw cooling air through the rotor internals, the road bike version drew fuel air mixture through the engine to cool it, which wouldnt be helpfull on the race bike as it would reduce the charge density. this vid shows the ejector input at the start of the muffler http://video.google.com/videoplay?docid=4795455775237376823 Maybe worth a google

Hi Yow Ling, I had a look at the video and ran a Goggle. It seems that the exhaust ejector is a noisy beast, not as quiet as I had expected. It was good to actually see one, thanks for the link.

.

F5 Dave
12th January 2009, 08:27
Battery powered vacuum cleaners don't shift enough air. YOU definitely need mains power for the vacuum cleaner.

Great! - so every time you pass him or are passed by him it will be like skipping rope with the extension cord.:wacko:

Buckets4Me
12th January 2009, 13:15
http://www.trademe.co.nz/Trade-Me-Motors/Motorbikes/Parts-for-sale/Other/auction-197093311.htm

http://www.trademe.co.nz/Trade-Me-Motors/Motorbikes/Parts-for-sale/Other/auction-196572229.htm

http://www.trademe.co.nz/Trade-Me-Motors/Motorbikes/Parts-for-sale/Electrics/auction-197213286.htm

http://www.trademe.co.nz/Trade-Me-Motors/Motorbikes/Parts-for-sale/Other/auction-197257944.htm

TZ350
12th January 2009, 18:45
.

Thanks for the links to those fans. I am most taken with the $90 one, ouch. :weep:


Here's a pic of my head and a CPU fan/heat sink that I thought had possibilities. Was thinking of using 4 of these on the head with the idea that they switch on and off as the head heats or cools.

.

speedpro
12th January 2009, 18:48
The more I think about it the more I think fans aren't the go, unless you have a LOT more surface area than a stock fin sort of setup. Of course then you wouldn't need a fan. The idea of using a stack of sheet copper to make fins seems the way to go, you'd just have to watch the weight.

In fact it appeals so much I might have a good look at it myself for the 100.

TZ350
12th January 2009, 19:41
.

Yes I am very taken with your idea of a stack of copper sheets bent into fins.

My original idea was to add fin area and thermostatically switched fans by attaching several CPU heat sinks but there is a problem with getting them close enough to the combustion chamber itself on an original head.

My next idea was to have a fan blow down through a duct directly onto the head. The duct would allow natural air flow over the head from the front and direct the fan down and slightly to the rear so it arguments the natural air flow.

I like your stack idea a lot and can see myself building several different versions to try incorporating all these ideas.

Not only do I want to improve the total cooling capability of the head I want to control the cooling so the system can maintain a steady combustion chamber temperature like you get with water cooling.

.

TZ350
12th January 2009, 19:48
.

Thomas with the F4 GP 3rd place cup and other Team ESE trophies. He was very pleased that his tuning work has performed so well.

Thomas is back onto the ignition. He has set the flywheel at the standard ignition point and is marking the position for the new ignition trigger button.

He has glued (Devcon) and screwed a metal trigger button on the flywheel.

Here he has the pickup that he salvaged from a cars distributor. Its like a Suzuki RGV pickup, it has a coil around some magnetic (nuts and screws stick to it) laminations.

The pickup is mounted on a sloted base so it has some adjustment.

Its adjusted so there is a 10-12 thou gap between the pickup laminations and the trigger button.

.

F5 Dave
13th January 2009, 12:48
Don't even begin to worry yourself with over cooling the head or barrel. Depending on how & where you measure water temp is best for power at ~ 55 deg C, although probably best for wear, fuel economy & anti-seizing at 70 deg. Pointless trying to overcomplicate the matter with cctry that will only be used first time through the gears.

Hmm, unbalanced weight on the outside of a hot vibrating piece of metal at 11,000 rpm. That might stay on.

bungbung
13th January 2009, 13:29
Thanks for the link - I wasn't thinking of using it - just interested in it as I hadn't heard of it.

Peltier modules can be found in some of the small 12V fridges sold at hardware shops, the 6 pack sized models: http://www.trademe.co.nz/Trade-Me-Motors/Caravans-motorhomes/Parts-accessories/Fridges/auction-197443299.htm

TZ350
13th January 2009, 18:54
Hmm, unbalanced weight on the outside of a hot vibrating piece of metal at 11,000 rpm. That might stay on.

It was screwed and glued, but a part of me shares your doubts. If it cuts loose it could be like a ferrite up me trousers.

.

TZ350
13th January 2009, 19:18
Don't even begin to worry yourself with over cooling the head or barrel. Depending on how & where you measure water temp is best for power at ~ 55 deg C, although probably best for wear, fuel economy & anti-seizing at 70 deg. Pointless trying to overcomplicate the matter with cctry that will only be used first time through the gears.

It looks like the mish is going to be to build the biggest fatist head possible.

Standard GP125's have an asbestos? like head gasket, is this deliberate? are they trying to keep the heat of the barrel away from the head?

My current air cooled head has metal to metal contact with the barrel.
.

F5 Dave
14th January 2009, 08:21
It isn't asbestos it will be normal suzi composite gasket. Never had probs with metal to Metal with MB. Actually encouraged it as I had a thermosyphon head on my 50. Whether you want to get the cases any hotter is a question.

TZ350
14th January 2009, 10:00
F5 is the main source of heat from the combustion chamber or the exhaust port tract?

Not had to realy think about this before but:-

Does heat flow from the cylinder into the head or the head to cylinder?

The head is the main heat source right?

.

Yow Ling
14th January 2009, 12:47
F5 is the main source of heat .

Not really fair to blame dave for that !

F5 Dave
14th January 2009, 15:18
Not really fair to blame dave for that !
:lol:Story of my life.

The combustion chamber is as you say is the source of heat. As Boyle's law implies (indirectly) the volume is decreased as the temperature is raised substantially, both increasing pressure (there is no 'explosion' of gas as common myth, it is burnt to increase temperature). Which forces the piston down reducing pressure, but that increased temperature still has to go somewhere.

That corresponds to the head & piston, followed then by the barrel & the gas escapes somewhat cooler out the exhaust port. If it was a 4 stroke the valves cop it. Fourstroke exhausts run hotter than 2 strokes & I always believed that this is because the gasses escape more directly from the head rather than half way down the barrel (at lower pressure through a bigger hole). This probably accounts for some of the higher BMEP of a 4 stroke (aside from purity of charge of course) & why 2 strokes really favour being water cooled. Ideally the cases which are a pump would be cool to make for a denser mixture.

Erm where was I?
Oh yeah so I think all the parts are trying to shed heat, head especially of most benefit, but the piston is shedding heat on the bore through the rings & contact & proximity to the head in squish area, but if it heats too much it has to affect that charge in the cases. Also piston life seems much happier with a controlled barrel.

TZ350
14th January 2009, 16:19
Thanks F5 for the confirmation, intuitively I thought the combustion chamber was the greatest source of heat. As there is a lot of surface area in the exhaust port to soak up heat. I didn't want to just assume. I have been tripped up before, by things that turn out to be counter intuitive. :mellow:

Thomas has got hold of some really large heat sinks. Had they been just a bit thicker we could have machined a combustion chamber directly into them.

Thinking about it, there is not enough depth for a combustion chamber and sparkplug but we could machine a combustion chamber into the heat sink and bolt another piece on top with a sealing ring for the sparkplug.

This way we could use 3/4 inch reach plugs (better selection than 1/2 inch) and the piece the plug screws into could be extended out to help shift the heat from the combustion chamber to the outer ends of the heat sink.

If the spark plug bit could be made in copper it would really help in cooling the combustion chamber area.
.

speedpro
14th January 2009, 19:29
range of plugs??

An "8" or maybe a "9" is all I've ever used from Shirriffs Road thru to Puke full circuit, on any motor. Outside of that I think you are trying to fix a problem by changing spark plugs. Just a theory.

TZ350
14th January 2009, 19:38
range of plugs??

An "8" or maybe a "9" is all I've ever used from Shirriffs Road thru to Puke full circuit, on any motor. Outside of that I think you are trying to fix a problem by changing spark plugs. Just a theory.


I have been buying surplus plugs in bulk from Ebay, 8's and 9's.

I would like to be able to get the plugs with the thin center electrode, gold palladium etc.

Thinking about it some more.

Have you ever noticed how the combustion chamber darkens around the plug area first. I assume this means it gets hottest here. Having a thick copper heat sink for this part of the combustion chamber might be a real benefit.

.

speedpro
14th January 2009, 20:58
I used to use precious metal centre electrode plugs and found them to be of no benefit. They gave no more power, they didn't last any longer in the motor that went through plugs, and in the motor that used to melt pistons now and again it melted them irrespective of what plug was in it.

Do not use "-EGV" plugs. Only the last little bit of the centre electrode is all that precious and evidently it sometimes parts company. It never happened to me but I've heard of it happening.

HOWEVER, in the mighty 1800 Legnum the platinum plugs are definitely an improvement

gav
14th January 2009, 23:06
Have you researched if you'd be better with a 100cc water cooled head and barrell and running a bigger carb? Would this setup make more power than your air cooled 125cc 24mm carbed engine?

F5 Dave
15th January 2009, 09:40
Yeah anything with a barrier layer is off to a bad start with heat conduction so while you can add area it would be better if the main head is one piece. This is why the japs cast the barrels around the sleeves and why inserted sleeves aren’t as good as std & in turn why straight cast ally plated was better still, not that there are many bucket motors like this.

Sorichio Honda liked to think of himself as a pure engineer. He was determined to keep the old race engines aircooled as the air was what was doing the cooling of water; so why have the water & all the complication?

. . . He was wrong about 4 strokes too.

If you make any head the common mistake is not to use enough material near the sealing surface. It needs to be substantial to cope with temp variations without warping.

With plugs, don’t expect them to shed any real heat.
As far as type go I agree with Mike to an extent, but disagree in other points. I think the plug needs to suit the combustion condition it is in, a bit like fuel really. No point having high octane in a low compression engine.

In my H100 it was air-cooled & comparatively low revving. So I didn’t push the com up too high but high enough. On the std ignition it burned through plugs, a CR ign stopped that. Then I experimented with different plugs on the dyno. No extra power at all. The system was good enough as was for the situation.

However on my MB50 with same ignition a smaller chamber, more revs & higher com it picked up over ½ hp with a fine wire plug. I’ve seen another bike pick up ½ (or was it a whole) hp with a fancy shmancy $80 racing plug.

But despite being the same type of engine with same ignition, revs, fuel etc, the same plug (I borrowed in the same session) made no difference in mine. There were reasons for that, but the point is experiment.

Also the EGVs are fine, been using them for years in the 50 & various other bikes of all capacities. I think it is the EVs that are for tuning or some-such. Dropping ends do occur with normal plugs in some bikes like RM250s etc from vibration & they need special plugs.

TZ350
15th January 2009, 21:09
.
A picture of my combustion chamber after Taupo. The wash from the transfer streams can be clearly see. If anyone can tell me anything about their shape, I would be interested to know if they look right or otherwise.

You can see how the heat builds near the plug, whys this?

I used a flat piston with a small dish in it. On the head you can see the squish area which is very clean, a darker area where the sleeve touches the head, then the ring where the "O" ring seals on the head and the black area is where the head and cylinder make metal to metal contact.

Thomas found a couple of these heat sinks and now we are looking at how we could use them.

As it turns out, they are thick enough so we could cut a combustion chamber in them or we could cut a chamber in a block of alloy and sandwich 3 or 4 sheets of 1.2mm copper between it and the heat sink.

With twice the heat transfer the copper would act like a copper bottom saucepan, spreading the heat from the center around the combustion chamber to the extremes of the heat sink.

The edges of the copper sheets would be bent out in a radial fashion so they form fins too.

I have wanted to try indexing the plug and even have indexing washers to do the job. Does any one have an idea about whether its better to have the plug gap facing the incoming transfer stream or should the gap face away or to the side even?

.

Fooman
16th January 2009, 09:55
Check the alloy of the heat sink before you do anything - it is likely to be a conductor grade material (e.g. 1100 - 99% pure Al) so it won't be too strong, and quite soft, whereas the original head will be a cast alloy with a fair bit of silicon (for wear) e.g. a 356 alloy or similar.

Cheers,
FM

F5 Dave
16th January 2009, 11:14
Good point, heat treating it afterwards 'may' help.

Squish should be clean if it is working. Heat tends toward the exh port side. In a large chamber I doubt which way the plug faces will matter. However in my earlier example of the 50 with the racing plug it had a very short chamber, thus it was shrouding & a racing plug helped (strap from side of plugface rather than a overhead hook). Don't believe dished pistons are used in modern engines, flat or just off has been normal practice, elliptical chamber theory or not.

TZ350
16th January 2009, 13:23
.

Fooman makes a good point about the alloy.

Dished pistons, I use them because I had a box of them, you know how bucketeers are.

Because of the dished (3.5cc) piston my combustion chamber is pretty small 5.5cc, deck height accounts for 1cc.

The diameter of the chamber is 42mm.

Not quite as small as the 50 but pretty small for a 14mm plug. I have been using B9HSC plugs, they have a tapered entry into the insulate area opening it up quite a bit compared to the ordinary B9HS.

B9HSC is on the left.

.

F5 Dave
16th January 2009, 14:02
Yeah I used to use those in my H100. . . because someone gave me a box of them:rolleyes:

Yeah that is a small chamber, expect a high MSV, but your squish probably isn't parallel reducing that. I'd consider reducing the squish area, but would need to recut squish to shorten chamber height.

[edit] Actually looking at the pic again that doesn't look that small & if 42mm on a 54mm bore (or were GPs a bit more oversq?) that only gives a 6mm squish, looks more like 8. ~ 70% chamber area would be good target, less if perhaps wanting Kart track explosive acceleration.

A decent squish area does help cooling piston so maybe don't go too small.

TZ350
16th January 2009, 18:47
I will measure the squish & head up with more care tommorow.

TZ350
16th January 2009, 19:05
range of plugs??

An "8" or maybe a "9" is all I've ever used from Shirriffs Road thru to Puke full circuit, on any motor. Outside of that I think you are trying to fix a problem by changing spark plugs. Just a theory.

Initially I dismissed the "Just a theory." idea, but thought about it some more. I was not looking for more power through a super spark plug, as I know a plug can't give more power on it's own, although it can unlock potential that is all ready there but if its wrong, fouled or just does not light the fire very well it can reduce power output.

Statistically the fire does not get lit every time. In the B9HSC's with their more open firing end and thinking about the way to orientate them I was looking for a plug end that is less masking and an orientation that was best for flame propagation.

I understand powers strictly a function of BMEP (how the engine breaths) and rev's but there is power to lose if you don't get the fire lighting right.

I remember TZ's would often go faster on exotic plugs but they were compensating for the TZ's notoriously poor ignition and oil fouling from Castrol R being run at 16-20 to 1.

I might be just looking for exotic plugs out of habit. If the bike runs better on these plugs, could the ignition be a little week?

Something for me to think about.

speedpro
16th January 2009, 20:23
The only time I've seen power increase from fitting a different type of plug was on a XS1100. It was all dyno tuned to hell and I fitted "J" gap plugs. Immediate 2hp increase.

If a plug helps then you have some other issue. Typically that other issue on a bucket is a weak ignition. JC fitted a FZR250 ignition to Olly's old CB125T on back to back dyno runs and got something like 3-4hp increase with no other mods. I've always run 80cc motocross ignitions as in the early days when I was starting to tune and test there was noticeable improvement in all-round engine behaviour with the better ignitions, easier to start, better throttle response, and a cleaner topend. Drawback was that they will fire "any" mixture including one that is a bit lean.

They run MONSTER ignitions on the blown methanol and fuel cars and the bigger the ignition the more power they make. My mates magneto has supposedly a 44A secondary. Whatever it is you will only hook yourself across it once, the spark is astounding even at one click of turn by hand.

TZ350
18th January 2009, 14:10
Why not try riding really fast and using the air flow to do all that?

I have looked into this some more and wouldn't you know it, good old nature challenges us again.

It turns out that cooling from the wind chill effect :cold: does not increase linearly with speed. Twice as fast is not twice the cooling.

The graph of the wind chill effect is steepest in the 0 to 30kma range and flattens out the faster you go.

In a generalized sort of way.

You only get 50% more cooling by doubling your speed from 30kmh to 60kmh.

To get 75% more cooling you need to have gone from 30kmh to 120kmh.

To get 100% increase in cooling means going faster than my bike can manage.

Doubling the fin area does not double the cooling effect either because the thermal path will have increased.

Because you get the most cooling for your blow at lower speeds it makes it worth looking at the larger fan cooled CPU heat sinks again.

.

Yow Ling
18th January 2009, 16:03
why not just get a really big aircooled head off say a MZ250 weld up the combustion chamber and machine one that suits your engine. i think you are really going to struggle with the fan thing . I was looking at a fan at work today that would probably do the job but it was 1.1KW 3 phase. Think how big the fan at the dyno is and thats just for short runs.

TZ350
18th January 2009, 17:57
.

Using a head like you suggest is a good idea. It would be interesting to test a fan cooled CPU heat sink. Any ideas how to conduct an experiment?

Thomas has found a piece of 1.2mm copper sheet at work and as I have a 12mm alloy spacer under the barrel he suggested replacing it with one made out of a stack of copper fins and a heat resistant block so that I wind up with some more finning for the barrel and a heat blocking spacer at the bottom so that the crank case runs cooler for a better incoming charge density.

As the clutch gets a real caning he also suggested an oil cooler for the gearbox like they have on auto trans gearboxes.

.

speedpro
18th January 2009, 20:11
As the clutch gets a real caning he also suggested an oil cooler for the gearbox

If F5 gets away without one you sure as hell don't need one.

speedpro
18th January 2009, 20:15
Using a head like you suggest is a good idea. It would be interesting to test a fan cooled CPU heat sink. Any ideas how to conduct an experiment?

Some sort of constant heat source applied to the combustion chamber or whole base of the cylinder head(s) and a fan blowing over the head. Measure the head temp. The better the fin system is at dissipating heat the lower the head temp will be. It'll be interesting to see what effect varying the air flow will have.

TZ350
18th January 2009, 20:34
If F5 gets away without one you sure as hell don't need one.

Your right, I can't claim to be making much more HP than him if any and he realy does cane that clutch, thats one real fast 50. How long does that engine last between rebores/overhauls?

gav
18th January 2009, 21:55
Probably easier just to move down to Christchurch, don't think anyone was too concerned about an overheating head at the last Battle of Buckets? :Oops: However fitting heated handgrips might be worth considering? :cold:

speedpro
18th January 2009, 22:07
We could kill two birds with one stone. Convert to 100cc, watercool the motor, route the coolant through the handlebars.

gav
18th January 2009, 22:12
KA CHING!!!
Brilliant!

TZ350
19th January 2009, 08:19
.


Probably easier just to move down to Christchurch, don't think anyone was too concerned about an overheating head at the last Battle of Buckets? :Oops: However fitting heated handgrips might be worth considering? :cold:


We could kill two birds with one stone. Convert to 100cc, watercool the motor, route the coolant through the handlebars.

Bucketeers realy are clever people. :clap: I like the idea and if I crash will that make me a snow goose? Sorry F5. :Oops:

Skunk
19th January 2009, 21:35
Has anyone one tried machining small horizontal fins on the sides of the vertical fins. More surface area without greatly increasing the cooling path.

craisin
20th January 2009, 03:06
Had your bike running today it's going great. I am ashamed to say the problem with it was all my own fault and pretty much what you predicted. Glad to hear you survived today. sound like you need a ballast resistor to stabilise voltage Maybe if something was set up to come on a a certain number of revs to burn off excess current

TZ350
20th January 2009, 07:54
Has anyone one tried machining small horizontal fins on the sides of the vertical fins. More surface area without greatly increasing the cooling path.


Thats very clever, hadn't thought of that, it's all about surface area, now your got me thinking.

Sideways Sam
20th January 2009, 13:12
I can see that us four strok boys are gonna have to do a lot of work to keep up with the sort of things your talking about on here.

:bleh:Either that or we're gonna have to do a lot of talking to keep up with you guys........

Buckets4Me
20th January 2009, 16:38
I can see that us four strok boys are gonna have to do a lot of work to keep up with the sort of things your talking about on here.

:bleh:Either that or we're gonna have to do a lot of talking to keep up with you guys........

start talking they are way ahead of you there :2guns::jerry:

TZ350
22nd January 2009, 18:26
Got the makings together for a new super Head.

Its going to be a very special head made from a large block of alloy, off cut of copper sheet and an extra heavy section of heat sink.

The plan is to sandwich the copper between the alloy block and heat sink for extra rapid heat dispersal to the outer parts of the heat sink.

The finished head will be about 4 times as heavy as the original GP125 head.

With all this alloy and copper, this has got to be the real deal, RIGHT. WRONG! Wrong! wrong! very very wrong as it turns out. :crybaby:

Another counter intuitive thing, bigger should have been better.

When Thomas saw what I was up too he nearly wet himself laughing.

Then he explained to me that Suzuki was not trying to save money by having a relatively small amount of alloy around the combustion chamber.

He said the Suzuki head is made thick enough for strength and for the combustion chamber shell to provide an adequate thermal path for the expected heat load. And thin enough so the thermal path to the root of the cooling fins is as short as possible.

Its for this reason that most air cooled 2 strokes of that era used ½ inch reach plugs and ¾ inch reach plugs were mostly used in the water cooled motors to allow more room for the water jacket.

If I was to make a head out of the block of alloy like I intended it would be able to absorb a terrific amount of heat energy but relatively too slowly to keep the combustion chamber cool.

There might be more fin area but the cooling fin tips would probably run cooler (cooler is less efficient at shedding heat) than the original Suzuki head. And the heat path would be to long and the combustion chamber would over heat (or at least be a lot hotter) even though there was more thermal capacity and fin area in the bigger head.

Its that the cooling bit will be to far away from the fire bit. :blink:

He suggested we continue to use ½ inch reach plugs and cut the alloy block down and mill steps in it so that cooling fins of copper (copper conducts heat away twice as fast as alloy) can be fastened to the alloy combustion chamber, shell as close as possible to the source of heat.

Even better would be to make a thin combustion chamber shell out of beryllium copper (for strength) and easy-flow copper cooling fins to it. :Punk:

.

koba
22nd January 2009, 21:35
Has anyone one tried machining small horizontal fins on the sides of the vertical fins. More surface area without greatly increasing the cooling path.

The gaps between the small fins MAY (and I'm just guessing here) not be open enough to get good enough heat shredding airflow.
I imagine there would be a hot area of little flow very close to the fin with the heat dissipated by the cool air moving fast past that.
This is all me just logicing out loud....
But lots of close fins do work for radiators...
Maybe lots of tiny radiator fins attached to the head.
Or a radiator cut and shaped to sit on the head and filled with molten copper which solidifies and fills up the area normally full of water....

ahhh, crazy ideas - this is why I love buckets. :clap:

F5 Dave
23rd January 2009, 08:42
Just be careful if you did get hold of some beryllium copper as it is quite poisonous to have floating about the air whilst machining.

Bren_chch
23rd January 2009, 08:46
Just be careful if you did get hold of some beryllium copper as it is quite poisonous to have floating about the air whilst machining.


Is there anything this man does not know! :2thumbsup

TZ350
23rd January 2009, 11:56
Just be careful if you did get hold of some beryllium copper as it is quite poisonous to have floating about the air whilst machining.


Thanks Dave. I dont want the...:doctor:

Sketchy_Racer
23rd January 2009, 14:24
Just be careful if you did get hold of some beryllium copper as it is quite poisonous to have floating about the air whilst machining.

Clean machining it is ok. If you grind it, or turn it molten it is nasty stuff. We make injection moulds out of a special alloy of beryllium copper and a few other secret additives to make it tough and very hard. Hard copper you ask? :innocent:

F5 Dave
23rd January 2009, 14:42
Can you shrink it into a ring that you might 'squish' up into some ally?:shifty:

F5 Dave
23rd January 2009, 16:28
Clean machining it is ok.
Also it sort of depends on your take on H&S. In my (very) limited knowledge I understand that most places overseas machining this stuff have special set ups, respirators etc, whereas in China it's probably no problem to be spraying your staff with fine machining swarf, by it's nature of being hard I suspect fine cuts are order of the day unlike ally.

Mind you only 20 years ago techs in NZ were wiping down the benches with a rag doused in MEK:no:. Times change.

Sketchy_Racer
23rd January 2009, 17:23
Also it sort of depends on your take on H&S. In my (very) limited knowledge I understand that most places overseas machining this stuff have special set ups, respirators etc, whereas in China it's probably no problem to be spraying your staff with fine machining swarf, by it's nature of being hard I suspect fine cuts are order of the day unlike ally.

Mind you only 20 years ago techs in NZ were wiping down the benches with a rag doused in MEK:no:. Times change.

I really should change what I say there, at work we just machine it. It is done in an enclosed CNC lathe usually the parts we do, and we try not to have to much contact with it. From my understanding is has a very slight radioactivity which is bad.

There are many different blends of it, but the tough stuff that we use I don't think has the heat transferring properties like oxygen free pure copper.

I could make a head for a air cooled two stroke out of one, but it will cost about $4000 for the material :bleh:

TZ350
23rd January 2009, 18:56
Yep I have wiped a few benches with MEK in my time.. :eek5: ..and cleaned a fair few vacuum systems with pure ethanol. Our idea of "Mainlining" and jolly good fun was to squirt a jet of ethanol past the nose and take a really deep breath...:thud:...how the concept of H&S and times change. It all ended when after an ethanol (like water) fight one very wobbly and wet individual dared another equally inebriated soul to set him alight, and the other shining light of intelligence obliged. :eek:

speedpro
23rd January 2009, 20:44
In the radar bay we went through drums of freon wiping up the silicon oil that was used as a dielectric and coolant in the radar systems. We upped the demand for that silicon oil in NZ by a huge factor. Previously massage parlours were the only ones who ordered it.

Fooman
23rd January 2009, 22:26
I really should change what I say there, at work we just machine it. It is done in an enclosed CNC lathe usually the parts we do, and we try not to have to much contact with it. From my understanding is has a very slight radioactivity which is bad.

There are many different blends of it, but the tough stuff that we use I don't think has the heat transferring properties like oxygen free pure copper.

I could make a head for a air cooled two stroke out of one, but it will cost about $4000 for the material :bleh:

Beryllium (as used in alloying) is not radioactive, but it is quite toxic. Is stiff and light weight so it is in a lot of aerospace structural alloys. I've come across it twice - it is transparent to certain wavelengths in the X-ray band, so it is used as a filter for x-ray spectroscopy equipment. Plus a mad post-grad student at the Uni I went to was doing research into aluminium-lithium-beryllium and magnesium-lithium-beryllium casting alloys. Was spectacular stuff to see be cast, especially when he held the Li in the molten Al. All the cutting of test samples he did was in a little sealed box and all the swarf, etc was bagged up and disposed of in hazchem containers.

However, Beryllium copper would not be a good material to use for heat sinks (other than the cost):

Thermal conductivities:

Cu - Be = 66 W/(m K)
70-30 Brass = 110 W/(m K)
319 Al (Typical Al-Si-Cu casting alloy used in engines) = 190 W/(m K)
Pure Al = 210 W/(m K)
CuCr or CuZr age hardening alloys ~ 200 to 270ish W/(m K) <- not too sure on this figure - I don't have access to my reference material at work
Pure Cu = 380 W/(m K)
Pure Ag = 406 W/(m K)

Cheers,
FM

TZ350
24th January 2009, 09:17
:Oops: Thanks Fooman. I will be back, after a bit more research.

Later.

After some more research it turns out that:-

Aluminum and its common alloys have thermal conductivities in the range 200 to 250 W/mK more or less.

Copper 380

(Pure) Beryllium 218

Beryllium copper alloys can have low thermal conductivities 66 88 etc. The hard alloys.

Beryllium nickle copper alloys. The conductive alloys, (made for their electrical properties) can have thermal conductivities better than aluminum and as nearly as good as pure copper. But these are made as sheet for electrical contacts.

So in real practical terms any Beryllium Alloy hard enough and in a suitable size that I can get is going to have a lower thermal conductivity than a block of aluminum and so of no real use.

Who would have thought making a better head than the factory would prove so hard. :eek5:

Thermal Conductivity = heat × distance / (area × temperature gradient)

λ = Q × L / (A × ΔT)

TZ350
24th January 2009, 17:45
The gaps between the small fins MAY (and I'm just guessing here) not be open enough to get good enough heat shredding airflow.
I imagine there would be a hot area of little flow very close to the fin with the heat dissipated by the cool air moving fast past that.
This is all me just logicing out loud....
But lots of close fins do work for radiators...
Maybe lots of tiny radiator fins attached to the head.
Or a radiator cut and shaped to sit on the head and filled with molten copper which solidifies and fills up the area normally full of water....

ahhh, crazy ideas - this is why I love buckets. :clap:

Maybe not such a crazy idea. :niceone:

k14
25th January 2009, 07:22
First I'll just say that this is a very intersting thread and I am checking back every day. But it needs to be said, stop going round and round in circles and learn to ride the thing better. From what I gather you have a bike that is powerful enough to be winning, so focus on the handling and your riding and you will be better for it :)

Skunk
25th January 2009, 08:44
I too keep coming back to this thread just out of interest. Really cool stuff both in the ideas and the facts.

I get the feeling he's like me - more interested in the engineering than the winning. I do things for the hell of it - not because I'll win (win? Yeah, right.) It's all good fun. There is no other reason to put an F6 into a ZXR frame eh? They both just happened to come together - never will be a winning combination.

TZ350
25th January 2009, 08:56
I'm glad you guy's find this thread interesting. My heart is with Skunk, but K14 is right, focusing more on the riding would pay off. My next opportunity to race is the 8th Feb; until then I have to entertain myself somehow.

The head thing has been a bit circular but its a shortcoming and I would like to improve it. I reckon I headed of in the same direction as any one would but as my understanding of the issues has grown I have come back to taking another look at the original head.

I am now looking at the posibilites of adding more (any is more than nothing) copper fin area to the original head. With the new fins having their roots as close to the combustion shell as possible.

Hopefully I will have two or three well thought out versions to try at the next meeting. My plan is to swap them during the day and use a go-cart data logger to measure at the spark plug seat the max temp of each during a race. Thats about as scientific as I can get.

Another thing I want to try is adding some fins and a heat insulating barrier under the barrel to isolate the cylinder heat from the crankcase.

In the old days on Dunlop TT900 GP's my bike would sometimes chatter so badly in a corner the foot pegs would break and the handle bars would get bent. I usually stayed on but it realy hurt my back.

With slicks and other changes things in the handling department improved but I would often find myself riding off the edge of the slicks. I have now changed my riding style from the 70's Hailwood upright and become comfortable with carrying my body weight over the side in a corner.

I have not yet got used to the greater corner speed this allows and still get a fright if my knee touches the ground, :crazy: hence the trainer wheels.

As for my riding, I need to lift my head and look further around the corner and be happy with the foreground only being in my peripheral vision and not be concentrating on it.

This looking further up the road is going to be a conscious try at the next meeting.

.

koba
25th January 2009, 21:26
This is a VERY interesting thread!
I also agree on the value of riding better.

bucketracer
26th January 2009, 11:16
How important is winning anyway? Is that what its all about?

Skunk
26th January 2009, 12:16
How important is winning anyway? Is that what its all about?
Nope. It's all about fun for me. Beating myself (shut up you dirty buggers :lol:)

saxet
26th January 2009, 12:44
How important is winning anyway? Is that what its all about?

It's the old thing, not every one is gonna win but we still try. On the rare occaisions I do win it's pretty cool but the main goal is to improve my bike in all manners e.g. power output and useability and improve my riding. I like to think most people are doing the same as this is what makes me try harder and, I hope, Makes buckets a great place for young people to come, learn off silly older buggers like myself and then maybe move on to bigger and better things.
P.S. this is a great thread that's been alot of help to me.:Punk:

nudemetalz
26th January 2009, 13:09
I might have to start a "Tuning the Loncin up to radical proportions to beat the 'strokers" thread....

Anyone got a huge supply of inlet and exhaust valves for me to purchase??? :laugh:

Skunk
26th January 2009, 13:46
Just come up with a method that does away with them.

Doh! Here we are! :killingme

nudemetalz
26th January 2009, 14:21
Just come up with a method that does away with them.

Doh! Here we are! :killingme

Clever prick !!! :laugh:

F5 Dave
29th January 2009, 10:24
. . .
I could make a head for a air cooled two stroke out of one, but it will cost about $4000 for the material :bleh:
I was thinking more along the lines of anti detonation squish inserts, but seemingly transfer isn't up to it anyway, I just thought that was what you were angling at, which is why I worded it that way.

wbks
29th January 2009, 10:51
Theres some high tech bucketeering going on in this thread hahaha. I'm not going to read through 13 pages, so, sorry if someone's already mentioned this. I was reading this book about racing in the 70's/80's that was made late 80's (so it had Crosby, Mamola, all the guys first getting the knee down with tape for knee sliders haha) in the days of two stroke triples and v4's. It mentioned the use of asbestos (use modern equivalent) wrapping to improve performance. It also mentioned stopping the rapid cooling = cracking of pipes but I'm assuming that is an old days thing because it's never happened to me. -

"You will often see expansion chambers wrapped with asbestos especially over the first part of their length. This can be done for several reasons. One may be an attempt to raise the temperature of the air in the chamber which will in turn raises the speed of the reflected wave. A wave that returns quicker will be effective at higher engine speed and hence wrapping the pipe may move the rev range a few hundred revs higher."

Can anyone vouch for the effectiveness of this? Works for old two stroke buckets? Sounds like it could help improve the over rev on a few two strokes

k14
29th January 2009, 11:59
I was thinking more along the lines of anti detonation squish inserts, but seemingly transfer isn't up to it anyway, I just thought that was what you were angling at, which is why I worded it that way.
Its quite common for 125 heads to have them. If you find a decent machinist it shouldn't be too much of a stretch to get them to do it. Also, as far as I understand it doesn't prevent detonation it just prevents damage to the head from detonation??

F5 Dave
29th January 2009, 12:11
Theres some high tech bucketeering going on in this thread hahaha. I'm not going to read through 13 pages, so, sorry if someone's already mentioned this. I was reading this book about racing in the 70's/80's that was made late 80's (so it had Crosby, Mamola, all the guys first getting the knee down with tape for knee sliders haha) in the days of two stroke triples and v4's. It mentioned the use of asbestos (use modern equivalent) wrapping to improve performance. It also mentioned stopping the rapid cooling = cracking of pipes but I'm assuming that is an old days thing because it's never happened to me. -

"You will often see expansion chambers wrapped with asbestos especially over the first part of their length. This can be done for several reasons. One may be an attempt to raise the temperature of the air in the chamber which will in turn raises the speed of the reflected wave. A wave that returns quicker will be effective at higher engine speed and hence wrapping the pipe may move the rev range a few hundred revs higher."

Can anyone vouch for the effectiveness of this? Works for old two stroke buckets? Sounds like it could help improve the over rev on a few two strokes


Well it can work, but there was some controversy over whether you want to be retaining the heat in the charge that is over scavenged & pushed back into the cylinder. However at speed in cold conditions cooling the chamber would make it act like it was longer so higher gears may have a lower rev peak power which may not be the best for top speed. Wrapping the pipes followed but has fallen out of favour for above reason + it rusts the pipes real bad (trust me). Titanium pipes retain heat more anyway so they stopped wrapping them anyway. I wouldn't lose any sleep over it.

Was quite popular in snowmobiles where it was a real problem, hence cracking issues referred to.

F5 Dave
29th January 2009, 12:18
Its quite common for 125 heads to have them. If you find a decent machinist it shouldn't be too much of a stretch to get them to do it. Also, as far as I understand it doesn't prevent detonation it just prevents damage to the head from detonation??

Yeah so a hardened copper vs brass might have been the go. Had some idea (probably false) that it did help with prone bikes but I haven't really had any experience with them as haven't had the need. Where do the Japs come up with their Brand names?, sheesh!

k14
29th January 2009, 12:49
Pretty sure they use brass. It has only come around since the move to unleaded though. If you are running avgas and getting detonation you have cocked something up along the way (too little squish, too much timing or way way too lean) so its of little value imo. I have never run a head with an insert, that photo is of a kit head that came with my bike when I imported it from Japan.

wbks
29th January 2009, 13:08
Well it can work, but there was some controversy over whether you want to be retaining the heat in the charge that is over scavenged & pushed back into the cylinder. However at speed in cold conditions cooling the chamber would make it act like it was longer so higher gears may have a lower rev peak power which may not be the best for top speed. Wrapping the pipes followed but has fallen out of favour for above reason + it rusts the pipes real bad (trust me). Titanium pipes retain heat more anyway so they stopped wrapping them anyway. I wouldn't lose any sleep over it.

Was quite popular in snowmobiles where it was a real problem, hence cracking issues referred to.Interesting! So you're saying with the extra heated gases being pushed back into the cylinders, it becomes a problem because it would raise the cylinder temp heaps, which would lead to detonation and/or overheating?

So if the heat of the chambers effects power spread and peak power; in theory, for bikes with little room to change the pipe design (which from what I read was a problem in the yamaha square four's) , you could just use different steels to change the power characteristics. Like for instance, you would use a pipe that dissipates heat rapidly for wet weather to make the power less peaky, and then use stainless in dry, fast tracks for max peak power. Cutting edge bucket technology theory lol

And can I ask if you guys have air filters on your buckets? On one hand theres 0.5hp to be made without one, on the other there's a new engine needed if you're un lucky enough to get a nice dirty puff of smoke sucked in when someone ahead runs into the dust off track. I'm not sure if I should adapt a little twin air one off a 50cc dirtbike or something or just leave it

F5 Dave
29th January 2009, 14:09
Not quite, the engine head temp wasn't the issue but the charge density, better that the charge isn't heated any more than ness & thus less dense.

Water injection has been used to change pipe temps when out of tuned freq but all this palava just seems to take attn away from the basics, leave it to those with the R&D resource to keep on top of it all.

I've never bothered with filters. Although I am getting keen on shields to make a makeshift airbox to avoid catastrophic grit ingress. Your engine may wear out faster, but not enough to lose sleep over (although I try not to run mine in dusty carparks like the Slipway). Beware a cheapo or dirty filter will lose a heap of power. A really decent one likely nothing. K&Ns can be really good, but copy ones can be dreadful.

TZ350
29th January 2009, 15:49
Yeah so a hardened copper vs brass might have been the go. Had some idea (probably false) that it did help with prone bikes but I haven't really had any experience with them as haven't had the need. Where do the Japs come up with their Brand names?, sheesh!

Brass has a much lower thermal conductivity than aluminium and in TZ’s it was used for its wear resistance to detonation.

We are currently looking at copper for its thermal properties, so as to suppress detonation of the end gases in the squish area.

I am working on a crankcase heat shield for the GP125 that goes under the barrel. Presently I have a 12mm spacer under the barrel and the idea is to replace it with some copper finning that's immediately under the barrel and then a heat-resisting packer between the bottom of the copper fins and the crankcase.

Hopefully this arrangement will get rid of some heat out of the barrel and also act as a thermal barrier between the barrel and crankcase. Allowing a cooler incoming air/fuel charge for a bit more BMEP.

We are also looking at ways of cooling the incoming air for the carburetor.

.

bucketracer
31st January 2009, 15:59
Does any one else think putting a heat sink/shield under the barrel a good idea? Is it likely to be of any use?

TZ350
31st January 2009, 16:23
Just popped the barrel off to have a look before the next meeting and low and behold the piston has four equal symmetrical seizure marks on it.

This could be a sign that the cam grind on the piston (from a water cooled bike) is not right for my air cooled setup.

Thought it got a bit slow in the last race at Taupo. :blink:

I had gone up 3 jet sizes from Mt Wellington too and was running a 122.5

As we have developed this bike the main jets have gone from 90 to 95, 97.5, 100.5 110, 112.5 120 and now 122.5

The picture of the cylinder is just for you speedpro, because you asked, I know its fast but yes my bike is a 125 (123cc actually) as it's on standard bore size. :bleh: A while back I was lucky enough to get a brand new one off Ebay for just a few dollars.

.

TZ350
31st January 2009, 16:30
.

Today I finished the crankcase heat shield and lower cylinder finning.

In photo 1 the thick alloy spacer can be seen.

Photo 2 shows the old spacer, the new heat resisting spacer and the copper fin stack.

Photo 3 shows the complete assembly and photo 4 & 5 shows the fin assembly sitting under the barrel. In the last photo you can just see the heat resisting spacer under the copper stack.

With this copper/heat shield stack I hope to add extra cooling to the barrel and keep the heat from transferring to the crankcase for a cooler incoming air/fuel charge,

More BMEP more Ponies!!! more punch out of the corners :banana:

.

Buckets4Me
31st January 2009, 22:21
The Itom had a cast-iron cylinder that got really hot with hard use. So the use of a shroud to keep it cooler

117798


117799

random pics
and Mike the bike was just a bucket racer before his time

he didn't lean off the bikes he went and raced cars instead

TZ350
1st February 2009, 08:44
.

Real great photos of Mike the Bike, didn't know he started on buckets.

See the upright riding style of the 70's but don't kid yourself that you could keep up with them.

These guys from the 60's & 70's have my respect.

A brief outline of Mikes achievements. http://www.pin-ashe.com/mike_hailwood_badge.htm

The Honda 6 wasent known as the "Beast" for nothing. There was one moment at the Island where Mike was coming down the hill on full throttle 160MPH. He was standing up on the pegs fighting the Honda as it was violently shaking its head.

It would have been curtains if he backed off before getting it under control. Unknown to him his wife had come out to watch the down hill run and she chucked up with the shock of seeing his life or death struggle.

On another bike in the rain a slide would not drop back and he was having to pull it up on the brakes as the engine kept trying to take off, he went on to finish and some of us brave bucketers won't even go out if its wet.

Eventually he left Yamaha and went car racing didnt do so well and suffered some horrendous crashes.

When Mike wanted to return to motorcycle racing his old team Yamaha would not give him a ride for the Isle of Man because he was old?? and might embarrass them.

He then went on to win at the Island in a very convincing way, riding a Ducati and beating the factory Yamaha TZ750's et all.

Later Mike and his Daughter were killed on their way back from the local Fish and Chip shop by a U turning lorry.

An old Indian fortune teller in South Africa had fortold Mikes Death by Lorry years before.

It could be said that Fish and Chips are bad for your health!

Read about it here, about 2/3's the way down the first page. http://forix.autosport.com/8w/hailwood.html

There is also a great bit in here about how Mike wanting to upset Ago. Mike took the 500/4 out for a few record breaking practice laps and when he came in he quickly swapped riding gear with a friend of his just before Ago walked past. Ago was stunned to see a petite blond astride the bike he had been struggling to keep up with, the mind games of GP racing 60's style.

In the top picture, on the little itom the ducting looks very much like what Thomas and I tried to do for Taupo.

Now imagine that made out of copper, clamped between the head and barrel for extra heat dissipation and you have an idea of what I am trying to make next for my bucket.

Bucket racing is a whole lot saner than 60' & 70's GP racing.

.

F5 Dave
2nd February 2009, 07:59
nice piston but air cooled use diff shape. Also have talked about this but gp125 carb needles are pretty thick, makes wonder if mains not making a diff.

TZ350
2nd February 2009, 09:54
I reckon your right about the cam grind on the piston not being for air cooled. Seizure front and back = clearance, four point = wrong shape.

You might have a point about the needle, we might have moved into an area of development where the needle is now the limiting factor at full throttle, will check that, thanks for the reminder.

Will remove the main jet and see if it floods on full throttle.

koba
2nd February 2009, 14:32
I know from the old mans mates that back in the day it was a hot mod to put Bonneville pistons in BSA singles, partly because of lack of availability. Because the BSA was designed for a more cam shaped piston than the bonne they would hand file them to the correct shape. :headbang:
If they didn't the would sieze good and proper!

TZ350
2nd February 2009, 19:25
I know from the old mans mates that back in the day it was a hot mod to put Bonneville pistons in BSA singles, partly because of lack of availability. Because the BSA was designed for a more cam shaped piston than the bonne they would hand file them to the correct shape. :headbang:
If they didn't the would sieze good and proper!

I remember those days, as I recall you could put a Bonneville piston in a 350 BSA single. I am 10 years younger than Hailwood, so Hailwood, Read, Ago, Redman among many others were all boy hood hero's and the Battles of the 60's and 70's around the European Circus and on the Island at that time were very immediate for me.

As an apprentice I spent many hours standing in front of a piston grinder grinding semi finished pistons to size, taper and profile and reboring the cylinders to suit the finished pistons.

The cam profiles were circular metal disks about 250mm in diameter and 12mm thick and the same blank could be used in the camshaft grinder too. You could take a blank, mark out the cam profile you wanted and file it to shape then use it to grind up a piston or hot cam lobe whatever you wanted.

When you look at a 4 stroke cam lobe you see a very big hill (say 8mm lift) on a small base circle but on the cam grinders profile it is the same 8mm lift but on a very big base circle. The base circle is now 242mm ie 250mm blank - 8mm lift = 242mm new base circle with 8mm lift.

The profiles look only slightly out of round but they have that same 8mm bump starting and stopping in the same place as the cam but in an exaggerated fat sort of way like the Michlan Man.

koba
2nd February 2009, 19:37
And this thread remains most interesting!

I think I know what you mean.
Kinda off topic but it makes me think of an article I read about this guy who made a small scale hemi V8 by making a mechanical reduction machining device of some sort and then ran the full size parts as templates.:clap:

TZ350
2nd February 2009, 19:47
I am always impressed by what people manage to do. You just have to have respect for something like that.

craisin
2nd February 2009, 21:17
I am wondering if some cooling of the incoming charge can be achieved by modifying the properties of the fuel itself:Oops:and lets just say it was all in the premix:2thumbsup

Buckets4Me
3rd February 2009, 17:54
I am wondering if some cooling of the incoming charge can be achieved by modifying the properties of the fuel itself:Oops:and lets just say it was all in the premix:2thumbsup

there is nothing in the rules that say you cant drop big hunks of ice into the tank

you compeditors thank that is :Playnice::buggerd::mad::lol::weep::oi-grr:
:beer::apint:

TZ350
3rd February 2009, 21:22
.

Because I secretly love the sound of a good four stroke.

Thomas and I went around to the local engine re-conditioners to see if we could get a photo of a cam grinder and cam profile master but sadly they didn't have one.

Got a photo of a boring bar in action and Thomas posing with a crank grinder.

We did get a photo of a page in a book that talked about cam profiles. The pictures neatly illustrate how the cam overlap is symmetrical about Top Dead Center.

This symmetry can be used on a single cam, twin cam, quad cam, anywhere from a 4 stroke lawn mower to a V12 Alison Aircraft engine, to check if the cam timing is correct, its all the same principle.

Simply rock the crank back and forth past TDC and an exhaust/inlet pair should just crack open/closed equally as the crank is gently moved back and forth. Look at the pictures and you should get the idea.

Now you know how to check this you should never be stuck getting cams setup to run.

I wasn’t able to get a photo of a cam grinder myself but here is a URL to a page with pictures and a bit of a story about how they develop their cam profiles.

http://www.jonescams.com/circle_track_story.pdf

.

koba
3rd February 2009, 21:22
Gordon Jennings:
"Actually, making a new cylinder head is fairly easy (it can be either cast or simply
machined from a block of aluminum) while the cylinder itself presents a far more
difficult problem in fabrication. So you may very well want to use an oversized, deeplyfinned
cylinder head to help cool a particular engine's stock, cast-iron cylinder. And if
that should be the case, remember that you'll need a maximum contact area between head
and barrel, and surfaces that will seal without any kind of gasket. There is a very sharp
temperature gradient across any joint, and even a solid copper gasket presents one more
pair of surfaces across which heat must flow."

Hmmm, may not be all good with that lovley looking base spacer you made but probably worth trying all the same.

bucketracer
3rd February 2009, 21:33
I am wondering if some cooling of the incoming charge can be achieved by modifying the properties of the fuel itself:Oops:and lets just say it was all in the premix:2thumbsup

Tell me more, are you suggesting adding something to the petrol or using something else altogether?

.

koba
3rd February 2009, 21:34
That Cam info seems interesting!

TZ350
3rd February 2009, 21:39
Thanks for the ideas. I am actually finding it very hard to make real performance improvements that actually work.


Gordon Jennings:
"Actually, making a new cylinder head is fairly easy (it can be either cast or simply
machined from a block of aluminum) while the cylinder itself presents a far more
difficult problem in fabrication. So you may very well want to use an oversized, deeplyfinned
cylinder head to help cool a particular engine's stock, cast-iron cylinder. And if
that should be the case, remember that you'll need a maximum contact area between head
and barrel, and surfaces that will seal without any kind of gasket. There is a very sharp
temperature gradient across any joint, and even a solid copper gasket presents one more
pair of surfaces across which heat must flow."

Hmmm, may not be all good with that lovley looking base spacer you made but probably worth trying all the same.

My thoughts are that some heat must flow from the barrel to the crankcase and if that is so then if it has to flow through a copper fin first some heat must be radiated before it can get to the crankcase and the crankcase must then run cooler.

You would think that all this cooper would be positive but the saying is "Best by Test" we will just have to try it and see but I am hopefully.

.

TZ350
3rd February 2009, 21:45
.


The good old faithful points ignition on the Red GP125 finally died and Tomas set about replacing it with a CDI unit. He rummaged around in the container of junk we have and came out with a couple of TF100 flywheels and Stators, CDI coil and a CDI box of unknown origin.

First step was to throw the lighting coils away and bolt every thing up and see if we get a spark. Our efforts are rewarded with a big phat blue crackling bolt of God’s own lightning.

Then Tomas used a DTI in the sparkplug hole to set the piston at the right advance and carefully marked the flywheel where the ignition should fire.

He ran the bike up and used a timing-light to see where the ignition was actually firing and it turned out to be randomly all over the place.

When he looked into it he found one of the magnets had been loose and was moving about and shifting the ignition point.

He replaced the flywheel with the other one and ran the bike up again and found out that the real ignition point was way off. After some more investigation he found that the TF100 cases have the barrel in a different place to the GP125.

The TF’s barrel is about 20 degrees advanced and so the ignition was advanced too.

To correct this Tomas cut a new keyway using a hacksaw fitted with three blades to get the right width for the key and elongated the slots in the stator plate.

The steps were.

1: Set the piston position at the correct firing point using a DTI in the plughole.

2: Clean and re-mark the flywheel so the actual firing point can be checked with a Timing light.

3: Make adjustments and go back to 1: Repeat untill you get it right.

There is about 15 degrees of retard built into the CDI and Tomas set the advance at 35 degrees BTDC at idle so the ignition retarded to the correct setting of 20 degrees BTDC at 8,000 rpm which is the point that the GP comes onto the pipe.

Tomas had to go through the process of making adjustments, setting the piston position and remarking the flywheel several times to get it right but it runs like a charm now.


.

koba
3rd February 2009, 21:54
hmm, worth noting all that as at some point I hope to see if I can get the roadgoing A100 working with RGV150 electrics.
I wan't to do this so I have lights that actually allow me to see at night.
It is quite interesting how similar the parts are even tho they are so many years apart in manufacture.
The thing stopping a direct bolt on in this case is the RGV's flywheel has a slightly longer (but same angle) taper so I need to tunt about 5-10 mm off that to position it corectly. The stator plate just screws straight in and all the timing marks line up.

TZ350
3rd February 2009, 22:56
Gordon Jennings: remember that you'll need a maximum contact area between head and barrel, and surfaces that will seal without any kind of gasket.

I have that now, but I think the head gets to hot.


Gordon Jennings: There is a very sharp
temperature gradient across any joint, and even a solid copper gasket presents one more
pair of surfaces across which heat must flow."

But why must the heat flow from the barrel through the head gasket and its two disruptive joints and then into the head before it is conducted to the air?

Imagine if that head gasket was thick say 2mm and extended out the front, back and both sides adding a great deal more fin area. Copper conducts heat nearly twice as fast as alluminium and so should shed a lot of heat.

The heat from the barrel crosses one joint to go into the new copper head gasket/fin and is conducted out to the air without adding more heat load to the head.

Likewise for the head, excess heat from the head crosses one barrier into the head gasket/fin and is conducted out to the air too.

Possible? I hope so as I have been working on this for a while and I all ready have got most of it made, but I may not be finished for next weekends racing and have to take the bike along with the old setup.

.

koba
4th February 2009, 06:35
Yeah, I like what you have been playing with!

I was just thinking of copper you used in your barrel spacer, how it was made of pieces joined together, maybe that wont conduct as good as it could?

I see your logic tho and as I'm no expert I have no idea whats waht but thought of your experiments while I read that bit and thought it might be helpful.

He goes on to talk of O-ringing heads to get rid of the 2 gasket joints.
He also points out somthing you know and this is somthing along the lines of "heads are easy to make, Barrels are hard" you can ad fins much easier by playing with heads (Or spacers under the barrel!!)

I really do like the insulator block.
As you say, we will never know until you try it.
I'm interested to see if it makes a difference.

craisin
4th February 2009, 07:46
Tell me more, are you suggesting adding something to the petrol or using something else altogether?

.Im just stimulating conversation about that type of thing and the rules surrounding that type of practice. Personally I think that too many opinions leads to what i call group mentality and leads to competitors getting the upperhand or maybe Im insane

F5 Dave
4th February 2009, 11:13
. . . or maybe Im insaneI think it's the last one. The rules are quite clear. Easy to find on various websites.

TZ350
4th February 2009, 15:27
.

Having decided that ceramic coating is this centuries biggest performance marketing con like last centuries shiny port and polish "boy racer must have" is.

Thomas and I have had a cylinder head copper sprayed in the combustion chamber and right across the underside. The copper is about 1.25mm thick and the objective is to have a thin combustion shell that readily sheds waste combustion heat to the furtherest fins.

As copper has nearly twice the thermal conductivity of aluminum we expect to see less localized heat build up in the combustion chamber and faster transfer of heat to the outer fins on the head.

The forth picture is the original head showing localised hot spots.

In the first picture the copper head is on the left and a standard head (less its outer fins) on the right.

The second picture is a better view of the copper head.

The plan is to make a copper head gasket/fin that's squeezed between the head and barrel and we expect all this copper to greatly aid the rejection of waste heat from the cylinder and combustion chamber.

The third picture is the Fan CPU Coolers we want to use.

With 4 CPU heat-sinks attached to the copper the effective fin area will be greatly increased (more than doubled) and we will try the fans on the heat sinks to see how they go and hopefully the CPU Heat-Sinks won't get so hot that the fans melt.

.

koba
4th February 2009, 18:28
Now THAT is cool!

TZ350
4th February 2009, 20:27
.
Thanks Koba

Why copper and not ceramic?

Well we were all for ceramic coating the combustion chamber to keep the combustion heat in and get more power out but then thought about it a bit and read some on the Internet and concluded that performance ceramic coating specialists were talking more advertising true speak than making technical sense.

If ceramic coating in performance engines actually worked they would not have to gild the lily extolling its virtues, like a snake oil salesman. Some simple facts and figures would do. But a lot of the blurb was contradictory and plain down right copywriter’s fevered imagination and not factual.

At first I thought it a good idea and I can see how ceramic coatings are useful in a turbine engine where you don’t want heat escaping into the turbines mechanicals.

I can also see where the thermal insulation of a ceramic coated combustion chamber and piston is useful in a diesel where you don’t want the heat created in the air from the compression stroke to escape before the fuel is injected. You want that air to stay hot so the fuel is ignited more efficiently, that’s what a diesel is about.

They claim that an air cooled two stroke will run cooler with a ceramic coated combustion chamber, that’s true I guess because the ceramic coating is an insulator, one side is hot, the other side the head side is cooler.

It retains more heat in the combustion chamber and is also hotter on that side. Do we want a big hotspot? I don’t think so, we don’t want an glow plug auto ignition two stroke. Ok if the auto ignition point is after the firing point but if the thermal condition changes (more load) and advances the auto ignition point to pre-ignition we could quickly go into detonation.

I suspect ceramic coated two strokes are detuned (although their owners think they are tuning them up) so as to stay within their reduced thermal limits. I accept that because of the retained heat in the combustion process they may be more fuel-efficient. But I don’t believe they can be made to produce sustained power because of localised over heating of the ceramic coating on the combustion chamber side.

If keeping heat in the combustion chamber is the go, then performance heads would be made of cast iron or stainless steel, any metal with pore thermal conductivity. But performance heads of all kinds are universally made of alloy and not just for lightness, they are looking to shed waste combustion heat.

In no way could all the heat leave the combustion process through the head. If it did the exhaust would not be hot and the motor would not produce any power and the head would melt.

Remember its roughly 1/3 of the combustion process heat for work 1/3 for the exhaust and 1/3 lost to the cooling system.

The thing that keeps heat in the engine to do some useful work is the small boundary layer of air/fuel charge clinging to the combustion chamber walls and piston. Detonation blows this boundary layer away, which allows the combustion gases to touch the metal of the combustion chamber/piston and over heat the piston and cooling system (head).

It’s this boundary layer that protects the engine and makes some of the heat of combustion do some useful work.

The combustion chamber shell needs to be cool, cold even. Not coated with ceramic that can run hot enough on its surface to auto-ignite the freshly compressed air/fuel charge.

I think once thermal energy (heat) has crossed the boundary layer its wasted and needs to be shed as efficiently and quickly as possible.

For what its worth we are going to try to improve the waste heat shedding ability of the combustion chamber shell cooling system by using a material with better thermal conductivity than aluminium.

Ceramic coatings, the Holy Grail! I now don't think so!

I would welcome any thoughtful explanations of the benefits of ceramic coatings especially if it points out where I may be wrong.

.

koba
4th February 2009, 20:44
.
Thanks Koba

It retains more heat in the combustion chamber and is also hotter on that side. Do we want a big hotspot? I don’t think so, we don’t want an auto ignition (pre-ignition) two stroke. Ok if the auto ignition point is after the firing point but if the thermal condition changes (more load) and advances the auto ignition point to pre-ignition we could quickly go into detonation.

.

I believe the idea is the ceramic coating helps spread the heap more evenly over the combustion chamber thus minimising localised hotspots.
Like you though I am sceptical of the benefits in insulating layer an aircooled engine thats power output is limited by its lack of ability to shed heat...

craisin
4th February 2009, 20:49
I think it's the last one. The rules are quite clear. Easy to find on various websites.so you need internet access just to read the rules and its entry level motorsport and you need to kiss certain amount of arse and even join a club :clap:and there heaps of outgoings but wheres the perks

TZ350
4th February 2009, 20:59
I believe the idea is the ceramic coating helps spread the heap more evenly over the combustion chamber thus minimising localised hotspots.
Like you though I am sceptical of the benefits in insulating layer an aircooled engine thats power output is limited by its lack of ability to shed heat...


Koba, How does a poor thermal conductor spread heat? Its those advertising chaps at it again. See what I mean! its suspicious don't you think.

I did read where they said it was the ceramics ability to reflect radiated heat, well polished aluminum or copper or even stainless steel does that and what about dirty ceramic.

.

koba
4th February 2009, 21:11
so you need internet access just to read the rules and its entry level motorsport and you need to kiss certain amount of arse and even join a club :clap:and there heaps of outgoings but wheres the perks

You make no sense at all.

koba
4th February 2009, 21:12
Koba, How does a poor thermal conductor spread heat? Its those advertising chaps at it again. See what I mean! its suspicious don't you think.

I did read where they said it was the ceramics ability to reflect radiated heat, well polished aluminum or copper or even stainless steel does that and what about dirty ceramic.

.

Suspiscious I do think...

TZ350
4th February 2009, 21:29
so you need internet access just to read the rules and its entry level motorsport and you need to kiss certain amount of arse and even join a club and there heaps of outgoings but wheres the perks


"wheres the perks"...Well......craisin....... You get to race with some really neat people but don't expect them to tolerate bad manners.

TZ350
4th February 2009, 21:30
Suspiscious I do think...

Yep, me too.

Fooman
5th February 2009, 10:20
Koba, How does a poor thermal conductor spread heat?


Thermal barrier coatings (as used to protect components in all sorts of heat engines) do even out heat flux. They don't really do it by conducting heat away, but they do remove hot spots in the substrate material - just so long as the substrate is cooled via some mechanism (e.g, air, oil or water cooling in a barrel).

Cheers,
FM

F5 Dave
5th February 2009, 10:58
I do agree with what you are saying TeeZee but I do wonder about coating piston crown & possibly crankcase & inlet so the inlet charge is less affected by the combustion hence more dense when pumped or sucked into situ. Then again it might still heat up just as much over time & not be able to shed the heat anyways.

F5 Dave
5th February 2009, 11:09
so you need internet access just to read the rules and its entry level motorsport and you need to kiss certain amount of arse and even join a club :clap:and there heaps of outgoings but wheres the perks

Yeah you don't make much sense. MNZ rulebook is supplied to all competitors when they join. . . . or you can download it free.

I think what you are saying is that bucket racing is too expensive for you. Perhaps barefoot running or starlight orienteering might be more affordable.

TZ350
5th February 2009, 12:17
I do agree with what you are saying TeeZee but I do wonder about coating piston crown & possibly crankcase & inlet so the inlet charge is less affected by the combustion hence more dense when pumped or sucked into situ. Then again it might still heat up just as much over time & not be able to shed the heat anyways.



Yes I am sure there is a place for thermal coating of the ports, especially the exhaust port. I think that could be very beneficial and possibly the piston crown too but I am not convinced about the combustion chamber at all.



.

F5 Dave
5th February 2009, 12:25
not cc, think that is counter productive. Ex port may be bad as well for same reasons as pipe wrapping is in dispute. maybe.

TZ350
5th February 2009, 12:26
Thermal barrier coatings (as used to protect components in all sorts of heat engines) do even out heat flux. They don't really do it by conducting heat away, but they do remove hot spots in the substrate material - just so long as the substrate is cooled via some mechanism (e.g, air, oil or water cooling in a barrel).

Cheers,
FM



I can see a benefit in coating valves, to reduce heat load, exhaust pipe headers for corrosion.

I would be interested in knowing more about the mechanism behind ceramics ability to even out temperatures within the combustion space.

I do recall one ceramic coating site extolling the virtues of ceramic coating the exhaust headers mat black to reduce under bonnet temperatures?????????

Mat black Exhaust + Exhaust Heat = Cooler under Bonnet!!! Not Likely

I don’t think so, that advertising copy writing kid was obviously asleep in science class or may be he majored in religious studies and works on a faith-based system.

.

TZ350
5th February 2009, 12:31
not cc, think that is counter productive. Ex port may be bad as well for same reasons as pipe wrapping is in dispute. maybe.


F5 whats the argument against pipe wrapping? other than heat corrosion as I was thinking of wrapping the header, mostly to stop the heat being blown back over the fins. Hows ceramic coating of the exhaust counter productive? I thought it might be a good idea to reduce heat take-up in the exhaust tract, but so much is counter intuitive to what I originaly thought was right.

.

koba
5th February 2009, 14:39
Just ran out of time but the second edition of A. Graham Bells book has a bit on ceramic coatings.
His conclusion is basically that it should only be any good on slow speed low throttle engines that lose alot of heat energy per cycle and it would be detrimental on a high speed competition engine.

Fooman
5th February 2009, 14:48
I would be interested in knowing more about the mechanism behind ceramics ability to even out temperatures within the combustion space.


Not so sure about the combustion space, but coatings even out the temperature of the substrate material (i.e. what the coating has been put on). If the substrate is sufficiently cooled (i.e. enough heat been taken away), then the poor thermal conductivity of the ceramic coating means that the substrate doesn't get the chance to heat up (as much). Hot-spots are "deposited" energy, like water in a sponge - if you waterproof a sponge it can't soak up water, so by coating a metal, you "heat" proof it to some degree - the energy does not get transmitted through the insulation to cause the localised heating in the substrate. Actually, I quite like that analogy!



I do recall one ceramic coating site extolling the virtues of ceramic coating the exhaust headers mat black to reduce under bonnet temperatures?????????

Mat black Exhaust + Exhaust Heat = Cooler under Bonnet!!! Not Likely



Actually the thermal emissivity of a object is not necessary related to it's colour - some things which look black in the visible spectrum may not behave like a black body in the IR spectrum - however, it is a good rule of thumb. Anyway, regardless of the colour of a ceramic coating, if it is there and the ceramic has lower thermal conductivity than the uncoated material (e.g. steel), there will be a greater temperature drop through the header wall - it will be cooler on the outside for the same exhaust temperature. A higher emissivity may mean that the cooler exhaust loses it's heat quicker, but it will be minimal (i.e. may be 0.90 rather than 0.80 (oxidised steel/cast iron), and I suspect the cooler skin temperature will dominate.

So, what will happen is the exhaust flow will not cool down as much, and therefore the heat that has not been lost at the headers will be lost somewhere else (out the back or in the muffler or under the body).

As a point of reference for you - note the following webpage:

http://www.newportus.com/Products/Techncal/MetlEmty.htm

Cheers,
FM

F5 Dave
5th February 2009, 15:54
I'm typing with one hand for next 6 weeks so won't elaborate, but we covered it last week in some thread here in buckets. Basically some charge disappears into header & returns with pipe pulse. I think a lot of it is swings & round abouts.

TZ350
5th February 2009, 19:28
Not so sure about the combustion space, but coatings even out the temperature of the substrate material (i.e. what the coating has been put on). If the substrate is sufficiently cooled (i.e. enough heat been taken away), then the poor thermal conductivity of the ceramic coating means that the substrate doesn't get the chance to heat up (as much). Hot-spots are "deposited" energy, like water in a sponge - if you waterproof a sponge it can't soak up water, so by coating a metal, you "heat" proof it to some degree - the energy does not get transmitted through the insulation to cause the localised heating in the substrate. Actually, I quite like that analogy!



Actually the thermal emissivity of a object is not necessary related to it's colour - some things which look black in the visible spectrum may not behave like a black body in the IR spectrum - however, it is a good rule of thumb. Anyway, regardless of the colour of a ceramic coating, if it is there and the ceramic has lower thermal conductivity than the uncoated material (e.g. steel), there will be a greater temperature drop through the header wall - it will be cooler on the outside for the same exhaust temperature. A higher emissivity may mean that the cooler exhaust loses it's heat quicker, but it will be minimal (i.e. may be 0.90 rather than 0.80 (oxidised steel/cast iron), and I suspect the cooler skin temperature will dominate.

So, what will happen is the exhaust flow will not cool down as much, and therefore the heat that has not been lost at the headers will be lost somewhere else (out the back or in the muffler or under the body).

As a point of reference for you - note the following webpage:

http://www.newportus.com/Products/Techncal/MetlEmty.htm

Cheers,
FM

As always FM you make some very good points.

Looks like I will have to change my:- Mat black Exhaust + Exhaust Heat = Cooler under Bonnet!!! Not Likely

To:- " Not very significantly"

I can see from your explanation how a ceramic coatings thermal insulating properties would allow the substrata underneath time to even out its hot-spots but I suspect all it means is that the ceramic becomes the hotter hot-spot instead.

Coba quotes Graham Bell as not thinking ceramic coatings have much to offer high performance engines.

Dale Alexander in "Squish It Until It Makes Power" (RD350s & 400s) talks of the temperature of the piston crown as being the limiting factor in making power and he used ceramic coatings on the pistons to reduce their thermal load. His coating's were three layers and 0.020" thick not the poxy thou or two you get from the Specialists! He specifically describes thin coatings as usless.

I can see how this works as the fire spends longer up in the roof of the combustion chamber and comparatively little time really close to the piston. So
the ceramic on the piston crown gets hot (but the piston crown is cooler) and the ceramics face is not as hot as it would have been if it was on the combustion chamber roof. Possibly??

Could it be that ceramic on the piston does not get as hot as the other uncoated parts of the combustion chamber, would that be possible? Could the face (fire side) of the ceramic coating on the combustion chamber find itself running much hotter than the ceramic on the piston crown?

Thats a great chart on emissivity, see how aluminum has really low emissivity even when oxidized. I did not realise it was as bad as that. I really should grit blast my head and paint it black with lamp black paint. I am sure your right, not all blacks have the same emissivity.

Thanks for the chart.

.

TZ350
5th February 2009, 19:30
Just ran out of time but the second edition of A. Graham Bells book has a bit on ceramic coatings.
His conclusion is basically that it should only be any good on slow speed low throttle engines that lose alot of heat energy per cycle and it would be detrimental on a high speed competition engine.

Now that is very interesting!

.

TZ350
5th February 2009, 19:34
I'm typing with one hand for next 6 weeks so won't elaborate, but we covered it last week in some thread here in buckets. Basically some charge disappears into header & returns with pipe pulse. I think a lot of it is swings & round abouts.


Sorry to hear your hurt, :doctor: but thanks for the thoughtfull and often amusing input to the various posts.

.

Yow Ling
5th February 2009, 20:13
TZ you have been putting alot of effort in trying to reduce the heat transfer from the barrel to the crankcase, maybe this is a wasted effortthe temp at the base gasket i pretty low, You talking about ceramics made me think that the real problem is radiated heat from the inside of the piston crown. It gets hot there sometimes hot enough to melt the aluminium (660 deg C) maybe this is a bigger problem than the other. The cool charge is doing double duty here in that it provides cooling inside the piston lubricating the bearings and cylinder and finaly providing the heat to continue the cycle. coating the piston with some flash stuff seems on the face of it a good plan

TZ350
5th February 2009, 20:47
Hi Yow Ling

Yes I think coating the piston is worth doing to reduce the conducted and radiated heat from the underside of the piston crown. I will get one done. It may take a few weeks as I want to get a .020 coat like Dale Alexander talks about and I don't think I can get that locally.

There is a gully port at the back of the cylinder that is feed by a hole in the piston. Part of the transfer stream goes up-inside the piston and cools the underside of the piston crown which heats up the air-fuel charge by conduction and radiation as its cooling the piston.

The charge then goes through the hole in the piston and up the back boost port into the combustion chamber. There is a photo in an earlier post where you can see the hole in the piston.

Tomorrow I will (hopefully) get the copper head gasket/fin finished and everything assembled for a tryout at work. The fin bit does not look much but it adds about 580 sqr centimeters of fin and then there is the 4 CPU heat sinks. Which I should have anodised mat black.

No fans as I am frightened that everything will get hot enough to melt the them. With the copper fin and CPU heat sinks the fin area of the head has more than doubled.

Yes I know the CPU heat sinks are quite away from the combustion chamber but I am picking the greater thermal conductivity of the copper fin will move heat to them quicker than the original alloy head can move heat to its outer fins. I will have a look at the relative temperatures to see if I am right.

.

Buckets4Me
6th February 2009, 07:49
.

Why copper and not ceramic?

Well we were all for ceramic coating the combustion chamber to keep the combustion heat in and get more power out but then thought about it a bit and read some on the Internet and concluded that performance ceramic coating specialists were talking more advertising true speak than making technical sense.


.

let me see if I have got this right
you are using copper instead of ceramic because

1. you are trying to get rid of heat from the head (not trying to keep the heat in the chamber and out the exaust with ceramic)

2. you think the ceramic would stop the head doing it's job and also get to hot on the face of the ceramic

3. you havent got the time or money to try both :buggerd:

4. you havent worked out how to wrap the head in ice (and have the ice last 2 hours)

TZ350
6th February 2009, 08:06
let me see if I have got this right
you are using copper instead of ceramic because

1. you are trying to get rid of heat from the head (not trying to keep the heat in the chamber and oput the exaust with ceramic)

2. you think the ceramic would stop the head doing it's job and also get to hot on the face of the ceramic

3. you havent got the time or money to try both :buggerd:

4. you havent worked out how to wrap the head in ice (and have the ice last 2 hours)

1. Use your spelling checker. "oput the exaust" Sheeeeeesh ! :bleh:

2. "the ceramic would stop the head doing it's job " Yes, that is my conclusion, its the boundry layers job to keep the heat in the engine. :angry2: Once any heat gets to the head it needs to be shed quickly. :cold:

3. You are right about "Time and Money" you must know me! ;)

4. That darn ice keeps melting. :crybaby:

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TZ350
6th February 2009, 19:03
Got it all together.

Picture-1. All the parts.

Picture-2. Underside of the complete assembly, I am running a flat piston, the copper fin extends right into the combustion chamber and forms the squish band.

Picture-3. Top side of the assembly, I have now painted the alloy head black.

Picture-4 Thomas doing a test assembly of the parts and making sure there is the correct squish clearance.

Picture-5 The bike just before its first run.

Picture-6 Thomas and Jan doing the cam belt on Thomas's "Fast Four".

The test run was just up the drive, around the car park and back!

I felt the copper head fin and it was just warm. The head was cold. This confirmed what I was expecting, That the copper transfered heat out of the combustion chamber much quicker than the original alloy head. After a minute or so of sitting the alloy head started to feel warm too.

I was also expecting this, it confirmed what I thought, that the alloy soaked up the combustion chamber heat but it was getting out to the fins through the alloy much slower than it does through the copper fin. The copper fin cooled off much quicker than the alloy head. No surprises there either.

After a run up the drive, around the car park and back. The head and copper were no more than just warm.

The big surprise was that when I felt the fins under the barrel they very nearly burnt my hand. They were so hot that I could not keep holding them. There is three fins under the barrel and the bottom fin felt as hot as the top one. So the heat transfer between them is good.

The under barrel fins getting so hot so quickly it absolutely floored me, the under barrel heat must have been there all the time and going into the crankcase. I am so glad I put a heat insulating washer between them and the crank case. It will be interesting to see if the cases run cooler now.

The head fin is a bit OTT. And if I was doing this again I would make a smaller simpler head fin but definatly put multi finning under the barrel.

Why the under barrel fins got so hot and would they remain hotter than the head fins during a race, I don,t know! but that is the first place I would put any copper finning on a new motor.


Hopefully on Sunday we will have a heat gun to read the tempartures and fingers crossed the bike runs long enough to get some good readings.

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koba
7th February 2009, 08:50
That is so coool!
It is great to see it all looking so promising!