Well that 23hp curve above looks pretty easy to ride at fairly lazy revs. Perhaps this doesn't tell the full story on carburetion at other throttle positions & abruptness of Disc valve closed to open transition that on a small track may count for a fair bit if it is upsettingly sudden. I haven't ridden one. Well not for a long time & that was at Taupo over a decade, closer to two ago.
Well I think I am fairly well informed to answer most questions about my bike. It does handle really well and is very driveable even at Mt Welly. My best laps to date are not up with the best but 31.6 I feel it is not all that bad for an old guy carrying a few kegs to much weight. A few of the guys have riden it and all are pretty impressed at the way it pulls out of the corners. Avalon has riden my bike on a fair few occasions and is pretty happy with it. She pushed it around to a 3rd place finish in an "A" grade race a few meetings ago, when she started from the second row. So I think that answers that question about how good it could be in the hands of a young talented rider. Now to loose some years and some weight lol
This is the type of pumper carb that Wobbly suggested to TeeZee that he could look at using, it has a slide throttle instead of a butterfly.
Ok, this week I have been given the job of collating the interesting links and posts from the last 10 pages.
First something for F5Dave.
Originally Posted by wobbly
If Diesels are the future then why have Evinrude , using E Tec got the lightest, most powerfull, most fuel efficient, least polluting outboard on the planet.
Yes its a 2 stroke and the only reason every 2 wheeled device used for transport isnt a 2 stroke right now, is that the technology used for effective direct injection is patented and stupidly expensive. This will change very soon and the big, heavy, slow, expensive to maintain ,polluting sacks of shit called 4 strokes, will be down the dunny along with Hondas corporate masturbation antics - exactly where both belong.
As I see it, having a powerful easy to ride bike with a very wide power spread is the key to beating the FXR150's with a Stroker. As part of the plan I have been looking for a practical variable inlet and Thomas came up with a good idea.
Originally Posted by wobbly
Have a look at this idea.The Lectron carbs have a venturi behind the slide, so you get high velocity at half throttle, but actually in bench tests they flow more air than the same size PWK when wide open.
Originally Posted by speedpro
Don't raise the transfers, blowdown is most important on a motor with a single ex port and you don't want to reduce it.
The RSA leads the way with the "refining" approach and its very evident that the inner radius size and angle is the key to keeping all the flow attached and heading in the right direction.
It has A port angles of 28 roof,16.5 floor. B port is 6.8 roof and 7.4 floor, Boost is 53.3 roof and 37 floor.
The flat roof B ports collide in front of the boost, this clears out allot of residuals that normally are left behind, and as these opposing flows slow down - they are pulled upward by the boost port ( its flow has already attached to the rear wall).
The A port flows over the top of the B port flow, and they all join together in the rear 1/2 of the cylinder as a slowly rising column - the famous "loop".
The idea is to create as much coherent flow entering the column as possible, and at the same time clear out as much exhaust residuals as we can, ahead of that column with no mixing.
Thus if the Delivery Ratio is high, and we keep the streams entering the cylinder "coherent" then the Scavenging Efficiency will be high.
Then if the pipe works properly the Trapping Efficiency will be high and lots of power is released.
If it all works together, then a 30+ Hp bucket is easy.
Originally Posted by TZ350
Mark the stator with a felt tip. Have your friend spin the motor over, now you should be able to pickup a spot on the rotor that matches the stator when the timing light flashes………….now you have a reference point for setting the ignition timing.
Gluing the Suzuki GP125 Engine Cases. These are the places that need gluing before porting the inlet and transfers. (check to post out to see the pictures)
Originally Posted by TZ350
Some thoughts on the over rev cough........... need to read the post to see the attached links.
Originally Posted by wobbly
…….The perfect rate of change in power is a straight line - so as you open the throttle, you get a linear change in power given.
Originally Posted by Fooman
…….. but doesn't that imply a flat torque curve (i.e. engine is operating at peak efficiency all the way through the rev range) as power is the integral wrt frequency of torque.
The new curve may not be perfectly flat, but it is certainly more efficient throughout more of the rev-range………….. FM
Originally Posted by wobbly
Dead right a flat torque curve gives a straight line power graph.
Here is sim of new F3 motor, RZ400 with around 120RWHp, near perfect throttle connection.
Because a few people have asked about the GP engine, to save wading through 270 pages, these links go to the more relevant posts about the 27hp engine. Different link collections can be found on the decade pages 80-90-100.....260-270 etc.
Originally Posted by wobbly
Find tdc, then drop the piston a small amount - fill the vol to 1/2 way up the threads, move the piston up/down, till fluid sits the highest, then fill to top.
Originally Posted by 50bucketracer
I’m not a regular on this forum but do have the occasional read. I note that this thread (& some others) have made the occasional reference to my Derbis. So I thought some of you might be interested in a bit of background. Its a long post, so pass over if you have a short attention span.……..
Originally Posted by TZ350
This is the RC Servo that I am going to use to close the V Tec below 7,000 rpm. Rotary Valve side shows the divider coming right up to the valve. In this view the valve rotates ant-clockwise. The inlet is 45 deg wide and the V Tec closes it 10 deg earlier, I would have liked 30 but this is how the first cut turned out.....
.........it also decreases the size of the inlet tract when the inlet closing point is reduced, this keeps the inlet tract gas velocity up. I tried the RC Servo out and it opens/closes the valve OK and quickly enough
OK, here is some info on how to utilise the servo option on the Ignitech............
Originally Posted by sonic_v
Another method that has been used before is two intake ports and two carbs with staggered throttle opening. This also allows you to run different intake lengths and even carb bores. See Cesare Bossaglia book from early 70's for some photos of kart engines running this set up. My father in late 70's converted a 125 air cooled disc valve engine to this setup that ran very sweet and had a lot of race wins.
………….In a reed valve setup,tuned for peak power around 12000 rpm, we find that the best tuned length is around 135mm from the reed tip, to the end of the bellmouth works best………...
Wobbly goes into intake resonance in some depth in the above post, its worth a look.
Originally Posted by TZ350
We haven't measured ours, but I found this on the net ........... page 270 has a lot of other info too.
Originally Posted by koba
I made this Scatter plot in excel to give a visual depiction of the differences between a few pipes. Note the steep angle of the RS125 baffle.
Originally Posted by wobbly
That old Honda pipe mod drawing is completely useless, it was never used by the factory in any form. The rear cone is insanely steep.
And the so called A Kit pipes were designed to work with high Ex ports - where the customer engines all had 83*ATDC to let them rev without an electric powerjet.
I have much better designs with a ton of dyno time on them, but of course they are all specific to 50Hp 125 cylinders, not 30Hp 100cc designs.
Here is one that has won dozens of 125 kart titles, but again it should just point you in the right direction for the 100.
Originally Posted by wobbly
Here is the A Kit spec RS125 pipe drawing.
Originally Posted by wobbly
Expanding bellys have various effects in pipe design it allows you to increase the effect of the reverse cone, without making it shorter. It also increases the volume and can reduce the propensity of the wave to create a shock front ( killing energy) as it reverses back toward the diffuser. This is seen as a quite noticeable blip in the sim, example below seen at around 20* before TPC, of the pressure ratio at the EX port
Originally Posted by kel
TZ mentioned how the Honda RS pipe inlet is larger than the GP exhaust port outlet, while this is common place on 4 strokes for the purpose of AR I wasnt aware it was used on 2 strokes but on reviewing RSA photos I came across this Attachment 239992 Attachment 239993
Jan Thiel "One wants the pressure wave coming back into the cilinder but NOT the burned gases that are hot and can cause detonation!"
Makes sense.
Originally Posted by TZ350
Frits Overmars
A powervalve does not really give you real resonance power; it just prevents the pipe pulses from completely messing up the power curve at low revs. I expect a sliding pipe will make more low-down power. http://www.pit-lane.biz/t1666p15-tec...ht=twin+rotary
Originally Posted by husaberg
http://www.lortim.demon.co.uk/alpha/index.htm This is it a narrow disk valve set up, One engine used the half circle crank as the disk valve so the engine looked piston port but was disk valve. Alpha also used to do a knife edged kind of eliptical cross section streamlined shaped conrod that also looks like it would show promise as an idea in a modern engine. There is pics of about three versions of the engine here below.
There are 1,600 or so photos on this thread.
They can be viewed by using the Thread-Tools option near the top of this page, click View-Thread-Images in the drop down box, then the pictures can be sorted using the Display Options.
The images can be displayed 70 at a time by using the Display-Options and clicking on the little blue N/A under an image will take you to the related post.
From page 80 all the decade pages have link collections, they were collected together as the thread went along to make it easier to find the good stuff.
suck and see inlet rack tuning 80/s style for reference.No fussy formulas here.
Originally Posted by wobbly
Just to add a little more to the intake tuning scenario,the TD and TZ piston port engines had an "insulator" spacer on the cylinder about 25mm wide.
We all thought this did what it was called ie kept heat off the carb,but no.
Shorten that spacer by 5mm and it was absolutely impossible to jet the carb.
Even blipping the throttle you saw huge standoff at the bellmouth.
Make it longer to pick up bottom end power, and for every 1 Hp gained at 8000 you lost 2 at 10000.
So again, reality fucks over theoretical analysis.
The shorter length was technically correct for the rpm,but was impossible to utilize.
Edit, the other thing I forgot to add before re Mr Helmholtz.
Its all very well making an assumption that the intake and the case vol is in fact a Helmholtz - the problem is there are 3 others doing his finest.
The case connected to the transfer ducts, the transfer ducts connected to the cylinder volume, the cylinder volume connected to the exhaust duct, and the exhaust duct connected to the pipe volume, and the pipe volume connected to the stinger.
How many did I say, anyway we have a multiplicity of ducts and volumes, trying to define one as independant of the rest is suspect to say the least.
This below was plagiarised from Design and Tuning for motocross interesting would be a good starting point still relevant aplogies if it has been covered already up to pg 70 now.
Could be a logical baseline to start testing from as most race are won on the track anyway.
Tuning of the inlet track is best resonance frequency is best done by a running test of the engine, altering the induction tract length between the intake port at the piston and the carburetor .The easies way to modify intake tract length is with a spacer blocks of different thickness es positioned between the reed valve assembly and the cylinder.
On engines without a reed valve. Induction length is critical; and carburetor manifolds of different length, positioning the carburetor closer or further away from the cylinder should be tried.
In order for the exhaust system not to effect testing of the intake tract resonance, The expansion chamber should be removed and replaced with just a short piece of header pipe, Long enough to prevent sucking of air into the exhaust port, Yet, not so long as to produce a tuning effect of its own. On 125cc engines this should be 3.5 inches long measured from the Exhaust port 4.0 inches 250cc and 4.5 inches for an 500cc bike.Testing results will probably be a compromise between of two findings concerning the inlet tract length .First, which provides the smoothest power .and the second which provides the quickest acceleration between to points measured by an observer.
For the acceleration runs, Try a rolling start from the same RPM each time and use a high gear to avoid shifting between the timed points. In most applications for High rpm a short tract works best while lower rpms and wider powerbands calls for a longer intake track length
Ouch! note to self pull the Zarco on F5 Dave if he ever comes up this way.
eh? What's a Zarco? It was a fair question, these decent power figures are comparatively recent & Auckland being Auckland in Spring means many wet races.
I haven't been to any races in Auckland for about 4 years.
I would have thought these engines would Smite all but the most enthusiastically ridden FXRs & the rest down to rider ability.
I think Ned writes that Av has ridden ok to get 3rds. So who was beating her & what were they riding?
Don't you look at my accountant.
He's the only one I've got.
I think its a reference to the recent 125GP race where Zarco pushed Terrol off the track on the final corner, in the run to the flag.
Was a brilliant undertake but dirty finish, he had enough room to finish cleanly but choose not to. Penalised 20 seconds for it so didn't even get a podium after all that!
I think we could change the unknown name of Zarco to NoMates, as Nige taught that guy everything he knows.
Bottom line with the 100cc buckets is that no matter what anyone may "think" about power/handling/ability, Nige has never once been "beaten" on that RG100/RS125 bike, he has a few titles but always he did one or more of the following -
A - crashed ( 4 year old tyres he will say)
B - crashed the opposition ( in the way he will say)
C - won easily ( nothing to do with 29Hp I gave him 5 years ago he will say)
Re the intake tuning idea of taking the pipe off - bullshit, the pipe affects the case pressure ratio, and this working with the intake length creates a tuned system.
I post again the graph of a 125 shifter engine,only change was the intake length, less 20mm, why fuck around when you get this easily seen result - 2 free Hp.
Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.
[QUOTE=wobbly;1130081602] A - crashed ( 4 year old tyres he will say) QUOTE]
Ha, my tyres are 2000 vintage meaning 11 years old (for those that cant count), pulled the bike out last night and the front was flat again, the split side walls are starting to look a little freightening, thank goodness we dont have scrutineering.
Ah, can't afford Sky & certainly not the time to watch it.
Yes after my crash at Ruapuna ~ 4 years back I decided to update my front slick which was a Denis Charlet hand me down from his wildcard GP entry qualifying. in 97.
I guess it was probably past it's best by then also ~ 11yrs. Nothing to do with the snow lining the outside of the track or the fact I was off line trying to pass the 3rd placed Hoozie CBR150 on my 50. I try to work that into conversation where ever possible.
Don't you look at my accountant.
He's the only one I've got.
eh? What's a Zarco? It was a fair question, these decent power figures are comparatively recent & Auckland being Auckland in Spring means many wet races.
I haven't been to any races in Auckland for about 4 years.
I would have thought these engines would Smite all but the most enthusiastically ridden FXRs & the rest down to rider ability.
I think Ned writes that Av has ridden ok to get 3rds. So who was beating her & what were they riding?
it might be some kind of love bite,so look out Dave!
I think we could change the unknown name of Zarco to NoMates, as Nige taught that guy everything he knows.
Bottom line with the 100cc buckets is that no matter what anyone may "think" about power/handling/ability, Nige has never once been "beaten" on that RG100/RS125 bike, he has a few titles but always he did one or more of the following -
A - crashed ( 4 year old tyres he will say)
B - crashed the opposition ( in the way he will say)
C - won easily ( nothing to do with 29Hp I gave him 5 years ago he will say)
Re the intake tuning idea of taking the pipe off - bullshit, the pipe affects the case pressure ratio, and this working with the intake length creates a tuned system.
I post again the graph of a 125 shifter engine,only change was the intake length, less 20mm, why fuck around when you get this easily seen result - 2 free Hp.
Originally Posted by F5 Dave
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