ESE's works engine tuner

[TZ350]

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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.

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[R6_kid:Me]

You imported a Vietnamese dude to tune you're bike...

You must really want to win!

[Rick 52]

Bloody hell that thing is quick already it will be a rocket ship when you have finnished
Good luck

[Pumba]

I hope he has all his visas sorted, as imigration may be about to get a tip off

[F5 Dave]

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]

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]

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]

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]

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 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.

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

Its Death or Glory at Taupo.

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[Skunk]

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]

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

[TZ350]

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!".


“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/per...raham-bell.pdf

Gordon Jennings

http://www.vintagesleds.com/library/...20Handbook.pdf


http://toostroke.blogspot.com/2007/1...-handbook.html

Engine Formulas

http://members.bellatlantic.net/~vze...es/engine1.htm

Reading Plugs.

http://www.dragstuff.com/techarticle...ark-plugs.html

Rate of fuel burn and how it affects power output

http://www.factorypro.com/tech_tunin..._vs_power.html

[F5 Dave]

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]

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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/per...raham-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.

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[TZ350]

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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.

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