ESE's works engine tuner

[TZ350]

Carburation.

One of the big things for me recently has been trying to get my head around the main air compensation jet and figuring out a way to find the right one.

Like everything, its simple when you know how, or at least think you do.



The Red line represents a main jet (135) that is correct at peak power but is too lean at 8.5k rpm.

The Blue line represents a main jet (155) that gives good initial drive at 8.5k but becomes to rich at peak power rpm.

The trick is to use the air correction jet to join up the two lines.

I guess the way to find the correct main/air correction jet combo is to do full throttle runs and lean the main out until I have found the best shape I can in the 11 to 13.5k peak power area of the graph. Then keep richening the main up until I have optimised the 7.5 to 9.5k initial drive area of the graph.

Then having found what the best at both ends looks like, I can progressively increase the size of the air correction jet until the rich, good at 7-9.5k main also works well at 11-13.5k.

On the dyno or track I had always looked for the main that gave maximum power, I now think that approach is limited.

So the next time I am on the dyno I will be looking for a main that gives its best at the beginning of the torque curve instead of maximum power and look for the air correction jet that maximises the rest of the power curve.

[wax]

I know this is for buckets. Over here in australia we also race scooters. This is my one with the 50cc engine at the moment. I also have an 86cc engine for it. The 86cc ones will go close to 30hp

[TZ350]

It looks great and I would be very interested in knowing more about the CVT transmission and where I could get a good one and tune up transmission bits from.

[wax]

Are you wanting to adapt on to a bucket. They would outlaw it really fast I would think. It will kill everything on the track

[husaberg]

It looks great and I would be very interested in knowing more about the CVT transmission and where I could get a good one and tune up transmission bits from.

Engines must be derived from non-competition motorcycles.
Motocross, Road Racing, Enduro and Go Kart motors and transmission parts are not permitted.

Seems legit to me.
I mentioned the Rokon earlier it appeared to have a Sachs engine and transmission direct out of a Snowmobile.
i will post it below but you may need a alternate method of starting the beast though TZ.

My initial thoughts were to use a CVT as well semi overdrive to overlap the gears.
it would of course have two problems it would have to be modded to only offer about a .75:1 reduction (not that hard limit the travel)and it would be near impossible to fit it on the primary drive with a conventional clutch set up still in place.
Whereas on the secondary drive it would spin about 1/3-1/6 engine speed (depending on what gear it was in)which may not be a bad thing.
Possible problems with the overlaping gear ratios principal would be you would know when to change as when the cvt od kicked in the rev counter would remain stationary........it also goes against the KISS principal
As a standalone unit the Salisbury unit on the Rokon offers a overall spread of ratios between 3.76 and .087:1.

RT340 TCR Automatic/CVT In 1974, Rokon produced the RT340 TCR Automatic, using a snowmobile-type Salsbury CVT, rear wheel drive only, and dual disc brakes. Another unusual feature was a pull cord to start the engine. The transmission freewheels with the engine at idle; starts to engage about 2800 RPM; and is tuned so the engine always runs near peak power, at 6,000 to 6,700 RPM. The lowest gear ratio is 3.76:1 and highest 0.87:1. Using a CVT allows a use of a 2-stroke cycle motor with higher power but narrow power band. The engine sound is unusual as the engine stays at a nearly fixed speed and the transmission ratio changes according to speed. The transmission freewheels when not driving forward, so there is no engine braking. The transmission is vented to the outside for cooling, and so is contaminated by stream crossings and other environmental exposure. Water causes slipping but quickly goes away; however grit can cause transmission sticking. Riding on loose surfaces is sometimes complicated, as rear wheel breakaway does not cause telltale changes in the engine sound. However, most other riding is intuitive and sometimes much more convenient as the automatic avoids engine stalls and other problems with gear selection. Operation is loud (90.3 dB(A)) as the engine is always running fast except at idle. Despite low front wheel weight, about 43%, it had trouble pulling wheelies, a problem for the targeted Enduro riding. Prototypes were raced by factory riders from 1971 to 1973 under Tom Clark; "TCR" stands for "Tom Clark Replica". In the 48th annual six-days trial, all four riders earned bronze medals for finishing. "Cycle Guide" test riders reported it superior for hill climbing and fast on hard surfaces, but poor on loose surfaces and going down hills.[1]http://en.wikipedia.org/wiki/Rokon_motorcycle

If you read the article it says acceleration was not a issue......... cornering on the tarmac might........

[wax]

water cooled is only allowed 100cc right ?? does it have to use the original cylinder.

[bucketracer]

water cooled is only allowed 100cc right ?? does it have to use the original cylinder.

Yes 100cc water cooled, 125cc air cooled.

A Bucket motor does not have to stick with the original cylinder you can fit something else if you want to.

The original scooter transmission is obviously non competition, but the after market parts are a little grey but probably legal as they are made for tuning up a road unit.

[wax]

OK there is a thing called the gp1 derbi it has a 50cc midmounted engine. this has the cvt as well as a chain drive. This uses the same cases as the 125cc aircooled piaggo engine so you can turn the 50 into a 180 if you so desire. Of course your limited to 125 and there is alot of cylidners for this engine.
http://www.stuntbase.com/slikice/derbi_project/3.jpg

http://www.sip-scootershop.com/en/pr...+for_r10008006
http://www.bgm-tuning.com/scootermat...-kit-125cc-ac/
http://www.sip-scootershop.com/en/pr...+for_r10008006

This is just a quick look around but there is alot better cylinders out there. most of them want to go 180cc but some dont. You will not be popular if you do this as it will set the bucket racing guys on fire

pm me for more information if you like

[wax]

you could use the water cooled cylinder and run an electric pump and do this.
http://www.youtube.com/watch?v=GDTXZAHGFJI
http://www.youtube.com/watch?v=p1Rp_IGqGfM
http://www.youtube.com/watch?v=Tf_ix5xMmI0

Like I said you will not be popular. I know its only 27 hp but its all the time. The motor will stay on the same rpm the whole time. max hp so no slipping clutches off the line just crank it on and you have 27hp from a stand still to the top speed. It also comes on so smoothly that you will be on the gas before any gearbox bike

[SS90]

you could use the water cooled cylinder and run an electric pump and do this.
http://www.youtube.com/watch?v=GDTXZAHGFJI
http://www.youtube.com/watch?v=p1Rp_IGqGfM
http://www.youtube.com/watch?v=Tf_ix5xMmI0

Like I said you will not be popular. I know its only 27 hp but its all the time. The motor will stay on the same rpm the whole time. max hp so no slipping clutches off the line just crank it on and you have 27hp from a stand still to the top speed. It also comes on so smoothly that you will be on the gas before any gearbox bike

I'm unsure if you have ridden a well sorted bucket, but you would find that a mid 20hp nice chassis (like an Rs125, or one if these Crazyman frames) would piss all over all but the most experienced scootermatic rider.

When raced "like for like" scootermatics are awesome to watch and compete it, and often close racing, however, (like all scooters), they oversteer chronically, due in part to their tiny wheels ( 10,12, or 13 inch for most autos), short wheels base and weight distribution.

Yes, acceleration is blistering, but it's not only about that.

CVT are great in standard form, for a host of reasons, but as soon as you want to optimise them for competition, a host of compromises must be made, not the least of all mid corner drive.

You can adapt your riding style of course, but it's one of a host of problems that make racing a standard CVT autoscooter against a modern competition bike unnappealing.

A really tight Kart track would prove a different story ( by virtue of holding everyone up mid corner, but out driving everywhere else, so much so that a scootermatic would be a weapon. But, only in this scenario, and winning this way is hardly Cricket.

Add to this that EVERY SINGLE tune up part, (with the exception of different weight rollers) come with the packaging "COMPETITION USE ONLY", yes, many people fit them on the road, however, this does not make them legal.

They are in no way eligible for buckets, I see no ambiguity in the rules that would allow this.

Now, if someone went to the effort of manufacturing different variator pullies, clutch weights, and so on, that's fine, but taking a 100 kitted cylinder (illegal), a Mallossi transmission kit (illegal) and fitting it all to set of (legal)Piaggio cases, will not all of a sudden make it legal.

I am of the opinion also that adapting (somehow) a CVT transmission to a standard bike would be more headache than it is worth, but would be happy for someone to prove me wrong.

[wax]

I have raced against something like that. they have cr85 engines in rs125 frames


Im not trying to get into a war whats better I never said a scooter was better or worse I was just answering a question that was asked of me, I dont know your rules which is why I was asking questions if you read just above
however i was suspecting this would be fitted into a bucket frame this get rid of the proplem of the high unsprung weight and short frame. If you look at the gp1 engine i was talking about you would see it was chain drive. I find when we race the bikes as in the picture you can eat them mid corner and while the cvt is a whole different scenario to ride diving up the inside and block passing is defiantly cricket in my mind.

[TerraRoot]

you have a great idea there wax, ss90 shot his mouth before seeing what the gp1 was.
i like the idea of a fast 125ac with 12" slicks, the 180 has such tiny squashed transfer ports.
i gotta say i don't like a CVT for corners in real life but on the track it could be great.

often though of shoving my 180 into a real frame but keeping the 13" wheels. no time.

[SS90]

. If you look at the gp1 engine i was talking about you would see it was chain drive. I find when we race the bikes as in the picture you can eat them mid corner and while the cvt is a whole different scenario to ride diving up the inside and block passing is defiantly cricket in my mind.

Like under arm bowling more like

In my experience, scootermatic racers against conventional geared stuff is only a novelty, as it just creates discontent from riders (like the days of F3 racing with 125GP in NZ)

Im am quite familure with the GP1, as I am sure most people are, but most of the advantages a conventional CVT scooter has (in regards to speed of turn in particularly) are negated by a convetional chassis.
I am of the opinion that putting a CVT engine into a conventional chassis would be an excersise in accomplishment only, as the reasons for desiring a CVT transmission usually come about because of too narrow power spreads, I do wonder what would be if GP bikes where permitted to use them, particularly in the 2 stroke days.
But certainly a conventional CVT set up is a pain in the arse to ride fast, but if everyone is on the same system, as always it's great racing.

I know several people over this side of the world have/are developing a system that gives more usable power delivery, but I have not personally seen a system that works in such
a way to negate the disadvantages compared to a conventional set up.

[Frits Overmars]

... I do wonder what would be if GP bikes where permitted to use them, particularly in the 2 stroke days.

They would have been a lot faster, and easier to ride as well. I would have built one decades ago but the 'maximum 6 speeds' rule prevented it.
Don't be confused by a CT's tendency to drop the revs when you close the throttle and then come back with some lag when you open it again; that is only in-built behaviour to increase the acceptance for street-riding. Don't think either that the main advantage of a CVT is that it will handle narrow powerbands better. It will, but the character of a good racing engine doesn't need this.
The CVT's main advantage is that there are no shift-related power cuts while accelerating. And no, it's not about the tenths of seconds that the power is absent; it is all about keeping the gas dynamics in the engine on full song all the time. When you shift, power has to be interrupted for a moment (seamless shift boxes excepted) which means the exhaust pulses will stop. After a shift event the engine sound will return immediately, but engine power will not. It may take as long as a second before full power is restored. But chances are that you will have to shift again within that second. So on the track you will never have the power at your disposal that you saw on the test bench.
The efficiency of a common scooter CVT is about 10% worse than that of a shift box; it is caused by the friction of the rubber belt that must constantly be pulled from between the pully sheaves. Nevertheless such a CVT will give better results than a six-speed box in a comparable chassis. For racing, a steel transmatic belt like you'll find in several car transmissions would be the obvious choice; then a bike with a shift box could as well stay in the pits and save the petrol...

[jasonu]

Add to this that EVERY SINGLE tune up part, (with the exception of different weight rollers) come with the packaging "COMPETITION USE ONLY", yes, many people fit them on the road, however, this does not make them legal.

They are in no way eligible for buckets, I see no ambiguity in the rules that would allow this.

That pretty much ends the arguement (as long as it is true of course and I see no reason to think it is not) and makes all other 'Bucket application' points moot.