ESE's works engine tuner

[Frits Overmars]

I know it doesn't answer your question, but when TeeZee tested his 24 against a 30 in a back to back test. The 30 didn't make anymore power than the 24 and so he thought that meant the 24 could do better yet as it must be something else holding the engine back.

I would think so too. Take a look here: http://www.youtube.com/watch?v=ju2X9...ature=youtu.be
That's a 50 cc engine with a 32 mm carb. Over 20 rear wheel HP, outstanding throttle response (it lapped the entire field on tight kart tracks).
But don't be deceived by the video: this is a reed valve engine! There is a rotary prototype version that gives over 1 HP more....

[wax]

Thats impressive

[wobbly]

Remember TeeZee I said agaes ago that I doubted that the 24mm carb would end up being the final restriction to power in the 125 Aircooled.
Based on the fact that 125 kart engines make mid 40Hp at the sprocket, low 40s RearWheel using a 30mm.
I would say that untill you have a cylinder that replicates the scavenging efficiency of the Aprilia, then you have plenty of work to do without worrying about the carb or CVT technology.

[TZ350]

Yeah i was surprised..... but then thought, well everything else on the engine was optimised for the 24mm carb anyway. I then assumed it was not really persevered with either. So how many runs and combination were actually tried?

The inlet from the manifold rubber to the rotary valve port and the port itself are optimized for 31mm. Both the 24 and 30 carb taper out to 31mm on the engine side.

The 24 has of course had a lot of dyno time. For the test the ignition and everything else was left the same as the 24 but the 30 ran reasonably Ok with the 24's jetting and was given sufficient runs to find the main jet that gave best power.

Interestingly the 30 required a much smaller main jet than the 24.

[Shorty_925]

The full set of results from the 1st round of the Pacific Club North Island Series and the Two Hour including lap times.

Do you have the b-grade laptimes from Saturday's racing?

[F5 Dave]

. . .Interestingly the 30 required a much smaller main jet than the 24.

Which makes me wonder if the test was repeated with another air jet/main combination? just a thought.

I'm still confused by my 24, 26, 28mm mikuni flatslide tests on my 1/2 piston port 50, where the 28 outperformed every carb (manifold was 26mm for test), 24 almost made same peak & 26 was worse everywhere.

I had hoped to find a kart track small carb setting & a long track carb. Just proves testing is always required. Something it didn't like about the 26 despite trying mains up & down. Piston port/ reed meant it wasn't particularly matched to a particular carb size.

In the end pwk better all round so a mute point.

[TZ350]

Do you have the b-grade laptimes from Saturday's racing?

Down load the PDF's and I think they are on page two.

[TZ350]

Which makes me wonder if the test was repeated with another air jet/main combination? just a thought.

It wouldn't matter as far as max power was concerned, as a mis match between main and air correction would only mean that it would be mixture correct at one end or the other of the power curve but not both. And by adjusting the main you can force it to be correct at the top for max power.

Optimum main jet and air correction will have the mixture pretty good at both ends.

For the test I was only interested in max power so fiddled about with the mains on the 30mm carb (which had been fitted with the 24's jets et all) until I found the sweet spot and as luck would have it, it looked good through the whole range.

I think the telling thing is the torque curves, they overlay each other very closely, and that suggests to me the engine ingested and retained the same amount of fuel/air whether it was running with the 24 or 30mm carb and this points to the scavenging of combustion products and retaining of fresh mixture as being the real issue at this point and not the carb size.

[Shorty_925]

Down load the PDF's and I think they are on page two.

only 1 page per pdf.

[TZ350]

.... looks like I have made a bit of a blue and only have the B grade superpole times, sorry.

[TZ350]

... I doubted that the 24mm carb would end up being the final restriction to power in the 125 Aircooled.

Yes it looks that way.

[F5 Dave]

It wouldn't matter as far as max power was concerned, as a mis match between main and air correction would only mean that it would be mixture correct at one end or the other of the power curve but not both. And by adjusting the main you can force it to be correct at the top for max power.
. . ..

Yeah that's what I thought, but that doesn't explain why my 26 was worse everywhere, perhaps in a finikity (peaky) 50 it wouldn't pull through cleanly if the initial air mix was so far out. A result isn't always conclusive, one has to consider if there was an issue with the question or the test plan. and maybe there isn't.

[TZ350]

For those interested in such things, its not the top gear ratios that make the GP gearbox difficult but the lower ratios. 1st and 2nd are to low for an already geared down bike on a tight track.

An early 5 speed TS gear box can be modified to fit a GP by shortening the clutch input shaft and modifying the GP gear selectors buy building two of them up on the outside of the forks to fit the sliding dogs and opening up the ID of the other to clear its dog.


Red Line is the standard Suzuki GP125 gear box.
Blue Line is the standard Suzuki TS125 gear box.
Purple line is the TS Box with modified gears, the different size gears can be made to fit by modifying the shape of the teeth.

A std TS gearbox suits a GP very nicely on a long track and a modified one works well on a short track.

[Buckets4Me]

Are you kidding hole-shots is what the cvt will give you.

The cvt is a weapon off the line. We were up against 85cc cr powered race bikes. You would holeshot them from back on the 2nd row.
I know mount wellington track I used to race kt100s on there. The cvt anillate will the gearbox bike into the top corner and you will end up playing from then on in.

You have to remember that you tune the cvt for the power of your engine so it will do both haul out of corners as well as off the line.
You can hold your engine on its power peak the entire track and at any speed if you can make the corners.

Your sitting on the power peak the whole time. If you tune a cvt wrong its easy to hold it on it the down slope of the rising slope as well and make a 30hp engine go like a 5hp engine if that where your holding the revs.

It would go great on the long tracks you would just have to change the sprockets on the chain. But that would be the same for the geared bikes

http://www.youtube.com/watch?v=x3UpBKXMRto

Awesome in the rain due to the smoothness as well. And it is new zealand after all. its going to rain

thats the problem you cant make the corners at Mt Wellington ( I can do 26's in a 125 rotax cart) but only manage 35's on the bike)
as for hole - shots I dont think TZ is all that bad at it. But the clutch gets a hiding

[cotswold]

Do you have the b-grade laptimes from Saturday's racing?

32 seconds or there abouts, bit disappointing as I had 30 bhp to play with ( do late 31's on Johns standard fxr )