Took a trip to see Tubbs at Moorespeed today for S1 day (mine, OF's and Mev's were there) and to pick his brains for setting up my S1.

We tinkered with the (Mikuni) carb and (Dyna 2000) ignition, and went from about 91bhp to about 95bhp (DIN corrected on the Dynojet). I think there was probably another hp or two waiting for me if I had had a 167.5 or 170 main jet. Would have also liked to pull some of the fuel out between 4 and 5, but had no smaller accelerator pump nozzle to try (nor time)...

Unfortunately the dyno ignition pickup was a bit shite, so I have had to use Excel to create my plots (if anyone knows how to modify the WinPep files so I can convert wheel speed to engine speed and hence calculate torque, let me know )...

Quite pleased, cos that is nearly 5bhp more than my Firebolt. Not bad for an S1 on standard (1996) cams

Piccies here for those who are interested. Runs were quite repeatable, however I have chosen the best of each configuration for fairness. I might do a blow by blow account, of what we did and what we saw, over the weekend...

Anyway, thanks to Tubbs for his time and knowledge (and lunch)...

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08 Specialized Langster

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Feros Ferio

Sorry I didn't make it down today Pash. I've had the 'Quickening', trying to get all the last minute jobs done today whilst being faffed about with flights etc. Calne is looking decidedly dodgy for me too. May be going to Aberdeen tomorrow or early Sunday now????

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I'm a Hornithologist, I get excited by exotic birds.........

I claim my prize. Looking at the runs I was spot on with my predictions 91bhp and the torque to be the same as last time but not tailing off when the revs rose above 4500 like it did last time.

Nice that you picked up 4 bhp by going up a jet size. liking the torque curve and good BHP increase as well.You have to be pleased with that.

Did you have the mikuni when we did the dyno runs at Blakemore's?

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Buell S1
Buell S3 (Topless for now)
Buell XB12S
Piaggio X8 400ie
Yamaha XTZ750 Super Tenere (x2)
Suzuki GSXR750WR
BSA B441VS
FJR1300

But with the increase in BHP it will be Morespeed

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I'm a Hornithologist, I get excited by exotic birds.........

Just been reading thru your dyno stuff nick with more than a little intreague.
My S1WL has a force winder into a HSR42-11 with a V&H 2.5" collector and can.
The carb has 160 main jet with a size 97 needle. I don't have access to a dyno. However I do have a 165 main jet and am now thinking of giving it a try, them extra 4 horses would make it a 404bhp monster with a shiny oil filter.
But seriously what do you reckon worth a go?
Tubbs you got any thoughts
Rich

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Buelling is exhillarating
But downhill bike racing is so terrifying it makes your arse grow teeth

404 bhp?
go for it

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Buell X1
Buell xb12s
Buell 1125r
Ebr 1190rx
Bimota Db7
Norton v4rr??



http://www.aph-performance-engineering.com

295 of it comes from a shiny filter apparently

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Buelling is exhillarating
But downhill bike racing is so terrifying it makes your arse grow teeth

_________________
Buell X1
Buell xb12s
Buell 1125r
Ebr 1190rx
Bimota Db7
Norton v4rr??



http://www.aph-performance-engineering.com

Interesting stuff here regarding ignition. Some time ago, I bought a Dyna 2000 DD2000-HD1E8P ignition module, the same box as a Screaming Eagle 32654-98.

The box has four advance curves and four rev limiter settings. See diagram below.

I had put it on from time to time but I didn't think it made much difference, and if anything it ran worse (I would have been using it on curve 1). The TubbsDyno was the place to learn the truth...

The instructions that come with it suggest you use the most advanced curve that doesn't give you knock. The results are below.

28 Curve 1 (most advanced)
27 Curve 2
29 Curve 3
30 Curve 4 (least advanced)
24 Stock (just like curve 2)

Results show that you can get a nice 15% power gain in the midrange (just right for overtaking) by retarding the ignition.

Curves 3 and 4 are indistinguishable, however as anyone who works in calibration will tell you, always pick MABT (minimum advance for best torque)... Curve 4 it is then...

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08 Specialized Langster

Dunno, you have those posh Thunderstorm heads, whereas I don't. I also have longer headers than you. We are only looking at small differences and our configurations are quite different (apart from the carbatoota and the cams). If you put the 165 in, would you be able to tell the difference? TBH I think the 165 gave me more power at the top, but took some out of the mid range where it appears to run richer. The mid range is the most important area for me (for wheelies and overtaking) and I only get that back with the more retarded ignition curve...

Next to try is a 98 needle to try and get 130 miles from my small (but beautiful) tank.

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08 Specialized Langster

very interesting
but seriously what are these carburettor things you speak of?

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Buell X1
Buell xb12s
Buell 1125r
Ebr 1190rx
Bimota Db7
Norton v4rr??



http://www.aph-performance-engineering.com

Tis the work of the devil...

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08 Specialized Langster

Have you ever tried altering the lengths of the inlet tracts to alter where the power is made? Longer tract, low down pulling power, shorter tract, more top end, plenty of gains to be had in the tract department....

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Spencer Racing... www.spencerracing.co.uk

So I have pulled together some plots to show the effect of the main jet only change.

04 is with the 160
12 is with the 165

So the increase in jet size is worth 2bhp at the top at the expense of 2bhp in the mid range. We are now seeing the constraints of a carb.

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08 Specialized Langster