Let's talk this through! With your 21T you got no less than 19% increased rear wheel torque over your 25T, with your original motor. You get the same benefit with your 131, although I can imagine it likes to look at the sky! If you put your gearing back to the stock 25T you will lose the benefit of the increased torque from gearing, although your 131 should more than compensate for that. However as you increase gearing further you risk damping down the performance of your new motor. Going from 21T to 27T reduces rear wheel torque by 28%.

Do you have torque figures for your original motor and 131 at say 3,000rpm?

 

Hi GTbrown,

You mentioned in an earlier post about MG and superchargers, my friends uncle Brian runs this garage http://www.dreadnoughtscotland.co.uk/supercharger.html and is a specialist on the subject. Ive been in his supercharged MG and its unbelievable, pulls clean from 500rpm in top ! Definately something to save up for.
Anyway, sorry to go off topic.
This lower gearing sounds perfect for the UK roads, have got to price it up. Did you scource parts from the States or can you recommend a supplier in the UK ?
Regards,
Jeff

 

Does your 6th gear light still come on?

 

Hi Jeff, I do know about Dreadnought and my MG would be a prime candidate for one of their supercharger kits. Unfortunately they ain't cheap! They use a kit from the USA, which I researched a few years ago. Fits under the bonnet (hood for US readers!) with no visible mods and very tempting.

As for the 21T kit it is an SE kit and comes with compensator and shorter chain. It was sold for converting TC88s for the drag strip. I don't know if it is still available. I got it supplied and fitted by a local dealer, although they have closed down since. We have recently sold the bike and the new owner seems pleased with it!

Roll-on acceleration in top gear is quite something, also normal road speeds are above the annoying vibration patch it had around 3,000rpm. Gearing is around 20mph/1,000rpm. Well worth trying to hunt down if you can find one. I understand the compensator also fits Evos, which may widen the net.

 

this is the link of the 95 stage 3 before the 131. http://i203.photobucket.com/albums/a...2007/dyno1.jpg

the power is day and night as you pointed out, the thing is that at 70mph she is turning 34k rpms and I am so worried of harming this motor. Even with the cooler she gets hot and I cant afford to rebuild this motor again. I am geady to baby it as much as I can. That 21T was great in the 95ci motor but this 131 seems to make those gears super short.

 

Boy, those 95 numbers can't be real. They are uncompensated to either SAE/STD data references. Very optimistic... The built up 95 I had (stage 4 with cnc heads) was in the low 87HP/98tq SAE corrected. I'm having a hard time believing 114hp/120tq on a 95


In any case I once had a 23 tooth on my primary and it was plenty low geared. You were done in 1st before you even thought about it. In 5th going 70mph it would turn at least 3.4K. However, in twisties all you mainly needed is 4 & 5th. I put the stock 25 tooth back on and I thought it was perfect. More shifting in twisties, but smoother.

Now with the 120R, its kind-of acting like the 95 with a 23 tooth. Wouldn't mind going up a couple teeth on the trans final. Maybe a 33 or 34. It gives more load in the lower gears, The funny thing about the HD 5-speed (which is what I have) the relative ratios change between 3rd and 4th. 1-3rd the stay close or even a bit lower than the 6 speeds. At 4th they become higher and 5th is between 5 and 6th on a 6 speed. Because of this I am researching 6 speeds. either one of the Bakers or a HD 6 speed upgrade. Should give better ratios across the range. Then maybe the high final too...

 

Your 131 is not turning any more rpm than the 95 was, however I can understand that with the extra performance it must give your 21T will seem way too low. Personally I would put back on the 25T, but as I said earlier any more will steal the performance you paid out for.

 

most well build 95ci stage 3's should do 100/100 easy. A 88 ci motor with a tunner, cam, heads and a good pipe should do 90/90 SAE.
The bored throttle body, performance baffle in the D&D Fatcat and the custom 575 cam just worked great togather. The 114hp 120TQ is in the STD mode, its more like 110hp 114TQ SAE.

 

this is one for a late model HD, Evolution 30 Tooth Motor Sprocket Kit EV-1012-1231 Harley Davidson for less than $300.00 off line more at a HD dealer..it should not take more than a hour of labor to change..

 

in some kit's you will lose the 6th gear indicator light, but if you have the right tuner you can fix that, TTS MASTERTUNE TUNER.