Hitchcocks Forum

The chain is due for replacement soon, I have an 18T sprocket now and I am thinking of going up to a 19T. I know the chain will have to be one link longer, so this seems like a good time to change the sprocket, but I am wondering if the engine will pull it up those long hills without changing down a gear. Its a 1999 500, Mr H's tuned head, free flow air filter and exhaust. Ample power now, but engine feels its running fast over (a genuine, not indicated) 55mph.

Hi Midge,

I'm not sure on your bike but when I changed to a 19T sprocket on my C5 the chain did not require an additional link. On the C5 there's is absolutely no performance problems with a 19T sprocket. I actually makes 4th gear a lot more purposeful; especially uphill the 4th gear pulls the engine to about 110 km per hour + on the speedo.

Hey Midge - mine's a 2000 500 and I changed to a 19 tooth sprocket a couple of years ago and it's been one of the best mods I've done. With a free flowing exhaust and air filter you should have plenty of power in top to cope ok. I also fitted Mr H's close ratio gears which, although a bit pricey, made third gear more useful, but even with the standard box you'll still be ok. Cheers. Tony.

Midge, going up one tooth will only shift the vibration range by about 3mph which may be all you need for medium cruising..

Problem is it can bog down a little on hills and your then forced to change down across that chasm to third gear and rev its nuts off, much as you do now..

Best thing i think is to convert to the close ratio box and include the larger sprocket, as per Riggers. Third becomes far more useful..

First is noticeably taller with a little extra clutch slip required to take off on steep junctions, also kick start ratio is altered slightly but there's always a trade off with these things..

All things considered i've been happy with the change, worth considering... Then you might want to upgrade to 5 plate clutch if you haven't already.. hey ho.. xmas comin

Gwilly, what is the advantage of fitting a 5 plate clutch? They use the same basket but fitted the extra plate in by making the fiber plates thinner, so they wear out quicker. If you have a reason as to why it is better I would like to know. I convert most of the 5 platers back to a 4 plate

Hi MIDGE----------as per the others----My 2005 Classic 500 has the free breathing mods with a suitable silencer to complement the set-up and I'm running a 19t g'box sprocket as well........ To my mind this is how the bikes should have been supplied for the Western market anyway...I haven't done the close ratio conversion just yet but others on here before all say the same as GWILI....Go for it !!!!

Norm, the clutch friction area will be increased by the extra plate[s], imagine if there was only one very thick friction plate and one very thick plain plate in the clutch, amounting to the thickness of the standard set up - you would feel just as much spring pressure at the clutch lever, but it would hardly grip at all. More plates = more grip, even at the same stacked thickness. Cheers, Paul.

Hi Paul that theory I agree with but apart from the fact the plates are thinner the fibers are also half the depth so if you did the maths on the square area of friction surface available I would say it is about the same or even less in the 5 plate

Hi guys------- NORM, the theory ( as I'm sure you know) is the greater friction area allows more power transmission and requires less clamping pressure, thus lighter springs and a lighter lever.....BUT (there's always one, eh ??) --- as the OE on the ENFIELD 4-speed box is more than capable of transmitting the usual upgrades and is fairly light in operation anyway, then I don't see the point of changing...For example, my No1 bike has the easier breathing carb----8:1 piston----de-restricted exhaust etc. and NO clutch slip at all at any stage of operation..... HOWEVER, with my 1980 TIGER 750, the standard clutch arrangement ---- even when fully oiled, adjusted etc. ----- is on the HEAVY side...So the extra plates upgrade, along with the softer springs, is very beneficial indeed.....On my previous T140 I fitted a Norton Commando diaphragm clutch and this is almost finger-light in operation...So much so that you can feel the point at which the pressure "fingers" go over centre.....Makes for a LIVELY start if you are not used to it.......!!!! Christmas on Bondi Beach this year then matey ?? Tinnies and a Burger ??--I'm in !!!!

---------Oopss, missed those last two postings.......It's all to do with the Co-efficient of Friction,the area of contact, the power being transmitted and the clamping pressure.................. Have a look at the variables in this calculator}----------- http://www.engineering.com/calculators/ ... mitted.htm -----------------