Hitchcocks Forum

Since I will shortly have two road-going bullets, I'm giving some serious consideration to converting my old faithfull 350 into a classic trials machine on the cheap (as in for doing a classic reliability type trial rather than riding over boulders on a classic bike).



The one thing putting me off is the clutch and its likleyhood of surviving a stupid hill restart. Even as it is, when it gets hot it tends to get grabbier and grabbier. I can see me being the subject of an humerous youtube video halfway up some godforsaken muddy hill in driving sleet, stalling the thing on a stop/start, having to kickstart it on a 5 in 1 slope then being unable to get a gear (this pretty much happened when I went for a ride along with a local vintage tractor run with my trailer on last summer).



Thing is, people DO do trials on bullets (even the riding over boulders sort) so it got me thinking about what I should look at doing with the clutch and I suppose the first part of that is thinking about WHY it gets grabby when hot. The lever comes closer and closer to the handlebars.



So the pushrod, that'll make it stiff if it expands through heat but shouldn't that make it slip, not grab? I can fit a ceramic ball bearing in the rod to reduce heat transmission in any case.



So are the plates expanding or what? One thought I had was to use a different lever with a longer "swing" to get larger seperation of the plates. It turns out, a GPZ500 clutch assembly with the adjuster screw removed bolts right on a bullet with the standard cable.



I know the ultimate solution is to get a Newby clutch but that's really the nuclear option, If I'm getting one of those, it'll be going on the 612! I'd rather do some sensible engineering solutions to the existing clutch. This then leaves the option of carrying a spare set of plates from my bucket full of part-worn bullet clutch plates on a trial without needing a second mortgage.

How old is your old 350. There are plenty of upgrade clutch parts in our hosts catalogue.

Pretty new, I call it "old" because it had a hard paper round. It's a 2007 with a 4-plate clutch fitted.



There are many things you can buy. I suspect most of them would do nothing useful to prevent a hot clutch grabbing. They mostly seem aimed at preventing clutch slip.

Speaking from experience, using a cheap oil will turn it into a type of lacquer at very high temperatures, which will stick the plates together. Use Automatic Transmission Fluid, it can stand higher temperatures. I have posted this a couple of times in the past.
http://www.snowvalley.20m.com/bikes/clutches.htm

I have never found a genuine fix, trust me I tried every trick I could think of, too many flaws in the design, not allowing enough lift on the plates. I have 9 springs in my Inter clutch and to get it to work I have to adjust it up when I get into traffic, and back it off when not in traffic and it still slips, so I just back off when it slips. I fitted a few Newbys and they solve the problem

My clutch (2004 sixty-5) was a bit sticky. It was much worse with a hot engine. I adjusted everything to no avail. Then I looked closely at the handlebar lever. It looked fine but the END of the lever touched the bar at max travel. I heated the lever and bent it a tad. To the eye it looks just the same, but now the MIDDLE of the lever hits the bar first so there is a little more travel. This has helped no-end. Still not perfect though, a bit more travel would help.

In the mean time I notice that the slack in the cable increases as the engine warmsj. Until I sort it, I take some slack out of the cable with the handlebar adjustment after the engine has warmed up a bit. I let it out again when the engine is cold - i.e. before I set out on a ride again.

I don't know about yours but a lever with more travel would sort mine. I'll do a bit mote metalwork on it over the winter.

Just a thought, have you got thick chunky handgrips fitted? They would reduce travel.

I have a 1965 Bullet engine in my classic trials / greenlane bike and do not have any problems with the clutch. I don't do the tricky riding over boulders type trial so the clutch doesn't get too much stick.

I use cheap and cheerful Indian clutch plates and the rest is a bog standard 62 year old RE clutch, although it only has three clutch springs rather than the usual six.

I think all Enfield clutches get hot and bothered if you stay in gear too long when stationary, such as traffic lights, but the stop and re-starts on classic trials are only brief affairs and are not likely to upset the clutch.

Aethelric: As stated above; replace the steel ball with a ceramic ball between the rods, this will lessen the expansion and contraction of the rods and might help with your constant adjustments when the things get hot and cold.

If you are still on standard road gearing, you may be over using the clutch off road causing it to get hot and drag etc.

Use the neutralselector lever as you slow down, no more sitting in 1st with the clutch getting hot, that is what its there for.