Triumphrat

johnny5 · 08-30-2005

I have a problem. Can someone help. :???:

I was experiencing severe vibrations between 4 and 5000 rpm. I mentioned this to my dealer when I took the bike in for it's 6000 mile service and was told there was no problem. The problem persisted. I returned to the dealer, who, after a proper look told me the cam chain tensioner was not keeping the cam chain tight and needed to be replaced. I was told no damage had occured. The tensioner has been replaced but the vibration is still there, just as bad and now the engine lurches, unless it is being ridden hard (not too hard mind), at anything under 6000 revs. I will be taking back to the dealer this week, but if anyone can hint at what this problem is I may be able to enlighten the mechanic.

Many thanks.

banda · 08-30-2005

Cam chain tensioners are about the simplest devices on the planet. I'm always mystified when I hear about them failing or being defective. The tensioner is a spring-loaded ratcheting plunger that applies a steady "push" to the flexible cam chain guide on the back side of the cam chain tunnel. As the cam chain stretches with wear, the spring and plunger on the tensioner press the cam chain gide farther inward so that the cam chain does not become loose and jump off the sprockets. The ratcheting part is what allows a mechanic to retract the plunger so that you can slacken the chain and remove the cams. If the ratcheting mechanism failed, it's possible that the cam chain could slap around in the tunnel under heavy engine loads, and the valve timing could be compromised, with intake and exhaust valves opening and closing at some random deviation from specification. That's a possible cause for the performance and noises you described.

Assuming a second bad cam chain tensioner, they're pretty darn easy to replace... a wrench, a screwdriver, and possibly a special holder tool for installation. I've never used the special holder tool... I just keep a phillips screwdriver engaged on the plunger screw and "palm" it during installation. The labor would be very minimal.

But I would also be concerned that there is something wrong with your cam chain... it may be stretched out of specification. The only way to tell is to take the valve cover off and measure. An excessively stretched cam chain could conceivably lead to early and repeated tensioner failure, or it could be the sole cause of the problem... too stretched for the tensioner to make a difference.

Of course, the problem may not be with the cam chain or tensioner. Lots of stuff can lead to the lurches.

I hope your problem gets solved to your satisfaction.

Will · 08-30-2005

If it is a cam chian tensioner, it is the first I have heard of on anything other than a Honda. They had cam chain tensioner problems, and still do. Go figure. For what its worth, when I tore down my blown up engine to see what happened, the entire top end was fine, including the cams, cam chain, and tensioner. The cam chain tensioner is the last place I would look. Could a cam have been put back in funny when the bike was apart for valve adjustments? That would really foul things up, most likely up and down the rev range. A simpler place to look is the throttle body synch- that can cause rough running, even though I would expect more of a stumbling problem than a vibration problem.

johnny5 · 08-31-2005

Thanks for your help guy's, I will mention the thrttle body sync to the dealer (who should know this sort of thing, surely!).

I have been looking for a speed four, TT, inline four Haynes manual, or any other make of manual for that matter, and am coming up blank, any ideas anyone?

Thanks again

banda · 08-31-2005

Order the service manual from your dealer. It's a bit expensive... I paid $65 for mine, but I'm a tinkerer, and when I'm not tinkering, I actually kind of like to read service manuals... for the vehicles I own, that is.