classic motorcycle forum

Motorcycle Discussions => British Bikes => Topic started by: Oggers on October 20, 2018, 05:35:57 PM

Title: Triumph torque
Post by: Oggers on October 20, 2018, 05:35:57 PM

66 Bonnie engine has been fully rebuilt - not by me - 500 or so miles ago. The bike is in excellent order throughout, but I haven't checked much just yet - preferrring to ride it at present, but I changed all lubrication oils last week. Once more, I feel I may be somewhat paranoid here so apologies, but it does "feel" somewhat reluctant to open up much above 3500. I have deliberately kept it below 4000 so as to allow things to bed in, but I would have thought by now things would have started to loosen up a bit and for the bike to "feel" as if it could at least reach 90 mph if required. No smoke, no rattle, no hesitation... Am I being impatient? 

Title: Re: Triumph torque
Post by: antoni on October 20, 2018, 09:10:40 PM

I bought the earliest version of that bike - when it was a 350 - and had a similar experience. It went well but did not seem to develop enough power at full throttle. Climbing a long hill it seized. Long story short, the main jet was much too small and it therefore ran with very high combustion temperatures when the throttle was fully open or close to.

During the rebuild that fact came to light.

Went much better afterward.

Title: Re: Triumph torque
Post by: TGR90B on October 20, 2018, 10:02:06 PM

Sensible reply. The plugs should give you a clue. If it is weak there could be several causes.

Title: Re: Triumph torque
Post by: iansoady on October 21, 2018, 09:55:10 AM

I always err on the large side for main jets as too big just soots plugs, too small - well we all know........

I always leave main jet till last (unlike the official Amal instructions) as if it's too big all the other tuning instructions are still valid and will give you a bike you can at least start and ride.