1992 Triumph Trophy 900 problem

Hi all I have aproblem I thought some of you experts might be able to help me with,
I have a 1992 Trophy 900 which I bought as a non running project due to the faulty sprag clutch, I have replace the sprag clutch replaced the ECU, the ignition sensor, plugs and leads and one coil to try and get rid of the missing and unstable tick over, I rebuilt the carbs and now it is stable and running on three cylinders but it is having the odd pop down the exhaust and I can not work out what is causing it, if you rev it up it is clean but hold the revs at say 3000 there is still the odd pop down the exhaust the same as on tick over, I am sure there are no air leaks but I have not ballanced the carbs yet but they are close as I set them up on the bench for a starting point,
I did think valve clearance but it would pop and splutter on the pick up if that were the case which it does not,
Has anybody got any ideas Please.

Keith

 

Thanks ram I will do that next, thanks
keith

 

Ok I have ballenced the carbs and checked the valve clearance there are a couple of inlets that are very slightly tight but not enough to worry about but, the odd pop down the exhaust is still there but it might be a shade better, I am wondering if it could be a sticky valve but I can not prove it, I have just about run out of ideas now, do any of you guys and girls have any ?
Keith

 

Hi Ram, thenks for,your reply,
well I have never see that happen before it is good you found it,

Yes my carb float levels have been set and the carbs stripped and cleaned with good use of an air line for the passages, the mixture screws were set at 1 1/2 turns the same of a second set of carbs I have , but I do not have an exhaust meter but it smells about right
Keith

 

Hi all, can anybody tell me what the carb mixture settings are on the 1992 trophy 900 are please, they are currently set at 1 1/2 turns on each carb is this correct ??, I have replaced shims to get the valve clearance right but I am still getting a poping down the exhaust every four to five seconds and the mixture settings are all that is left to make sure it is correct.
Keith

 

Thanks for that ram, mine are about right then, this turning in to a real pain in the bum
Keith

 

Yep done that Ram33 but it made no differance I am affraid, I think I will have to play ariund with the mixtures and see what happens but they are a pig to get to without the special right angle screwdriver, the only other thing I thought and someone suggested is a sticky valve ? because it only happens every four to five seconds running at 1000rpm,
I do not know how long the bike has been standing, but going by the rear calliper in which the pistons are solid and will not move even with an air line or grips resulting in me having to order a second hand one, I would thing quite a while.
Keith

 

Oh thanks for that Ram I have ordered one, when I re set the mixtures yesterday I was able to do the two outside carbs just, but I could not do the middle one and ended up taking the carbs off to alter the mixture, not something I wanted to do, this tool should do nicely
Keith

 

Well THANK YOU all very much for you help, I opened up the mixture screws to 2 1/2 turns and the poping has gone and the tick over is now very stable, having got that right I can sort out all the other problems, I was worried at one stage because I can not keep pooring money in to it and I did not want to strip it down for parts as it is quite a good bike over all, so onward
Keith

 

Why did I noy think of that ram, what a good idea Thanks, I will have to go and buy a large raw bolt

 

what size is the raw bolt Ram ?
Keith

 

Thanks for that Ram I will have a look in b&q's,
I got the new calliper from Triumph ant this afternoon complete with master cyl and pipes and it looks almost new so that was a result but I re sealed it anyway