I sit it on the centre stand and it will rev up and over 8500 rpm, no problem at all, but take it out on the road and it stutters at 5500rpm and will not rev past it...But then again it IS a TSS ho hum...
Mk2 Amals, fully serviced...no dodgy fuel. Could a coil break down under load on the road, but not whilst merely revving its nuts off on the centre stand I wonder....I have a brand new set of 'saved for a rainy day' Lucas original coils ..I don't seem to have a lot of luck with these German coils which abound..Certainly the ignition is bang on..But again would it behave perfectly on the centre stand if the timing was out? Fuel tank is clean, two sets of plugs tried and different HT leads..still stutters at 5500rpm. I was aiming for a 120mph attempt this year...made 115 last year..fitted rear sets and jota bars..It'll blow up..I know...I know....ho hum
Yeah, the coils can go on you. But you would think that there would be some evidence even unloaded. I had a bad batch of those PVL (German) coils and have much better results with the cheap Taiwan coils and the Original Lucas items.
Does it start easily and idle smoothly? Getting any blowby from the breather? I still would suspect compression.
When did this start happening? Is it progressive?
I agree, it could be the coils. If you rev it on the stand they probably don't get a chance to heat up much but once out on the road they may start to fail when they get hot. Otherwise it sounds like a fuel related problem as you seem to have eliminated the plugs which can misbehave under load.
Can you tell if it is just one cylinder having the problem?
I'm with kadutz. Once you know where the advanced timing mark lines up, you can re-time them at idle (make a note of the needle alignment at idle just after setting the timing at revs) and just CHECK the advance if you think it's dodgy later.
I'm surprised you haven't launched a rod through the barrels!
It probably is missing while free spinning,but is not noticeable with no load. Bad coils can definitely cause the symptom you describe. Coils have to work harder to produce a spark at higher cylinder pressure.
Higher RPM + higher load= higher cylinder pressures.
What do the plugs look like? I'll bet it's running too rich. That'll make it sputter at high RPM too. All that cooling gas going in there is probably all that's kept it from blowing up, free spinning at 8500 RPM and all! :tongue:
When I say revving to 8500, what I mean is that the bike freeely soars past 5500rpm and easily will for a split second hit the red. Now remember this is a TSS NOT a T140, so we have proper balanced cams and a crank to die for, sadly we also have oil leaks to mop up but these bikes do like to rev and are in that respect nothing like a T140..They also blow up, but this is due to liners slipping or valve seats dropping generally, however, the stubby conrods are sound, the crank superb ...
They are alot like that little girl::When she was was good, she was very, very good...but when she was bad...?"
It's to the coils I shall look then...I'll get back to you later on..
hames,just get on and ride the rocket.its ok for when your proper bike is broken.and dont mess with the rocket fuel tank.makes the tank show empty when its full boy.so,did you find what was wrong with the rocket?
my bonnie has a leaky tank at the moment.the leaks on the top seam.filled it with that plastic metal stuff.i wished i knew about the leak before i sprayed it all in three colours with coach lines cos its now all peeled off.
i have to put up with riding the rocket for a few days.
the tank lining paint is useless.this plastic metal stuff is great for petrol leaks.i glued a broken float bowl with it and it was still ok when i sold the outboard motor on
The 71 tanks leak because they pump out and back with the vibration. The later tanks had a strap connecting the two sides. If you have the tank off and are "fixing" it, I would braze in two inserts to hook up one of these straps. Look at the underside of a T140 tank to see what I mean.
It couldn't hurt to just make sure that the carb needles have their clips secure and in the right grooves. This would cause problems at mid-range and then clear up at full chat when the needles are all of the way out of their jets.
hi meccanica,i know the strap you mean across the front of the tank.my other usa tank leaks from the bottom so i have to repair that one also.tank sealant seems to be no good on my tanks.i will see how long this plastic filler lasts.did you realise that the 71/72 tanks fetch about $300 over here in the uk?if you visit,bring a few over.1959 era mudguards fetch about $2000 a pair.and 59/61 bonnies are around $20,000.you guys around the usa are getting bargain bikes boys.oh,and the 69 bonnie is around $11.000
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