Bike revs up and down

[calvinTZR2503xv]

Hello all. I have just had my 3xv motor done, everything is going well, but there seems to be a problem with the revs , when idling the bike idles at 1500 or 1000 but then all of a sudden it goes up to 3000 when idling, so it gets to top revs too quickly before at max output, then it will drop back to 1500 rpm...please can someone explain what going on?

[calvinTZR2503xv]

Hi there....anybody got any ideas as to what is going on? is it the carb?

[Warwick]

Intake air leak or just poor set-up perhaps? Check the condition of carbs, clamps, vacuum hose etc., Check the condition and tension of the throttle cables and clean the pilot and choke circuits maybe? And re-set tickover, air screws and cables to see if it's something simple like that. Worst case scenario would be a crank seal, but simple poor set-up or air leak are much more common causes.

[calvinTZR2503xv]

ok thanks, will check where the carbs join to the airfilters...last time there was a similar problem it was that the airfilter was not on the carb properly and it was sucking air direct into the carb...will that do that

[Warwick]

No, it's only really induction air leaks between carb and motor that could be the problem. The carb needs plenty of air air into the bellmouth so a poorly fitted airbox generally wouldn't have that kind of effect. If you are not confident with this kind of maintenance stuff already or have a strong desire to learn about it, you'd probably be better off taking it to a mechanic though as it's easy to make things worse if you don't know what you're doing.

[calvinTZR2503xv]

Thanks a lot Warwickb, but this idling up to 3500rpm when in neutral problem is very irritating, the guy that worked on my bike says its a dry joint problem, does that make sense, what is a dry joint anyway? like i said i can be riding and all of a sudden the problem will dissapear and the revs drop down to 1500rpm as it should, then i can get the powrband etc, when the revs are up to 3500rpm , it doesnt reach powerband and with the accelerrator open half way it wants to go past 12000rpm without reaching powerband?? what is this problem

[Warwick]

The problem could be many different things as indicated above, Calvin, so it's impossible to offer a simple diagnosis here. If you don't feel that you can strip, assess, repair, rebuild and adjust the carbs and cables (and maybe the motor itself) yourself then I'd suggest taking it to a mechanic who can give you a more accurate diagnosis than to suggest a 'dry joint' problem (no, I've no idea what he means by that either really... Maybe he's suggesting it's a cable lubrication issue?)   

[ash33]

Revs increasing by them self usually means a lean condition in the carb jetting. As Warwick says  it's most likely a air leak around the manifold boot(where the carb fits to the motor) or between the carb and the engine somewhere.
Other options are cracked rubber manifold which would make it hard to start as well.

[Warwick]

I seem to remember Wullie had a split boost bottle (the black plastic 'resonance chamber' thing that plumbs into the top of the reed block rubber). They're made from cheap moulded plastic and Wullie's had split at the seam as I recall? Worth a look-see while you're poking around I'd imagine. Chceck the fit into the rubbers too and that clips are fitted. 

[calvinTZR2503xv]

Thanks a lot it seems everyone is saying the same sort of thing, will have a someone have a look at what everyone has said, hopefully we can sort this out, irritating cos bike wont peak through each gear, jst flat and wants to rev through the clock, cant wait to get back that powerband for each gear. Will keep updating here with news ....this is really a great site where everyone is so helpful.

[calvinTZR2503xv]

Sorry just one small other thing, very small but irritating, the powervalve on the left side below the tank is leaking oil, when traveling at speeds the oil sprays out onto my leg, now I don’t have a a pair of jeans without oil on the one left side. What solutions are there to sort out this problem, like I said it a small but damned irritating problem???

[Marty stinkwheels]

That sounds like a very bad leak from the seal around the power valave, I have never seen them spray oil out of there, only thing to do is replace the seal, also check the stem of the valve for wear.

[calvinTZR2503xv]

Sorry I feel that I may have explained myself incorrectly before, I am going to try again to be as clear as possible. Whilst riding my bike everything is fine,  revving is normal , power band is normal, speed in top gear at 9000rpm is 150kph, then all of a sudden whilst riding, it suddenly changes, it now wants to rev up past 12000rpm but now speed in top gear at 12000rpm is 130kph, its like whole powerband falls away and also the engine sounds spluttering and has a different sound all together. Then maybe a day later whilst riding it can all of a sudden go back to normal. I have been told this has to be an electrical problem, please can anyone offer any ideas , and if this is electrical can someone please help me with a place to start looking, thanks a lot, I know I have been going on about this problem , but I feel before I want clear, but now hopefully it is more clear...

[wullie3XV9]

Sorry I feel that I may have explained myself incorrectly before, I am going to try again to be as clear as possible. Whilst riding my bike everything is fine,  revving is normal , power band is normal, speed in top gear at 9000rpm is 150kph, then all of a sudden whilst riding, it suddenly changes, it now wants to rev up past 12000rpm but now speed in top gear at 12000rpm is 130kph, its like whole powerband falls away and also the engine sounds spluttering and has a different sound all together. Then maybe a day later whilst riding it can all of a sudden go back to normal. I have been told this has to be an electrical problem, please can anyone offer any ideas , and if this is electrical can someone please help me with a place to start looking, thanks a lot, I know I have been going on about this problem , but I feel before I want clear, but now hopefully it is more clear...

Clutch slipping & revs hitting the rev limiter ? ? 
And yes, my R/H cylinders boost bottle had a split the length of the underside seam which caused some agro !

[peterbike]

 I'm not a mechanic but it sounds electrical. The dry joint he was talking about  is a bad solder joint (looks ok- but) Do you have a spare CDI there ? Or if when it starts running bad , watch an see if the exh. power valve is working,  etc.