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Hey guys, I bought this bike about a year before, after my previous one got totaled in an accident. This one proved to be quite a good purchace. It is overbored with 60mm pistons (I found out after it blew the head gasket) Anyway, the old bike would go much more than 180km/h with an unrestricted cdi, but this one won't. In 4th gear and about 182-4 km it misfires before it reaches the rev limiter. If i shift up, the revs just go down. What could possibly be the cause? I have changed the cdi unit, but, no defference. I have also taken out the tacho cable to go for a change but nothing. I measure the speed with an onboard gps. thank you in advance for your time and knowledge.

Hope you mean red line - no wonder your blowing head gaskets if your hitting the rev limiter every gear

Still sounds like a speed restriction as that is set at 180kmh , from memory it wont go past 8k revs in top gear or as soon as you hit 180 in 3rd and beyond it will kick down to 8k rev limit.

Hmmm, bad going to the rev limiter eh .... Anyway, yes, rev limiter is what i mean, a bit into the red line. the head gasket was blowing because the previous owner must have had a problem and replaced the gasket with a stock one, with 57mm piston holes. I bought a new permanite one with the right diameter for the pistons and never had a problem since. much more robust than the stock one. I am troubled about the speed not going more than 180 because I have changed the cdi to an unrestricted one (with the letter M). Also the speedometer isn' t connected to the wheel, just to the electric circuit, so the bike is not limited at 10.000 rpm.

Something mighty strange going on there then.

Yes indeed I 'd say. I just discovered that the plug of the regulator rectifier is in pretty bad shape. (seems melted) Also there is a fuse hand installed on the plug. could the cause of the problem reside there?

If you have a UK CDI box then it matters not that the speedo is connected either to the wheel or the loom....................with a UK CDI box the 110mph Japanese market restriction is GONE


You would appear to have a host of other issues.

Could the source of the problem be the regulator?


Just removed the regulatetor rectifier. seems to have melted

regulator could have been struggling to supply the battery with enough juice at high rpm, causing it to miss and feel like a limiter?

I was thinking that is possible for a short circuit to be causing this behaviour. I cannot think something else to be the reason....
Changed the regulator. Bike runs better now, still can' t go more tha 183ish.

Well guys, I don' t know how much of a future reference this topic will recieve, propably none I measured the bike on the road with my gps again. this time the bike achieved 185 km/h , and could maybe go more if I didn' t close the throttle. After I changed the regulator the bike runs much smoother. Thank you for your time and your thoughts.

its still slow, mines an almost standard road bike and does a gps measured 205km/hr, have you considered a dyno run to check the fuelling, and see if the operator can reproduce the fault?

The dyno was my first thought, but it is pretty expensive. I have a quad of 34 cvk carbs from my old bike, so, anytime I have some cash, I am going to repair the carbs, installl them, and then the bike will be on dyno for testing... but it is a long plan.

May I ask, is it possible to experience power loss because of valve clearances? My valves are all very tight. Especialy the inlet valves. the 0.05 feeler passes in only two of them.

yes, check/replace the shims as necessary, check the camchain, tensioner, and tensioner blade and replace as necessary.

Cam chain and tensioner were all good, replaced the shims to have the indicated by the manual clearences and the bike is much different now. much more full in midrange and far more responsive. big difference I 'd say. Thank you for your time and advice. when I go for top speed I 'll let you know about the results. I think it is going to be more than 180ish. I hope sso at least