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Rev4t Has A Hesitation Off Idle When Warm

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Guys, has anyone had a hesitation when their bike gets warm?

The bike starts fine. Easy infact. As i ride around the yard for balance practice the bike develops a hesitation and lumpy idle just as the fan is kicking in. A slight snap of the throttle has the bike slowly pick up ...and on the way back down to idle the bike will easly stall. I don't even rev the bike past 1/4 throttle. There is no missfire at low or high revs. It doesn't go away until the bike cools down.

I have two plugs and changing between the two makes no difference. I have tried the fuel mix screw 2, 3, & 4 turns out. I have drained the tank and flushed it out. The carb has been stripped, remove jets (standard), blown out and inspected 3 or 4 times. Float height is set to 13mm. I have a new fuel filter fitted.

Any thoughts?... and thanks in advance. Ralph

Hello NZRalphy,

I had also the problems, that my REV 4 went out after some time. Also it doesn't rev very high and it stuttered.

The reason i found, was that the ventilation of the tank-cap didn't work. Open the tank-cap a little bit (to let air in) and try it again.

German Munster

Edited by German Munster

  • Author

Hi Munster. Yes i have tried the bike with the fuel cap loosened. It made no difference. ;)

I had this problem, cured it by backing the mixture screw out 4 turns from stop, it's located front center under carb, they do make a tool to do the job, I made my own and used a little mirror to make sure I was getting the turns correct.

I think the stock setting is 1 1/2 turn out. I also found it didn't stall as easy.

When I called JL; they rocomended stock pilot, 112 main, mixture screw 4 1/4 turns out, fully lift needle clip on bottom setting.

Gday, have you checked your valve clearances? One tight one will do that.

Cheers,

Stork

  • Author

Nice one Stork. I'll check that as i adjusted the valves a few weeks back.

I have jetting changes this weekend - will report.

  • Author

The jettings changes done, as above, and all is well now. Because the fuel screw is now 4 turns out it really is rich at idle and just above. No choke needed now!

I'll get onto valve checking/adjustment this week.

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