Hi. Any ideas why the revs should vary at idle? After a few minutes the revs will surge to 2000 or slightly more, then drop back to around 1300-1400. Then pick up again a while later...

I've just stripped and cleaned the carbs, but the bike used to do it before anyway. I'll try and get a video of it happening. But in the meantime I was wondering if anyone might know what could be causing this...?

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Hi minimoto, no expert but on the 24 common problems are, blocked jets and perforated rubbers that connect the carbs to the blocks. Air gets drawn in by the vaccum caused when the engine runs, the revs raise and then more air gets sucked in etc etc.

Also check that the circlips on the rubbers are tight. I had one missing! hardly surprising my revs were all over the shop!

Cracked intake manifold or more probably wrong carbs syncro. In any case something on the fuel intake side.

Minimoto wrote:Hi. Any ideas why the revs should vary at idle? After a few minutes the revs will surge to 2000 or slightly more, then drop back to around 1300-1400. Then pick up again a while later...

I've just stripped and cleaned the carbs, but the bike used to do it before anyway. I'll try and get a video of it happening. But in the meantime I was wondering if anyone might know what could be causing this...?

Sent from my Nexus 6P using Tapatalk

as above... likely an airleak / craked old carb rubbers / bad fitting carbs.

occasionally carbs can be well out of balance but most likely air leak if all carbs are set right.

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