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[Brazilla]

I'll gloss over the fact these carbs are on a Ural and hope that someone may help out. I think even just typing what my issues are may help my thinking on the subject. The Mikuni seems pretty similar to the Mikcarb on my Enfield anyway!





For some months I have been trying to get the Ural tuned with varying degrees of success. I have lapped valves and checked timing/plugs etc, I have cleaned air filter and tested for vacuum leaks. my main bug I have never managed to get rid of is persistent popping in the mid range mainly through the carb, I have had a fairly nice idle going but this popping won't go away (it can bog the motor when throttle opened quick) and the WOT seems to never get full power.





Today after cleaning the carbs for the umpteenth time I experimented with different needle settings and discovered that the popping stopped with the needle clip in the lowest slot (this is as rich as it will go right?) short test ride revealed that low and mid range was great but top end still bogged down.





If it runs best in the richest setting the carb has I am assuming that means it is too lean. The top end from the main jet is not getting enough fuel to develop full power. This is my thesis anyway. I am suspecting either a fuel flow problem from the tank/lines or perhaps float level (although I have check that)




Thanks in advance, please correct anything that sounds like a faulty assumption.

[PeteF]

Mikarbs are Mikuni copies. It sounds like the top end is lean. I would try a larger main jet and possibly a larger needle jet if that is an option on the particular carb.

[Presto]

Agree with PeteF (as usual!) It does in general sound as if the carb has been set too lean. If the engine runs better when the throttle is eased back a little from wide open that usually indicates that the main jet needs increasing. Maybe a larger needle jet will also help, with the clip being moved up the needle a little to compensate.