Idle jet problems

[wheeliepup]

I?ve got an ?85?Max (California model) that?s giving me carb problems. It seems like the problem is in the idle circuit because the # 1 Cyl is not firing (cold Exhaust, intermittent popping out the exhaust) during idle. I have removed carb rack twice and thoroughly cleaned it yet I still have the same problem. Being impatient, I then decided to purchase a set of ?94?carbs off eBay (lower 48 model)?cleaned them ? synced them and now the problem has moved to the # 4 cylinder. I have done just about everything ?Cleaned block jet and idle jet, replaced idle air jet, adjusted floats, you name it! My question is, could these carb bodies be trashed for some reason, and if so can they be repaired? On the ?94? carbs, I noticed that the butterfly valve plate was removed from the problem carb. I think the guy who sold me the carbs knew there was an issue. I thought about swapping the carb bodies around but I prefer to keep things original. Has anyone else had this problem before?Any suggestions ??

 

[wheeliepup]

Found the problem, someone had drilled the orifice in the slide to a larger diameter. I repaired it by inserting a brass tube with the proper size orifice. problem went away. The second set of carbs had all of the slides orifices drilled out which is why it would not run worth a crap! I believe that those who installed a stage three dyna jet kit had to modify their carbs by drilling out these slides and one of those slides just happened to find its way into my carb...Alls good now!!

 

[kaboom]

Thanks for the update!!!:clapping:

 

[one2dmax]

Drilled slides are normally fine with about any carb setup. BUT, you don't want one that way and the rest not drilled.

Sean

 

[wheeliepup]

The factory holes that are on the bottom side of the diaphragm slides are there to meter the amount of vacuum created in order to open the slides a certain amount. You can kind of consider this as a calibrated leak and took some engineer and special equipment at the Mikuni plant to determine its proper diameter. Although I'm not am engineer, I am pretty certain that these holes should not be F%@ed with or you will more than likely have a noticable change in performance. The larger the hole, the longer the slide stays closed (less fuel and air to intake during higher demand).

 

[one2dmax]

The larger the hole (and softer the spring) the faster it opens up (less restriction to movement for the air to move from the front side to the back). It will open up slightly earlier with the drilled hole and a more rapid rate. This is why it's drilled out for most jet kits.

Sean

 

[wheeliepup]

Good point...makes sense! But you know what that means don't you? Now I'm going to need to disassemble the vacuum slides to check the softness of each spring. !!! Crap, more disassembly!

 

[Jayhawk]

Good point...makes sense! But you know what that means don't you? Now I'm going to need to disassemble the vacuum slides to check the softness of each spring. !!! Crap, more disassembly!

Attention, Dannymax. Please pick up the white courtesy phone. :biglaugh: