Carb Problems! or Maybe Not

[boy1der]

thanks ratbyk!

I set float level to 7/8" and she's startin to come around. I still think I have a problem. I'm now questioning if the slides are operating at the correct rate. After performing the sprayon fix they seemed a bit stiff. This could be a big portion of my lack of fuel problem.

I saw partsnmore has diaphrams for sale but they only list for 81 and 82 was there any differance in the slides from 79SF to 81?

[beechfront]

did you for sure clean the pilot jets? on a 79 SF they are covered by a screw. you need to remove the screw to get to them, and then they can be a bitch to get out.

If you did get them removed - did you replace them? if so did you replace with stock or with what was in there? given the setup you have (INDY filers, exhaust, etc.) you will probably need much larger jets than stock.

[skids]

If you sprayed the entire surfaces of the diaphragms, they may be a bit stiff. The diaphragm slides are different between the 78 and 79 models vs. the 80 and 81's. I have tried monkeying with different pilot jet numbers, but have always gone back to stock mikunis 42.5. Having the wrong pilots can cause you to play with the jet needle settings. The right ones (pilot jets) have three columns of holes parallel to the axis, 2 in each column, 6 total. You can order these from Dennis Kirk if needed, or clean the ones that you have with a wire or guitar string (if they are the right ones. BUT, it seems that your pilot circuit may be OK). Did you take a look at the plugs when it died to see if they are wet? Be aware also that the bike will not run properly without the vacuum hoses attached to the nipples on the air box.

Really, once you can keep her running, you should start tuning with the mains first. Then adjust the mid range by changing the height of the jet needles (but I try to avoid this by leaving it in the middle slot). Then, if you can keep the 42.5 mikuni pilots, adjust the idle screws. You will find that the main jets have an effect on the pilot circuit as well because the pilot jets draw fuel from the main jets through a small cross-bore (that is why they are capped).

Originally posted by boy1der
thanks ratbyk!

I set float level to 7/8" and she's startin to come around. I still think I have a problem. I'm now questioning if the slides are operating at the correct rate. After performing the sprayon fix they seemed a bit stiff. This could be a big portion of my lack of fuel problem.

I saw partsnmore has diaphrams for sale but they only list for 81 and 82 was there any differance in the slides from 79SF to 81?