Main Jet question

[teck_mountain]

Hello

I'm Wondering if I should be increaseing the size of my mainjet. the old jets were 137.5 and the kit I have had 137. With the oversized pistons and rings would this make a difference?

79 xs1100 special

[TopCatGr58]

Hey there Teck,

With the oversized pistons and rings alone, that won't make a difference in required jetting, especially since yours was just the 1st oversize, barely noticeable to the engine!! It will just work more efficiently with the air/fuel that it draws in. When I did my "little=1179cc"Big Bore kit, I was still running stock jets and it ran just fine. However I also had changed the intake and exhaust, and so that led me to make some changes because it breathed different/better than it did with stock intake/exhaust!

So...if you are running the stock intake box, and stock pipes, then no rejetting should be required, but it you have modified one or both, then you may need to increase your main jet size. Check your plug color, if you are getting a decent tan/gray color now, then you are okay. If they are pristine bleach white, then you could be running too lean! HTH.
T.C.

[teck_mountain]

Main jet

Thanks TopCat

I'm still running fine. Still have a little hesitation around 3000 RPM but nothing I'm going to worry about.

3/4 of the way with the break in. Seems to be settling in just fine. I think I have a couple of smaller valve shim as I can hear a bit of noise coming from the top. Will check this out when I do my next service in about 200 to 300 Km.

Overall very happy with the way it's running. Validates the work on the top end

Teck

[teck_mountain]

Air box gas spill over

This problem is getting worse. I have put petcock repair kits on both sides. Seemed to work for a while. Then I noticed a little gas, then a bit more and yesterday flooded. (Thank god I was planning to do an oil change). Couple of interesting notes. it only seems to happen when I go on a long trip and all four gas line are full tight.

Any suggestions.

Teck

[Czekus21]

Are the lines run correctly. OR, are the petcocks correct. Sounds to me like they'er in prime. Prime will keep the fuel flowing. even with the engine shut off. ( bypasses the octopus ). I had that problem on MIYAMI when I first got her. it was plumbed totaly wrong. Was getting lottsa fuel in the air box. replumbed, fugured out what "prime" ment. good to go so far.

[teck_mountain]

leaking petcocks

Double checked every thing and the lines were run properly. The o-rings on the valve taps appeared to be worn. I replanced them and so far so good. The bood says I should have a seal that sits on the black gasket with the four holes. I don't, for what ever reason. Would this be an issue?

[srq68]

Is your gas tank clean? If you have some rust powder in it or debris, it will lodge itself in the petcock valve and prevent a good seal of the valve when the vaccuum stops.
Put in line filters between the tank and the carbs.
I placed mine between the carbs, can't see them and they work fine.