1978 xs650 special running carb issues

[ems16]

Hello to all that help with this, if you happened to come across my last thread, You will have known my bike to have a few electrical issues, but I believe I'm past those problems hopefully in the foreseeable future.

But my new problem begins with this. The bike is now a runner, I mean first kick everyday she'll get up and start. but I have begun to see problems with my carb tuning, I have my idle set so when she starts without choke she will idle around the 1700-2200 rpms and that's with pump gas that I believe is 87 octane, BUT when running I noticed a few problems that I know are not good.

1. When I looked down on the left hand side of the bike to tune the idle to an good rate, it seemed like there was a backfire with a spark that went was at the base of my vacuum line near the carb boots. which overall worries the crap outta me.(first sign of a fiery death)
2. when running their also appears to be access fuel coughing out the back of the carbs.(highly visiable due to not having an airbox set up or filters at the moment)
3. even when I let off the throttle it sometimes allows the bike to go up even higher into the rpms, but will eventually come down from them. almost like the throttle is sticking some how.

also if anyone can tell me properly how to adjust the air fuel mixture to an good level on the twin 38's that would be nice.

Any help would be greatly appreciated and I would really like to get on to riding this bike in a few weeks.

 

[5twins]

You need to rebuild your carbs. You can't expect to run one of these (or any bike for that matter) after it's sat for years without doing that. And not that it will make any difference at this point but you should be running hi-test.

 

[CoastsideXS650]

http://www.xs650.com/forum/showthread.php?t=43

Read it. Several times. And you will know just about all you need to rebuild those carbs.

 

[ClOckwOrk]

My carbs on one of my bikes did this. The high idle amd such. The tjrottle plates were out of sync. A lean four stroke engine can hold revs high I noticed mine did it more without filters and my short exhaus. If your carbs are leaking, replace the needle amd seat they are probably allowing float bowl overfilling

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[XSLeo]

Most of these bikes won't start well cold with out the enrichener. Once warm they start fine. On a warmed up engine it should idle arouns 12-1500 rpm.
On the 78 it has points, if the advance rod sticks the timing will stay advanced and not let it idle down. Leaks in the air intake can lean out the mix and cause a high idle. And if you see fire around the carbs on a back fire then that leads me to believe you have a cracked carb holder. This may be where the air leak is.
Carb work starts here, www.amckayltd.com/carbguide.pdf
Leo