No idle ??? Please help

[gentlemanjim]

Where have I gone wrong?

I'm rebuilding and XS500 (I know a traitor) But the good news it has B38 carbs. Thoroughly cleaned all new jets 30 pilot 125 Main, needle and seat, floats set at 25-30mm. Revs like a whore in heat, but won't idle. I am very competent in carb rebuilds, but I'm stumped.

 

[Bob Kelly III]

I would guess that the idle circuit is plugged.
.....
Bob....

 

[650Skull]

Gj maybe some info in this thread............http://www.xs650.com/threads/aus-tx500-resto.33248/

 

[Bob Kelly III]

Duh ! why didn't I do that !
well done Skull !
Bob......

 

[650Skull]

Duh.........i wouldn't know.....

so it meats your approval

 

[Bob Kelly III]

of course.... nuff said !
....
Gentalmanjim ! in my experience where a motor would not idle I found it to either be the idle circuit in the carb was totally blocked or the PO turned the idle mixture screw completely closed....or just barely open .
after cleaning my carbs 2 times the 3rd time was the charm and i finally found the culprit it was the passage way in the float bowl ! LOL
stuffing the carb cleaner snorkel in the hole and giving it a squirt many times did not clear it... I had to use a wire to drill it out.... !
the monster gave me fits ! it wouldn't start without quick start and didn't want to idle either ....
my bike is a 82' xs650 with BS34CV carbs btw.
....
Bob.......

 

[gentlemanjim]

Thanks,

What I didn't mention was it would rev freely and would not return to idle when the throttles was released still hold a high speed even though the butterfly's wear closed. If I backed off the idle speed screw it would slow down and eventually stutter and stall.

 

[Bob Kelly III]

and then it wouldn't want to start again without additional fuel of some kind added.... i bet....
yep sounds like the idle circuits are totally plugged to me ! or perhaps the pilot air screw closed completely try opening them up more
and see if that helps like if their at 3/4 open now try 1 turn then 1 1/2 turns and so on and see if it will like that better !
engines are fickle things they want certain things or they just will not play your game ...kind'a like spoiled kids I guess ! LOL
a weak ignition system can give you those symptoms too having a weak coil that brakes down at idle is not totally unheard of , though it is rare ! or for that matter points all out'a whack gap too wide or too small .....chances are though that if it runs at high RPM and mid rpm your ignition is probably OK..... i suspect fuel first and foremost.
hope ya find it !
keep after it,.... you'll get that puppy running in short order !
.....
Bob........

 

[5twins]

I would set the floats at 25mm. That's the spec for that carb set. 30mm would be too lean and may be the cause of the hanging idle.

 

[gentlemanjim]

Update. I pulled the carbs and checked the idle circuit all good., But the feed hole at the bottom of the float bowls that feeds the jets, appeared to be obstructed. Cleaned and blew compressed air, Seems to be clear now. Soaking in carb cleaner to be sure. Will reinstall this weekend. Thanks for all the advice.

 

[XSLeo]

Might possibly be an air leak, leaning the idle mix. Just a guess, the idle circuit the most likely.
Leo

 

[gentlemanjim]

Issue solve. Thanks for all the advice. Turns out it was a timing problem. With the timing plate at full advance it wasn't advanced enough. I trimmed the stops and added a little more advance. Checked with timing light spot on idles smooth and steady and revs quick and snappy. A strange one for sure.