She's just not starting anymore

chef.tay · Posted: July 9, 2009, 10:49 pm Post subject: She's just not starting anymore

Hey guys,

I've had my 71 XS1B halfway dismantled for the last 3 weeks and now it wont start on me.

All I did was replace the gaskets on the head covers, Install a new wiring harness( I think i put it in right), Adjusted the cam chain tension, Put a new set of points in and gapped them to .014 I think, and I bent back the springs on my atu one ring so that they actually work as springs.

When i got to putting my carburetors back, they kept overflowing on me and i found that the problem is that when i set my floats at the 24mm as indicated in the manual the float valve needle almost falls out of the seat and jams so that the gas flow cannot shut off. To fix that i just raised the float level to where the needle would not jam any more but now my float is well over the 24mm.

Occasionally I will get it to fire up for a couple seconds but it only seems to be firing in my left cylinder. I'm getting sparks on both plugs and on both points but the right plug is showing no signs of an ignition and the exhaust pipe stays cold while the left pipe heats up slightly.

I really do appreciate your guys help!

Taylor

schtipp

" i found that the problem is that when i set my floats at the 24mm as indicated in the manual the float valve needle almost falls out of the seat and jams so that the gas flow cannot shut off." this seems really weird to me i would give it a long second look before proceeding in another direction. that said, spray some starting fluid in those throats and see if it runs for a short time when the carbs are out of the equation. if so think fuel delivery. if not let us know

schtipp

" i found that the problem is that when i set my floats at the 24mm as indicated in the manual the float valve needle almost falls out of the seat and jams so that the gas flow cannot shut off." this seems really weird to me i would give it a long second look before proceeding in another direction. that said, spray some starting fluid in those throats and see if it runs for a short time when the carbs are out of the equation. if so think fuel delivery. if not let us know

tacoswild · Posted: July 17, 2009, 1:26 am Post subject: Re: She's just not starting anymore

yeah that's not right you never want to change the float level from the spec. If you're a super tuned racer and want to move 1mm fine, but more than 3mm and they'll piss, been there.

I have a 71 too, no way the normal float level would make your carbs piss unless the floats are sunk. Luckily these floats are brass and you can solder them if they have a leak. The other possibility is the little switch is buggered. Those are the only two things that can cause the carbs to overflow as far as I know.

Oh re-reading your message at the normal float height your switch almost falls out, that means someone cranked your floats down relative to the tab that closes the switch. The spec is only relevant to non-mangled floats. Once they've been bent the only accurate way to set them is with a clear sight tube. Details are in the yamaha manual.

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