Stall when switching choke

rdgerber2 · Posted: October 30, 2009, 9:09 am Post subject: Stall when switching choke

I am not sure if the problem is fuel related, but I am going to post it here.

I have cleaned the carbs with spray cleaner and soaked them in carb cleaner which did not fix the issue. The bike is hard to start. When I switch it from choke to no choke it stalls. After I warm it up with the choke on I can start it with no choke. It runs rough and when I give it any throttle I get a mean backfire.

Ive been contemplating whether this is a carb issue or if it is elsewhere.

Do any of these symptoms point to other issues ? Backfiring makes me think possible timing issue and I have never checked the cam timing. Should I investigate these before I pull my hair out over the carbs ?

The only reason I am stuck thinking its carb related is the choke issue. When going from full to half or full to no choke the bike stalls.

pablohoney · Posted: October 30, 2009, 2:24 pm Post subject: Re: Stall when switching choke

I don't know much, but I know that advanced Ignition timing causes backfires. Also I would check to see what the plugs look like, might give you a hint if your carbs still have problems.Hope this helps.

Taylor

pumps · Posted: October 30, 2009, 2:25 pm Post subject: Re: Stall when switching choke

You don't mention the year or history so I don't know if you have points or TCI. I'll say to start with a general tune up if you haven't already. Check timing, gap if a points motor, advance timing unit, cam chain adjustment, adjust valves etc.
How old are the ignition components? Plugs, plug wires, points, condensers, coils. An old timer told me you can't fix ignition problems through the carbs. Have you got a manual? I always start at the beginning.
www.knucklebusterinc.c.../XS650.pdf

rdgerber2 · Posted: October 30, 2009, 2:51 pm Post subject: Re: Stall when switching choke

Ooops I did forget the year. It is an 82 with electronic ignition. Bike had sat for years in a garage and I went through the carbs and cleaned with spray cleaner and used new seals and gaskets.

Plugs are new, however I did not replace the wires and coils. I could try this next but for some reason I dont feel like I have the carbs adjusted correctly.

I did not perform the dead cylinder method because I read somewhere that if done incorrectly it can damage the ignition timing unit.

I have a haynes manual which is what I used when I rebuilt the carbs. I am going to read it tonite and check the cam chain tension, and if that checks out ok I am will "attempt" to sync the carbs.

pumps · Posted: October 30, 2009, 5:59 pm Post subject: Re: Stall when switching choke

Be SURE when disconnecting a plug to use a grounded plug to the engine when you run it. It could damage the coils. Somewhere is a picture of such a tool...Ok found it. A spare plug with a piece of wire hose clamped to it with an alligator clip to the cylinder is how I do it. Hope this picture shows it well enough. Credit to Retiredgentleman for his idea that I copied. Scratch that stuff I said about the advanced timing unit as yours doesn't have it. Only points style bikes.

rdgerber2 · Posted: November 2, 2009, 8:32 am Post subject: Re: Stall when switching choke

I have a tool that plugs into the spark plug wire that you ground to test for spark ? Would this do the same thing ?

xsjohn · Posted: November 2, 2009, 8:47 am Post subject: Re: Stall when switching choke

Pilot jet to begin with is "too" lean in those carbs.....along with everything else....and the timing is a bit advanced........

fuel has to come out freely from the 3 tiny holes in the throat that lead from the pilot circuit and the pinhole starter jets in the float bowl have to be clear............

Pilot jet 45 to 47.5
135MJ
and suffer with the stock needles

And I have to be somewhat careful and go slow when switching from full to medium choke.........I put a notch in between the full and medium choke positions on the choke rod.........helps

xsjohn

rdgerber2 · Posted: November 2, 2009, 9:51 am Post subject: Re: Stall when switching choke

Thanks for the jet info. Thats what I was gonna tackle next.

pumps · Posted: November 2, 2009, 10:34 am Post subject: Re: Stall when switching choke

rdgerber2 wrote:

I have a tool that plugs into the spark plug wire that you ground to test for spark ? Would this do the same thing ?

ost likely that will do the trick. If there is any doubt it is easy to rig something up.If a normal grounding method is not used the ignition coil will build up a charge and seek it's own ground which basically means the coils shorts itself out.

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