running bad

silverfox · Posted: June 7, 2008, 6:56 pm Post subject: running bad

i have a 78 xs650 it starts ok and runs ok, but when it gets hot or say aftre 10 miles or so when i slow down or stop it runs iraticaly ,the revs go up and down and thretens to cut out and if it dose cut out or i stop it its very hard to get it started agein Sad

pleaes help its driveing me mad

Cooltouch · Posted: June 7, 2008, 8:00 pm Post subject: Re: running bad

Sounds electrical, mostly because you report that it starts acting up once it gets hot. Could be condenser, I suppose, or coil(s). I'd try checking for spark after it acts up like this and see if I'm getting any.

Best,

ichael

kingwj · Posted: June 7, 2008, 9:27 pm Post subject: Re: running bad

I'm thinking timing, advance or vacuum leak. A good running XS should start up almost instantly when the starter button is pushed. Timing is critical to this occurring. The bike will run with the timing off but not optimally.

Vacuum leaks can be found with carb cleaning fluid sprayed on joints and carb exteriors. Timing is easiest using a test light but the advance needs a timing light. If your idle is high you might be advancing the timing.

dpmphoto · Posted: June 8, 2008, 5:53 pm Post subject: Re: running bad

Make sure your coil and condenser connections are not too close to the top of the motor and there insulated and secured tightly,also wires from the points. When was the last time your checked valve gap, Did you gap them cold?

silverfox · Posted: June 8, 2008, 6:49 pm Post subject: Re: running bad

thanks for the info, points and condensor fitted new at the begining of the summer. going to take it for a long run tomoro night and stop into my brothers on the way home he dose all my mechanical work so i can let him see the problem and we can try and find the fault while its happening.we will check out all your sugestions. ill keep you posted.
cheers

silverfox · Posted: June 9, 2008, 6:20 pm Post subject: Re: running bad

well took it for a run and then into the garage, checked points seemed to be ok but not a very good spark, took them off and gave them a clean and tryed again timeing was ok then after a while could not get it started at all, battary went flat on me. started to kick it over with a jump start and after a few tryes the vacume pipe on the right hand garb going to the fuel tap kept blowing off Confused

never had that happen befour, what causes that Confused

any way battarys on charge over night and we will have another go tommoro night. o how can you check if the coils are alwright Question

Retiredgentleman · Posted: June 9, 2008, 7:34 pm Post subject: Re: running bad

silverfox; For the ignition.............you could take out a plug ,leave the lead connected and ground the body of the plug to the engine. With the bike in a dark garage crank the engine to see if you have a healthy blue spark or a wimpy yellow one. If running the old stock coils, you could think about putting in an aftermarket dual output coil, they give a much hotter spark.

oldskoolcool · Full Member Joined: Sep 08, 2007 Posts: 372

how old is the batterY?

silverfox · Posted: June 10, 2008, 7:15 pm Post subject: Re: running bad

well my brother got it to go to night it still dose not sound right so hes going to work on it tomorro
the batterys new and tested

dpmphoto · Posted: June 16, 2008, 9:33 pm Post subject: Re: running bad

I would also check rotor, stator and regulator/rectifier.

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