1981 MX175 problems

[Jacobite]

I know this is not even close to an XS - but I know there is a lot of mechanical talent on this forum. My son is fixing up a 1981 MX175 dirt bike. He cleaned the carb and got it running. It works good when it is cold (10 - 15 minutes), and then , apparently when it is warmed up, it dies. You will be driving along and it just quits - no sputtering, stop for a few minutes and it will start with the first kick. Drive along another few minutes and it dies again.

I'm thinking its an electrical problem - any ideas on where to start looking?

[Ken Talbot]

Sounds more to me like a fuel delivery problem, possibly from a plugged tank vent hole.....

[Jacobite]

Thanks Ken - I will check it out. That would be a nice solution, sometimes it is something very simple and we try to over complicate the solution.

If you are coming through Southern Alberta this summer on the way to Bozeman drop me a note & maybe we could meet for a coffee (if I don't go to Bozeman - not sure yet). I work in Lethbridge.

[Ken Talbot]

At this point, our plan is to overnight in Lethbridge on the way to Bozeman. We had a nice time there last summer on our way home from Manitoba. We stayed at one of the big chain hotels downtown across from the tourist info place. Can't remember the name right now, but they had a nice indoor water park.

[Winterhawk]

Check and see if you have fire when it dies. Could be something as simple as a kill/ignition switch.

[wildbill]

Check and clean the carb good might have missed{all jets and openings} something.Check vents{tubes} on side of carb. and the gas cap.When the engine quits pull the plug,check for spark also check the plug to see if the engine is getting fuel.I agree it is proably something simple,just take your time.Good luck.

[chevy45412001]

sounds like a coil prob.

Sounds just how a coil going bad acts.Remember the old ford four cylynders acted.The coil would get up to temp and quit,set for a bit ,it would start right up and go til it got hot again.Just my paso's worth

[Jacobite]

Thanks for all the suggestions. Tank vent is clear - changed the spark plug. There is fire after it quits - but it starts back up after it dies - then runs for a short distance. The kill switch doesn't seem to work at all.

I actually was thinking of the coil too. I had a GM 6 cyl. that had a bad wire on top of the coil - worked perfect until it got hot, and then would start acting up. It took a long time to find, but a new wire and it was good as new.

My son cleaned the carb, but we will check it again.

Ken, send me a PM when you know what date you will be in Lethbridge - I don't know for sure if I can go to Bozeman (I want to!) but I would like to say hello in any case.

I think it was the Ramada you stayed at.