Total Motorcycle Community Forums

Hi,
My xs400 has been giving me starting problems, and I have no idea why. I check the ignition coils, wires, all seem to show the right resistances as in the manual. The spark p;ug cap resistances are also fine. I put in new plugs, and get a good spark.

Carbs were just cleaned and rebuilt, and gas flows into the carb bowls. I try giving it the choke, but it doesnt start. I thought the starter motor might be slipping, but I feel the blast of air coming out when the plugs are out? So what could be the problem here??

Any suggestions??

Thanks a lot, in advance, and alsofor all the other help so far!!!

Is this a new problem, or was it hard to start before the carb work?

At this point, the only thing I could suggest is a compression test. Since you've got fuel flow and spark, that's about the only thing left.

Weel the bike was sitting for nearly a year. My friend who I bought it from said he had it running, but lost interest in the project later on.

What instruments would I need for a compression test? How can I check if the starter motor is turning at the right speed. Im guessing if it is not turning fast enough, the engine would not start??

I hate to tell you this but, if the bike sat for a year with gas in it after the carb work, it'll likely need another carb cleaning. Over time, gas in the carbs turns to varnish and gum which clogs up the passages.

What makes you think the starter is not working right, Kar? Does it sound funny, or what?

About the compression test, you'll need a compression gauge - most automotive parts retailers have them. It's a small gauge with a flexible hose that you screw into the spark plug hole.

Good luck!

No, (hehe...) The carbs were cleaned just last week by me. But the bike was last started and running a year ago.

Well the starter works, it seems that its turning too slowly. The battery on my bike seems dead, so I hooked up my car battery, which is brand new. The starter did turn faster, but im still not sure if its fine. I doubt there is a problem with the linkage to the engine, but I just need to know if there's a correct rpm for the starter.

I guess the next thing to do is the compression test.

I think I will check the points, and see if they need replacing. Apparently with new plugs the spark isnt too good either, but as Ii said, the coil resistances are fine.

Got it!!! The throttle was stuck half open (Bad cable), so even giving the choke was no use. Also, whats a good idle setting ? Should the valves be 10% open?

Probably somewhere just above 1000 RPM, and what do you mean about 10% open?

I was talking about the butterfly valves in the carbs. The reason Im asking is with these completely closed, the bike starts and idles only with the choke on. However, if I let go of the choke, it obviously stops. Now how do I handle this situation when I, say, stop at a light? Sorry if its a crazy donkey question....

Not a bad question. You do need a carb cleaning, though. Should idle without choke when warm.