hard starting XR

[tristan18au]

i own a 1998 modle XR250 which is very hard to start hot or cold and back fires when you try to start it.we have replaced the spark plug and check the valve clearance and have even put spit fire valve cleaner in it.it has compression and does rattle a lot when it gets hot. whats going on? please help!:(

 

[Shaw520]

?

Could be one "or two" of several different things,..... you say you adjusted the valves,.?? was it done correctly?.....if so, the next step is to check carb bowl, main and pilot jets for debris. These bikes are known to be jetted lean from factory, so any blockage will only further complicate things. Its a process of ellimination, "POE".
Some things to check;
Dirty air filter
Bag Gas
fuel line/ pet cock
consistant spark

Good Luck!

 

[arossitt]

Maybe decompressor

Had a similar problem with my 95 model xr600r.Turned out the auto decompressor on the camshaft was causing the problem.As a result the whole unit was removed and a lot of little demons went with it.If tour bike is fitted with a auto decompressor get someone to check it out and maybe chuck it out as well.cya.

 

[penguin]

the backfiring and rattling suggest either a lean jetting condition or out of adjusment valves. Did it start doing this after the valves were adjusted? You also need to drain your tank and get that "valve cleaner" out of the fuel system, it is not good for motorcycles. I would check the jetting first to make sure your jets aren't partially clogged.

 

[mtngoat]

One possibility is during the valve adjustment, you actuated the auto compression release and have a mis-adjusted exhaust valve causing the backfires. Given the symptoms, I would fix before any further riding. Check the post on XR4 valve adjustment and do it again. Good luck.