XR400 Piston Jam/Cease?

[moombaz]

I'm not sure what happened to my bike. All i know was this started 1 week ago.

1 week ago - Bike difficult to start + lots of backfiring

4 days ago - Went to a local track to ride hard

2 days ago - Bike got no compression at all. Managed to start it after 10Min's. Reached my destination. Off my engine and try starting it back. This time it has got compression. Hmm..

Yesterday - As usual, bike difficult to start. There was once while coming to a stop, my bike stalled.

TODAY - Had a very very difficult time to start. manage to start after like 15Min's or so. Bike stalled before coming to a stop on a red light junction. Best thing is, before coming to a halt, my bike fires up like nothing. Try to get it start but to no avail. Furthermore, while kicking to start the bike, theres a clank sound inside my block.. So, parked my bike on a pathway n call for a tow truck.

BTW, i didn't experience any white/black smoke coming out of the exhaust.

I'm very disappointed because I'm looking forward for another hard riding action in this weekend. Can someone please enlighten me to what is the problem. And does it cost a bomb to get it repair? Please help. ??

[09nate]

check oil level by draining the lot of it out, if it was way to high this can make it play up a bit

[XR6's_rule]

it may only have a tight valve. Check your valve clearances they should be 0.12mm for exhaust and 0.10mm for inlet. Also, it may have a dirty carb, drain it out for starters while you're at it. Good luck!

[creeky]

These engines along with the '96 and later XR250s are famous for the intake valves cupping into the seats which causes the rocker arm clearance to get smaller until the valves are being held open. Adjust the valves. After this happens 3-4 times, it is time for new intakes.

[moombaz]

i dont think its abt engine oil bcoz i juz had it changed the day before.. how to know if my rocker arm or other parts are damaged? there is a clank sound when i kick start my bike. Its like theres a metal piece hitting the block when the piston is moving while i kickstart.. im very confused. if my piston is jammed, i cant even kick but now, i can kick but it wont start plus the clanking sound.

[XR6's_rule]

i dont think its abt engine oil bcoz i juz had it changed the day before.. how to know if my rocker arm or other parts are damaged? there is a clank sound when i kick start my bike. Its like theres a metal piece hitting the block when the piston is moving while i kickstart.. im very confused. if my piston is jammed, i cant even kick but now, i can kick but it wont start plus the clanking sound.

Hmmm, after that post it sounds a lot worse as in the engine letting go in a big way. I wouldn't try to start it again. I think the time has come when you have to open that wallet and let loose on that engine! If you feel confident, you could rebuild it yourself. Let us know how you go.

[moombaz]

Just came back from the bike shop. The mechanic tried to start my bike. Said, he's gonna open up the engine soon to see watz happening inside and call me to discuss.. Damn, can't wait to know. I'll update u guys as soon as I've got the results. Thanks for all the inputs. Do add in more. Pls. Tanx!

[moombaz]

These engines along with the '96 and later XR250s are famous for the intake valves cupping into the seats which causes the rocker arm clearance to get smaller until the valves are being held open. Adjust the valves. After this happens 3-4 times, it is time for new intakes.

looks like this is the prob. my mech said so. gona get my bike back tomorow. tanx mates..