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Kxf 450 motocross. bike will not kick up. its had new piston and rings,valves adjusted(spot on)new stator coils. starts (just) if you bump it. it had this problem before it had the new parts. i am pulling my hair out over this.any advice would be greatfully recieved. cheers.
Re: Kxf 450 motocross. bike will not kick up. its had new...
Check the ignition module yet? It sounds like the problem your having. If no spark is getting to the spark plugs with everything new installed that is your proble if all fuses are good
hi, thanks for speedy reply. there is a spark . no fuses as it is a mx bike. kick start only ,no electric start. cheers kev.hi, thanks for speedy reply. there is a spark . no fuses as it is a mx bike. kick start only ,no electric start. cheers kev.
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if it is running and not making any noises then I would only consider the piston, rings and liner as a last resort
If it has valves , (4 stroke) , check the valve clearance and adjust to specifications as valve stems get longer when hot and if the clearance is not sufficient when cold then a valve will be held slightly open when hot
next check the coil and ignition module and the timing
Assuming it all back together correctly as you had so much practice now I sure all your timing set correct and your valves clearance are all spot on
There is a few things I would be attempting firstly being its virtually brand new motor I would be checking your stator with multimeter testing its resistance readings - let me know if you want info on this ?
if the stator all good then I would be suspicious of the CDI unit especially as you have cooked motor beneath it the heat could have killed it ?
if these two theory fail then your next option would have to be leak down test to confirm your new head is sealing valves in it are sealing and you not losing compression past the rings
From what you have written I would be mostly concerned with electrical side first
Dont be fooled either just because spark plug has a spark does not mean stator and CDI are correct?
have you tested kicking over with spark plug laying on head bolt or something is it sparking at all?
regards Jamie
when the ignition parts like the coil and the transistors in the cdi unit gets warmed up they dont work as well as when there cool,,,so a problem thats not there when cold will be there when its hot,,,,if the stator has a small fault in it when cold when it gets hot it turns into a big fault! the best way to find this fault is by swoping one part at a time till you fine the faulty part,,,or put it into the bike shop and pay through the knows for the fix? have you a friend with the same type of bike you could swop the parts with??? it a big big help if you have! i would start with the coil then the cdi unit,,,there the most likley parts to play up when they get to hot they go faulty!
sounds like maybe valves were shimmed too tight,check service manual for clearances...better a little loose than too tight,can cause alot of damage to cam & head,be careful!!
THE STATOR PLATE HAS A LINE ON IT (CENTRAL TO THE LEFT BOLT SLOT) WHICH SHOULD ALIGN WITH THE POINT ON THE CRANKCASE, IT SHOULD ALSO BE DEAD CENTRAL TO THE BOLT/SCREW HEAD. THIS IS SUZUKI'S RECOMMENDED TIMING POINT. ANY STARTING PROBLEMS MAY BE DUE TO OVERUSE OF THE CHOKE, RM'S EASILY FLOOD, IN WARM WEATHER I RARELY USE IT, IF I DO- ONLY FOR A COUPLE OF KICKS THEN STRAIGHT OFF IF IT FIRES. THE CORRECT PLUG IN GOOD CONDITION IS ESSENTIAL- NGK B8EGV WHICH I REPLACE REGULARLY. A WEEPING FLOAT NEEDLE VALVE CAN ALSO CAUSE PROBLEMS, HOPE THIS HELPS, WILL.
Do a compression check. It should be 120lbs or above. Check the compression release. Is it closing fully? Burned valves may be at play here also. Bad piston rings or seize scars on the cylinder wall? If you need a service manual you can download a free PDF from the site below.
You need to inspect the valve clearances. It is common for the intake valves to wear a little.
Inspection of the clearances should take place at 15 hour intervals if you are racing the bike.
When the valves leak, the bike does not maintain compression and kick starting becomes tough. The fact that the bike starts when being bumped, shows a loss of compression.
An easy DIY compression test is to remove the spark plug, place a finger over the plug hole and press down on the kick start lever. The air should be forced past your finger at a high rate and you should hear the air escapeing. You must not be able to prevent any air from escaping.
doulbe check the grounds, & you might need to add and extra ground wire to the bike, closer to the starter. This should help. There is a valve that release the compression when you kick it off.You might see if you can pull this release the compression valve while pushing the start button????
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