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Discussion Starter #1
I have an 06' ltr450 that a friend just installed a big bore kit on, head was totally rebuilt with new valves and springs and has a dynojet controller on it. The bike will not start. It turns over fine and every other time or so as its turning over it will backfire out the exhaust. I have checked the timing 3 times now and it is right, everything the bike is doing keeps me wondering how it can't be the timing. If anyone has any input on this please help. Thanks
 

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Discussion Starter #5
valve clearances are perfect just installed head and re shimmed today. The engine mechanics are perfect, I am starting to think maybe the cdi is causing the problem.
 

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check for spark?
did you check fuel pressure?
also check the injector
 

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try removing the PCIII and trying it. Then remove the crbm and PCIII and try it. Sounds like a fuel management issue. Check throttle position sensor, vacuum hose from TB to IEC sensor and all other sensors.

You are certain the timing is good right? "T" mark lined up and cams at 10:00 and 2:00? ACCT is setup right?
 

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Discussion Starter #8
try removing the PCIII and trying it. Then remove the crbm and PCIII and try it. Sounds like a fuel management issue. Check throttle position sensor, vacuum hose from TB to IEC sensor and all other sensors.

You are certain the timing is good right? "T" mark lined up and cams at 10:00 and 2:00? ACCT is setup right?
Things I know for sure are working: Timing is correct, fuel pressure is good, fuel pulse is good, injector is good, spark is good, compression is good.

I removed the power commander V and reverted everything back to stock, still had same issues. I will check the vacuum hoses and sensors and see if there is a problem there. Thanks
 

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I bet I know what it is. Did it run previously? Before the build? The timing may be spot on, but I bet its really not. Check that flywheel key. :) I bet its sheared off. So when it says its in time, its really not. the spark isn't created at the right moment. gas builds up but doesn't pop on the compression stroke. This is why it backfires every now and then, because the gas finally pops.
LMK what you find out.
PS on a rmz250 I found out I had a cracked piston after doing a compression check, compression was good. I replaced the piston and it started right up
 

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I've had the flywheel key break on one of these. They say you need a special flywheel puller but I used a 3 jaw puller from my work, o Reilly's.
 

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Discussion Starter #11
It seems as though the starter motor is having a hard time turning the engine over. Again yes the valve clearances are perfect and the timing is correct. Could this be because of the big bore?
 

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Discussion Starter #12
I bet I know what it is. Did it run previously? Before the build? The timing may be spot on, but I bet its really not. Check that flywheel key. :) I bet its sheared off. So when it says its in time, its really not. the spark isn't created at the right moment. gas builds up but doesn't pop on the compression stroke. This is why it backfires every now and then, because the gas finally pops.
LMK what you find out.
PS on a rmz250 I found out I had a cracked piston after doing a compression check, compression was good. I replaced the piston and it started right up
Pulled the flywheel key was still in tact and in place. And yes it ran before the build.
 

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What map do you have loaded in your dyno jet fuel controller[/QUOTE

I have no idea. I tried disconnecting it and same issues. The bike should run without a controller, this thing wont even start just backfires after a few cranks.
Ya I think it is starving for fuel
Try hooking it back up and find a map that is similar to the mods you have
 

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Discussion Starter #17
Ok, I got it to run with a bump start and it sounded perfect but would only run as long as I kept the throttle on. When I try to start the bike off the battery the starter has a hard time turning the engine over. This is killing me!
 

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you did check the throttle position sensor right? I'd check the injector. Pull it and back pressure clean it. your starter was strong before the rebuild and now it's barely turning it over right? sounds like you have some binding. If it were me i'd pull the head and cylinder and inspect everything and start over. Oh ya, also take some voltage readings on the starter while cranking.
 

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Discussion Starter #19
you did check the throttle position sensor right? I'd check the injector. Pull it and back pressure clean it. your starter was strong before the rebuild and now it's barely turning it over right? sounds like you have some binding. If it were me i'd pull the head and cylinder and inspect everything and start over. Oh ya, also take some voltage readings on the starter while cranking.
I just put the head on and shimmed it and then took off the flywheel and inspected everything on that side. If there was any binding it would be in the bottom end but the engine runs fine when bump started. I will take some voltage readings on the starter and let you know.
 

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Discussion Starter #20 (Edited)
peak voltage at the starter when cranking is 21V the battery shows 26.8V. I am not sure how I can test the tps without the testing harness but I can't move it by hand so unless someone removed it, there is no way it was moved. Also FI light has not come on yet!
 
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