crf250r hard to kick over after rebuild

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8/8/2020 1:52 PM

so i bought a 2007 crf250r in a basket. i spent a month going through everything making sure i had every washer, bolt, gasket and what ever to put it back to geather. i put a pro x crank, wiseco piston, sent the head out got new seats, guides, seal, valves, springs. got everything back togeather, and can not get it to run. also this is a b!tch to kick over. i have checed timing at all 3 marks and timing is dead on. i have new guides, tensioner, and chain. i have checked and rechecked valves and they are within spec. i have spark and fuel, but the thing that has me concerner is how hard this thing is to kick over. the dealer that did the head said the checked the decompressor and it works fine. is it possible the gear has spun on the cam? im a big guy and with this bike on the table it take both my arms with all my 260lbs of body weight to turn this over with the kick starter by hand, now remember i bought this in a basket and have never had this running so there might be another issue, but i have spark and fuel on the plug. any ideas

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8/8/2020 2:45 PM

just went and rechecked valves again
both exhaust .009, so .002 out of spec
intake .004 and .005. so thoes seem fine.

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8/8/2020 4:05 PM

How easy does in turn over w spark plug out?

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8/8/2020 5:44 PM

after kicking for a while it is getting easier to kick over, every once in a while she will fire for a couple seconds and shut off. pulling the carb tomorrow

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8/8/2020 8:13 PM

.009” on the exhaust is fine, if not better, than the factory spec of .011”... the fact that you’ve stated it’s starting to turn over easier is an indication to me that something’s incorrect internally (could be something as simple as an incorrectly Installed crank seal) ... like asked before how does it turn over without the plug? Or prior to installing the head and cams how did the engine turn over with just the piston and cylinder installed? A fresh engine should not be hard starting nor should it rotate with any abnormal resistance...

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8/8/2020 8:19 PM

Recheck cam cap torque and release the cam chain tensioner and be sure Its not bound up.

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8/8/2020 9:07 PM

You didn’t remove, then reinstall the cam chain tensioner without retracting it by chance, did you? Not sure it would bolt down all the way, but the thought occurred to me.

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8/9/2020 12:54 AM

omalley wrote:

You didn’t remove, then reinstall the cam chain tensioner without retracting it by chance, did you? Not sure it would bolt down all the way, but the thought occurred to me.

Was going to suggest this too. Definitely sounds like cam chain is too tight, remove and retract the tensioner then screw it back in to let it auto-tension

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8/9/2020 3:01 AM

omalley wrote:

You didn’t remove, then reinstall the cam chain tensioner without retracting it by chance, did you? Not sure it would bolt down all the way, but the thought occurred to me.

GaryC1 wrote:

Was going to suggest this too. Definitely sounds like cam chain is too tight, remove and retract the tensioner then screw it back in to let it auto-tension

i did retract it when i installed it but i will remove and do it again to be sure. im really hoping its in the carb, probally should of taken it apart while we had the motor out.

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8/9/2020 5:49 PM

Check cam chain tensioner. I’ve made that mistake once before

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8/10/2020 4:52 AM

IS IT POSSIBLE THE GEAR IS SPUN ON THE CAM? ive read the lobes need to be facing towards the back of the bike when timing marks are lined up but when the timing marks are line up my lobes are facing more up and to the back of the bike

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8/10/2020 7:57 AM

take pics of your TDC if its off your prob could be valve touching piston at some point
take plug out and check how free it turns over

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8/10/2020 8:11 AM

Factor E wrote:

take pics of your TDC if its off your prob could be valve touching piston at some point
take plug out and check how free it turns over

ILL GET PICS TONIGHT WHEN I GET HOME THANKS!

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8/10/2020 3:17 PM

So I got home and went out to take pictures and in my infinite wisdom decided to stick my brand new snap on bore a scope in to the spark plugs hole to see if it would reveal anything, didn't really see much except for when I pulled it out the end of the the 600 dollar Fu(!ing boro scope fell off in the cylinder. So I ended up tearing it down to remove the piece, but everything looks good, piston is in the right way. Is there any marks on the cam to see if the gear spun? I'm almost to the point where that has to be it

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8/10/2020 4:48 PM
Edited Date/Time: 8/10/2020 5:04 PM

SAINT1000 wrote:

So I got home and went out to take pictures and in my infinite wisdom decided to stick my brand new snap on bore a scope in to the spark plugs hole to see if it would reveal anything, didn't really see much except for when I pulled it out the end of the the 600 dollar Fu(!ing boro scope fell off in the cylinder. So I ended up tearing it down to remove the piece, but everything looks good, piston is in the right way. Is there any marks on the cam to see if the gear spun? I'm almost to the point where that has to be it

Some camshafts have holes in the cam gear that align with corresponding holes in the cam lobes... I believe your cam gear unfortunately does not... The most accurate way to check if the gear has spun would be to degree your camshaft... the easier way would be to locate another (Known good) camshaft and compare lobe positions... If you reassemble the top end and post pictures at TDC that would be very helpful To everyone in here... edit: You could even just set the cam shaft in the head on a bench and align the timing marks...

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8/10/2020 11:06 PM

here are pictures
Photo
Photo
Photo

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8/11/2020 12:26 AM

The orientation of the lobes looks correct... How does it turn over with the head off?

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8/11/2020 3:25 AM
Edited Date/Time: 8/11/2020 3:26 AM

Paul_Pitzonka wrote:

The orientation of the lobes looks correct... How does it turn over with the head off?

Turns over with almost no resistance. I'll be putting it back togeather tonight

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8/11/2020 7:17 AM

Are the cams located correctly? Looking at the middle picture it looks like its not quite correctly aligned and is sitting off to one side slightly so I wonder if when you tighten the cam holder and top cover is it just forcing them further into the wrong position?

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8/11/2020 7:40 AM

GaryC1 wrote:

Are the cams located correctly? Looking at the middle picture it looks like its not quite correctly aligned and is sitting off to one side slightly so I wonder if when you tighten the cam holder and top cover is it just forcing them further into the wrong position?

I'll check that when I reinstall, but I think it looks like that because I just set it there to take pictures. Thanks for the insight

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8/12/2020 5:35 PM

Thanks everyone for the help. Put it back togeather tonight, rebuilt the carb, all new jets, diaphragm, read about starting procedures, 3 slow kicks, twist throttle 3 Time and the big kick and she fired 1st time . Just got to hang the rest of the plastics and break her in. Thanks again

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