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Discussion Starter · #1 ·
Hi,

I bought an '06 450ER at an auction for next to nothing and have spent the last few months rebuilding it. It was pretty beat but I paid hardly anything for it so I thought it'd be a fun project. The guys at the auction did have it running at one time but I wasn't able to start it when I got it home. Checked the compression it was real low 50psi (with the decomp disabled). So after that I wound up putting a wiseco piston in (with stock compression ratio), had the head rebuilt to stock specs (leakdown showed the exhaust valves leaking), the cylinder was honed and measured up fine.

The carb was cleaned and re-jetted etc etc... I went right through the bike.

Now the part i don't get is that the bike is timed absolutely correctly according to the manual. I've double and triple checked all the dots and lines to make sure they lined up properly when the bike is at TDC, but I still get 30psi with the decomp on and now 60psi with it disabled (and I've checked the gauge too, its working correctly).

I've already backed off the decomp adjustment and it made little to no difference (going .010 at a time), the valves are set correctly to .006 on the intake and .011 on the exhaust. The camshaft does not look worn at all and again checked the timing. When I've adjusted the timing one tooth either way the timing mark on the crankshaft looks way out. So I don't know. There are no leaks or anything else that I can tell. Whats the next step? Could the timing chain be stretched and throwing things off? I don't see how a worn cam could cause that because if a lobe was worn it would just increase the compression.

Hopefully someone can give a fresh perspective cause I think I'm at the point where you've looked at something for so long that you get tunnel vision and can't think outside the box.
 

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Is spinning the cam flange even a possibility? It looks like its a machined part of the camshaft not a press on flange...[/b]

do a leak down on the motor. See if you got something seriously wrong ( eg. warped head/block ) That will also tell you where your presure is going. ( out exhaust/ intake, cooling system, blah blah blah )
 

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the cam flange can twist on the cam.. its pressed on. the lobes on the cam are kinda pointed towrds the back and up in the bike when marks are lined up. if that is the case the valves prob would hit the piston tho. unless it was only a little bit. cant think of any thing right off hand other than that.
 

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the cam flange can twist on the cam.. its pressed on. the lobes on the cam are kinda pointed towrds the back and up in the bike when marks are lined up. if that is the case the valves prob would hit the piston tho. unless it was only a little bit. cant think of any thing right off hand other than that.[/b]

By all means, do a leak down test. I dont even use compression testers on these engines anymore, just leakdown. Itll tell a better story. Also FYI, I have put several pistons in these engines that were an absolute bear to seat the rings, right down to the point that it wouldnt even start. If its not starting, put a few drops of oil into the cylinder so the rings will seal, then after the intial fire they are usually OK.
 

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Is spinning the cam flange even a possibility? It looks like its a machined part of the camshaft not a press on flange...[/b]
yes it is possible i dropped a valve and when the valve hit the piston it spun the lobe on the cam. took me forever to figure out what had happened
 

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Just throwing a possibility out there...are you sure you are lining up the punch mark on the drive gear to the mark on the crankcase cover?I have seen instances on here in the past where others have been using the wrong mark (hole) as the timing mark.
Just a thought.
 

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Discussion Starter · #9 ·
Alrighty, thanks for the input. I'll do another leakdown test as soon as I finish a few other things on the bike. I have to admit it seems like the timing is out because there is very strong suction at the intake port and seemingly very little exhaust pressure. I checked the timing again and for sure the timing marks are lining up (I don't see any other holes on the crankshaft wheel) and the valve lobes, like someone pointed out, are at the top and pointing toward the back of the bike at TDC. After the leakdown and trying to seat the rings properly I'll report back... If that doesn't work the flange must be spun, its kind of a pain not knowing the history of the bike, all I know it was in rough shape and not cared for but I don't know if they ever bent a valve. So if it is the cam, anyone got a stock cam they want to sell?

Thanks again guys...
 

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i have 2.... out of 07s and you can have one of them for the cost of shipping

mite want to go to dealer with your cam and see if they have one for a CRF or trx and compare it... mite get lucky and they have one
 

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Discussion Starter · #11 ·
Well, we finally got out of the deep freeze here up in Alberta and I've had a chance to look at the quad again. A leak down test showed a maybe 2 - 4% loss (Air just leaked a bit past the rings which is normal). So the only logical solution is the timing has to be off... At some point the a valve must've hit the piston and spun the cam flange a bit. Like I said before the mark on the flywheel will line up with the engine housing but the timing marks on the camshaft or just a bit off (and moving the cam one tooth either way makes it worse) and in previous experience those marks are always dead on.

So go figure... Hopefully I put a cam in and she'll fire up, we'll see in a few weeks...
 

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2006 trx 450er. Stock motor, sparks full exhaust, elka legacy series shocks, and many more boltons!!
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What’s up slickpoppin95? What are you riding? Got any pics? And do you know how to work on these trx450,s bumper to bumper. Need some new mechanics on this site. If so I got a couple questions to pick your brain. Lmk broski
 
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