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06 crf450 probs

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hi all

Im trying to get a mates bike going and im having some problems. It was running but now it wont start. I have changed the valve shims and the inlet shims are good but the exhaust shim gaps are still 0.05mm to big. Is that close enough or not?

Also when i put the cam chain tensioner back on the chain still seams quite loose. When fitting the tensioner it is possible to fit it when the tensioner is fully extended which seams odd to me but then im new to this.

It has a spark and fuel

:thumbsup:

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Did you install the cam sprocket to ensure all 3 of the markings are lined up properly. Strange for exhaust to be off that much but .05 is outside the tolerances (if i'm remembering correctly it's +/- .03, not sitting here with my manual open though). I'm wondering if you took your measurements at something other than TDC.

When reinstalling the tensioner I always retract it with a small screwdriver and keep it retracted with one hand while tightening the other bolts.

If it's not starting and you didn't get everything lined up to TDC and your cam lobes pointing back and slightly up then the timing sounds off. heck almost sounds like you could be off 180 degrees. The left side engine plug, infront of the cover needs to be removed to ensure you are lined up with the "second" dot to confirm timing is correct (again the other alignment marks need to be in the correct positions). If all three from manual aren't lining up at the same time, bike won't run. if it's line up with the first dot then it is firing on the wrong part of the stroke.

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I removed the engine plug on the right side (kickstart side) and lined up the two dots. Also i lined up the the cam sprocket with the arrow and the cam lobes are pointing back and slightly up. Are there any other timing marks i should use?

The bike had running problems before I had a look at it. My mate was riding it round a farm but after a while it died and became very difficult to start and is now impossible to start. At this point i had a look at it and started to check the valves and cleaned the carb.

Before i checked the valves i did a compression test and i think i got about 70psi after a few kicks but was unsure if this would have anything to do with the auto decompresser?

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I removed the engine plug on the right side (kickstart side) and lined up the two dots. Also i lined up the the cam sprocket with the arrow and the cam lobes are pointing back and slightly up. Are there any other timing marks i should use?

The bike had running problems before I had a look at it. My mate was riding it round a farm but after a while it died and became very difficult to start and is now impossible to start. At this point i had a look at it and started to check the valves and cleaned the carb.

Before i checked the valves i did a compression test and i think i got about 70psi after a few kicks but was unsure if this would have anything to do with the auto decompresser?

You seem to have two of the 3 (well 3 of the 4 if you count the cam lobe position). the third is the engine plug on the other side of the case (shifter side). It's smaller than the other side. This is where the two dots i was refering to are. You'll see two dots on the flywheel when spinning the crank on the other side by hand. All three need to be line up at the same time. Just be sure it's the second dot and not the first. They will appear close together when you see them.

All 3 of these need to be lined up to ensure TDC when you take your valve clearance mearsurements as well.

sorry bro unless someone has another way I'm not aware of it sounds like you'll have to drain the fluids again to doublecheck this part. Once you get it all lined up, I would go ahead and recheck the valves again, just to be sure you didn't get inaccurate measurements and shimmed based off of wrong info.

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. I had a look and found the compression was only 50psi so i checked with a leak down tester and it was leaking 20% at tdc and 60% when piston was lower in the bore. Now that i have removed the head and barrel i can see the head has some small dents on the flat bit in the combustion chamber and the cylinder is scratched, its easy to feel the scratch. I guess it needs a rebore and a over size piston?

Also i can feel a small amount of up and down play in the big end. Is this normal on a 4t or does it need a new bearing?

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