[JOHN TRIOLO]

I just shimmed my valves on my 450x I did not check to see if my valve timing was corrrect.
Of course it did not start, I did not reset the valve timing as of yet, does any one know if this caused any internal valve train damage.
I know that on older cars when the timing belt broke that the valves would not clear the pistons and a valve job was in order.
any info on this matter would be appreciated

[marks crf]

just check the piston and valves for damage like half moon spots on the piston

[JOHN TRIOLO]

Any Way to check without removing the head.

[Asmith]

Does the engine cycle through the stroke completely? Or does it get hung up?

[JOHN TRIOLO]

yes it cycles through
it does feel like there is a bump I suppose its the compression release.
The CRF model has never turned over as smooth as a Xr even with the spark plug removed.

[Asmith]

yes it cycles through
it does feel like there is a bump I suppose its the compression release.
The CRF model has never turned over as smooth as a Xr even with the spark plug removed.

That is correct. The decompressor will cause a "bump" as you cycle it.

You've got nothing to worry about if it will cycle through. You are most likely off by a tooth on the timing. Enough to keep it from starting, but not enough to cause interference.

[JOHN TRIOLO]

~ thanks for the info, I'll move the cam chain a few teeth and this time I will make sure I am at TDC and the timing marks line up, on the cam and the lower one as well.
What had thrown me is there was more than one punch mark on the bottom gear on the right hand side.

[Asmith]

Use the timing marks on the left side.

Remove the plug, rotate engine until the second mark lines up with the cutout. Much more accurate than the mark on the right side.

[JOHN TRIOLO]

OK now the timeing is correct and i turn the engine over with th starter, it still did not start I felt the exhaust and it was warm so something was happening.
so I grabbed a 25 year old compression guage off my shelf..no compression at all I decided to pull the head to see if I had any valve damage I found nothing it held gas until it evaporated.
Crap I pulled the head for nothing.
off to the dealer for a head gasket and possibly a manuel if i cannot find for free on line.
any sugestions.

[Asmith]

Let's go back to square one.
Why did you shim the valves?
Was it all of a sudden not starting?
Was one of the valves zero'ed in clearance?
What were the clearances before? After?

[JOHN TRIOLO]

Heres the history, bought the bike used not many mods
origanal owner said that the valves have never been touched.
I rode it down his block stock it felt a little bogged down as did my 650r did before any moods so I bought it on 5/0/09
still have not even rode this bike
I did the air box mod, changed the jetting and went with the ncys needle clip on 3 kept the stock leak and the stock pilot.
162 main to start removed the defuser from the exhaust. I installed a flex air screw and thats about it
the carb had a qs2 on it with the wire mod.
I also installed a stealhy 9 OZ flywheel weight for for chugging the back trails.
since the bike was tore down I checked the valves finding the ex was at 005 and intake at 004
decided to by a shim kit and shimmed it just as I had many crf 250's without any problems.
after replacing all parts removed I tried to start and no go.
I realised the valve timeing was off wen my so had told me he was not sure what mark he saw when we reassembled. I had not realised there was more than one punch mark on this model.
could the auto compression release be the culprate?
I am not at all familiur with the workings of this part I am old school.

[marks crf]

did u take out the sparkplug and forget to put it back in

and also did you make sure you put the right shim in the right shim pocket

[JOHN TRIOLO]

Ok here is the scoop, just as ~ has said to set the valve timing using the timeing marks on the flywheel he said it was more accurate.
I slept on it and started from there of course this was after removing my head only to find out it was ok
All of my wounds are self inflicted I had been confusing top dead center with compression stroke thats why I could not get the bike to start, when I took off the timing chain I had to turn ove r the motor and did not find the COMPRESSION SROKE until this morning the bike started with a little effor.
Now its time to tune the carb to match the airbox mod
the 162 main jet may be to small I will check out the jetting links,

Thanks for all the feedback

[JOHN TRIOLO]

OK will not start again no compression took off head and checked valves for leaks took off cylinder to check rings both seem to be in great shape.
Took down to the local rebuild shop had a vacuum test done on the valves no problem there.
The bike has been down for 16 days and I'm ready to put it out by the dumpster.
I put it back together and still no compression I was about to buy a leak down tester when a buddy said he had one maybe I 'll find out whats happening to it.
After this if I dond figure it out I,ll need a good shop to take it to.
I live in Cypress any suggestions.
And if I've fixed your bike no crap from you guys I just can't fix my own.

[124]

Didn't you say in the post above that you re-timed the cam and "it started with little effort"???

Engines don't lose compression overnight.

If your timing is changing after being set correctly, then it is possible that you've mis-aligned the cam chain on the crank gear. It could be barely on the crank gear allowing some resistance, but jumping on and off. Double check the alignment of the cam chain in the bottom on the crank gear. Use a good flashlight...