[leecrf]

Has anyone and a camshaft sprocket spin after a bottom end sieze

Ive done a full rebuild and cant get the timing marks aligned making me
Think the sprocket has spun
As the marks on the cam are either 1
Tooth back or forth from where they should sit cant get it in the middle

I have had the bike run since the build but was a pig to start ive checked my clearances think they are ok

[leecrf]

Forgot to say its 2004 250r

[JimDirt]

It could be possible , it is a pressed on gear ........ Do you have another cam to match it with ??? , that way you can compare where the teeth are in relation to each other , they should be exactly the same ....

[leecrf]

No dont have another one im
On the verge of buying a new one but im not sure

[JimDirt]

Just a question ...... Did you replace the timing chain ?????

If you did not replace it and it is stretched , then that could account for the difference (other than the gear slipping) , as I can't see any other reason aside from the timing marks not checked correctly , but if you are certain the other marks all align , then either the gear has in fact slipped , or the chain is stretched .....

I don't personally know of any other scenario that could cause it to continually be misaligned ....

[leecrf]

Sorry for delay yes brand new chain
When i have it lined up untensioned its fine but as soon as i do the tensioner up it pulls it too far so it looks a tooth out so i move it back a tooth then its not enough

I might have to have it all apart again and make sure everything was put back right
Other than the cam sprocket slipping i cant think what it could
Be

[JimDirt]

Check the Balancer Shaft gear(on the clutch side where you check the arrow/dot alignment thru the round plug , make sure it is on when the flywheel mark and the sprocket marks are level , you should get all three if everything is correct , since it is a new chain , that eliminates the stretch issue that would cause misalignment , so it is back to installation ...... or gear slippage ..... What you might try , is look on EBay at some used stock cams from the same year , see if they have side pictures of the sprocket , so you can see distinktive casting marks and where they align with the gear and cam , then compare them to yours , and see if everything looks the same ..... compare several of them to make sure there are consistent points that are the same , this would be the reference points to confirm the gear has slipped or not ..... that should give you a good conformation on whether the gear is the issue , or it is something else ..... aside from also checking the gear marks in the large plug on the clutch side and the small plug for the flywheel on the ignition side , and then look at the cam again and see if it is off ..... since ALL 3 should align no matter what , so compare the cam gear marks to the Balancer , then with the flywheel separately , see what aligns and what does not , each on its own should align

Cam gear/Flywheel marks ... Aligned ???

Cam Gear/Balancer .... Aligned ???

Balancer/Flywheel ... Aligned ???

Balancer/Cam Gear ... Aligned ??? , etc. etc. , no matter the order , each should align with each other every time ..... and should do so with tension on the chain .... and all 3 should be in alignment as a whole ...


Also , when checking ...... Align everything as close as it will get , then rotate the engine by hand a revolution , so the cam lobe is pointing back at the same 2 O-Clock position again , then recheck marks , they should be the same , and/or aligned , this will eliminate any variance from chain slack throwing off visual marks .... every complete revolution , everything (all 3 marks) should be aligned or in the same location , every time , check it several times , to get a consistent reading ..... .... That should point out any variance that would be causing a issue , if it comes up that the 2 others are aligned , but not the cam no matter if you move it 1 tooth in either direction and then check , then it is possible the the gear did slip .....

[JimDirt]

Ya know what ..... I just re-read your first post , and missed the part about the bottom end seize ..... That could very well have caused the gear to move on the cam , the sudden stop and especially if you were riding it and it was in gear , the sprocket could have spun ..... like I mentioned , recheck those marks with each other , if all align except the cam , then the gear is probably off from where it should be ...... if so , just look for one on EBay , and call it a day .... much cheaper than new , and give you the same results .....

[leecrf]

Thanks for the reply thats really helpfull
Before i saw the post i bought a good’ secondhand camshaft on ebay
Threw it back together and lines up so much better now
But when i kick it now it feel like it has no compression

I will go back over all the points you said when i get a bit of time to check the balancer shaft

Besides that my hot start cable was missing and the brass valve was jammed in the carb so i replaced all those parts so i dont know if that is contributing aswell?