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03 crf450 timing

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Hello guys, just found this site after only recently buying a 4 stroker and instantly running into issues! 

 

Ive searched and seen loads of stuff on the timing etc, i have a good mechanical knowledge/skill etc

 but im still a bit unsure,  the bike is an 03 crf450, nightmare to start, and mean terrible, plenty compression,  had valves shimmed etc recently by the "specialist" i bought it from last week, 

 

today i thought id check timing etc as starting is beyond a joke,, 

lined up marks correctly at bottom end for tdc, cam lobes pointing towards rear of bike  but slightly pointing up the way, 

the cam gear mark appears to be 1 maybe 2 teeth out? Would this cause the terrible starting? 

Pic attached

Many thanks for any help, 

scott

IMG_7290.JPG

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Yes your timing is off and depending on the condition of your cam chain you want that mark slightly above the triangle on the cam tower.cheers

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28 minutes ago, wingman111 said:

Yes your timing is off and depending on the condition of your cam chain you want that mark slightly above the triangle on the cam tower.cheers

Thanks very much for the reply, 

cam chain is brand new so will adjust it to just a tiny bit above the arrow on head, 

only managed to start the bike twice in 3 days of owning it! Hopefully this will fix it!

 

scott

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Yeah that will help tremendously. Any engine would have issues with cam timing being off but a 450 motocross bike takes that to new levels!

Be very glad it wasn't another tooth off because you can't have had much clearance between piston and valves when it did start

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Yea i was worrying about the clearance after i noticed the timing was out,  

must have been close!

will be happy to get it spot on and running sweet, 

i knew they can be/are harder to start than the 2 smokers im used to but after an hour of kicking and resting and kicking again i knew something had to be a miss!  Can barely move my right leg today! :banghead:

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1 minute ago, HRC27 said:

Check the cam chain tensioner as well. The OEM ones are prone to failure.

Thanks, i was just reading about the tensioners on here earlier, 

will be something i will be replacing i think!  

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I rode CRF450's from 2003 up to 2014, most of them 100-120hrs MX racing and never suffered any problems with timing chain or tensioner.

I did wreck several transmissions and clutches though.:banghead:

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Yeah on the cam chain tensioner front I concur with frankdecrosser,I have worked as a technician in a giant multiline dealer in El Cajon CA and during the entire run of CRF450r's I have seen only two failed automatic cam chain tensioners i.e. the stock ones. Both of the failures that I have seen have been on supermoto used machines, that is high rpm and then slam the throttle shut on pavement.That being said I always replace cam chain components and tensioners on my personal machines at top end time.cheers

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well i corrected the timing, turned engine a few times with plug out to check, shims are just within spec although i cant remember what they were :facepalm: (waiting for shim kit to arrive then will re-do them anyway)

put back together, cycled the kickstart twice very slowly, no choke, kicked it and it fired up straight away! :thumbsup: very happy

I will be ordering a manual tensioner like you guys have mentioned, although dosent seem to be a great deal of choice in the uk! 

 

Scott

 

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