450R piston hitting valve

[moogie66]

I have installed a high comp piston and web cam suggested by a major retailer. When timed up as per spec I have found the intake values only just hit piston on rocker stroke. Exhaust is OK
The cam grind allows intake opening quicker after exhaust. If I retard cam 1 tooth the valves dont hit but come close. I am trying to get info from the retailer
Does anyone out there have any comment or experience in this matter or if this retarding will work
The piston and cam should be compatible
please email shaun
scarab@emerge.net.au
or reply post

[chad502ex]

Originally posted by moogie66
I have installed a high comp piston and web cam suggested by a major retailer. When timed up as per spec I have found the intake values only just hit piston on rocker stroke. Exhaust is OK
The cam grind allows intake opening quicker after exhaust. If I retard cam 1 tooth the valves dont hit but come close. I am trying to get info from the retailer
Does anyone out there have any comment or experience in this matter or if this retarding will work
The piston and cam should be compatible
please email shaun
scarab@emerge.net.au
or reply post

what the "H" is the rocker stroke?

what compression piston are you running?

what web cam are you installing?

retard timing one tooth would be fine- assuming your timing is correct in the first place.

[450robot]

te rocker stroke is when the rocker side of the valve train hits the valve,

make sure your timing is correct, nomatter what piston setup or cam, they should work in conjunction

and if not, try looking at yur valve specs again

[chad502ex]

well if the rocker stroke is on the rocker side of the engine- then in the trx450r, the rocker side if on the exhaust side and that is clear from what he said.. :confused:

anyway, check timing

[moogie66]

When I say rocker stroke i mean when the piston is TDC and valves are rocking, eg exh is open then intake opens as exh closes as piston goes over TDC...Opposite of compression stroke
Thus term rocking ( normally used when talking eng with rocker arms on both exh and intake )

Anyway i have found that if you use a certain Web cam that has high lift you use a adj cam sproket to retard cam slightly so the valves come close but not touching

The company that supplied cam and piston may have forgotting this little bit of info i think ????

thanks for the posts

[370kingR]

Originally posted by chad502ex
well if the rocker stroke is on the rocker side of the engine- then in the trx450r, the rocker side if on the exhaust side and that is clear from what he said.. :confused:

anyway, check timing

You know Chad, when the rocker stroke rocks and rolls to the music of the piston hitting the valves. Just loosen the shims up and put some washers under the head bolts...lol

Come on Chad, get your learnin on :rolleyes:

[chad502ex]

Originally posted by moogie66
When I say rocker stroke i mean when the piston is TDC and valves are rocking, eg exh is open then intake opens as exh closes as piston goes over TDC...Opposite of compression stroke
Thus term rocking ( normally used when talking eng with rocker arms on both exh and intake )


ahhh, i understand what "rocker" is being referred to. Guess, I'm still being schooled on terms. I'd rather think of rocker stroke as the point where overlap exist, or the point where the exhaust ends and intake begins...

Thanks for taking time to clarify..

[rodenberg35]

I have seen the sparks cam do this also with the 13:1 je piston. but only at high rpm. oh ya **** went boom