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Hi there, i have a 2005 CRF450X and i have been checking the valves after doing 1400 miles and some of them don´t have clearance and i would like to know what possible damage that would do to the bike.
This is not in inchs, is in mm but you can have an idea.
Exhaust valves (between 0.25mm & 0.31mm):
Right:
-0.33mm can fit but rubs a lot
-0.30mm can fit rubs a little
-0.28mm fit nicely (i think this is good clearance)

Left:
-0.30mm fit but get really stuck
-0.28mm fit nicely (i think this is good clearance too)

Intake valve (between 0.13mm & 0.19mm):
Right:
-0.13/0.10/0.08/0.5mm none of this fit (no clearance, what possible damages can do???)

Left:
-0.13mm dont fit
-0.10mm fit but get really stuck
-0.08mm fits nicely
-0.05mm fits nicely

To summarize this the intake valves have less then the 0.13mm minimum, what could this do if i keep riding the bike like this.

I have a 2003 CRF450R hotcams the timing to see the clearance is the same as the stock hotcams.
Sorry for the long post, thanks.

What it will do , is one of 2 things first

It will either stop running/be very hard if not impossible to start ....or the valve will break and cause the valve head to go into/thru the piston , pretty much destroying the engine, as it will ruin the piston , possibly the cylinder , and if the piston slams the head with a valve stuck in it , it will take out the rod bearing , requiring a new crank , piston (cylinder) and head

Either way , its got to be fixed , once they bottom out completely like that , you may only get 1-2 hours of ride time , then its done

Either way , you can't just forget about it , its either going to stop running , or the engine will be destroyed , one or the other or both will happen , it can take a few minutes , or a few hours to happen ...sorry ....

JimDirt wrote:What it will do , is one of 2 things first

It will either stop running/be very hard if not impossible to start ....or the valve will break and cause the valve head to go into/thru the piston , pretty much destroying the engine, as it will ruin the piston , possibly the cylinder , and if the piston slams the head with a valve stuck in it , it will take out the rod bearing , requiring a new crank , piston (cylinder) and head

Either way , its got to be fixed , once they bottom out completely like that , you may only get 1-2 hours of ride time , then its done

Either way , you can't just forget about it , its either going to stop running , or the engine will be destroyed , one or the other or both will happen , it can take a few minutes , or a few hours to happen ...sorry ....

The bike is running great, only a little hard to start (i just use electric start) and some times turn off while riding. I will try to take care of this, i dont want to ruin a good engine just because of lack of maintenance.
The hotcams for being of a CRF450R the timing dots are aligned as stock or differs ?
Thank you for the help .

Timing Marks are the same for either bike , so it should line up either way

Yea , once the valves start moving , its just a matter of time before the bike either quits running , or the valves cause major damage , the starting/stalling issue is a sign that they are on their way out , so if you act before something "bad" happens , then it will save you a lot of money in the long run , switching to Stainless Intakes will make the interval between valve jobs much much longer , its what the majority of people do (i did) when the valves start to go , is to switch to Stainless , and it cuts the maintenance down dramatically , less worry and more riding is the result of doing the swap.....

As a example , my valves went about 6 months after i got the bike new in 06 , i did the Stainless Intake swap and have not had to adjust them since , its been 10 years without needing to adjust valves , now not every bike is the same , but it just shows that the swap is well worth it

Jim,
Just a note in regards to the 5 valve Yamaha heads, they seem to let you keep starting with the obvious scenario you described. Maybe Hondas not starting is a blessing.

Yea i have heard of that with them doing that right till the head of the valve breaks off and it eats the bottom end (i have seen a few of those that have had a valve cut loose , what a mess)