CRF's Only Forums

Hi everyone,
im Alex,from Rhodes,Greece.
I have a CRF150R motard use and on my last practice i had cut intake valve on the keepers.I bought the bike used and was allready using PROX valve's.
Does any one faced a similar problem before ?
More or less 5-6 hours of working hours.

Welcome to the site !!

I have not heard of that happening before , Ken the owner here does valve jobs all the time , hopefully he will chime in and give some info if he has seen this issue before ......

So basically the valve stem broke off where the notches are for the retainers ??

more photos...
and believe or not ...nothing broke.only valve bended a bit

Is this a Stainless valve ?? , if so were the springs changed to accommodate the extra weight of the Stainless ?? , the reason i am thinking is that it may have been some kind of spring bind or the spring not being stiff enough for the RPM's and the keeper came off and the spring retainer is what got caught in the stem notch for the keeper and tore the end off , also allowing the valve to bend , I am guessing the valve did hit the piston ??

Stainless yes,ProX.Valve springs are OEM and the engine is running no more than 12.800rpm.The thing is that happend on revolution(from 4th to 5th gear)on 12.500rpm acording to the AIM telemetry,so i dont think its a valve float issue.If you notise on foto Nr.2 and Nr.3 the valve on top is grained.This means the valve was turning(like it should be)but not all together(with the springs,the retainer and the keepers.From what i saw,keepers and retainer didnt move on the same of the valve.and thats what i cant understand

Yea , it does not make any sense to me either , how did the retainer clip look ?? , did it look like it had just failed/broke in half or all banged up ???, if it was not RPM related , then it could have been that the retainer clips were not seated properly when installed prior , maybe one side of it was , but the other maybe not and the only side holding it , could not take the load any longer and just decided to give way or it cocked sideways and then started cutting into the stem

The bend in the stem has me concerned about piston or rod bearing damage

Hi magicjuice,
What do you mean by grained?
Any chance of a close-up of the collet end of the valve from two directions say 90 degrees apart.
Have you taken the rest of the valves apart to see if there is any strange wear or damage.

I have seen things like this when old collets were reused and hammered the valve groove. Hadn't taken the top off the valve yet, but you could guess that may have happened in the future.

Everything is stock except the valves which are ProX.It doesnt have many working hours.the other valves are all OK,no sighn at all.

You are so lucky man. So so lucky. My 450 was just put back together. Everything in order with timing set to the T and clearances!!! But then, what happens??? Mr ProX valve decides to break clean off, and i mean clean!. Conrod breaks and ends up through the casing. Sad sad day ... so pissed off. Feel like going back to the smokers. By the way, this happend half throttlle 1st gear...