crf150 seized.

[Timmay#678]

Ok only found the macro mode on my camera so I've got some better close ups for ya!

crack in the inlet bridge:


Inlet lifter:

Camshaft:

The piston chases the exhaust valve closed near TDC and if the exhaust valve doesn't get settled on the valve seat in time you end up with the exhaust valve closer than normal near TDC and they'll hit the piston. A sure sign that an engine is being over-revved and floating the valves is bent exhaust valves. Patman's son did the same thing on his hot rod XR95. Patman explained what was happening to him and it was never an issue again.

Hey Rich, I fully understand what you're saying here, and this was the case with this engine from the marks on the exhaust side of the piston. However, from the damage done to the cam and lifter over one of the inlet valves, I'm assuming it was this that caused the engine to lock up. What would be the cause of this, could the inlet valve have stretched if the engine had overheated?

 

[SHSPVR]

Timmay#678 I would have that head pressure check

 

[SHSPVR]

Timmay#678 take close look at this just be sure that it was hit the cam lode
As for Inlet lifter it look it seized up in bore ocen agine due lack of oil

 

[Rich Rohrich]

. However, from the damage done to the cam and lifter over one of the inlet valves, I'm assuming it was this that caused the engine to lock up. What would be the cause of this, could the inlet valve have stretched if the engine had overheated?

From those new pictures it's clear that the intake bucket stopped spinning in it's bore, and caused the groove to wear in the bucket and cause the cam lobe wear pictured. That could account for the lifter bore breakage as well.

As SHSPVR pointed out, this could easily have been caused by repeatedly running the engine low on oil, but it would be wise to verify it before just assuming.

One thing seems very clear. This engine has been abused for a while, and probably has more problems than the ones we are seeing here.

This is the type of job that smart mechanics run away from. ;)

 

[whenfoxforks-ruled]

What kind of torture was done to the bottom end? I would hate to see the charge for a new engine. 1500 U.S.A. dollars in parts?

 

[Rich Rohrich]

Educate us Rich, what do they coat the cam with and what benefit does it provide?

Joe - It's my understanding that it's an anti-friction coating to ease the cam break-in. I'll try and get a hold of Tony Tice who used to work for Hot Cams, to see if he can shed some additional light on it.

 

[_JOE_]

Joe - It's my understanding that it's an anti-friction coating to ease the cam break-in. I'll try and get a hold of Tony Tice who used to work for Hot Cams, to see if he can shed some additional light on it.

Thanks Rich. Struck me funny that the lobes are coated.

 

[Patman]

Looks like the old addage of "Believe half of what you see and NONE of what you hear" REALLY REALLY applied to the so called rebuild on this bike. Also another reason I'm not a huge fan of buying somebody elses race bike.

 

[whenfoxforks-ruled]

Also another reason I'm not a huge fan of buying somebody elses race bike.

And the kid on the farm that never changes the oil or air filter?

 

[Patman]

And the kid on the farm that never changes the oil or air filter?

If it's and XR then no problem :laugh:

 

[Timmay#678]

And the kid on the farm that never changes the oil or air filter?

Funny enough the kid never really got the chance to change the oil, chap had only had it 2wks and couldnt have put more than 3/4hours on it. He problem was he hadn't discovered the dipstick on it yet :bang: . I'd say it was mainly low oil, combined with no rebuild and the kid reving the bike wayyy too hard.

And he didn't come near my farm either :whoa: , I'd only let chaps I know well and aren't nutjobs ride here!

Anyway, I'm kind of stumped as to what to do with the bike now, its an 07 bike and probabely worth 1700euros here in Ireland. A full top end rebuild is going to be 600quid in parts. Should I be splitting the case and putting in a new crank also? God knows what other horrors await me down there :)

Including labour and all that I'm beginning to wounder if it would make more sence to strip the bike!

 

[Patman]

Wouldn't make any sense NOT to do a full rebuild on it if the plan is to keep it. It might be worth looking for replacement engine though instead of time and money in to a rebuild. Service Honda might be able to help you out since they have never been run take outs available.