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crf 230 cam bearing loose

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I just bought an '04 crf230f that needed some topend work. This is my first bike (i'm 26) and i'm just want to put the stock piston and cam in it. My question is the cam bearing furthest from the timing chain slides on and off very smoothly by hand. That seems to be too loose to me, or should it go on very easy like that. I would like to not by a new cam but if i have to its not a problem. Thanks for any help

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I can tell you the bearings are a press fit and are ordinarily very difficult to remove- should not be sliding off by hand. Don't know if it's OK to re-use offhand.

What exactly is wrong that it needs top end work and what have you done to it so far?

If you do wind up needing a new cam and seeing how the engine is already apart, I'd suggest an aftermarket cam and a higher compression piston even if you don't bore the cylinder for a bigger piston. Good jump in power without sacrificing any reliability or driveabilty.

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Thanks alot thats what i needed to know. I'd like to replace just the bearing but i may need a new one. I bought the bike and it ran but smoked alot. The previous owner said he flipped it and it sucked in sand/dirt and then didnt run right. I pulled the engine, pulled the topend and checked everything. I would like to do high comp piston and cam but i dont really want to spend that much right now.

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Thanks alot thats what i needed to know. I'd like to replace just the bearing but i may need a new one. I bought the bike and it ran but smoked alot. The previous owner said he flipped it and it sucked in sand/dirt and then didnt run right. I pulled the engine, pulled the topend and checked everything. I would like to do high comp piston and cam but i dont really want to spend that much right now.

You can check, but not sure if you can buy just bearings. Bearings come installed along with the cam sprocket on the cam for everyone I know that has swapped cams. If you can buy just bearings, they have to be pressed on properly or they'll be damaged and chew themselves up after the engine's running. Surprised no one else has chimed in on this- maybe everyone else is out riding.

Did you find anything abnormal when you pulled the engine- apart from the loose cam bearing?

Sucked in dirt and doesn't run right and smokes ever since? Was he using an air filter? I've heard of them sucking water, but not enough dirt thru the air filter to wreck the engine. Ouch! I think the dirt would go directly into the combustion chamber and do the damage there mostly- meaning chewed up rings and scored cylinder walls. That would make it smoke and not "run right" probably due to the compression being shot. Did you do any compression testing or leak down test before you pulled the engine?

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I found the dimensions of the new bearing online and of looks like the can is the worn part so I think ill just get a whole new one. The previous owner did have an air filter by it had sand all in it and when I removed the Carb there was the same sand in the throat also. I assumed the sand caused the low confession but when I went to do a leakdown test I didn't have an adapter for the small spark plug hole. The cylinder itself is not scored at all so I'm hopeing it just needs piston and rings.

I found the dimensions of the new bearing online and of looks like the can is the worn part so I think ill just get a whole new one. The previous owner did have an air filter by it had sand all in it and when I removed the Carb there was the same sand in the throat also. I assumed the sand caused the low confession but when I went to do a leakdown test I didn't have an adapter for the small spark plug hole. The cylinder itself is not scored at all so I'm hopeing it just needs piston and rings.

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Sorry for the double post. Also is it worth he money for me to get a flex hone since the cylinder looks good, no scoring?

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Sorry for the double post. Also is it worth he money for me to get a flex hone since the cylinder looks good, no scoring?

It'll need to be honed regardless, otherwise the new rings will never seat properly.

Since you couldn't do any testing, wondering when the engine was smoking. Worst on start-up, hard acceleration or on deceleration? If hard acceleration only- probably just rings. If start-up or deceleration, valves are probably suspect. It would suck if you got the engine all back together, and it turned out to have valve issues too.

So now that the cam is NFG, are you interested in a different cam than stock- 'cause we've got lots of suggestions for ya.

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At first it just smoked all the time then after 5 min it would mostly only if I Rev,d it. I pulled the valves last night and I don't see scoring or burning on the valves or seats so irk. Also I'd like a better can I just don't want to put $200+ in cam, springs etc when the stock can is $70. Appreciate the help

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At first it just smoked all the time then after 5 min it would mostly only if I Rev,d it. I pulled the valves last night and I don't see scoring or burning on the valves or seats so irk. Also I'd like a better can I just don't want to put $200+ in cam, springs etc when the stock can is $70. Appreciate the help

Smoking on start up means oil getting past the valve seals, smoke on decal means bad valves- oil gets pulled in by the engine vacuum, smoke on accel or revving means bad rings. Little hard to diagnose, but 5 min after starting, the rings may be sealing better after warm up, and not from oil leaking past the seals when it sits.

A wiseco piston and some hotter cam would be pushing $400 for everything. It can add up fast. How much did you pay for the bike?

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I paid $475.

Sounds like a good deal if the rest of the bike is in good shape.

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Yeah i hope it was a good deal. Its also got the upgraded front and rear BBR springs. I measured the ring endgap tonight per the manual and the gap is more than double the limit the manual states so i think the rings are my biggest problem. I was also planning on replacing valve stem seals.

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Yeah i hope it was a good deal. Its also got the upgraded front and rear BBR springs. I measured the ring endgap tonight per the manual and the gap is more than double the limit the manual states so i think the rings are my biggest problem. I was also planning on replacing valve stem seals.

A lot of people run 1 BBR and 1 Stock spring in the forks because 2 BBR's are very stiff/harsh. Just keep in mind for down the road.

I suppose if the rings have been ground up, that would make them a smaller diameter, and so they would show a larger gap when measured in the cylinder.

I like the idea of replacing the seals. Little uneasy about all the smoke on start up- possibly bad seals.

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What are your thoughts with the valve seats? They dont look burnt etc. but maybe I'm missing something. Good to know a about the fork springs. Any idea what oil I should run in them? I read somewhere 10w oil, I have to replace fork seals so I need oil

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What are your thoughts with the valve seats? They dont look burnt etc. but maybe I'm missing something. Good to know a about the fork springs. Any idea what oil I should run in them? I read somewhere 10w oil, I have to replace fork seals so I need oil

Don't know much on how to check valve seats other than with a leakdown test- too late for that. You could run it by a machine shop and let them take a look for an opinion. From what I know, bad valve seats won't make an engine smoke, but they can cause low compression.

Probably be better to post a separate question about the oil and fork springs. Quite a few have done that route. I have a different setup with emulators in my forks.

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Thanks again for all the help. I'll get it all together and see what happens.

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i just got my new piston and rings and checked the end gap. The new top ring end gap is .016" and the old one is .107" the service limit is .020 so i guess they were worn out!

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That sounds kinda shot- shot run a wee bit better now!

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