Time to check valve clearance?

[kjjz28]

I've been on 3 rides on my CRF...probably less than 3 hours "tach" time and most of that riding fairly slow speeds with my son on his 70 and an occasional lap or two around the track (nothing lightning fast). The previous owner stated the bike had about 15 hours on it when I bought it and he had checked the valves and the clearances were still in spec.

I'm wondering if I need to check valve clearance at this point? Everything seems fine but I'm not sure what to be looking/listening for? I have the shop manual but I'm still a little anxious about getting it done right. I just don't want to get behind the 8 ball on this thumper and pay big money down the road! Any suggestions/comments would be much appreciated. Thanks folks!

[P1M]

I'm pretty bad about checking stuff on my own bike seeing that I have 60hrs on my CRFX and most of those are race hours and I still haven't checked mine but you should check them. The first sign that the intakes are getting tight is when it becomes hard to start.

[Woody_393]

I suggest every 20 hours just like the book says.

The problem with waiting until the bike is hard to start, is that they are already @ 0 clearance.

I was nervous the first time I checked mine (had never done it), but after doing it I wondered why I waited. It's not a bad job at all. Changing a tire is 3x worse

[AL_CRF450]

I check mine every 10 hours whether i think they need it or not!

[kjjz28]

O.K. Got the cylinder head cover off and have my feeler gauge. It appears to be an odd angle to try and get the feeler gaugeunder the cam lobe between the lifter. Is the gauge supposed to slide all the way through from the front to back? With the angle of the rocker arm, I can't slide the gauge exactly horizontal but it's a few degrees higher. I'm trying to slide an .012 through and even tried a .006 and it won't move. Am I approaching it at the correct angle?

I can usually start it after 2-3 kicks and on the 1st kick after it's warmed up so I don't think it's out of spec.

Any help/suggestions would be appreciated. Thanks!

[Silver_Fox]

Originally Posted by kjjz28

O.K. Got the cylinder head cover off and have my feeler gauge. It appears to be an odd angle to try and get the feeler gaugeunder the cam lobe between the lifter. Is the gauge supposed to slide all the way through from the front to back? With the angle of the rocker arm, I can't slide the gauge exactly horizontal but it's a few degrees higher. I'm trying to slide an .012 through and even tried a .006 and it won't move. Am I approaching it at the correct angle?

I can usually start it after 2-3 kicks and on the 1st kick after it's warmed up so I don't think it's out of spec.

Any help/suggestions would be appreciated. Thanks!

If you can't fit the feeler gauge in, your valve clearance is to tight. They get tighter as they wear more.

[Woody_393]

You should be able to get it in there. It does take some english to get it, but it should slide all the way through with a slight drag.

Keep trying, if you don't succeed, you need thinner shims.

[kjjz28]

Thanks Woody. What causes the valves to tighten so quickly? The previous owner told me he checked them just before I bought the bike back in October and they were in spec. I've only put about 3 hours on it since then. What can be done to lengthen the valvetrain life from here on out? I also recall reading something about decompressing the springs by putting the bike in gear and rolling it backwards till it stops.

[Rydawg1]

Watch this to get a good idea of what to do

[Only registered and activated users can see links. ]

[Woody_393]

Once the valves go to zero, they are pretty much toast.

The solution IMOP, is getting new Stainless steel valves.

[kjjz28]

Thanks for all the info folks and that was a great video to watch but I'm not to the point of confidence to re-shim them after having checked them a couple of weeks ago.

I did take the bike to the dealer over the weekend and sure enough, one intake valve was out 1/1000th and the other was 3/1000th so they were re-shimmed. The exhaust valve was fine. My question now that I have a "benchmark"....is there anything I can do to "extend" the life of the valves other than frequent air filter and oil change services? I don't race so don't overly rev the engine.

Thanks again for the help!

[Woody_393]

Just keep checking them @ 20 hours, and adjusting as necessary.

The stock valves have a hardened coating on them, once that coating is gone, they won't stay in spec for very long. I saw 3 rides tops before they were back to zero again.

[wyseguy007]

I have an '03 that I bought last spring if like new condition, I would say it had less than 5hrs of riding around the guys house. I rode all last summer and pulled it appart today to check the valves. Exhaust valves are perfect, one intake has about 2 thou clearance, and the other one has 0 clearance. Without pulling the head, how do I know when the valves need to be replaced. Is there a shim thickness that would indicate badly worn valves? I am positive this is the first time the engine has been opened up. It has always started great. Any advice would be great.

Thanks

Mike

[Woody_393]

No there's not.

My method was to shim and ride. If I only got another 3 rides out of it before it started running crappy and wouldn't start worth a darn, I knew it was valves. Which also meant it was time to replace them. If the hardened coating isn't worn off you'll get a lot more than 3 rides.

The bottom line on these is to check them often (20 hours minimum), and adjust when out of spec. Waiting until they hit 0 is a recipe for replacement.