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Top end rebuild question

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Im rebuilding the top end in my 250f and I have a few questions on the cam chain. I purchased a new cam chain and it seems to have some side to side flex in it. So my question is how much flex should it have exactly? If any. I guess that leads to my next. When I actually get to replacing it do I need any special tools. They recommend a flywheel puller from motion pro or yamaha, but is it possible to do it with just regular tools?

My next question is regarding the valves and the clearence. Now correct me if im wrong but can you actually pull of the head and check the clerance as long as the timing marks on the cams are right? I remember seeing on the dirt rider write up that the had the head off and checked the clerance.

Thanks

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There is some flex to the chain, it is not a piece of metal tubing. I don't know how to measure how much. Don't worry about it if it is new.

Yes you need a flywheel puller. You should be able to pick one up for $25. Just get one. I also recommend a air impact wrench. I have have tried with several bikes to get the flywheel nut off and torqued correctly and the impact wrench and a little common sense makes the job way easier.

You can check them with the head off, but the manuel says to check the vlaves with the cam chain tight.

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Im rebuilding the top end in my 250f and I have a few questions on the cam chain. I purchased a new cam chain and it seems to have some side to side flex in it. So my question is how much flex should it have exactly? If any. I guess that leads to my next. When I actually get to replacing it do I need any special tools. They recommend a flywheel puller from motion pro or yamaha, but is it possible to do it with just regular tools?

My next question is regarding the valves and the clearence. Now correct me if im wrong but can you actually pull of the head and check the clerance as long as the timing marks on the cams are right? I remember seeing on the dirt rider write up that the had the head off and checked the clerance.

Thanks

A flywheel puller is a must. Go get one, they aren't too expensive, and if you're keeping the bike for a while you'll use it more than once.

You don't have to pull the head to check the valve clearance. But if you are planning on pulling it anyway, checking the clearance on the bench is easier than on the bike, 'cause you don't have to wrestle with the frame while trying to do it (not that it's really that hard).

If you do it off the bike, put the cams and the cam caps back on while the head is on the bench. Use the proper torque wrench and torque them down to the proper spec (7.2 ft lbs, or 84 inch pounds). Make sure you use a good torque wrench for this, one where that 84 inch pounds is in the middle of the range of the wrench. If you tighten these bolts down to lets say 10 ft lbs (120 inch lbs) you may ruin the head.

Once the caps are torqued down, turn the cams with your finger. They should easily move back & forth. Set the cam to the timing mark, and check the clearance. You may have to hold the cam there while sliding the feeler gauge in , but as long as the mark is where it needs to be, your measurement will be accurate.

Good Luck!!!!

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Remember that you have to remove the cams to fit the head back on the engine. The timing chain won't go around the cams if they are installed. There is not enough clearance in there.

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Remember that you have to remove the cams to fit the head back on the engine. The timing chain won't go around the cams if they are installed. There is not enough clearance in there.

Yeah that's true. I didn't say that, but you have to remove the cams to get to the 2 head bolts too, so I figured he'd figure that out.

But you're right you do have to pull the cams before bolting the head back down.

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..AND a Torx 30!

I forgot to say that, my bad. I have a #30 TORX bit mounted on a 3/8 drive socket, and a hammer impact driver, so you can break the 3 bolts loose that hold the stator plate on. If you try to do it with just an "L" shaped torx wrench you'll probably strip them. They are really tight.

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Ok i will pick up a flywheel puller. I think I might even have one. Also what is a torx 30? Is that just an allen head? I have an impact wrench for the stator plate bolts. Ive checked the clerances while it was on the head I was just curious if it could be done off the head. It would be easier also. Anyway thanks for the info guys.

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Torx #30 is an actual size of head on a screw/bolt. Visit your local tool store (Sears, etc.) and they will show you. Its more of a "star" shape than an allen head. Good Luck!:applause:

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Ok ive gotten everything dissasembled and have put in the new piston. While I was cleaning off all the old gasket I noticed that one of the valves looks as if it had the hard anodizing of whatever they put on them is chipped off. All was in clerance so I was wondering how much longer can I go on the valves. Was planning on going a couple of months anyhow and replacing all of them. Is it safe to ride with it like that? Also is any motorcycle antifreeze safe to use? Thanks.

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Ok ive gotten everything dissasembled and have put in the new piston. While I was cleaning off all the old gasket I noticed that one of the valves looks as if it had the hard anodizing of whatever they put on them is chipped off. All was in clerance so I was wondering how much longer can I go on the valves. Was planning on going a couple of months anyhow and replacing all of them. Is it safe to ride with it like that? Also is any motorcycle antifreeze safe to use? Thanks.

It's your engine, and you can do anything you want. If it was mine however, I'd remove the valves & look at the seating area where it touches the head.

It the contact areas are silver, then the valve is gone. If the metal is eroded away and the beveled edge where it seats looks like you could shave with the edge, then they are way past gone, and you're lucky it didn't blow up.

If it blows up, unless the bike is only a year or 2 old, it's gonna cost more to fix it than it's worth. Valves & cam chains are nothing to skimp on.

Any motorcycle coolant is good. Just get it mixed 50/50, or get straight stuff & a bottle of deionized water at Kragens & mix it yourself. Don't use tap water, as it MAY have lots of minerals in it that can eat away at the motor.

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