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Cylinder Head Removal / Top Dead Center


BDS

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I'm in the process of removing the heads on my '04 R1150RT to remove the carbon build-up. I did the left side first. Everything came apart and went back together just fine. I then went about disassembling the right side. I had a pin in the TDC lock in the flywheel, same as I had done when I did the left side. The arrows on the camshaft sprocket were horizontal, so I proceeded to remove the head. When I pulled the head I was surprised to see that the intake valves were open, and the piston was not quite out to the edge of the cylinder (maybe 1/16"). I thought that when the the engine was at TDC that the valves would be closed, like they were when I did the left side? I want to remove the valves and decarbon them along with the head and piston face, but I'm hestitant to proceed. Any thoughts?

 

Thanks,

 

BDS

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skinny_tom (aka boney)

The valves on the R bikes are 360 degrees out of phase. Just like when you adjust the vavles, you need to rotate the engine 360 degrees to TDC to work on the other side.

 

Or:

 

When the left cylinder is at TDC, between the compression/power strokes (all valves closed), the right cylinder is at TDC of the exhaust/intake strokes. Accounting for cam shape and duration, your findings of the intake vavles being open a bit are probably correct.

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The valves on the R bikes are 360 degrees out of phase. Just like when you adjust the vavles, you need to rotate the engine 360 degrees to TDC to work on the other side.

 

Or:

 

When the left cylinder is at TDC, between the compression/power strokes (all valves closed), the right cylinder is at TDC of the exhaust/intake strokes. Accounting for cam shape and duration, your findings of the intake vavles being open a bit are probably correct.

 

Thanks for the repsonse. I'm thinking that I should put the head back on, re-attach the camshaft chain sprocket and rotate the engine until I'm back at TDC with the valves closed and then try again?

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skinny_tom (aka boney)

I can't guide you there (I don't know).

 

The manual makes mention of "firing TDC" when removing the head. I think that's your answer.

 

 

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Joe Frickin' Friday
Thanks for the repsonse. I'm thinking that I should put the head back on, re-attach the camshaft chain sprocket and rotate the engine until I'm back at TDC with the valves closed and then try again?

 

What would be the point of doing this?

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You are at the top of the beginning of the intake stroke, not the top of the compression stroke where you needed to be before pulling the head.

 

You are in kind of 'be very careful' territory here because with the head off, camshaft chain disconnected, the pressure of the open valve springs will likely force the cam to rotate so they can close. If you put it back together that way valve timing will be way off.

 

If it was me, at this point I’d pull the front cover so you can see the intermediate shaft timing marks and re-verify valve timing as you reassemble it all.

 

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Thanks for the repsonse. I'm thinking that I should put the head back on, re-attach the camshaft chain sprocket and rotate the engine until I'm back at TDC with the valves closed and then try again?

 

What would be the point of doing this?

 

I guess I'm concerned about removing the valves while they are open and that it may be more difficult to get everything back into place when reassembing as compared to starting with the valves in the closed position. I suppose I could go ahead as is and then after the valves are back in manually rotate the cams to get the valves back where they were. Since the key on the camshaft chain sprocket has to line up with the slot on the valve gear that should assure everything is back in the right place? I hope!

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Anton Largiader

I'm guessing your right side cam keyway is facing up?

 

Read this through and if you don't understand my description don't even start.

 

I would leave the head off the bike, put the bolt on with a spacer* and turn the bolt in the tightening direction to turn the cam until it's free. It won't take much force. Then remove the bolt again. Now the cam is at firing TDC.

 

Now you have to turn the engine to match it, which is a piece of cake. Pull the other plug (if it's not already out) and just rotate the engine using your favorite method (I usually bump the rear wheel in top gear) while making sure the chain doesn't get sucked in or otherwise bound up. It'll only move half a turn of the sprocket; just eight or nine links worth. When the engine is back at TDC you'll be ready to reinstall the head.

 

When you do, you'll be able to freely rotate the cam in the head. Make sure the keyway is down, sprocket key is down, etc.

 

* spacer to keep the bolt from bottoming out in the cam. Personally I'd probably use the cam sprocket itself since I don't always mess with zip-tying that to the chain, but assuming you have the zip-tie in place just use a thick washer.

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I'm guessing your right side cam keyway is facing up?

 

Read this through and if you don't understand my description don't even start.

 

I would leave the head off the bike, put the bolt on with a spacer* and turn the bolt in the tightening direction to turn the cam until it's free. It won't take much force. Then remove the bolt again. Now the cam is at firing TDC.

 

Now you have to turn the engine to match it, which is a piece of cake. Pull the other plug (if it's not already out) and just rotate the engine using your favorite method (I usually bump the rear wheel in top gear) while making sure the chain doesn't get sucked in or otherwise bound up. It'll only move half a turn of the sprocket; just eight or nine links worth. When the engine is back at TDC you'll be ready to reinstall the head.

 

When you do, you'll be able to freely rotate the cam in the head. Make sure the keyway is down, sprocket key is down, etc.

 

* spacer to keep the bolt from bottoming out in the cam. Personally I'd probably use the cam sprocket itself since I don't always mess with zip-tying that to the chain, but assuming you have the zip-tie in place just use a thick washer.

 

What you said makes sense to me. I have to say, as a someone without a lot of mechanical experience, I really appreciate the feedback I get from this forum. Thanks for the advice!

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I'm guessing your right side cam keyway is facing up?

 

Read this through and if you don't understand my description don't even start.

 

I would leave the head off the bike, put the bolt on with a spacer* and turn the bolt in the tightening direction to turn the cam until it's free. It won't take much force. Then remove the bolt again. Now the cam is at firing TDC.

 

Now you have to turn the engine to match it, which is a piece of cake. Pull the other plug (if it's not already out) and just rotate the engine using your favorite method (I usually bump the rear wheel in top gear) while making sure the chain doesn't get sucked in or otherwise bound up. It'll only move half a turn of the sprocket; just eight or nine links worth. When the engine is back at TDC you'll be ready to reinstall the head.

 

When you do, you'll be able to freely rotate the cam in the head. Make sure the keyway is down, sprocket key is down, etc.

 

* spacer to keep the bolt from bottoming out in the cam. Personally I'd probably use the cam sprocket itself since I don't always mess with zip-tying that to the chain, but assuming you have the zip-tie in place just use a thick washer.

 

What you said makes sense to me. I have to say, as a someone without a lot of mechanical experience, I really appreciate the feedback I get from this forum. Thanks for the advice!

 

One very important point. Under no circumstances allow the engine to turn backwards - especially with loose cam-chains - as this will often lead to breaking the plastic cam-chain guide fingers. Replacing those requires that the crank-cases be split. This adds a lot of time and complexity to the job.

 

Andy

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What Anton say is (of course) correct. Still, call me paranoid, but having now pulled the head with the cylinder in the wrong position, I’d still like to verify valve timing with the front engine marks if it was me. Crashed valves = no fun.

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What Anton say is (of course) correct. Still, call me paranoid, but having now pulled the head with the cylinder in the wrong position, I’d still like to verify valve timing with the front engine marks if it was me. Crashed valves = no fun.

 

Thanks for the advice. I followed your suggestion and got everything put back together correctly. After scraping about 1/8" of carbon out of the head and piston face, I can't believe how much better the bike runs. No more pinging on acceleration. The bike runs just like it did when it was brand new. A lot of work, but a project well worth the effort. One piece of advice I'd give anyone, if you suspect that you've got a serious carbon build up, adding techron or sea foam to your fuel will not remove it. I probably ran 6-7 tanks through. I also tried squirting some supposed carbon remover directly into the combustion chamber and let it soak for several hours. After finally deciding to take the plunge and remove the heads, I couldn't believe the amount of carbon I found. I probably spent about 10 hours carefully scraping it out with a hard piece of plastic and brushing with a soft steel hand brush. Removed the valves and cleaned them as well.

 

I will continue to run techron or seafoam through on occasion in hopes of preventing this nasty build up in the future. I'm not sure why I developed this problem. My bike only has 24,000 miles on it. I think I may have been babying it a bit and also my commute has a fair amount of stop and go to it. So for the next 24,000 miles I plan to keep the RPM's up a bit and "ride it like I aint got a dime in it"!

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Joe Frickin' Friday
So for the next 24,000 miles I plan to keep the RPM's up a bit and "ride it like I aint got a dime in it"!

 

RPM's alone won't do it. You need some heat to burn that crap off (and keep it off) the combustion chamber surfaces.

 

Due to stubborn knock/ping, I pulled heads at about 40K miles and scraped carbon, just like you did. Ran great at first, but knock came back in about 12K miles. Pulled a head again, and this time, also the cylinder. Measured ring gaps, examined surfaces - and concluded that whatever knock I had wasn't doing any damage. I put it back together and put some earplugs in, and started whaling on the engine. On-ramps? WOT until I hit 90-something, then back off a bit to merge. Twisties? WOT any time I left a turn. The knock gradually faded away, haven't really had a problem since then. Have not used any fuel additives since then, either. 130K miles now, engine is the only thing on the bike I have not had to mess with! :grin:

 

By all means, once the engine is up to temp, pretend it's a rental; your engine will run better because of it.

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