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RE: Compression Question - 8/28/2008 2:38:26 PM

Gearloose

Posts: 87
Joined: 9/12/2007
Status: offline

quote:

Along with adjusting the valve clearance, I''''m going to try reassembling it with some better assembly grease and hope the tapping/knocking goes away.

I doubt that assembly grease will make any difference other than for the first couple of engine turns while engine oil gets up to pressure. Instead I''d get the manual and check all possibilities by troubleshooting from first principles. Also check that you have the caps in the right place (not transposed), and cam chain is not so loose that it causes problems with timing for example.

May be a very simple & cheap-to-fix cause, just needing thought to track it down.

(in reply to stinemonster)

Post #: 16

RE: Compression Question - 8/28/2008 2:44:40 PM

Hurricane rider

Posts: 621
Joined: 8/23/2008
Status: online

this is very true. the cam caps are VERY specific, since cam cap A only matches the mating surface on the head marked A.

the bearing surfaces on these are line bored, and basically non interchangable with other caps, or locations on the head. check this. I wasnt even thinking about that until it was mentioned.

(in reply to Gearloose)

Post #: 17

RE: Compression Question - 8/28/2008 4:16:51 PM

stinemonster

Posts: 81
Joined: 7/26/2008
Status: offline

I made sure I put the caps back on correct.

I have a video clip of what''s happening. I used the wifes cell phone. It''s a .3gp file. The file size is 292 KB. Nero opens it. How would I go about loading it or would I need to email it?

It''s like something is binding up and then lets loose and pops. It was doing this when I was setting the timing during assembly but it wasn''t popping. I didn''t think much about it. Just thought it was due to the slop in the chain. So it was doing it before I ever started it.

From what Im understanding here, the crank will make 2 full 360 deg rotations to the cams 1 full 360 deg rotation. The chain binds up and pops every 180 deg CRANK rotation. So every 90 deg CAM rotation. I have the CCT backed all the way out. So the chain has full slop in it.

When I went to turn it after I torqued the cams back down, I couldn''t get it to turn by hand. Had to bump the starter. After that it would turn easy by hand.

It''s almost like valves are sticking but I can''t imagine that many valves sticking.

I still haven''t checked the valve clearance yet. Had to put the cam caps back on and make sure the timing was still good. Im going to go check the clearance while waiting for reply on this post.

(in reply to Hurricane rider)

Post #: 18

RE: Compression Question - 8/28/2008 6:27:50 PM

stinemonster

Posts: 81
Joined: 7/26/2008
Status: offline

I just finished checking the clearances. I had 3 valves that were about .001" out and one exhaust valve that was about .009" out. Still didnt fix the problem.

It may be coming from the bottom end. May have a rod bearing going. If so, that''''''''s cheaper than cam bearings as long as I didn''''''''t trash the crank.

I tried to look down into the spark plug holes. Didnt see any signs of valves hitting. I also couldnt see much of the piston. I pulled the exhaust back off (I reused the old exhaust gaskets just in case) and it didn’t look like any of the exhaust valves were sticking.

The pop is consistant. Pops twice on every 360 deg rotation of the CRANK. Once just before TDC and once just before BDC.

I was able to set up a YouTube video. Heres the link…

http://www.youtube.com/watch?v=ZVE6Ago3DWw

Never made a YouTube post before. Hope it works.

The video quality is bad. It''''s from a cell phone. My wife is turning the crank while I videoed it.

I’m stuck. I don’t know what else it could be. I think I''m going to take a break from this thing for a week or two until I can find something out. I''ve been spending all my free time for the past few weeks working on this thing. Was hoping all I had to do was the head gasket.

I will pull the carbs off later to see if any of the intake valves are sticking.

< Message edited by stinemonster -- 8/28/2008 6:33:47 PM >

(in reply to stinemonster)

Post #: 19

RE: Compression Question - 8/28/2008 6:37:26 PM

Hurricane rider

Posts: 621
Joined: 8/23/2008
Status: online

I honestly dont know, to me, that doesnt quite sound like a bearing going bad, so I seriously doubt a lower end bearing of any sort.

(in reply to stinemonster)

Post #: 20

RE: Compression Question - 8/28/2008 6:40:25 PM

stinemonster

Posts: 81
Joined: 7/26/2008
Status: offline

did the YouTube link work?

I''m going to examine the chain guides closer and check the intake valves. But the compression seamed to make it look like a valve was not sticking.

(in reply to Hurricane rider)

Post #: 21

RE: Compression Question - 8/28/2008 8:11:13 PM

Gearloose

Posts: 87
Joined: 9/12/2007
Status: offline

Your video comes over clear enough. I think the cam chain is too loose - almost seems like the front or rear guide is not in place, or the hydraulic tensioner pre-tensioning spring is missing, or you have an aftermarket manual tensioner and the bolt is backed off too far. (I assume also you have removed the top guide to make it easier to see the looseness - if the top guide isn''t there, maybe the chain is flapping against the valve cover - hence knocking noise only when the valve cover is in place). Sorry if this seems obvious - you have probably checked all that side of things anyway.

With the chain that loose I think it would be hard to check the valve clearances accurately.

The front guide should have a curve in it, like "J". I accidentally straightened one out when setting up the cams (because I let the loose cam chain get doubled over inside the front guide and when I barred the engine over, it forced the chain against the guide bending it and also broke the lugs at the top of the guide). I had to get info from Michigan_313 so I could bend it back to the right shape and glue the broken lugs back on (still working well!). See http://www.cbrforum.com/m_439208/tm.htm for pix of good and bad guides - hope this helps or at least eliminates one potential cause.

(in reply to stinemonster)

Post #: 22

RE: Compression Question - 8/28/2008 8:27:08 PM

stinemonster

Posts: 81
Joined: 7/26/2008
Status: offline

I was just out there looking at it again. I used the stethoscope as I turned the crank. The noise is the loudest coming off the cam sprocket. Makes me think it has something to do with that chain. Im having problems seeing down into the motor with it in the bike. I’m going to take a break for a while. Maybe look at it again this weekend.

I just don''''t want to have to unbolt the head again to make sure the front chain guide is correct. I don''''t like reusing a head gasket and a new one with shipping will be about $50.

I do have an aftermarket CCT. I had all chain guides installed and the chain adjusted correctly when I first put it back together and the tapping/knocking was bad. Like I was saying before, it sounded like the CCT was not installed. When it was still assembled, I tried tightening up the CCT to see if the noise would go away and it wouldn''''t go away. I still think it may have something to do with one of the chain guides.

I have the Manual CCT backed all the way out right now.

On the valve clearance, from what I saw, as long as the lobes are not close to touching you should be able to get an accurate clearance. I feel pretty comfortable with that part of it.

Thanks you guys for your time. Maybe I can get it figured out this weekend. If so, I will let you know.

< Message edited by stinemonster -- 8/28/2008 8:29:51 PM >

(in reply to Gearloose)

Post #: 23

RE: Compression Question - 8/29/2008 12:33:27 AM

Gearloose

Posts: 87
Joined: 9/12/2007
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I agree that it''s a last resort thing to take the head off - and that''s the only way I know to see if the front guide was bent out of shape. Before doing that, the main thing to establish is whether the cam chain can be tensioned correctly - your video shows it is way too loose in my opinion. Does it get any better when the manual tensioner is tensioned up?

I can''t remember the exact figure, but the slack in a chain should only be about 2% or 5% of the distance between the sprockets. You have 3 sprockets - I''d say 5% of the distance between the cam sprockets should be a reasonable starting point, but I have no experience with the manual adjusters.

I take it you have tensioned the cam chain adjuster according to the manufacturer''s specs. Also there is plenty of info on the net about manual adjusters.

(in reply to stinemonster)

Post #: 24

RE: Compression Question - 8/29/2008 7:19:57 AM

stinemonster

Posts: 81
Joined: 7/26/2008
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I originally had the cam chain tensioned correctly. The manufactureer instructions calls to tighten the manual tensioner to 1/4" - 3/8" slop in the chain. All of that was done the first time around. I have it loose trying to see what''s going on. I will tighten it back up again and check everything. First I''m going to try to get a better look down into the motor.

I will take another look at it this weekend. I''m ready for a break from it.

Thanks

(in reply to Gearloose)

Post #: 25

RE: Compression Question - 8/29/2008 9:42:19 AM

abrooks09

Posts: 7
Joined: 8/17/2008
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I watched the video, and I gotta say I don''''t know much about engines, I just took apart my first one over this last winter, but I saw some things I wonder about in the clip. Mostly what curious about is every time you get to the "pop," your wife paused cranking the engine. Is that cos it became difficult to crank momentarily, before or after the pop? Is that a clue maybe? Best of luck bro, RE: my electrical probs you found in my forum, I am in fact feeling your pain.

-Anthony

< Message edited by abrooks09 -- 8/29/2008 9:43:21 AM >

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(in reply to stinemonster)

Post #: 26

RE: Compression Question - 8/29/2008 11:09:10 AM

stinemonster

Posts: 81
Joined: 7/26/2008
Status: offline

While turning the crank, it tightens up consistently every 180 deg CRANK turn and then pops. Once just before TDC and once just before BDC. Once it pops, it loosens up and you can see the chain slop up in the video.

The crank turns easy until it tightens up a little in those two locations.

I would almost think it was a piston pin or rod bearing. I have a cheap automotive stethoscope that has a rod coming out of it instead of the normal cup that doctors use. You can stick the rod on a surface and it will magnify the vibration noises on that surface. I have placed it on the cams/head/rocker arms/outside of the crank case/outside of the cylinder block and on the cam chain sprockets. The sound vibration is very strong on the cam sprockets. Not just one cam sprocket but both cam sprockets. That makes me think it has something to do with the chain.

I may have just installed the front guide wrong but it''s hard to see down in there with the head on and in the frame. But why would it be consistent every 180 deg CRANK rotation?

I''m trying to check all options before I pull the head again. I don''t want to pull the head again unless I just absolutely have to. I don''t want to order another head gasket and I don''t like the idea of reusing the one I just installed.

This is why I''m going to try to take a break from it for a few days. I just know it''s going to keep eating at me until I find the problem and fix it.

I''m hoping someone will read this that has had this problem before.

Before I pull the head again I will start another post and list everything I have done and what''s going on. I want to check into it a little more before I do that.

(in reply to abrooks09)

Post #: 27

RE: Compression Question - 8/29/2008 5:31:56 PM

stinemonster

Posts: 81
Joined: 7/26/2008
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I think I figured it out. It looks like the rear chain guide was in a bind to one side and binding up the chain. I dont know why it was a consistent pop every 180 deg crank turn but it appears thats what the problem was. It was that consistent pop that really threw me off.

I got home from work and it was eating at me to find the problem. I had to remove the thermostat housing so I could get a better look down into the motor.

One thing I can say, I know the top end of this motor very well now. If this fixes the problem and the thing runs good once back together, I will be convinced these motors are indestructible. Especially how hot I got this thing after the gasket went.

About to recheck the valve clearance now that I have the CCT tightened back up and the slop out of the chain. Not taking any chances. Ive already spent this much time on the motor I may as well add another 15-30 minutes to it.

Took pictures of the Manual CCT installation that Im going to post in the "HOW TO CCT" post.

Should have it all back together in a few hours.

(in reply to stinemonster)

Post #: 28

RE: Compression Question - 8/29/2008 9:39:41 PM

stinemonster

Posts: 81
Joined: 7/26/2008
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Got the valve cover back on and the exhaust hooked back up.

That pop is gone.

But it sounds horrible. I think the cam chain guides may be bad or my valves are rattling real bad. It sounded like this when I first started it up the first time around and then I tightened up the CCT and thats when the popping started. Most of the noise went away when I tightened up the CCT, if I remember correctly.

It didnt sound like this when the valve cover was off. Makes me think its the chain guides.

I am going to try to get some more video clips sometime tomorrow. I will record it how it is and then what it sounds like while I tighten up the CCT. And then one more with the valve cover off.

I will probably start another post once I get the video clips.

Also snapped one of the exhaust mount studs.

Have a funeral tomorrow so not sure when I will get the clips made and posted.

You guys wouldnt have any used cam chain guides laying around that you would want to sale? I need to try to find something cheap to see if thats what it is before I spend another $125 + s&h on new ones.

(in reply to stinemonster)

Post #: 29