4 Stroke Top end knock?

[MPDano]

Just restored my Fat Cat. I didn't have this noise before the build. I never opened the engine besides replacing a leaking clutch cover. I did put 10/40 instead of 10/30 4 stroke motorcycle oil in it. I was also thinking I could have put the brass exhaust gasket in crooked? Valves adjusting?

Disregard the high idle, I rebuilt the carb and used the needle in the kit and I noticed it was a little different in diameter.

Oil pump not getting oil to the top? Any thoughts on this noise?

https://www.youtube.com/watch?v=ifguTX-tZTs&feature=youtu.be

[MPDano]

I also didn't drain the fuel as it was sounding fine prior to the rebuild last month. Old fuel detonating? Gonna drain it regardless.

[MPDano]

Drained gas and added a little slosh old stuff out. Tank reinstalled and filled with 91 octane. Replaced carb needle, same noise and the idle is smooth but upon throttle up, I get the high idle and slow coming back down. Seems like I got an air leak.

Noise is still there and will verify valve adjustments. Oil is new 10/40 and oil level is good.

Weird how this noise wasn't there before. Ughhhhhhh.

[Doink]

MPDano,
If you're hearing a noise, it is not likely the fuel.
Start by checking the spark plug (detonation oil/gas fouling), re-tighten all mounting bolts (rattles), and drain and examine the oil and the oil filter (burning or shavings). If all that checks out, then I would recommend having a pro listen to it for better advice.

[MPDano]

MPDano,
If you're hearing a noise, it is not likely the fuel.
Start by checking the spark plug (detonation oil/gas fouling), re-tighten all mounting bolts (rattles), and drain and examine the oil and the oil filter (burning or shavings). If all that checks out, then I would recommend having a pro listen to it for better advice.

Fuel change is because I didn't know the age of the gas, hence possible detonation due to old gas. Spark plug looked perfect when I checked this morning. Gave it a blast of air to make sure nothing was in there as well. Going to check the valve adjustments after work and then verify compression. She runs strong regardless. That idle speed up could also be a sign of an air leak and leaning. Either way, we can all figure this out together, no need for paid (pro) help, lol.

[wrightracing]

Check the gap on the valves and the slack in the timing chain, not the chain on the rear of the bike. lol.
It sounds like a consistant rotating mechanical issue from what I can tell from the video, so those would be my first stop. It could be the exhaust leaking, but unlikely. The cam would be the next thing to check out while adjusting the valves.

It should be something is those areas. Good luck.


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[Shep1970]

Did you possibly double up the soft copper exhaust ring? I know sometimes its hard to tell when there smushed flat they look like part of engine. I had the opposite with a slow rising idle, it was either carb top related (fixed) or not using a new orings in the intake. (Fixed).
If you smoke hold one near the exhaust flange see if theres any flow (leak)(carefully)......
Ok the smoke may not be a good idea but you know what i mean.
Nice bike by the way.

Shep

[MPDano]

Check the gap on the valves and the slack in the timing chain, not the chain on the rear of the bike. lol.
It sounds like a consistant rotating mechanical issue from what I can tell from the video, so those would be my first stop. It could be the exhaust leaking, but unlikely. The cam would be the next thing to check out while adjusting the valves.

It should be something is those areas. Good luck.


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Will be checking the valves after work. Is the timing chain adjustable or does it slack from getting old and stretching? I do know this engine has a tensioner on it.

[MPDano]

Did you possibly double up the soft copper exhaust ring? I know sometimes its hard to tell when there smushed flat they look like part of engine. I had the opposite with a slow rising idle, it was either carb top related (fixed) or not using a new orings in the intake. (Fixed).
If you smoke hold one near the exhaust flange see if theres any flow (leak)(carefully)......
Ok the smoke may not be a good idea but you know what i mean.
Nice bike by the way.

Shep

I had used a screwdriver to make sure the surface was clean before installing the copper o-ring. Lol, yes I do smoke but was going to try the torch gas trick after work as well. Torch unlit of course.

[Shep1970]

Timing chains stretch over time, i dont think i've ever read on here about a tensioner failing but if you find yours is junk dont buy one- i have extras i'd just send it to you. Did u use synthetic oil?
Just put the old oil back in maybe the noise will go away. (Just kiddin)

Shep

[MPDano]

Timing chains stretch over time, i dont think i've ever read on here about a tensioner failing but if you find yours is junk dont buy one- i have extras i'd just send it to you. Did u use synthetic oil?
Just put the old oil back in maybe the noise will go away. (Just kiddin)

Shep

Ha ha, I just use Yamalube dino oil. Even on my KTM 250SXF I only use Semi-Syn. That Synthetic stuff is pricey

[Shep1970]

If you feel the need (probably should) you can check for oil pressure. Its the small rusty one in my pics, if you look u can see where the oil travels up and past that bolt then drips/pours i have no idea how much on to the cam where the orings are. If you take it right out you'll know pretty quick if its getting oil up there.
I suppose u could run it for no more than 10 seconds or kick it over a few times w/switch off. Just dont forget to put the bolt back in!!!

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Shep
Did u use rtv or a new side cover gasket when u replaced it?

[MPDano]

If you feel the need (probably should) you can check for oil pressure. Its the small rusty one in my pics, if you look u can see where the oil travels up and past that bolt then drips/pours i have no idea how much on to the cam where the orings are. If you take it right out you'll know pretty quick if its getting oil up there.
I suppose u could run it for no more than 10 seconds or kick it over a few times w/switch off. Just dont forget to put the bolt back in!!!

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Shep
Did u use rtv or a new side cover gasket when u replaced it?

Nice tip to check the oil pump operation. Clutch cover is just gasket, no RTV. Sealed perfectly.

[MPDano]

Put it TDC per manual. Marked original settings. Adjusted per procedure and they were almost spot on, not much change. Also verfied the exhaust copper gasket was in correctly. Starting this think the prevous owner put heavier oil to hide an issue. Also broke the cap right below the valve adjusters. Ughhhhh, another Honda order and delay.

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[Shep1970]

i was thinking decomp cable but i dont think there is on on the fat cat right? On the 86/87 200x (its close to the same topend) if the cable is to tight it'll click like crazy up there. But prob not your issue. I see the lever now in your middle pic does it move freely(spring back) it only moves 1/4 inch anyway.

Shep

[MPDano]

i was thinking decomp cable but i dont think there is on on the fat cat right? On the 86/87 200x (its close to the same topend) if the cable is to tight it'll click like crazy up there. But prob not your issue. I see the lever now in your middle pic does it move freely(spring back) it only moves 1/4 inch anyway.

Shep

Yeah, no cable to the decomp. It springs back. I did move it while it was running a few days ago, it clicks when pulled but stops when released. I haven't tried to start it since re-adjusting the valves. Ran out of daylight. Actually broke the sight plug, which is on order now.

[MPDano]

Definitely not the valves. I started it up and could move the adjusters and same noise. Also, verified I am getting oil to the top end. I am now thinking chain slap/worn chain guide. Need to verify my tensioner is actually tensioning.

[MPDano]

What a pain to remove the cam cover. Had to loosen all the bolts holding the engine and remove the muffler/header to loosen the upper rear engine bolts. Took the covers off and the chain is nice and snug. No slack whatsover. Checked if anything is loose (cam caps, etc). All is tight. I am starting to think piston slap now but not ready to remove the cylinder head to find out. I read somewhere that the timing chain guide could be faulty.

Does any of these pics help? Do the guides look correct? Any thoughts?


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[MPDano]

Again, knocking not present when idling. Just when revving to a higher rpm. Stumped guys.

[Shep1970]

You may have to dig deeper.
How are your rocker pads worn/smooth or gouged?( On the rockers )
U can take out your cam chain tensioner/remove the chain (try not to let it fall into the case it could be difficult to retrieve)
Lift the cam out spin it(the bearings in your hand) smooth?
Its your call, but easy to put back together-kinda

Shep

[MPDano]

You may have to dig deeper.
How are your rocker pads worn/smooth or gouged?( On the rockers )
U can take out your cam chain tensioner/remove the chain (try not to let it fall into the case it could be difficult to retrieve)
Lift the cam out spin it(the bearings in your hand) smooth?
Its your call, but easy to put back together-kinda

Shep

Rocker visual looks fine. No play on them either. I can remove the chain without pulling the head off? I ask because once that comes out, I'll have to get a top end gasket kit.

Honestly, the only thing removed from the engine was the clutch cover and had to remove and install the parts from the old to newer one. I am starting to 2nd guess how I assembled it. Can noise travel from there to the top?

[3 Wheel Drive]

Is your cam sprocket set in the right position? You may want to make sure the timing is set at TDC.

My ct70 made noise similar to that when my timing was off.

[MPDano]

Is your cam sprocket set in the right position? You may want to make sure the timing is set at TDC.

My ct70 made noise similar to that when my timing was off.

I guess I might as well since I have the cam cover off. Honestly, it really does sound like the valves hitting the piston top, so you might be on to something there.

[MPDano]

Cam timing is spot on. Also, put a screwdriver and pushed on the chain and I can see the tensioner working.


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[yaegerb]

Just listened to this. Sounds like a big end conrod bearing or small end going out to me. Pull the cylinder and leave the piston attached. See if you have excessive play in the piston pin. If not then pull up and down on the conrod. Should be zero play up and down on the crank pin.

[MPDano]

Just listened to this. Sounds like a big end conrod bearing or small end going out to me. Pull the cylinder and leave the piston attached. See if you have excessive play in the piston pin. If not then pull up and down on the conrod. Should be zero play up and down on the crank pin.

Would a thicker oil like 20/50 make that noise go away if it was a bearing? The reason I say is that the oil did seem thick when I drained it. Thicker than the 10/40 put back in, which is when the noise appeared. Also, shifting was a bit harder when I first got it, but after the oil change it became very easy to shift. PO hid a bearing issue with thicker oil?

[MPDano]

Also verified the tensioner had tension by removing, then using a small screwdriver turning clockwise to retract it and it sprang back as it should.

[yaegerb]

Would a thicker oil like 20/50 make that noise go away if it was a bearing? The reason I say is that the oil did seem thick when I drained it. Thicker than the 10/40 put back in, which is when the noise appeared. Also, shifting was a bit harder when I first got it, but after the oil change it became very easy to shift. PO hid a bearing issue with thicker oil?

Possible but unlikely.

[3 Wheel Drive]

I'm pretty sure you should not be using 10w40 oil in your motorcycle engine. You should use a lighter oil if I'm not mistaken, either way that will not affect the noise.... but it can cause your clutch plates to stick together.

[MPDano]

I'm pretty sure you should not be using 10w40 oil in your motorcycle engine. You should use a lighter oil if I'm not mistaken, either way that will not affect the noise.... but it can cause your clutch plates to stick together.

Here is a screenshot of the Official TR200 Service Manual

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[MPDano]

After starting her up again. I am starting to think I didn't assemble someone correctly on the inside of the right crankcase cover. I need to drain the oil and take that cover off again and verify. She fired right up though.

[MPDano]

I really think it's some of these parts I didn't put together right.

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[Rob Canadian]

I really think it's some of these parts I didn't put together right.

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Attachment does not come up on my end(?)

[MPDano]

Attachment does not come up on my end(?)

I re-uploaded it. Can you see it now?

[Doink]

I was able to see it both times. I know that there are very particular tolerances for assembly of the right side. A service manual is essential, since it describes the order and arrangement of the teardown and reassembly process. Unless you've put many of these together, the parts manual is a poor substitute.

[MPDano]

I was able to see it both times. I know that there are very particular tolerances for assembly of the right side. A service manual is essential, since it describes the order and arrangement of the teardown and reassembly process. Unless you've put many of these together, the parts manual is a poor substitute.

Yes, I just took the old parts from the damaged cover and transferred to the new one. I do remember that I wasn't sure on re-assembly of the parts. The pic is mainly to show where I think my problem is.