Topic: OEM Honda Gasket Not Cut Properly

[hockeyteeth]

So I have a new hiccup in my top-end rebuild: the cylinder base gasket (Honda p/n: 12191-300-306) has the cam chain hole cut off-center. It is 20mm away from one cylinder cutout and 25mm away from the other cylinder cutout. I could not get the gasket centered on the case because it is butted up against the cam chain tensioner. I bought OEM gaskets so I wouldn't have problems like this. Bummer...

Can I cut a couple millimeters of material off the gasket to compensate for the hole being off-center or do I need to return this gasket and get one which is cut properly?

Thanks for your patience and help, everyone!

Here's a photo to illustrate. Sorry my camera is so bad: http://tiny.cc/ay0qgw

[Don R]

Does it help to flip it over?

[hockeyteeth]

No, it's the same problem but on the other side of the engine when I flip the gasket.

[bjbuchanan]

If it lines up at the bolt holes and all the other places just trim where it is contacting the chain. It's not a major concern and for all you know the next one could be just the same

[dave500]

id just modify it if its not drastic,i cant quite see the pic clearly,,if the honda shop has one in stock id get a replacement,,or will it be a two week wait?

[Terry in Australia]

Does it help to flip it over?

That would have been my guess too Don, I've never seen a factory gasket that didn't fit, once it was oriented correctly. Cheers, Terry.

[hockeyteeth]

If it lines up at the bolt holes and all the other places just trim where it is contacting the chain. It's not a major concern and for all you know the next one could be just the same

Great. I'll just cut it a little.

id just modify it if its not drastic,i cant quite see the pic clearly,,if the honda shop has one in stock id get a replacement,,or will it be a two week wait?

Yeah, it would be a two week wait. I'll just modify it. Wasn't sure if that was a bad idea or not. Back to work!

[hockeyteeth]

Sorry, Don. I thought I had flipped the gasket last night, but I guess I didn't because I tried that this morning and... VIOLA! Fits like a glove. Got my cylinders installed this morning. Will put the springs back on my valves tonight and try to get the head installed so I can torque and check hardware in another day or so. What a pleasant start to the day. My bike will be back on the road in no time!

Edit: I used another member's method of putting vice-grips on the studs to lower the cylinders onto the bottom end. Worked great. I only have one piston ring compressor so I had to install the pistons into the cylinders then line up the connecting rods and push the wrist pins in.

[Terry in Australia]

Sorry, Don. I thought I had flipped the gasket last night, but I guess I didn't because I tried that this morning and... VIOLA!

It turned into a stringed instrument? Wow!

[Don R]

Happy to be of service. My theory is if there is two ways it can go, 9 out of ten times I'll get it wrong on the first try. Lol.

[hockeyteeth]

I now have a related issue but didn't want to start another thread about it.

My 750 manual (the original shop manual) did not specify how many repetitions of cylinder head nut tightening to do. I ended up tightening all 16 nuts finger tight and then going to a full 15 ft. lbs. in one sequence. I didn't hear any weird noises while tightening but am concerned about what possible effects I may look forward to when I start riding the bike again. Anyone care to comment on any potential issues?

Other than the tightening sequence repetition issue, I finally feel like I'm on the home stretch of my top-end rebuild--I put my cam in yesterday and set the timing. Tomorrow morning I am going to put my rockers on and set the valve clearances. Then I will put my valve cover back on before waiting for my rotor cover gasket to arrive and completely button up the engine. I'm very excited!

[scottly]

I never go to full torque in one sequence on anything, so I wouldn't know about possible effects. I usually go at least 3 times around. Then I go around again, sometimes several more times, until the bolts quit turning at full torque. You will find that the first bolt in the sequence will turn a bit, after the bolts around it have been tightened down. That's what I would do in your case, repeat the sequence at full torque.
Hope you are using the proper size torque wrench; a wrench with a max rating of 120 ft-lbs won't be very accurate at 15 ft-lbs..

[Terry in Australia]

+1 on Scott's comments, never go to full torque in one sequence, if you don't end up breaking a stud you'll unevenly crush the head and base gaskets, and you'll get leaks.

I actually torque CB750 head's down to 20 ft lbs on the OEM studs, but I do it in small increments of 2-5 ft lbs, then leave it overnight. In the morning I loosen them all off and torque them all down again. Try this, and you'll be amazed at how much more those gaskets will crush down next time around.

Make sure your threads are nice and clean and lightly oiled first though, if they're not, you won't be applying even torque to each stud, and you'll get leaks. "Do it right, do it once". Cheers, Terry.  

[hockeyteeth]

Hope you are using the proper size torque wrench; a wrench with a max rating of 120 ft-lbs won't be very accurate at 15 ft-lbs..

Ah, I was borrowing a torque wrench that is rated to 100+ ft-lbs. I will go buy a nicer one for lower torque and follow Terry's advice. Thanks guys!

[lucky]

I now have a related issue but didn't want to start another thread about it.

My 750 manual (the original shop manual) did not specify how many repetitions of cylinder head nut tightening to do. I ended up tightening all 16 nuts finger tight and then going to a full 15 ft. lbs. in one sequence. I didn't hear any weird noises while tightening but am concerned about what possible effects I may look forward to when I start riding the bike again. Anyone care to comment on any potential issues?

Other than the tightening sequence repetition issue, I finally feel like I'm on the home stretch of my top-end rebuild--I put my cam in yesterday and set the timing. Tomorrow morning I am going to put my rockers on and set the valve clearances. Then I will put my valve cover back on before waiting for my rotor cover gasket to arrive and completely button up the engine. I'm very excited!

IF you were using a workshop manual to put your engine together it tells you how to tighten the cylinder head.

If you tightened each bolt to its max in one shot, the cylinder head could be warped now. Hopefully that did not happen but there is that risk when not tightening the cylinder head like the workshop manual explains.

[bollingball]

Give them a book teach them to read. But still