When I spruced up my CL77 over the winter, I ordered OEM gaskets from Western Hills Honda. What I got were a number of NOS gaskets. All of them were marked Asbestos, which tells me they are pretty old. I decided to save most of the NOS gaskets and use them as patterns to cut new gaskets. I did that for just about all but the oil pump/screen gaskets. Even though those NOS gaskets looked kinda hard, I used them anyway, with no gasket cement or sealants because it a miserable place to have to clean of the surface should that pump have to come out again.
When I finally got around to filling up the sump with fresh oil, I came out a few days later and found oil on the lift. Yup, oil pump flange was leaking. I tighted up the bolts a tad and it slowed it down, but it continued to weep every so slighty. And that is with 40 degree oil.
So today I pulled the oil pump. Gaskets looked fine, no bad areas. All the gasket surfaces were rechecked and were fine. I cleaned the oil off the gaskets with min spirits and set them on the bench. When they dried, they looks like they had never been used. Only the slightest of impression was made at the two mid-flane bolts. The side with the Asbestos writing on it, was still shiny smooth.
I've had gasket material dry out before. I have roll of gasket material in my tool box that is more like a giant potato chip than gasket paper. Why I have not thrown it out is a mystery. I suspect that if I flexed those NOS pump gaskets, they would snap.
I used them initially because I was concerned about proper pump gear engagment with the crank gear. US gaskets are 0.0315 (1/32") and the Honda gaskets are between 0.020 and 0.025 which a 0.5mm roughly. I was going to reuse them and some Yamabond, but thought I'd just cut new ones instead. I did take a section of new 1/32" gasket material and squeezed it in my toolmaker's vise and it squeezed down to 0.025. So I figured it would be fine. Plus others here have mentioned the use of cut gaskets with no ill effects to the pump gears.
So, my point is, I would not recommend using NOS gaskets because they have lost their ability to compress. My NOS gaskets are more like asbestos tile than gaskets. I'm going to keep them as patterns to cut future gaskets and that's all they will get used for. If you don't want to cut your own gaskets, I suggest new aftermarket kits versus OEM. They should seal much better than OEM just because of the age of the NOS gaskets.
And yes, I had to toss that fresh fill of oil because some crud fell into it during the draining process.
regards,
Rob
Thought/Observations regarding NOS gaskets
Hi,
Not to offend, but when I see other people prepare the gasket area (make it clean and flat), and say it is ready for assembly, I would start were they ended. Gasket surfaces should be flat and absolutely clean. I use 10W oil, rather thin) and encountered no problems with the NOS gaskets (several engines). If oil is leaking look for deep scratches, warped surfaces, and old gasket elements on the surface. When the surface is on a split between crankcases, check alignment. I do use a torque wrench for the oil pump bolts, and re-torque after a while. I know how many people think about using torque wrenches and working absolutely clean but I seldom encounter problems as described so often here on the forum. And when I encounter leaking issue's, it's my fault, not being precise and clean enough (or in a hurry). Jensen assembly of Japanese motorcycles requires great peace of mind (Pirsig)
I don't disagree with you Jensen that 90% of gasket leaks are surface prep issues. But I have a little experience with that. On gas turbines, we have to seal hot gasses on turbine shells and compressor cases with metal to metal fits and no sealers. We do it by stoning the surface to get as close to 100% contact as possible and proper torque on the joint bolts. Same goes for bearing housings, which must also be oil tight and are a metal to metal fit. An oil leak in forward bearing means fouling the compressor which destroys turbine performance.
My surfaces were as close to perfect as possible. The bolts were torqued and I never in a million years expected a leak. A gasket is intended to compensate for minor surface irregulaties. Those two gaskets were more like sheets of glass than gasket material. I did recheck everything before reassembly. I really do not like the design of sandwiching that screen between the two gaskets. It's a stamping and the factory wrinkles are obvious. I did put that screen flange in my toolmaker's vice and made sure it was a flat as possible. I really did not see any difference in it after I did, but it made me feel better. I will not say that you cannot have good luck using NOS gaskets of reasonable age. And if you have had good luck with 40+ year old NOS gaskets, that's great. But I won't be using them anymore. Life is too short to dance with ugly women. regards, Rob
Hi,
Like I said, not to offend you. Did you check the area around the screw holes ? When used improper torque (PO ?) the area will be pulled above the area. But using a wet stone (with petrol) will straighten up the area. I don't like the idea of sandwiching the screen between two packings either, but that's how it is designed. Jensen assembly of Japanese motorcycles requires great peace of mind (Pirsig)
You didn't offend me, Jensen. Like I said, most of these problems are exactly for the reasons you mentioned.
Besides the metal sandwich, I also do not like the gear mesh being at the mercy of gasket thickness. Makes you wonder if any bikes died an early death because somebody cut 1/16" gaskets for that assembly. I tend to prefer a flat file on aluminum rather than a stone. But either works. Working upside down on that damn pump area makes you want to get the job done as quickly as possible. I got a muscle cramp while torquing the bolts that had me bent like a pretzel for a couple of minutes waiting for it to relax. Nothing like trying to torque small bolts on the bottom of an engine with the torque wrench scale upside down and wearing bifocals. How's that joke go? "The circus just called, they want their contortionist back." regards, Rob aka "The Great Spumoni"
Hi Rob,
My torque wrench says "click" when the torque I want is reached (pre-set the torque level with a knob). I listen, instead of looking, make things easier (and I have the bike on the bridge when wrenching , that does help too), Jensen
assembly of Japanese motorcycles requires great peace of mind (Pirsig)
Hi,
Check out this picture (from Hoosier Tom on the thread "1962 CB77 Restoration underway") . http://www.honda305.com/forums/download.php?id=5702 This is exactly what I meant, the surface is oxidized, the surface isn't smooth, . Locater pins are in, I don't know if they were out, but it is almost impossible to clean and check with the pins in. I don't say that this surface will cause leaks, but if it leaks I'm not surprised. Jensen assembly of Japanese motorcycles requires great peace of mind (Pirsig)
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||