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I have to put a lower crankcase on my 73 CL350 where the PO broke off the left engine frame mount. While I have the engine apart I want to replace all of the gaskets, seals, and rings since they are all original. (5,500 mi & 175 psi comp) I am thinking about going to electronic ignition also. What are the best brands to use? I also want to clean the engine and re clear coat also. Is there anything else I should do while I have it apart?
 

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I got my rings and seals off eBay. I quite like the seller: dream305. He used to race 350s flat track, I believe.
Gaskets, I think common motor had a good looking set. Make sure to get the set that comes with orings for the rocker pins.
You don't need valve seals, so don't worry if they're not in the set.
Oil pump gasket is also good to have. Also in the common motor set, I believe.
 

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For o-rings and shaft seals, I prefer to take them off the bike, and take them to a shop that specialises in seals. For the bikes I've worked on, they've always had them on stock. The good thing about this is that I can be certain I get what I want. They have seals for various applications, and I can tell them in what kind of environment they will be (f.e. they need to be resistant to oil and many chemicals, need to withstand some heat ect...). You can't know what comes in a seals kit - it may work fine, or it may just fail soon. Also, there are many various types of seals for various needs. A seal that fits may not be the correct one. Very often on motorcycles, the seals have an additional outer lip that seals from dust (if dust gets inside, it may make the seal leak). Some are wavy to spread the contact surface further on an axle, to prevent excessive wear. Some have even more lips... I prefer to keep the design the same as stock, and definitely not inferior (f.e. use a seal without a dust lip somewhere where there previously was one).

When I buy shaft seals and bearings, I prefer SKF (or also *** for bearings, not sure if they make seals). I suggest you inspect the bearings well. It does not cost much to replace them if you already have the engine apart.

I am finicky even about the paper gasket seals. For my own bikes, I really prefer to buy high-quality paper gasket sheet, outline the old gasket on it and cut my own out (and get the holes out with a punch). It takes patience and precision, but I take the time for my bikes. I sometimes do stuff for other people, but then I usually just use aftermarket gaskets (paper gaskets usually don't fail that often either way). Sometimes I even buy aftermarket ones, just so I can draw them on my paper. With the paper I use, I can normally remove the cover without tearing the gasket, and I even reused it a few times without any problem. When assembling (on any paper gasket over 0.5mm thick, the thinner usually require a sealing compound), I always use copper or graphite grease on the gasket. I've never had a leak this way, and it makes removal easier. If I for some reason want a really good seal, I sometimes use Hylomar on the gasket (and it is also easy to remove if you ever open it up again, hylomar hardens between the gasket and the metal, and is not too hard to clean off afterwards).

If there was no gasket originally (although, if there is no obvious interference problem, I sometimes even make my own paper gasket for some side covers - but many bikes have oil routed through them, and in those cases the gasket thickness may cause problems), I use Loctite 518 anaerbic sealant. It only hardens where there is no air - between the flange surfaces. Not ideal if there are larger gaps (f.e. very scratched surface), but in case of engines, there shouldn't normally be gaps of that thickness (it always worked well for me). Good thing about it is, that even if you use too much and it gets pushed out, it will not harden. So, it will not block an oil passage, and it gets removed (like the assembly lube) at the first oil change. You can also simply wipe it off on the outside, and it looks like as an originally assembled engine (no ugly silicone sticking out everywhere). Because it does not harden on air, it also means you can take as long as you want to assemble it (no need to hurry). It's not the cheapest - but at least the tube also never hardens, so you can have it for a very long time (unlike most silicone gaskets and hylomar...).



So, in short, if you want the best, you have to search for every piece. But I understand how convenient it is to just buy a complete set and use it (and it may be just fine too...).
 
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