For the instant gasket use Three bond 1215. I just went through the same process looking for yamma bond . Needed a finger full for the pv cover on my 300, ended up with a 250ml tube cos thats the smallest one they do. I think it just ovef ten quid from Demon Tweeks.

If you pay for the postage I'll send you the 95% unused tube I've got here. Guaranteed it will be set solid by the time i need another finger full of it.

I use Dow Corning products. I'm a little bias because I'm a BMW tech and it's what we use on BMW engines. But it really is great stuff. BMW use it instead of gaskets on their new bikes. And I've NEVER EVER seen it fail.

07580397777 BMW Sealing Compound Dow Corning - 35ML - 2WheelPros


However, from BMW it's very expensive. £40 a tube etc.

However, there is no reason not to use their standard RTV sealant.

https://www.antala.uk/dow-corning-70...ngine-gaskets/


Last note. Anything with a "Yamaha" brand on it is basically just something else re-branded but 4x the price !!

So don't be thinking you to spend big bucks on big brands.

More than often, you can buy any generic high temperature RTV sealant.

https://www.ebay.co.uk/itm/Simply-Hi...wUKxYk3OP#rwid


However, for the main engine cases, it's always nice to have that piece of mind to have a good brand sealant. Because if your build has gone right, those cases won't be coming apart again for a long time ! IF EVER !

Thanks for the advice and the generous offer of free sealant from Timus. I've found some 518 in the local auto shop so will go with that. Just waiting for my rebuilt crankshaft to be finished so I can start on the very scary job of getting all those bits back into the crankcase in the right order.

Putting it all back together
 

Long time i looked for the meaning of 'HS' on Koyo bearings, now found this site below:
http://www.koyo.com.br/upload/koyo/c...20Bearings.pdf
So it may be a good idea to use the correct spec bearing.

'My manual says i should replace the oil strainer...' it is possible to open the strainer, carefully, and clean the mesh. Be aware that the strainer fails to protect your engine and oil pump from transmission debris, particularly from 5th gear. Bond some magnets to the strainer trap these in future.

Best,
p

Haha yeah I've spent some time puzzling over that too until I decided to turn the bearing around and read it as SH - or Special Heat as Koyo describe it. (They also claim ten times the life span over other 6307s) Apparently they only make them for Yamaha so I've put my trust in Kedo and fitted the FAG ones they supply for main bearings. I'm not planning on any extreme riding so figure I'm unlikely to need something with ten times the lifespan of a FAG bearing. Which is my cue to go find a piece of wood to touch.

Thanks for the tip about using magnets to back up the oil strainer - I'll open it tomorrow (carefully) and clean. Is there anywhere in particular the magnets should be fitted for maximum effect?

Putting it all back together
 

Here is where you will find some stuff on magnets. I found good ones in old hard drives, cut and filed them, bonded in place with JB weld or high temp silicon.
There is quite a bit on the forum on 5 gear and oil pumps if you look.

http://www.horizonsunlimited.com/hub...solution-80123

I use neodymium bolt on magnets and either use a screw or bolt already inside or drill & tap a hole to mount them https://www.mcmaster.com/#magnets/=1bcwsgb (open the "magnets" icon to get to the screw-on option, this site cuts out the full link)

I usually have one somewhere on the clutch cover down as far as possible , someplace that I can clean it if I have the cover off , plus a magnetic drain plug . It's nice to have them where the oil is splashing near the screen.



.

Quick panic here. I've got the crankcase in the oven and the bearings in the freezer ready for the re-install but I've just realised I don't know which way round the oil seal on the balancing shaft goes. Is it metal side in with the U-shaped side facing out?

Just saw this , open side faces bearing .

Thanks jjrider. I had it with the metal side facing inwards as I read somewhere that the markings on oil seals (which are on the U-shaped side on this one) should always face outwards. Fortunately the oven wasn't hot enough so I was saved from making a big mistake.

This seal puzzles me though. If it stops oil from being thrown up the breather pipe how does it release any excess air pressure in the case? There doesn't seem to be any way for the air to escape.

I believe it sucks through the shaft from the clutch side and the seal is so the breather isn't sucking through the bearing itself and just venting from right there . It's been a while since I studied the oiling and venting so it's not fresh but there is a reason for doing it this way . It is an odd setup since the balance shaft has 2 holes usually used for oiling , but they may just be intake holes instead to vent the inner case as well. The E-start motor has another small vent tube right next to that bigger one but doesn't have the one up in the valve cover so they must have thought it could be better.



.

Well the crankcase went together beautifully with a nice even bead of 518 all the way round so I'm guessing it has sealed ok. I've wrapped that bit up in an old sheet while I get on with cleaning up the top end.

I thought I'd come me up with a brilliant idea when I decided to fix scotchbrite kitchen scourers to my Dremel to get the carbon off the valve side of the head. It was working great with wd40 until I figured I'd better check the net to see if this was a good idea or not. All the advice seems to be it is a very bad idea - clogging up oil ways with abrasive aluminium oxide particles and potential damaging the surface of the mating faces. That'll teach me.

It won't be the end of the world , if you stayed down in the chamber area and with the valves installed not much harm done , I take unitized wheels on my small polishing sanders and various scotchbright belts on my Dynafile to polish most of my chambers to a nice shine plus the exhaust ports . It's the mating surfaces that need to be kept away from .

A good and thorough cleaning will remove the grit and debris .



.

That's reassuring. Thanks jjrider. In my ignorance I had already used the scotchbrite to clean half the mating surface on the top face of the cylinder head but it doesn't seem to be damaged. I'll use some 518 with the gasket just to be sure.

I'm stuck on one more thing though - turns out that the Kedo 'full gasket set' doesn't include the gasket that sits between the oil pump and crankcase. The other mating surfaces of the oil pump have no gasket so I'm wondering if I can get away with leaving this gasket off? I know short cuts are generally a bad idea but it'll take another five days to order one in and I'm getting impatient. The sun is shining outside.

Putting it all back together
 

May i betray my complete admiration for Yamaha engineering:thumbup1: but I have not found a reason for this gasket and have not had any issues by leaving it out.
p