[Hoffman]

Good morning all,

So I bought a CM400T with the engine partly dismantled - a young fellow had picked it up but couldn't afford to put it back together to get it out on the road, so I got a great deal. The first thing I noticed on bringing it home and taking the rest of the cylinder off, was that there was no proper head gasket - the previous owner had used gasket maker ONLY and it must have leaked like a sieve!

I picked up a gasket set on Ebay and cleaned all of the gasket maker material off with a razor blade and some very fine emery cloth. It's looking much better now, however I noticed a couple of things that I thought I'd better bring up.



Firstly, there are a couple of smaller holes in the cylinder that might accommodate dowel pins (as in the red circle region), but there don't seem to be any. Is this normal?

Also, the gasket set I picked up doesn't seem to fit well along the groove on the right hand side (also in red circle). Would this be a huge concern or could I just trim this gasket to better fit?

Hoffman

 

[Hoffman]

Well after some more cleaning and reassembly today, I took a peek into the crankcase with a flashlight, and discovered one of the old dowel pins inside - yikes! I'll be dropping the oil pan to find the other and inspect for any more gasket maker residue. The pistons and rings appear to be in good shape.

 

[longdistancerider]

There should be a restrictor jet/dowel in each hole

The gasket fits poorly on one side, normal

 

[Hoffman]

I'm having one heck of a hard time getting the camshaft sprocket to align, as the chain is just too tight. Is there a trick to getting this loose enough to center it on the camshaft with the proper alignment?

 

[540nova]

I'm having one heck of a hard time getting the camshaft sprocket to align, as the chain is just too tight. Is there a trick to getting this loose enough to center it on the camshaft with the proper alignment?

Have you backed off the chain tensioner?

Sent from my SM-G955U using Tapatalk

 

[Hoffman]

I did a quick google search and found that suggestion - yes thanks! The sprocket could be one cog to the left to have both alignment marks level, but I'm not sure if it's a complete cog so am thinking of leaving it as-is...

 

[longdistancerider]

The cam gear marks always seem to look a few degrees off, not much but not dead straight either.

 

[Hoffman]

The manual is saying that I should apply molyb-denum disulfide grease to the camshaft bearings - funny thing is I can't see bearings at all, just steel end-to-end for the camshaft itself. Are there different variations of this arrangement?

It also mentioned liquid sealant on the head contacting faces of the camshaft holders. Do I use liquid gasket maker for that or what sort of sealant would it be referring to?

 

[longdistancerider]

The camshaft bearing surfaces are the machined areas of the head the cam run on, no actual bearing per se.
The sealant is Honda Bond and only a very thin smear is applied like the case halves. It's there to seal imperfections in the machined surfaces

 

[Hoffman]

The camshaft bearing surfaces are the machined areas of the head the cam run on, no actual bearing per se.
The sealant is Honda Bond and only a very thin smear is applied like the case halves. It's there to seal imperfections in the machined surfaces

Jim, are you suggesting I apply the Honda Bond on all of the surfaces, including those that you have a physical gasket on?

 

[longdistancerider]

No, the Honda Bond is used only on the case halves when assembling and on the base of the rocker stands. Gaskets are a dry application, no sealer used.

 

[pikl]

I always use graphite or copper grease on gaskets (or sometimes hylomar, if I want a really good seal for some reason). It prevents them from sticking on the aluminium if you ever open it up again. Otherwise, I like to use Loctite 518 anaerobic sealant. It seals well, and only hardens when not in contact with air. So any excess that gets pushed out can be wiped off, and it does not block oil passages on the inside (the oil flushes it off too).

 

[Hoffman]

Thanks guys - I'll need to look into picking some of this up this week. I was considering the Loctite sealants early on - just hadn't found someone who tried them.

 

[pikl]

Well, Loctite does a wide variety of sealants. But as long as you do not have any deep scratches in the case halves, Loctite 518 is awesome. It is not cheap, but one (50ml) tube is enough for a few engines (and it will not harden in the tube either)... The good thing about it is, that since it will harden on air, it does not matter how long you take to get the cases together - you can adjust everything perfectly, and it will not harden until you screw them together. On some more tuned racing engines, I've used solid soft aluminium cylinder head and base gaskets, and this stuff - it also held up well. Another great thing is that, even if you do not manage to clean and degrease the surface 100%, this stuff will still harden regardless. Also, after assembling the engine, you simply wipe off the excess, and it will look factory assembled (because engines with some colourful silicone sealant sticking out just instantly give me the chills).

 

[Hoffman]

Well after some failed attempts to get to Princess Auto for some Loctite sealant, I eventually had my wife pick up some Honda Bond from a local dealer in the town where she works.

I had called ahead, and asked them about the molybdenum grease for the camshaft bearings too. The service guy there told me that they only use oil to lubricate those. That came as a surprise. I'm tossing over the idea of using Super Lube multipurpose synthetic grease. Just checking quickly online, it looks like it has operating temperatures between -50F to +500F. Any thoughts on this approach?

Last week I was able to get the camshaft sprocket oriented properly which was a huge relief - thanks for the tips there.

Today I decided to tear open the side cover. After draining the oil and cleaning up the severely dried gasket, I noticed that a small chain appears quite loose inside so snapped some pictures.


Does this chain appear to need tightening somehow?

One other thing that's troubling me is that the gasket kit I bought has a few mystery items that I don't recognize so far. I'm attaching a picture of these as well, and I've labelled them with letters to help sort things out.

 

[dtsmjr8dan]

That chain is normally loose like that. No adjustment necessary or provision made for adjustment. Those seals are from left to right....(2) exhaust valve seals, (4) intake valve seals, (2) exhaust flange gaskets, and (2) intake boot to head orings.

 

[Hoffman]

That chain is normally loose like that. No adjustment necessary or provision made for adjustment. Those seals are from left to right....(2) exhaust valve seals, (4) intake valve seals, (2) exhaust flange gaskets, and (2) intake boot to head orings.

Beautiful - thank you!

 

[Hoffman]

Hey guys,
I'm at the point where I need to disassemble the springs on my valves, but I'm pretty lost about what type of spring compressor I should have - there are so many different types. Can anyone recommend what I should be looking for?

 

[HerrDeacon]

This is the one I have and found it works good. I've used it on a number of bikes like KZ650, CB400T and CB350. Price seems a bit high now, I picked it up on sale pretty cheap around 10 years ago.

https://www.princessauto.com/en/detail/valve-spring-compressor/A-p8003725e

 

[dtsmjr8dan]

If price is a factor, you could substitute a 'c' clamp and a short piece of pipe with a cut out. When I do mine, I put the head in the vise (with protection on the jaws) to do this. I use an automotive valve compression tool similar to the one Perry showed.