MGD CB360 Tear Down, Opinoins Needed.

BlueCB360

BlueCB360

Been Around the Block
I've got a 1975 360 in need of seals, gaskets, and a cylinder swap out. I've got all the seals, cylinders, and I have found complete D&K gasket kits for under $40.00. I've rebuilt the carbs, and also had PJ work his magic on them for pod style filters. The engine ran just fine when yanked out a couple months ago. I'll be removing the starter in the tear down. What else should I be including in my budget? What else should I plan on inspecting?






Thanks for the help.
 
CB360 Going in for the Tear Down, What to plan for?

You'll want to check the cam chain tensioner for sure.
What's the mileage on the engine? A cam chain is a good idea as well.

Inspect all the bearing surfaces, and the bearings themselves.
 
Re: CB360 Going in for the Tear Down, What to plan for?

The stock tach shows just over 16K. The bike was all original when I bought it, so I have no reason to believe the tach is true.
 
CB360 Going in for the Tear Down, What to plan for?

I'd replace the cam chain or sure then they aren't expensive.

How was the compression before teardown?
If it were me I would go ahead and do rings and hone the bore just because you have it torn down.

So:
All gaskets
Oil seals
Rings
Cam chain tensioner
Cam chain
Stainless bolt kit

On the head get you a brass wire wheel for your Dremel and clean up the combustion chambers and valves. Test the valves for leaks with some kerosene.

Most of this is "optional" on a motor that was running before teardown, but trust me it sucks to have to tear it down again in a couple hundred miles because you didn't bother to do it right the first time.

On the 360 there are also some oil flow mods you can do to help avoid top end oil starvation.
 
Re: CB360 Going in for the Tear Down, What to plan for?

I have the stainless allan bolt kit, and the seal already. Gaskets, cam chain, and tensioner.

Do I need to get any special tools to be able to get this bad boy apart?

The counter shaft seal worries me, I have no idea how to get the new one in and positioned correctly. It looks like I have to split the lower case, completely, or not?

If there is a thread I should be reading, please lt me know.

Thanks
 
Re: CB360 Going in for the Tear Down, What to plan for?

Yup. Top and bottom cases need to come apart for the countershaft seal. Or you can leave the old one in place and then have to take your engine apart a second time when it leaks (like I did). ;D
 
Re: CB360 Going in for the Tear Down, What to plan for?

Sonreir said:
Yup. Top and bottom cases need to come apart for the countershaft seal. Or you can leave the old one in place and then have to take your engine apart a second time when it leaks (like I did). ;D
Click to expand...

And the bottom end of these engines really isn't that hard to tear down and rebuild. It'll be worth it in the long run. I did it the first time with a Clymer manual. That will allow you to drill out the oil feeders in the top crank case as well without worry of dropping shavings where the sun don't shine. At the least on the head, even if there is no valve leak, I would do a mild fine grit lash to the valve seats just to clean the surfaces up. I guarantee they're dinging a seat ring in at 16k. Again, it'll cost you less that $50, and that's if you make your own valve spring compressor.
 
Re: CB360 Tear Down, Opinoins Needed.

I knew I needed to replace all the seals and gaskets going into this, but I want to show you all what the internals look like.

Also, the front of the cylinders was pushing oil out of what looked to be a welded crack in the housing.

I would have never thought to bubble gum up a cylinder casting, but some one did. And it still leaked.

I have another set of cylinders and housing to replace this broken one. I just thought you guys would get a kick out of seeing the pictures.

I need input on the wear of the top end, and what to replace/upgrade while I have it apart.

It's not going to be heavily modified, just cleaned up and running correctly.

Chain tensioners look brand new. I suspect this engine has seen the chain let go, breaking the jugs in the process.

I could be wrong though. Anyway, I would love to hear from you guys about what you see. Thanks.

















 
Everything "looks" OK to me. You'll want to measure the cylinder bores while you have everything apart. Do an acetone test on the valves, too.
 
I'm waiting on a Valve Spring compressor. I went to Harbor Freight, NAPA, Autozone and Sears, still only found the automotive type compressor.

















 
When you replace the countershaft seal, pay close attention to the orientation of the seal. there is a rubber tab that aligns it. The reason the alignment is important is that the seal is a double seal, inner and outer. There is a small pinhole on the outer surface of the seal, centered between the inner and outer surface. This delivers oil to the center portion of the seal and then feeds the transmission countershaft through holes bored through the center.

If you look on the top case where the seal is, with the seal removed you will see the oil feed hole.

So, when putting the seal in, make sure the oil feed hole in the seal is not blocked by stray rubber, don't use sealer on the seal, as it will clog the hole, note the hole location and make sure it lilnes up with the same hole on the upper case.

I have pictures, I'll get them later..

If you don't line that up right, the transmission will starve for oil and fail prematurely.
 
Thanks, I saw that once I removed the old one, which shows a failure.

This is why I questioned a shop around me last year, that said they could change the seal without pulling the engine.

Glad I did it myself.
 








I'm now at the point where I need to remove the valves, clean the ports, clean the valves, an replace the seals.

Plus I ordered a copper head gasket, just to show a little improvement over stock.
 
I pulled all the valves, cleaned all the ports, and replaced all the seals.

I installed both the inner and outer springs with the open ends facing up.

I think that's right. If not let me know. With the right tool, pulling valves is pretty simple.

I should have my copper head gasket by the end of the week, so this engine should get finished very quickly.

 
Hey man thanks for your replies on my thread as well. I was waiting on getting one of those rubber deadblows today to get my jug off. Worked like a charm

My sears has this valve compressor do you think itll work?

http://www.sears.com/kd-tools-valve-spring-compressor-new-style/p-00999887000P?prdNo=35&blockNo=35&blockType=G35

I have a similar gasket kit to yours, what was your reason for getting the copper gasket made? Did you use any gasket sealer or anything on the other seals when installing them?

Also what did you use to get everything SO clean, your motor looks brand new haha.

I also looked at my valve springs on both the heads that i have and the open ends are all over the place, not sure it matters.
 
That compressor will work.

I half assed one together out of an O2 sensor socket on top of the retainer and a large C-clamp plus some duct tape. It worked well enough to get the four valves apart and back together. If I had some more time and motivation, I would have welded the socket to the clamp and made it a real too.
 
Feisti said:
Hey man thanks for your replies on my thread as well. I was waiting on getting one of those rubber deadblows today to get my jug off. Worked like a charm

My sears has this valve compressor do you think itll work?

http://www.sears.com/kd-tools-valve-spring-compressor-new-style/p-00999887000P?prdNo=35&blockNo=35&blockType=G35

I have a similar gasket kit to yours, what was your reason for getting the copper gasket made? Did you use any gasket sealer or anything on the other seals when installing them?

Also what did you use to get everything SO clean, your motor looks brand new haha.

I also looked at my valve springs on both the heads that i have and the open ends are all over the place, not sure it matters.
Click to expand...

I bought that Craftsman valve spring compressor first, I don't like it for small engines. The spring cup is too big for the 360 head casting.
I think it's more of an automotive compressor.

I wanted the copper gasket to bump up compression, just a little.
It's against my nature to blow apart an engine and NOT give it something over stock.

I didn't use any gasket sealer on the seals, but I did use Threebond to seal the surfaces that don't have gaskets, lower case, valve cover, and on both sides of the copper head gasket, as Lani suggested.

As far how clean my engine is, it soaked in my parts washer for days. First parts went in overnight . . . and I scrubbed them down.
then back into the bath for another day or two . . . and scrubbed them again. The cylinders jugs were glass bead blasted, with the mating surfaces duct taped to prevent damage to the mating surfaces and cylinder walls. they were not original to the bike, so they looked awful at first.
I'm using a degreaser from Harbor Freight called Green Stuff. One gallon mixes with 20 gallons of water. Works well, but I prefer a petroleum base solvent.

The valve springs are a progressive rate spring, both inner and outer. Check out my build thread(link is in my sig), and you can see the difference on page 12 I think.
When I say "open" end I mean that the spring coils are farther apart on that end. So the "open" ends of ALL the valve springs need to be closest to the valve cover.
 
You must log in or register to reply here.

DTT Light or Dark

  • DTT Light

    • Spread the Love

    Back
    Top Bottom