CJ360 (CB360) Rebuild, electric starter, 6 speed

ManuR

Active Member
I am starting to rebuild my CJ360 Engine.
since the CJ version has no electric starter an 6 speed, i am gonna swap these over from a CB360 Donor engine.

To be done:
- Dissasemble the engine
- check: valves, springs,
- check: Cilinder, piston, rings
- check: Cam chain, tensioner, spring
- check: clutch plates, springs
- maybe drill oil path under camshaft
- swap upper cranck case with a CB one
- soda blasting combustion chamber, valves, piston
- soda blasting engine
- painting engine (thought about powder coating it, but i will stick to aerosol)
- install 6 speed gear box
- change gasket
- change oil seals


Some info from before tear down
it was running on the right cilinder only

compression test
First time i tried was cold and without some oil in the chamber.
Right: 135 psi
left: 145 psi

The second time i poured a little oil in the chambers. use a bit to much in the right cilinder.
Right: 175 psi
left: 155 psi


a complete picture of a bike did never hurt anybody
i have orderd a brown leather saddle. and i will maybe repaint the tank, not sure jet.
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Disassembling the engine
sorry for the bad pictures, they where taken before i decided to post my rebuild.

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The previous owner advertised the engine as rebuild 4000 miles ago, but i didn't know anything about his rebuild process, so i will have to check a lot of things (if i can get my hands on the right tools)

This picture is of the gearbox from the cb360 donor engine
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Checking: Valves, Springs, ...

i was lucky to have bought a valve spring compressor a couple of years ago, so straight to the point.

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Left intake valve
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Left exhaust valve (something seems missing :eek:)
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these where the measurements i got. (sorry, it's al in mm)
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I wasn't able to measure the valve side clearance, and the face with of the exhaust valves.
just to be sure, with valve face width they mean the part that is actually grinded right?

i have read somewhere that the valve spring is only important if you do high revs, an that not a lot of people even bother to check the lengt.
is this true, or am i being a cheap ass? :p
 
Stock valve springs are fine with stock cam. You only need to change them if they are below spec or you fit a 'race' cam. I've had 360's rev to about 12,000rpm with stock parts, the ignition system is the limiting factor so you need something better for high rpm operation. Your outer springs are fine but inners should be changed. They will work OK if you use stock redline but you'll have very little 'reserve for missed shift, etc
 
Now That i am putting the effort in of rebuilding the engine I decided to do it properly. So i am buying nos valve springs, inside An outside as Well. I would actually like an engine that can really go when necessary.


I also started to soda blast some Parts, never soda blasted engine Parts so i uses the bottom crankcase of the donor engine. En piston of donor engine.

Piston.
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I don't actually know what a new cylinder feels like, so I don't know if it is to rough, but soda doesn't affect the aluminum itself so I should be fine.



crankcase
Haven't had a lot of time so only a tiny part hase been blasted.
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So next, i had a chanse to messure the valve to guide clearances. The intakes where ok, but exhaust where way of.
The stems are fine (measures them egain with a micrometer). So I will replace the valve guide's.

Do I need to know anything special here. Or just put them into place? Never done this before.

And do I need to change the valve spring seats?

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I ordered new springs as I could find them. I still need one inner and one outer one.

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Then it was time to pull the cylinders.
It was very difficult to get lose, but then just used some common sense.
Some old scrap wood. And 2 screws, which came from the crankcase :D they where absolutely perfect for this job.

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Is the scoring on this piston bad? Or normal wear?

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Tomorrow I am going to measure the cylinder and Pistons. Curious to what they have to say.



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Piston is pretty normal.
Is that wear on the bore though from a missing circlip allowing pin to rub?
If your removing valve guides, safest way to do it is drill thm oversize, tap a thread, screw in a bolt then heat heat to about 375f and knock them out from combustion chamber side. It's also a good idea to make sure the ends are clean so carbon build up, blasting media or dirt doesn't scratch hole. Fit new guides while head is hot. They should really be pressed in but using a correct size mandrel will be OK as long as your 'tapping' and not wailing on them.
You know valve springs have a top and bottom for correct fitting?
 
there where no missing clips, so that cant be it. i will take a better picture when i can.
thanks for the insight, i have a press that i can use, so i shouldn't be a problem.
is there a possibility that the head will warp from the heat?
i guess it will be in the manual, logically dense coil side down? might be usefull for future reference

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So today it was time to measure the piston and cylinders.
the rings are fine but i broke one ... so yeah :p guess i will have to replace one set.

if anybody would find it useful, i could repost the tables in inches.




I work at a shop from some people i know, so i always have limited time, the piston ring clearances, will just be measured at home when i have time.


the guy who worked there told me i could use this to hone my cilinders, never honed a cylinder before, its gonna be ineresting?
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Head will be fine, you could check before and after if you want though.
To get a cross hatch don't run drill flat out, around 400 to 600 rpm will work best.
Spinning too fast will give radial lines.
Move flex hone up and down/through cylinder relatively quickly while it's spinning to get a 45 degree angle on cross hatch.
When I was teaching people to do this we found cordless drill turned about right rpm.
You would be surprised how 'logical' people can get when fitting valve springs with closed coils ;)
I always check posted pictures to check, habit from running workshops then working at MMI
 
Thanks for all the tips.

I have received my VHT engine enamel paint. (Difficult to get hold of here).
I am busy with soda blasting al the parts. I didn't think is was gonna take this freaking long to get it clean.

I have build a diy drying booth (electric heater is gonna sit inside as well).
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And I finally finished my paint booth.
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All the parts are now organized and ready to finish soda blasting, rinsing, last degreasing, masking, painting and curing. (What a list)
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To finish them off I am gonna use my converted shop oven.
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Well ... Can't really stretch this part more than I already have :p. Next up will be the painted parts.
 
So i started painting.
Everything with painting and prepping is almost mind numbing.

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Now I have to wait for the paint to cure, sand the fins, and apply clear gloss.

I guess 24h wil be enough between the color and clear? I was kinda confused with what the can said.


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So finally done with the paint. I shamelessly copied the paint scheme of a do the ton member.

Now just let it dry and then cure it in the oven.
I am reasonably pleased with the result.
But I need a better soda blaster, grime is so hard to remove. So now the paint has chipped a on some edges, but it's okay for now.

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So the workshop finally has some moving room again.

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Next will be some real engine work again


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Some nice engine breast in the oven.

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Cam cover
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I tried tapping the valve guides when the cylinder head came out of the oven. But no luck.

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There is a wire circlip on them to stop them falling into combustion chamber, BUT, if you drive new ones in too deep, it compresses and fractures the guide (I've seen new single cylinder 125~230cc engines direct from factory with broken guides)
They come out from spring side so head has to be supported 'upside down.
If machining was done right there will be about 0.003" interference fit (damn tight even when hot) Tapping doesn't work, need a real good smack.
Best way to do it is drill guide out slightly and thread it for a long Allen bolt. I have a 360 head here that needs doing when I get to it I'll take some pics (sorry it's taking so long Timberwolf :-[ )
 
Yeah i Will have to give That a try, i thought about using the spring seat, small tube, washer and Allen bolt, but I can't get the c clip from the guides, so maybe I can slightly drill the seat out. As long as it doesn't leave a deep groove.

I started to prepare the assembly with installing some smal things and gearbox. But i notice that I can pull and push on the kickstart shaft quite a bit, is this normal?

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Left is CJ

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Cleaned up shift drum

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Left is CB

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Thinking about what accent colors I can use, obviously this circus clown red isn't the way to go. (Should I be posting in the paint section of this forum? )

And to keep me motivatie, a quick Peek.
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So removed the valve guides. I drilled them out tapped them. I drilled one out to big so i had to mess around with the press.

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Then i honed the cilinder walls, and indeed, the cordless drill is perfect for this. I have never done this before can somebody tell my if the cross hatch looks ok?

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I didn't had a lot of time lately, i will check the bores as soon as i have time.
I receved the new valve guides, but the valves won't fit (valve guides not installen in engine).
Am i supposed to machene these after i install these?
 
ManuR said:
Yeah i Will have to give That a try, i thought about using the spring seat, small tube, washer and Allen bolt, but I can't get the c clip from the guides, so maybe I can slightly drill the seat out. As long as it doesn't leave a deep groove.

I started to prepare the assembly with installing some smal things and gearbox. But i notice that I can pull and push on the kickstart shaft quite a bit, is this normal?
You don't remove the clip, you flip head upside down and use drift from port side.
As for kickstart shaft, it shouldn't have much movement but clutch cover prevents it moving outwards, just don't forget thrust washer. It will still have a few mm movement though
Cross hatch a slightly 'flat' but will be fine. You were probably moving slightly too slow in and out of bore. There 'should' be a 90 degree angle between 'scratches' Angles can be modified for different applications though so that will be 'best for longevity' (holds oil slightly differently and doesn't 'wipe off as easy)
Tapping valve guides is the best if not the easiest way to do it.
 
So, i think i Will have Some time again to work on the engine.
I starter by trying to ream a valve guide without it being in the engine, it isn't really expensive and i have never done it before, so rather Buy a new one (if it fails) then having to pull it out of the engine again.

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I have now reamed one valve guide. But there is An ever so small play.
i couldn't ream smaller because the tip of the valve would't fit, even now it was a bit tight to get it true.
Is it possible to ream without any wobble or not?
Guess i wil have to put it in the engine and then measure the play.
 
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