Possibly entering the 378 club!

Pj, I've used stainless valves on cast guides for years in automotive application. The KPMI valves are microscopically coated anyway, should not need bronze guides according to their tech qa https://www.kpmi.us/tech-support---faq.html

I did in fact call them and they assured me the factory guides in cb350s and cb360s have been used successfully.
 
So, rebuilt the engine, fitted the ancilliaries and it fired right up!

But only running on one cylinder.

Right cylinder not contributing to the fun and spark plug seems to be dry so probably a fuel issue.

I’ll investigate tomorrow.

Pics, and video!, to follow shortly :)

Steve
 
Great to hear it's a runner.. Use stock Kei-Hin pilot jets instead of aftermarket kit ones. Set float height to 21mm. CJ carbs are exactly the same as late CB (I brought a set back last time I was 'home')
 
Up early and re timed the ignition, as wasnt confident it was correct, and we have success!

A quick spin around the block indicates a beefier sound and strong pull at low revs, and clutch slip as soon as the motor get to about 7k. Which is disappointing as i did fit ‘heavy duty’ clutch springs. Sourced on ebay so maybe crap.

I wonder if i need new friction plates as well as hd springs?

Where’s a good source for springs and plates guys ?

I’m very happy the bike is running properly as this was my first engine rebuild, albeit only the top end.

Here’s a pic of the CB389 resting after its first run.
 

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I only use Bore-Tec springs for 'race' 350's. Were they thicker wire and slightly shorter than stock Honda? EBC do a set but I haven't tried them. Stock plates are probably better than anything else Barnett tend to 'grab' a bit but are a lot better than 30+ yrs ago when they were 'drag race only' Glad you have a very noticeable difference in performance, it's even better when clutch stopps slipping as you have at least another 3K to go 8) 8)
 
Hi PJ

The ‘heavy duty’ springs are longer than standard and seem to be the same thickness/strength.

I’ll look out some of the ones you recommend.

What do you think of EBC clutch plates?

Really looking forward to giving the new motor a good blast once the clutch is fixed!

Steve
 
Bore-tech is closing the doors, due to health issues. so when they're gone - they're gone.

I was glad to see they still had the springs available when I ordered them for Piglet, I ordered an extra pair just to have on the shelf for any future bikes.
 
Had a search and found the bore-tech site.

Springs very reasonably priced but shipping quoted at $55 which is a bit silly.

Guess i’ll try ebc!

Steve
 
USPS went nuts a couple of years ago so shipping is crazy for anything outside USA. Medium flat rate box used to be around $27.50, last time I looked it was $48.00 to Britain. Even sending stuff to Canada more than doubled. Even so, $55.00 is way OTT as about 6 sets of clutch springs would fit in a small flat rate box and that should only be around $20.00 or less.If you could find a few more people who wanted them you could have them sent to me and I could re-post to you with Customs Declaration, I doubt a single set would be cost effective?
 
I ship all over the US and world with parts I make and sell. I don't get hit with shipping like that at all. I just shipped some parts (rubber plugs) to Australia for $13.54. First Class International.
 
An update, one step forwards and two back !

Dubious of the ‘hd’ springs i whipped them out this morning and compared with the std springs. Wire thickness on the ‘hd’ springs is thinner than the std springs, no wonder the clutch slips!

So back in with the old springs and out for short test ride, very short....... as the engine seems a little rattly then stops suddenly.

Took out plugs and span motor over, valvs not opening so off with the rocker cover and I find the timing chain is off the sprocket, which is broken and the bolts are out.

I’m sure i tightened the bolts but obviously not as it looks like one undid, then the sprocket wobbled and ripped out the other bolt and destroyed itself.

I’m assuming it will have bent a valve in the process, not had head off yet.

I’ll obviously need a new sprocket, and probably the cam too as one thread looks knackered, or could helicoil it?

Thoughts?

Steve
 

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That's a bummer. I always use Loc-tite on those cam sprocket bolts just in case.

You could helicoil or tap to the next size up, although I don't know if swapping up to a larger bolt (added weight?) would affect the balance of the cam while its spinning at speed...could be negligible ?
 
Took a closer look at the cam and the threads are ok, one is perfect and the other cleaned out ok with an m7*1 tap ( was surprised it was m7)

So i may get away with a new sprocked and pair of bolts, any suggestions as to where to source those ? (Sprockets common on ebay in us but not sure for bolts)

I remove the head later and assess valve damage ......
 
Get new bolts from Honda, pretty sure they still use them on various motors but you'll need a parts guy who knows how to look up superceded numbers (probably a lot of them?)
 
Thanks PJ

I’ve found a source of bolts here in the uk, cam sprocket too but cheaper to have it shipped from the us!

I have two bent exhaust valves, one slightly and one very bent !

Inlets look ok, no marks on the valves or pistons.

Is this what you’d expect 360 experts??

I’m regretting not double chcking those cam sprocket bolts !

Steve
 

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Checking wouldn't have mattered if you over-tightened the screws. Over-stretching from over-tightening will also cause failure- either breaking or loosening.
 
In all honesty i’m not sure i went back to the first b9lt at all, after rotating the cam to fit the second !

New valves ordered very cheaply from isreal...... wonder if they’ll turn up!

Watch out for the next episode in ‘Steve’s first engine rebuild’ :)

Steve
 
this is precisely the thing that scares the crap out of me when building an engine

sure I was able to do my CB360 myself.... but hitting that starter button for the first time was a little nerve wracking
 
More than once I've re-stripped top ends to check cam bolts. So far, I've always had them tight but it's so 'automatic' to me I forget I've done it. I don't think it's possible to over-tighten those bolts? I use a long 1/4" drive extension and 6 point socket. so I can get 'outside' head. Never yet had one come loose (yet). It is likely you 'got excited' and only did them finger tight? It's more normal for exhausts to bend, they can get tangled with intakes and pistons., they close 'later' as things start going wrong You need to pull intakes to check them, just in case there are any marks on edges. Is there damage on head/cam bearings where bolts backed out? Generally eay enough to filer off any burrs (I fixed a lot of CB/CJ250's before UK had 125 learner law)
 
Thanks PJ

I may indeed have not tightened at least one of them up properly!

Thanks for the tip on intakes, thay look unmarked and were watertight when i cleaned the head in the parts washer to clear out any metal fragments, but i guess i should remove them to check edges.

Am now awaiting a sprocket amd bolts from the US and two exhaust valves from Israel, wonder which well get here first ( prob the sprocket as thats no use until i have the valves!)

Its all a fun learning exercise, lucky i have a few other vehicles :)

Steve
 
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