1976 Honda CB360T - The first step is admitting I have a problem build

This thread rises from the dead yet again! :eek:

So, updates. The CB650 is sold for what I was asking for it, so that's good. The new owner seems very happy with it, and he should be because it was running great when I sold it.

Also, I have the 360 running pretty well on a replacement set of carbs. PJ and I speculated that the carbs that came with the bike were just too badly corroded to support proper running. I found a set off Craigslist for $30 that were very nice. I cleaned them out and put them on the bike, and along with a fresh set of plugs now have a bike that idles between 1000-2000 RPMs and doesn't stall. It's still not running perfect, so I need to check the valve clearances again and fiddle with the carb settings, but it runs, and that's something.

I think I'm going to get a replacement pair of mufflers for it at some point too. Right now it sounds like riding a chainsaw, and I like my neighbors ;D I also suspect that the very open exhaust may have something to do with the tuning difficulties, so I'd like to get some stock backpressure, uh, back in the picture.

Also also, an '86 Yamaha SRX 600 has arrived via the mail and the Greyhound bus. I think I'm ready to go for a ride on it!

SHBN3upl.jpg
 
Pull all the brass out of the corroded carbs and fit it into the 'new' ones.
It should then run fine with K&N's
 
Check out www.hondacb360.com (NOW COMMON COLLECTIVE ) see my Honda twins build thread for pictures. Nice sounds, period correct look for mufflers if you want stock type system

Sent from planet Earth using mysterious electronic devices.
 
So for now, I've just been riding the bike as-is around town and to the local bike night. The idle is still a little variable, but it doesn't stall any more, so that's a plus.

I did notice that the oil stunk more like gas than I was comfortable with late last week, so I dumped it and put another couple quarts of Rotella into the sump. Looks like the rings are still breaking in and the oil was black as night, but that's to be expected with only a couple hundred miles on the rings and too many short trips.

I keep the petcock turned off when the bike is parked, so I think the gas is due to too much idling while I was trying to get the bike working properly. We'll see how the oil holds up now that the bike is spending time on the road and not in the garage.

I'm waiting for motor oil seal bits for the Yamaha SRX 600, and have to bore the jug over at least 0.25mm to deal with some wear on the cylinder wall. I can go up to 1 mm comfortably on the stock jug, and if I need to bore it 0.50mm it will be a lot. Bummer is that I need a new piston as well, as the skirts on the stock one are scuffed very badly. The rings are just worn, no breaks or anything else, just out of spec for end gap as I'd expect with the wear in the bore.
 
Holy cow bro, this thread is just about to join the 60,000 club. Where you at on this project?
 
You know, I fired up the 360 yesterday for the first time this year. I was able to put some good miles on it at the end of last season, but it's still pretty good at fouling spark plugs. I just keep a box of them lying around.

I ended up with another CBR900RR, this one set up for drag racing. I bought it as "has no spark", and as it had a spark, I had it running in about 15 minutes. Needs a new fuel pump, however...
 
I also found a clogged (like packed with mud) float bowl vent on the left side carb, which I think may explain why that side wouldn't reliably fire. Turns out if you pull on those little brass bits hard enough they come out, and you can scrape the mud out of them. One of the four vents I'm talking about is circled in the picture below. We'll see if this helps the bike run better!

qjNQmhv.jpg
 
May make a slight difference at top end but it is only float chamber breather so shouldn't have any effect at lower rpm.
I spray cleaner through all the vent's when I 'fix' carbs, no idea how that got missed?
Where are fuel screws set at present?
 
PJ, remember I picked up a second set of carbs to try to diagnose my running issues. This was all my fault - your modified carbs were spotless.

I went for a nice ride this evening, and the bike was running pretty well, though a little cool on the left side, which has been an ongoing issue no matter what the setup on the bike. But, this evening it was idling well, pulling hard, and so on. Good things all around!

I had put a fresh set of plugs in the bike, and when I got home I pulled them to read them. They were a little dark, but were dry. Good things again! I also cleaned up the kill switch, as I noticed that just bumping it slightly killed the bike. It has a much more positive engagement now.

However, when I went to reinstall the plugs to check if the switch cleaning fixed anything, I saw something in the combustion chamber on the left side. I grabbed a flashlight and shined it in there and found...

<drum roll>










<more drums cause you all know this is the issue that was causing all my problems>












A FUCKING PISTON RING!!!!! It is still in part of the piston groove best I can see, but it's come past the piston and is just sproinging up and down like a fucked up Slinky. What a pisser. Guess the head's coming off...and this is my only running bike too, doh!

At least I found the issue with the cold left side and the gas in the oil...
 
Yea, but I'm oddly happy to have found the issue. Must be carbon monoxide poisoning...

$50 later a good used jug and pistons are on their way to me, but I'm pretty sure I can't get away with reusing the head gasket, right? What about the base gasket and o-rings?
 
I would replace the head gasket. the o-rings will be fine, Im sure the lower gasket is fine also. but I dont know that for sure. I bet you bought the jugs I was looking at this morning...grrrr ;)
 
Man sorry to hear about that, I've seen something like that once in my life on a really large tractor engine. Dad still has the piston around some where, has had a couple of inch wide fan shapes in the side of of it where it ran for prolly 1500 hours before the ring finally broke and blew out the exhaust and consequently through the turbo.

I'd get a replacement for that base gasket or at least have some paper handy in case the damn thing tears when you pull things apart. There used to be top end gasket kits on ebay and amazon for a good price I can't find them this morning just over priced stuff...
 
trek97 said:
I would replace the head gasket. the o-rings will be fine, Im sure the lower gasket is fine also. but I dont know that for sure. I bet you bought the jugs I was looking at this morning...grrrr ;)
Click to expand...
Do you need a set of jugs? I sent a good set to E with the 360 when I traded him.
 
deviant said:
Do you need a set of jugs? I sent a good set to E with the 360 when I traded him.
Click to expand...

Ohhh Ill send him a text after bit.

Are you telling me you traded off the 360? :eek:
 
Yep. Now it's Jenn's bike. She needs a running, titled bike.


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deviant said:
Yep. Now it's Jenn's bike. She needs a running, titled bike.
Click to expand...

Hells YES! I always thought your bike was little better suited for a GIRL anyways! ;)
 
I just bought the gasket set - with my luck I'll need the little rubber pieces and a new base gasket and whatever else, and I don't want to have to wait again for the mailman when I dig into this thing.

I gotta say I'm pretty surprised how well the thing ran with a ring escaping. I'm very interested in how well it will run with two functional cylinders, heh. And, I will finally get a chance to experience the full fury of PJ's modded carbs!

Here's a picture of the bike still together in any case...

D783zDxl.jpg
 
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