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

Hopefully it's just a 24~48hr thing.
If you do get a chance, just pull the filters off and try it with open carbs, sounds like it's damp enough not to have any airborne sand and dust around
 
I pulled the carbs off and found my issue. I had vacuum synced the carbs last fall, and things were running pretty good. However, when I bench synced the carbs, I found that the left side (the trouble side) was much "tighter" (more closed?) that the right side. I rebalanced the carbs and noticed that the lock nut on the adjuster screw was a little loose. Hmm.

In any case, after that the bike fired right up, both pipes got hot, and I was able to dial in the idle in about 20 seconds. Woo.

I'll put the filters back on tomorrow (I was testing without them on) and take some test rides to see how things are running. Man I'm glad to have that problem solved! I guess I should put the new coils back on the bike at some point as well.
 
You are so right! I figured the sync was fine as I had done it with vacuum gauges. I'm sure it was fine - until things started vibrating all over the place. Ah well, (another) lesson learned.

Unrelated, but my brother picked up (another) 1986 Yamaha SRX600. It was a one year wonder (in the US) 600 cc thumper.

bSjtRxW.jpg


Quite the hot little number there. He has one that's his daily ride, but got another for cheap as it is in boxes and missing the carbs, head, and fuel tank. The frame is titled though...

I posted in the "Buying" forum looking for parts, but had no luck. I don't suppose anyone reading is a closet Yamaha fan with a stash of SRX or XT 600 parts? ;D
 
Im now having the exact opposite of this problem.
I installed the carbs this morning put the gauges to em.
They were a bit off.
now that I got them synced, the bike runs good until I start to accelerate.
It gains speed and climbs rpm just fine...but all the while it pops and coughs.
seems to be both cylinders.
It was running good when they were off a bit.

I did swap guages to make sure it wasn't that.

It did get good and hot while I was adjusting, its such a bitch to tighten the nut without turning the screw. I had to re-do it like 15 times. finally got it.

gonna check timing...again.
uggg
 
That sounds like running lean, what with the popping and coughing. The syncing would only affect idle type stuff (as I just painfully learned :p ).

What else would cause it to lean out after a carb reinstall and sync?
 
Damn it Trek, your darn carb sickness is contagious! ;D

I hopped on the bike yesterday evening to go for a test drive (with air filters on), and the damn thing popped and coughed up to about 4000RPMs and then would stay there no matter how much throttle I gave her. It would idle ok though :p

I pulled over and removed the filters (thanks cargo net for your holding skills!) and if anything it was worse on the ride back. Putting the choke on made things even worse!

I'm starting to think I have found the first case of human -> motorcycle disease transmission, as the bike was running like I feel. H1N1 Bike Flu!
 
That's the thing that baffles me, that they worked great on your bike. I'm going to disassemble the petcock to make sure there's nothing restricting the flow of gas and just go back through everything again. So strange!
 
Damn, should have thought about that. ::)
Just a couple of days ago Brendon mentioned his runs better with a full tank and starts to crap out below 1/2 tank.
I know I had problems with the 378, but that was because initially I didn't have any tank filters just inline filters.
The drillings in the tap kept blocking up, filter in tap bowl was OK but the bowl was usually 3/4 or more full of rust particles.
Ended up making a filter from some thin-wall brass tube and tin plated copper mesh (I think it was designed to heat shield wiring?)
 
You know, there is a little less gas in the tank than normal. I'll top it up after I check the petcock. I'll check the running with the gas cap open as well. My 900 had a vacuum issues because the idiot PO stuck a bolt in the breather hose end, which caused the fuel pump to create a vacuum in the tank. My first clue was the "HIISSSSSSS" when I opened the fuel tank after it stalled out...

Trek, you're fine ;D Did you have any luck with resolving your lean running issues? What does the lambda sensor tell you?
 
Worst cb650 ever said:
You know, there is a little less gas in the tank than normal. I'll top it up after I check the petcock. I'll check the running with the gas cap open as well. My 900 had a vacuum issues because the idiot PO stuck a bolt in the breather hose end, which caused the fuel pump to create a vacuum in the tank. My first clue was the "HIISSSSSSS" when I opened the fuel tank after it stalled out...

Trek, you're fine ;D Did you have any luck with resolving your lean running issues? What does the lambda sensor tell you?
Click to expand...

Didnt mess w it. Frustrated and just parked her for the day.

This pair of carbs are VERY touchy w vac sync screw...I dont know why.

I believe o2 read the same as it has for the past few days. (without trouble) I will re-check the vac gauges and make certain nothing changed there during my test run. I adjusted vac without filters...Then installed them. (maybe I got one that flows better than the other)
But, I got a pair of leaner primaries coming soon and will up the secondaries. To get closer to 12.5 - 1 ratio on acceleration. So that may help w issues.
ALSO, it took a lot of idling time to set vac, I know the gas got good and warm in the tank.
and now its raining most of this week. grrr.
 
and I wasn't gonna say anything, but now I am. Because I know warm fuel can cause weird issues. Ive had that before.
Forming bubbles in the petcock and lines.
I to have noticed the bike runs better w a full tank. Same as Brendon. I think that could be a warm fuel related issue.
Half a tank or less could heat up quicker than a full tank.

Just saying, its simply a suspicion.

and yesterday was the first time I had this problem and I know my tank was much warmer than usual & half full.
 
trek97 said:
and I wasn't gonna say anything, but now I am. Because I know warm fuel can cause weird issues. Ive had that before.
Forming bubbles in the petcock and lines.
I to have noticed the bike runs better w a full tank. Same as Brendon. I think that could be a warm fuel related issue.
Half a tank or less could heat up quicker than a full tank.

Just saying, its simply a suspicion.

and yesterday was the first time I had this problem and I know my tank was much warmer than usual & half full.
Click to expand...
I've questioned this too. Sitting the bike in the hot sun enough to cause the tank to expand seemed to make things change with my bike during initial tuning. When I went back to it that evening, it ran cleaner. There were some other factors that made it hard for me to be confident that could be an issue, though. I'm not running clear fuel lines, so I wasn't sure if air was getting into the lines. I also assumed that the float bowls and the petcock would counter any pressure in the fuel tank that wasn't being evacuated through the tank filler.
 
I may put clear fuel line on the carbs for grins to see if I can gather any data that would help us. The petcock definitely needs to come off to be disassembled and cleaned first, however. It's a new aftermarket reproduction unit as the one that came with the bike was missing several important pieces.

Does the bike use 3/8" or 1/4" ID fuel line? I can't remember what I put on the darn thing anymore...

I could always add a fuel pump to the mix as well. Let's throw more complication at the thing! :eek:
 
The fuel line is 5mm or about 1/4" ID - answered my own question with Google ;D
 
I originally used 1/4 inch Tygon on my bike. The ethanol make it soften and swell....I went to 3/8. A little tighter fit (as pita), but they remain firmly attached, and not sliping off...

If you aren't looking for transparent line, you can get 5mm line from Honda yet, ethanol resistant
 
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