Bike starts acting up after warm up (need Help!)

CB360ty

CB360ty

Active Member
So for the last few months my bike (74 CB360) has been running really bad after it warms up, usually about 5 or 10 minutes of riding. Basically it starts to idle bad and dies if I am not on the throttle and if I am on the throttle there is serious loss of power which gets worse as I increase the throttle. And finally while it is doing this it kinda sputters, it feels as if its running on one cylinder or something and it gets sporadic bursts of power. I also used a heat gun thingy that reads temperatures and it showed that one side get much hotter around 200F at the head of the exhaust, compared to 140F or so on the other cylinder.

I have changed the plugs, and tried my stock exhaust with no change. I ditched the stock air filters at the beginning of spring for some screens, however this problem didn't crop up until a few months after that. As of right now I'm running straight scrambler pipes too. And I no longer have the stock exhaust either (sold it, stupid I know).

My only guess is that it has to do with the jets possibly needing to be replaced with bigger ones.

Any help would be great, I finally got the bike how I want it to look and I haven't been able to ride it much because of this problem. The cheaper the solution the better, Im an unemployed collage student.

Thank you in advance!
-Ty
 
you know, that sounds awfully similar to the way my bike felt recently (cb350) i am starting to think i have an electrical issue tho.
i noticed last night that i had arcing from the left plug boot to the cover on the points. so maybe bad resistor boot? maybe yours is kaput too? worth checking, cause its easy to do and change. also gonna check running it on a different battery.
 
Big Rich said:
Are the valves adjusted and timing in spec?
Click to expand...

Im not sure exactly how to tell, would that account for the problems Im having or wouldn't that affect the performance of the bike whenever its started and not just after its warmed up?
 
space pup said:
you know, that sounds awfully similar to the way my bike felt recently (cb350) i am starting to think i have an electrical issue tho.
i noticed last night that i had arcing from the left plug boot to the cover on the points. so maybe bad resistor boot? maybe yours is kaput too? worth checking, cause its easy to do and change. also gonna check running it on a different battery.
Click to expand...

Really? now that you mention it my resistor boot came off of one side while I was changing the plugs once a while back. Could I use electrical tape an tape it up to see if that fixes it?

EDIT: But now that I think of it that doesnt explain why the problem only comes up after the bike warms up...
 
Does anyone think the problem could be related to the stock airbox being removed? It still has stock jets...

Thanks for the help so far.
-Ty
 
yes, Are you using the choke when cold? Then taking it off as it warms up, the choke richens the mixture and when you take it off your bike is leaning way out. Pull the plugs, what colour? If black, you are rich, if lgith tan to white, way lean, you likely are way lean with pods/stacks and open exaust on stock jets, you likely need to go up 2-3 sizes on the main jet. the difference in temp on one side verses the other could be elcetrical, weaker spark or arching, or fuel, float hieght, or carb sync etc. Jets are cheap, like 2-3 bucks each and you can sometimes get kits in ranges for really good deals. Running lean for a long period can cause all kinds of bad things to happen to your motor.... I lost a piston and learned the hard way. Cheers.

Maritime
 
Someone here has posted Try a search on Jets, you may get lucky ;D, I just went to the local dealer and bought some in the sizes I needed. They were 2.00 ea and I got 3 for each carb. but I have seen the kits on Ebay, depending on the brand of carb and style of jet. I got lucky that one of the sizes I bought had her running well. But I have a different bike, 82 CB450 with Kihein carbs. Not sure what you have on your 360, but the priciple is the same on most.
 
Try DCC for the jets they have everything, you may want to check your floats in the carbs, I had a similar problem with my cl350 come to find out the float on the left side was out of adjustment, made the proper adjustment and it fixed all my issues with the bike running on one cylinder and having lack of power.
 
Once she warms up, try running the bike on ~1/4 choke, see if it gets better.

I have a '75 360 in pretty close spec to yours, CL pipes, no muffler just straight, EMGO cheapy pods for now.
When i run choke OFF it runs like shit (too lean) runs a champ with ~1/4 choke. If so, go buy 2-3 sizes up.

I know it's not a permanent solution, but for me, i just wanted to get the bike running right around the block sans re-jetting prior to starting cosmetic mods.
 
Gyi2os said:
Once she warms up, try running the bike on ~1/4 choke, see if it gets better.

I have a '75 360 in pretty close spec to yours, CL pipes, no muffler just straight, EMGO cheapy pods for now.
When i run choke OFF it runs like shit (too lean) runs a champ with ~1/4 choke. If so, go buy 2-3 sizes up.

I know it's not a permanent solution, but for me, i just wanted to get the bike running right around the block sans re-jetting prior to starting cosmetic mods.
Click to expand...

I will have to give that a shot. Have you installed bigger jets on yours?
 
I have a VERY similar problem with my '74 360. I thought it was jetting from the pods and straight pipes, it wasnt. I pulled the points cover and cleaned them. I also found some carbon marks on the inside of the points cover, so I doubled the cover gasket to space the cover out some, and I smeared some RTV over the area that had the marks so that it couldnt arc there. This helped a lot at the beginning of a ride, but the bike would still die in the exact same way you described. I checked my voltage at the batt with a multimeter and it was something like 4.5v while idling. I unplugged the regulator and read the voltage and it was 18v-19v @ idle. So it looks like a bad regulator. The bike would run well off just the battery initially (because the regulator was preventing juice from the alternator from reaching the rest of the system), but as the battery drained, things would start to shut off, like the lights, and then one cyl wouldnt get spark, it would sputter and surge momentarily until it eventually died (because the batt was completely drained).

Right now I'm waiting for a new batt and a 80's cb400T reg/rec unit (CrazyPJ's recommendation for replacing the stock unit) to come in the mail. after they get here I can tell you if that was indeed the problem.

Keep us posted on this, it seems to be a common problem on this board (i think ive read about 3 or 4 other people having this issue this summer).

-Dan
 
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