Topic: CB350 twin has us perplexed

[Scott S]

 Picked up a non-running CB350 a while back. A friend decided he wanted it and we got it running.
 I adjusted the valves and cam chain and cleaned the carbs using Simple Green/water, carb cleaner, compressed air, etc. I pulled all the jets and installed new O-rings. Diaphragms looked good. Trimmed the plug wires and installed new caps.
 Didn't really mess with timing or points.

 The bike ran but not so well. We noticed one pipe bluing and, on further inspection found that one carb wasn't acting right. One side was lean, the other rich.

 Pulled carbs and had them ultrasonically cleaned. Ordered genuine Honda O-rings. Set float height using the tube in the float bowl method. Meticulously adjusted cables, mixture screws, etc. Re-assembled and the bike is running much better and on both cylinders now. However....

 A fresh set of plugs and a plug chop showed us the same thing on the carbs; one side lean, one side rich.




 The plan now is to install a Pamco and probably new coils to eliminate anything electrical. We'll also check valve adjustment again....could bad valve lash cause something like this?
 We're using the old, stock air filters and they're not the cleanest, but we did blow them out with compressed air. Could they be the culprit?




 The bike is otherwise stock, except for the mufflers.


 Any ideas or suggestions are much appreciated.

[trueblue]

First things first, I would chuck a new set of air cleaners on it. They may look ok but not pass enough air. Given the 350 twin has CV's on it blocked air cleaners can play merry hell on your mixtures.

[Scott S]

Forgot to mention: We replaced some cracked intake manifolds with good used ones.

The old plugs looked better and had started getting a little orange color, but that was mostly parking lot testing. Installed new plugs and did a proper chop, and you see what we got. It's almost like something is going on with the mains, but what/why?

[Scott S]

 I know it would be lean, but would running without the air filters briefly.....just to test that theory....be OK? Since genuine filters are so hard to find and very expensive, and not sure we want to get into pods...

[ohiocaferacer]

You can run the CB350 with open carbs and stock jetting.......wont be a problem.
It looks like that cyclinder isnt firing correctly.....your points may be bad or timing is off.

[tbpmusic]

.........
 Didn't really mess with timing or points.

That's probably the issue - go to HondaTwins and read the procedure.

[grcamna2]

I'd make sure my emulsion tubes are tight in their bores and see to it that both primary and secondary main jets are sealed well at both their o-rings along w/ making sure the leaf spring inside is putting even pressure on both main jets.How does your pilot jet system operate? does she idle smoothly on both sides w/ clean even response from 0-1/8 throttle ? I imagine you've check out the floats/needles

[Scott S]

 The mains are tight with new O rings. Isles well on both sides and mixture screws have an effect. Floats were set and checked using the tube on the float bowl method.

[Scott S]

.........
 Didn't really mess with timing or points.

That's probably the issue - go to HondaTwins and read the procedure.

 This procedure?:http://www.hondatwins.net/forums/50-electrical-discussion/23580-how-time-honda-twin.html

[tbpmusic]

.........
 Didn't really mess with timing or points.

That's probably the issue - go to HondaTwins and read the procedure.

 This procedure?:http://www.hondatwins.net/forums/50-electrical-discussion/23580-how-time-honda-twin.html

Yeah, that's it - it's a bit counter-intuitive, so I suggested you read it.
Gap the left, time it by turning the whole plate.
Then time the right by just adjusting the gap - you'll end up at whatever gap it is on the right.

[Bill/BentON Racing]

+1 just did one yesterday, waiting on new filters, runs so good! Man they fun bikes, subdivision stalker! yeh, time it just like he said, buzz box or light works great, then can check running with strobe, Bill
My model had no index mark?

[Scott S]

 A friend stopped by the shop today (I was out) and adjusted the points. Not sure what method he used, but I'm getting reports that the issue is much, much better. Still needs to be timed.
 Who knew that points would make THAT much difference?

 Pamco on the way soon, so may wait until then to do timing.

[tbpmusic]

  Still needs to be timed.
 Who knew that points would make THAT much difference?

 Pamco on the way soon, so may wait until then to do timing.

Hmm, I think I did.....
Do the timing and get the bike running good BEFORE you put the Pamco on - one thing at a time is best.

[tbpmusic]

My model had no index mark?

Gulp - that would make it tough.......

[Bill/BentON Racing]

Could, but I cheated, looked in my old school manual, it's rt in the middle of the stator pack, the one @ 10:00. Couldn't see anything broken, first time Ive encountered no mark on ignition. Did run into early model VF500 Interceptors with no index marks on cam sprockets.That was fun! Bill

[SF]

Great looking bike nice condition, hope to get mine running soon. I'll be watching this one, thanks for posting


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