[alehman]

Hi all,

Really loving my new 73 CB350! Unfortunately, history of the carbs is a little murky and PO had a mechanic doing past work so he doesn't really know/remember details. What I can tell is that he ran pods for a short period of time on non-stock mikunis and when it didn't work out, he reverted to stock carbs and filters. However I cannot tell if the stock carbs were also re-jetted for pods or if they are perfectly stock. I have yet to tear them off and look at whats in them as I live in manhattan and wrench on this thing on the sidewalk. What makes me suspicious of these carbs is that the bike doesn't have any power at WOT--- no "kick" that you would expect. When I fully gun it at low RPMs, it dies, and at high RPMs it doesn't really return any power. PO told me his mechanic also rebuilt these carbs but I know from experience that's pretty much worthless until I can open it up and see/do it myself. Added seafoam to my last tank fillup so seeing if that cleans the carbs out much.

Is this lack of power at WOT consistent with overly rich jetting that might have come from a pods setup, or should I look to some other maintenance issue? Spark advance, points, etc. Thanks!

 

[doode]

How do your plugs look?
Just what gear, rpm, speed is WOT?
What's your compression?
What octane gas you buying?
How's your battery and charging system?

 

[JamesPal]

I would start with a full tune up and oil change. Make sure the timing is spot on and the full advance is kicking in. If the bike has points, it may have ran fine when it left the shop last time. Over time the tune fades and needs to go back to the shop for the next tune up. It should be easy to check the jet sizes. The correct sizes are listed in the parts fiche. If you are going to own a classic Honda Twin, you must have a place to work on it of a good mechanic and lots of money to spend. Most of us on this site do not understand the practical meaning of "I live in Manhattan." You need a garage, storage space or extra bedroom to keep it in. There was a time in my life I kept a '75 CB360T and '64 BSA Thunderbolt in my dining room. The BSA made a great TV stand, but the Honda always ran

 

[alehman]

Thanks for the replies guys.

Doode:
I just installed new iridium plugs and the ones I removed had a nice tan color.
my problem with bad power at WOT happens at any gear, any speed, but when gunning it from a low RPM.
I have yet to run a compression test. Will report back.
I buy the highest octane available. 91 or 93 or whatever is generally available.
My battery is good but my charging system is disabled at the moment until my new R/R arrives from Sparck. Still, that shouldn't affect throttle at low RPM, correct?

JamesPal:
Yeah, it's the tuning of the advance and points that I am very unfamiliar with. My manual mentioned how to clean and gap points but what's required for checking the advance?

Also sorry for my vague comment about living in Manhattan. I just mean to say that I'm inner city so I don't have anything close to resembling a workspace. Luckily I do all my own mechanical work so I don't have to rely on/pay a mechanic and have gotten used to wrenching in less than ideal places. I owned a cb750 here for 4 years and did all my maintenance on the curb of the street... last summer I reshimmed my valves on the sidewalk (carefully).

 

[76TWIN]

What happens if you run the carbs without the stock air filters? Does the throttle respond better? If so then it's most likely the carbs have been rejetted.

Are you running with stock unmodified exhaust?

Edit-
Also to proper tune the ignition you really need to use a timing light in order to check for the advance.
Your bike should hit full advance at about 3000 RPM or so.

timing

 

[alehman]

I'll give it a shot along with a compression test and make my report back. I should note that the PO put on a much more open exhaust. Loud! Good thing police in NYC don't have time to pull you over for noisy pipes

Where can I buy such a timing light? What's the process?

 

[76TWIN]

Open exhaust you say? That's gonna be a problem. These bikes need a certain amount of back pressure to run properly. I would suggest adding baffles to the mufflers and see how the bike respond then.

 

[alehman]

It's not 100% open... has small baffles on the ends but doesn't do a huge amount in the way of suppression or I imagine back pressure. I'm going to do full tune up and then report back... held back at the moment by some seized up tappet covers but I'll let you know if valves, points timing, and sync resolve this.

 

[doode]

Your bike will run like crap without correct exhaust and you're wasting time trying to remedy it other ways.

 

[alehman]

doode, I can't afford a new exhaust at the moment so I'm going to do what is in my power. Thanks for the advice.

 

[doode]

No harm getting the rest of the bike tip top, just don't want you to be disappointed if there isn't significant improvement

 

[76TWIN]

doode, I can't afford a new exhaust at the moment so I'm going to do what is in my power. Thanks for the advice.

make your own baffles

http://www.hondatwins.net/forums/8-pictures-videos/42872-76-cb500t-3.html#post785441