Honda Twins banner

1 - 5 of 5 Posts

·
Registered
Joined
·
40 Posts
Discussion Starter #1
73 CB350G. Stock except I just replaced mufflers with a common-motor set (Honda CB350 Mufflers | Common Motor Collective). Air filters are new and clean. New boots, no leaks there. Carbs cleaned...many times. Bench synced. Main jet is now at 110 and secondary main jet is 68 (one step down for both). Nothing else changed in the carb. Diaphragm in great shape. Float height at 26mm, at an angle, just touching the needle. New plugs, properly gapped. New coils, cables, points, condenser. Cam chain, valves, timing (static and strobe) all good. Compression good on both sides.

But since putting the new pipes on I'm running rich and even with idle air screw turned in to 1/4 it's still showing sooty. Starts easily, idles strong at 1200. When warmed up the idle sometimes drops and threatens to stall at lights.

Is it possible that I'm missing something or do I really have to rejet that far just with a muffler change?? Thanks
 

·
Registered
Joined
·
2,274 Posts
You have a carburetor problem. Did you use aftermarket kits when you rebuilt the carbs? are you positive that all the O-rings were installed? Are your carb boots sealing to the head and carbs? Sometimes the carbs will leak vacuum at the throttle shaft seals too.
TOOLS
 

·
Registered
Joined
·
40 Posts
Discussion Starter #3
Thanks TOOLS1. Yeah, aftermarket rebuild kit from 4into1 last year. Damn sure o-rings are all there. I might consider tearing it apart again though and putting the stock needles, emulsifiers etc back in just to see if that helps. Jetting kit was from common-motor, so not too worried about the jets. I kept the original floats as they were in great shape still with no leaks.
I've used WD40 to test for boot leaks...nothing there. I have not replaced the throttle shaft felt seals though...I'm not really looking forward to trying that though unless I have to.
 

·
Registered
Joined
·
40 Posts
Discussion Starter #4 (Edited)
UPDATE -
After reading other posts and giving it a good think I decided to put the original keihin bits back into the carb. When I bought it I figured while I was updating other stuff I'd be doing myself a favour by updating the "worn-out" carb with a rebuild kit. Been struggling to get the tuning right every since and figured it was part of my learning curve.
So side-by-side the rebuild jets look the same as the original ones as far as general shape. Looking closer the emulsifier tube hole sizes are DIFFERENT even though the labelled "size" on the jets are the same. Not sure why that is, but I swapped the originals back in and balanced and tuned up the carbs again to manual specs. She fired up nicely, ran her around town a bit and viola...nice beige plugs again. Lesson...new is not always better.
Thanks TOOLS1 for the help.
 

·
Premium Member
Joined
·
2,941 Posts
We've said it here MANY - MANY Times.
The ONLY reason to replace the Brass Parts (Float needle seats an exception) is "IF" the Previous Owner abused and buggered them up.
They are NOT a Wear Item.
Even the OEM Honda Kits don't include them.
The OEM Kits are O-Rings and Needle Seats ONLY.
 
1 - 5 of 5 Posts
Top