Rebuilt engine only firing on one side

[stelrad]

Thinking about it logically it has to be the float height. The carb kits had new float valves and needles which I fitted and measured the float height to be around 26mm. However the CB77 should be 22.5mm. The petrol in the float bowl must therefore be around 4mm lower than it should be which means that the bottom of the main jet is probably not even in any fuel ? (not sure why the right hand carb works though - probably right on the edge).

I'll double check both carbs when it stops raining.

I live in Hull by the way. Normally go to Cala D'or twice a year

[stelrad]

Still no joy. In desperation I've bought another pair of carbs from Ebay - should be here in about 10 days. Was tempted to buy a pair of Amal Concentrics but didn't want to upset LM.

[Phil-UK]

Hi Stelrad,

Good job I wasn't bidding against you for the carbs on ebay ( the one with bits from 3 ? ).

When you swapped the carbs over did you connect the fuel lines onto the same ( i.e. original )
outlets on the fuel taps ?
Was thinking that if you had then maybe the problem lies in the fuel tap not letting fuel thru equally for both outlets. My CB72 used to do that when the petseal I had used was breaking up and I'd have to clean out the tap.

The other thing is that spraying carb cleaner thru the drillways etc is definitely NOT as effective as a high pressure airline. I recently went through similar messing about with my carbs and despite checking everything was clear with carb cleaner, when I used an airline at 40psi+ some crap came out.

Finally, Steve said the datum point for checking float level is the edge of the carb body and not the recess; I have an old Motorcycle Mechanics showing Alf Briggs of Honda UK using a metal plate like the one in the diagram and its sat on the recess. Mind you maybe it has been made to allow for the difference between the two ( @1.5mm ) either way you measure it the engine should still have been OK.

Keep an eye on Maplins & Aldi as they sometimes sell ultrasonic cleaners for @£20 that you could just fit the catb body into and really clean the thing out !

good luck

Phil

[e3steve]

Absolutely right on the button with that observation, Phil, and to clarify my intention I should have elaborated by stating that I did add the lip to the card gauge that I cut out. As you see from the Honda/Silver line drawing, measurement 'h' is taken from the lip, not from the recess. Now, this is not the easiest of setup procedures to carry out without 1.5 pairs of hands, or 3, whichever is the greater; it's even more difficult if you have to judge the lip/recess shortfall.

Make the gauge 'legs' a little longer, was the answer. Sorry. Shoulda pointed that out!

All that behind us, we still ain't sorted stelrad's problem. With the floats floating at the required height, the only possibilities I can think of are fuel starvation (as you've mentioned by suggesting flipping the supply lines) or obstructions/water within the drillways. Carb cleaner or WD40 will displace any water; methinks a good blast with an air nozzle is in order.

[stelrad]

Thanks for the ongoing help. Just double checked the flow from the petcock to each carb and that seems OK. Also checked the fine mesh filter in the banjo on each carb and they where OK as well.
Double checked the timimg etc just to make sure. Can still re-create the problem by swapping the carbs over ie right cyclinder OK left not firing unless fully choked. Swap carbs over - left cylinder now firing OK but right not unless fully choked. I'll give the carb a good blast through with compressed air this weekend. New carbs where bought on Ebay from the states - should be here in about ten days hopefully. At least I'll have another carb to try.

[LOUD MOUSE]

Remove the screen from the bango bolts.
HONDA discontinued it in 1967. ..............lm

Thanks for the ongoing help. Just double checked the flow from the petcock to each carb and that seems OK. Also checked the fine mesh filter in the banjo on each carb and they where OK as well.
Double checked the timimg etc just to make sure. Can still re-create the problem by swapping the carbs over ie right cyclinder OK left not firing unless fully choked. Swap carbs over - left cylinder now firing OK but right not unless fully choked. I'll give the carb a good blast through with compressed air this weekend. New carbs where bought on Ebay from the states - should be here in about ten days hopefully. At least I'll have another carb to try.

[e3steve]

Good evening Meester Moore, we've been expecting you!

"You eckshpect me to talk, Goldfinger?"

"Ha ha, nooooo, Meester Moore, I expect you to die!"