Hello one more time....Well, the Mikuni carb situation is DOA. We finally found out what the problem is, and it seems that it can't be addressed (not without a series of modifications taking place that aren't worth it). The Mikuni round slides (VM26) will not work well when bolted to the engine as the original Keihin's are -- they do not give the gasoline enough space to atomise. The only solution is to move the carbs further away from the engine to give the gas more space, but it can't be done because the darned petcock is in the way. I think if you could either relocate the petcock or use a different gas tank this would be possible, but under a stock configuration it can't be done. If I'm wrong and someone knows a solution, please share it!
So, it's back to the stock carbs, which seem to run fine anyhow. Look for a nice new (relatively) set of 26mm Mikuni's with accessories on eBay soon, I suppose.
Mikuni CarbsHi Vince,
curious, what did you not like with the Keihin carbs? is this the brand that is stock on these bikes? Is it possible to get new ones for a CB77? I forsee carb troubles with my current (and first) rebuild. I would love to have a new carb option for this bike. I don;t really care for correctness, I only want to ride it. Anyone? David
Mikuni Carbs UpdateWell, there wasn't anything that I didn't like about them, but they are 40 years old and worn. The bike had a hard time holding its idle, and though the mechanical advance was replaced, it would still do it from time to time. There is a rebuild kit in them, but there's play in the slides, etc. The Mikuni solution was to update to something new, plus the reliability of Mikuni's. They would work, but you'd have to use a different gas tank and have the carbs further away from the head rather than bolting them directly on. I still have them, by the way, plus the custom-made mounting flanges, extra jets, slides, etc. The original Keihin's are back on, and the bike seems to be running fine. As far as 'new' carbs go, good luck trying to find a set of NOS Keihins....I don't believe current brand new ones would work, unless someone out there has info to the contrary.
Hi
Don't know if its of use but here in the UK the recommendation from one of the bike mags back in '69 was to use Amal Concentric carbs on tuned CB77s. The Triumph Trident used 26mm handed carbs and the stud spacing is the same as the original Keihins, so if you feel the need to replace the originals you could go that way. Concentrics are still in production and all parts inc jets, slides etc are available. cheers Phil
Mikuni Carbs are Now Amals!Hello Once Again -- Out of frustration with the worn out Keihins, my mechanic took a pair of brand new Amal 626's meant for a 500 Triumph and installed them on the beast. And you know, the thing ran great! Idles fine, good power, no pipping or popping and you can rev the heck out of it. The only thing they did was remove the choke from the carbs, as they were deemed unnecessary. Just tickle the carbs and fire it up! I'll be picking up the bike today, so I'll post specific numbers and maybe some photos when I get it. The only number I know right now is a 160 main, which they initially thought was too fat, but the plugs have a nice tan colour, and there's only a bit of a 'cough' in 2nd gear right at the top (redline) but it doesn't happen in 4th, so they're going to leave it for now. So there you go -- there is life after Keihin after all! If you need more info or want a set of 626's from the proverbial 'horse's mouth', you can call Wolf Cycles at (410) 247-7420. Hooray!
Mikuni Carbs are Now Amals!Here we are again....
Picked the bike up today and took 'er for a ride. Runs fantastic! The throttle is heavier due to the stiff springs in the carbs, but WOW! The one thing is that these carbs don't like to be snapped, but prefer to be 'rolled' on. As well, these carbs have had their chokes removed, but they can be reinstalled if needed, but my mechanics determined that I don't need them. Here are the numbers as they came out of the box: Amal 626 (26mm), 160 main, cutaway throttle valve 3, 106 Pilot, standard Amal needle. They mount up with no problems as you can see, and look totally appropriate on the bike. Cold starting requires that you 'prime' each side using the plunger located on each carb...just keep pumping until you see gas coming out of them. Crack the throttle slightly, hit the start button and there you go. So, for those of you who are tired of your worn out Keihins and aren't concerned about OEM carbs, these babies are the ticket! Thanks to Phil in the UK for the suggestion!
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