right now i am in need of your collective wisdom, so bad.
i am in the process of fixing up a 79 CB650 and have run into a roadblock. it appears a bad mechanic happened to the carbs while the previous owner had them gone through (they are pretty clean), and in addition to such fun things as not having the main jets screwed in, the plastic piece that the choke cable hooks up to is broken off..i originally wanted to do pod filters on the bike, and with the pods i was able to take one off and choke the bike by pushing the butterfly up or down, and the bike ran fine, with the choke on, but when you let it off it swamps out, too much air. methinks.
sooo, i put the air box and stuff back on (best to have it stock) and now my problem is i cant start the bike, there is no way to choke it. so these are my three options, as i see it, feel free to add another.
1) buy the choke linkage and tear the known to be semi good carbs apart and reassembling them with the choke
2) go for a new carb rack which has all the necessary pieces, but may need to be cleaned or rebuilt
3) some other option, perhaps a 750 carb would fit this bike, i don't think it would, but my brother is convinced this is the way to go
thanks for all the help in advance
Ahhhh... and what a roadblock.
I happen to own a '79 and a '81cb650.
How about I give you my experiences with this bike and carbs....
I initially rebuilt the 650 carbs(pb50a i believe) and ran good.
90 mains...
tried using:
pods
almost every mainjet from 135 to 90.
modified intake filter cover
no air filter cover
(i regret it) drilled a set of '79 cb650 carbs.
new aftermarket accel and aircutoff diaphragms.
Several COMPLETE teardowns, and rebuilds of 2 sets of carbs
In general....
Pods with STOCK carbs... ok, as long as you don't put your feet in front of your motor(highway pegs) bogs then... but nice overall...(picky to jet right though 107.5's worked well for me)
I am running a set of carbs off a (?)'73 cb750 currently.
The gas milage I have been getting is pretty nice.
Actually better in town MPG than the stock cb650 carbs were by about 5-10MPG
At speed the best MPG has gone to just under 60mpg, the worst upper 46+MPG.
The max I ever got from the stock CB650 carbs was just under 67MPG, average 45+MPG
However, the 750 carbs are just more responsive(when synchronized well) and better at idle than the stock cb650 carbs.
The stock CB650 carbs gave ok acceleration, and IMO, the cb750 carbs pull harder.
And thats with the stock airfilter and cover.
When I abused my 650 (hard acceleration....) the mpg dropped to about 35mpg..
The 750 carbs....
I have yet to get less than 40MPG. No matter how hard or long I hammer it.
I love it.......
l8r
P.S. In your boots, knowing what I have tried, and what was horrid, and what hit the sweet spot....
I would either go with the 750 carbs or rebuild the stock carbs....both run well.
probably the 750 carbs..... get rid of the pullcable for a choke and go with the 750's side of the carb rack choke lever.
