I have a Franken bike with a bored and stroked yamaha banshee 2t twin that I just recently put a 38mm cast smartcarb on. Took it out for its first real ride only to find its super rich. Burnt almost two full tanks in 50 km and couldn't get the bike to pull in anything but first gear. It would just bog out and sometimes die. Now i've searched the forum and read the posts and they don't always make sense. They say it needs to be broken in, some say it runs rich then cleans up when broken in. Others say that it richens up when it breaks in. Some are saying it's 100 clicks out on the rod and still rich, doesn't turning the rod out make it rich and in is lean? Should I give it a bit, or scrap the thing and get a lectron?
Smartcarbs
- Thread starter moparmadman40
- Start date
you have too rich of metering rod. the "clicks" only effect idel to 1/2 throttle. after that, its all rod. get a smaller size.
i'd love to see pics of this motor in bike. could be a blast!
I want to see this bike too! Would love to try out a well set up modded banshee snow bike.
Sweet! Why couldnt a second pipe go out the other side?
OK I would talk to smartcarb... Something to understand if you have great airflow in and exit it will increase how much fuel gets thrown into the engine... I have a cr500 ported and head cut for 100 octane.... I was running a q5 last year with a fmf fatty and stock airbox... This year went tss so got the new instake with a custom huge pipe.... Airflow through the roof... I added an egt... What I found is that I had to use a LEANER rod q11... Which is the stock rod. It made that big of a difference .... Now I have ran it since November in negative 10 to 40 degrees... From 5000 to 11000... I run 12's all day long... Keepbin mind I am about 100 clicks lean on this rod also... I find there is a small window of about 15 clicks on my bikes that give you the perfect set up. So once you get the top end dialed with the rod you use the idle and low end adjustment to fine tune..
What rod do you have in it?
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What rod do you have in it?
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It probably could have gotten twin carbs and pipes but the architecture of the bike would have needed to be changed. Airbox would have needed to go and the plastics would have been weird. Plus I would have needed to buy two carbs and two pipes to modify. The pipe is about 8 hours of work. And the bike width is getting a little wide with one pipe. If I had unlimited time and funds I think two D shaped expansion chambers back to back with a y rightr before the silencer would be neat.
It has the stock rod in it, I believe q11. Doesn't have any markings on it but the tip is 0.080 width
Plugs are very dark brown, like I said it runs good in the low to mid throttle. But is too rich and falls off the power band up top if you load up the machine at all. It will pull in all gears on the trail as long as you don't throttle it too much. Wondering if they lean out when they break in? I would have thought it would broken in with 4 hrs run time on this high volume and high vibration engine
Its not going to break in that much... I bet you with the 2 cylinders you have so much draw that it's flooding out.. They have a LEANER rod I would explain the problem and see what they have ... The advantage to a lectron is they have so many more rods to choose from and you can manually lean out the top end with the power jet...
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feeding the monster
keep in mind on a carb a quick open of the throttle on top end is ADDING A LOT OF AIR not gas, so if you have to creep the throttle open to make it run its likely toooo LEAN.
brown plug mean very little about top end not working, if its way rich / or lean you should have sooty plugs, black, once you let an engine come back down to idle and take a plug out ? top end running doesn't mean much to the naked eye when looking at plugs.
can you run the stock carbs and get an idea about how its can run ?
keep in mind on a carb a quick open of the throttle on top end is ADDING A LOT OF AIR not gas, so if you have to creep the throttle open to make it run its likely toooo LEAN.
brown plug mean very little about top end not working, if its way rich / or lean you should have sooty plugs, black, once you let an engine come back down to idle and take a plug out ? top end running doesn't mean much to the naked eye when looking at plugs.
can you run the stock carbs and get an idea about how its can run ?
I ran it with a mikuni flat slide when I first built it. Never got the jetting quite right up top. But I had a huge main jet in it to be on the safe side. It ran considerably better and would pull good in the first three gears but then fall off in the same fashion if you tried to go full throttle in a higher gear. This leads me to believe it is very rich with the smartcarb. I will probably put the mikuni back on until I can get some leaner rods.
Depends on the carb he is running... The smart carb even when he is drowning the top will still be dark brown... Its hard to get that regular carb sticky look... Does the bog at the top get better as you lean the rod or does it stay consistent...
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Seemed to be pretty consistent. Couldn't tune it out with the adjuster. I re-did the initial setup yesterday and the carb starts and runs great. Ended up at 57 clicks from full rich with zero lean bog when doing throttle chops. Runs better than any carb i've ever had. Just not when it counts
are you in soft snow when testing? my rotax bike will not run with pipe exposed to snow, i know the bike guys dont cover most of there pipes but it is a must for me. keep it in mind. cold pipe kills
No, was a fairly low snow day. Definitely too much load and not running right just pulls it out of the poweband
