I added a SBP expansion chamber, "Speed carb", and 36T sprocket to my bike. Something's going wrong with the carb. It takes way longer than it used to to start the engine. It bogs for a super long time whenever I hit the gas and as soon as I let go I can feel the bike accelerate. After it gets started and I pull the clutch in the engine revs to infinity. Anyone know what's up?
Upgrades fail - carb
- Thread starter ZRTMWA
- Start date
I see where you're coming from but I know it's the carb that's causing the problem though. When I switched from the standard NT carb to the new "speed" carb, I did just unscrew the top from the old carb and transferred all the parts you see here: http://motorbicycling.com/attachmen...le-carburetor-install-rebuild-carbpict004.jpg
from the old carb to new carb. They looked exactly the same and it saved me the trouble of reinstalling the clutch cable. Maybe they weren't interchangeable though. I'll try switching th old carb parts back tomorrow.
from the old carb to new carb. They looked exactly the same and it saved me the trouble of reinstalling the clutch cable. Maybe they weren't interchangeable though. I'll try switching th old carb parts back tomorrow.
I have the speed carb. I had to use teflon tape and grey gasket to seal the carb on the intake manifold. The slots on the carb opening were causing an air leak. It took me awhile to get it right, I put grey gasket sealer both on the end of the intake, and closed off all the gaps in the carb opening. I'd want to rule out air leak.
I thought that I read on here somewhere that the speed carb is more prone to that.
I thought that I read on here somewhere that the speed carb is more prone to that.
ZRTMWA, I fiddled a bit swapping parts between the two, as I recall there is a slight difference in needle taper (very slight & that'd prolly be ok) and I don't really remember - but I think one of the two slides was jus' a hair too big for the other carb body (take the NT body and see if the Speed slide will fit)... but I might be wrong on that, I've been messing with waaaay too many carbys of late lol
It's easy 'nuff to switch back to the original body for a quick test run, even the smallest of changes to the carby can alter performance - if the slide is a lil too small, that'd wack it out fosho *shrug*
It's easy 'nuff to switch back to the original body for a quick test run, even the smallest of changes to the carby can alter performance - if the slide is a lil too small, that'd wack it out fosho *shrug*
I finally got around to looking at these. Within 10 seconds of eyeballing the carb internals, I could tell for sure that these needles are NOT interchangeable. As BarelyAwake said, the tapers at the end of the needle are different. But more importantly, the stock needle is about 1/8" longer than the NT carb needle. the springs seemed a little bit different but they are probably switchable. I'm in the process of switching the NT parts back now. Hopefully this gets the bike running.
Well I switched the whole assembly back and it works fine. The clamp that comes with the carb (to connect it to the intake) is absolutely horrid. It has this lock nut thing so that you can only use a Phillips head screwdriver to tighten it. It came loose after only a few miles of riding. I'll probably put the stock carb clamp onto this carb so that I can tighten it with a wrench.
