My new carbs are running too lean????

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BananaKatana · Wed Jul 11, 2007 1:26 pm

Hi guys,
Finally got a new-er set of carbs for my 93' katana, the donor bike being a 2002 katana. The new set had been sitting for a while, but cleaned up just fine and I did not see any potential problems inside or out. Once I got them, I cleaned them all out carefully, modified the choke and throttle cables to fit on my bike, and slapped them on, making all the necessary adjustments for everything to work correctly.

Whats Happening:
The bike will start up and hold a rough idle, but after 4k RPMs it backfires a big flame out the tailpipe and dies. After some careful checking of the jets and diaphrams and things of the nature, and letting it run for a while to blow out some of the gunk, I still get the same reaction when I rev it up. It's also running very hot, I could even see the tip of the tailpipe getting darker from the heat after about 10 minutes of running (a first for this bike).

The queery:
The bike seems like it's running very lean, but where the adjustment needles were on my old carbs, now there is nothing. When I turn the choke up the bike seems to be able to breath better and will let me rev it a little more. There seems to be no way to tweak these carburetors as far as fuel adjustments. Any ideas as to whats slowing me down here??
Thanks , Sam

thespirit · #2 Unread post by **thespirit** » Wed Jul 11, 2007 3:15 pm

You will probably have to rejet the carbs, meaning you will have to buy new jets to put in it. Check the spark plugs and see what they look like. If they are really white, then you need to go up in jet size, if they are black you need to go smaller in jet size.

You may have to shim the needle if it's not adjustable to tweak your mid range.

BananaKatana · Wed Jul 11, 2007 3:32 pm

I checked the plugs after the intial start up with the new carbs, they were pretty dark but I wouldn't call them fouled. I cleaned them off (I got them to look 90% new), reset the gap to about .030 and put them back in and it made no difference. They're pretty new, but still I planned to replace them anyways because of the previous carb problems stinkin them up.

As far as the jets go, I did notice what looked like very light corrosion on them, but they still passed my inspection...but then again im no "expert".
Thanks for the advice, Sam