Running Lean again

[bandit ed]

Need some info anyone can help. A little history first. Purchase a 2006 1200 bandit well working in Edmonton Alberta. Have the bike now in Windsor Ont. It need to be rejet and dyno since the sea level elevation is different. Note: has a K & N filter and also change out muffler complete) The bike was running to lean here. After the rejet and dyno the bike ran fine. A few wks later it was running to lean again. Had to raise the needle jet 2 notchs ran fine again for about 700k's. Then it start running to lean again. Anyone have and ideas what is causing this and also what should the temp of this bike be running at???

[Red01]

Given your description, it sound like you have a vacuum leak that is getting worse.

[bandit ed]

I will let them know tomorrow. Will put it back on the dyno to make sure of things. Where would the vacum leak possibly be at??

[pmackie]

Somewhere between the carb inlet and the inlet valve in the head.

Most likely, (in no particular order)
a) the carb boots that the carbs fit into, (carb to intake manifold)
b) the connection between the intake manifold and the head,
c) a vacuum hose connected to the carb (I would start here first)

This generation of Bandit (2nd gen, oil/air cooled) tended to work better with a STOCK air filter. Lots of guys have had problems getting consistent performance using a K&N filter, but OTOH some people don't have problems.

I would buy a stock air filter, and look for vacuum hose problems first, then move on to inspecting the carb/intake manifolds.

[bandit ed]

Thank you for the help. Had the bike on a dyno yesterday and found out as I thought the # 3 cyclinder is running hot. Did  a compression check and all cyclinders are good. At least this rule out the motor its self. Will start looking for a vacum leak.

[bandit ed]

Is it possible that I could be having a problem with the igintion to case the over heat on the one exhaust????

[pmackie]

Not likely it's an ignition problem on only one cylinder, as the coils are shared between cylinders, and you can't advance the timing on one cylinder only. More likely, cylinder #3 is running lean. Look for your air leak here, but maybe you have a plugged jet in this one carb? I would suggest you remove, inspect and clean the carbs.