tech question conerning 01 m750

[Joshua]

I have an 01 m750 w/ arrow slip on's & open airbox. 
I am having a little bit of trouble in the 3-4000 rpm range. It is very sluggish and misfire's if I try and cruise in that range. sometime's, not all the time, as I accelarate through that range it does it also. I know for  a fact that she is running rich. is this a carb problem?

I also should mention that I do have a minor, minor oil leak at the base of vertical cylinder. it is the gasket on the back end of the engine. Could that be causing a loss of compression.

Other then in the 3-400range she really rides beautiful and I would like it if it was smooth all the way through. I do some city driving it it alsowas make's me dread going at a slow steady pace. any Advice will help. If it does turn out to be the carbs that would be an easy fix if it is because of the richness. I don't know. please help.....

[bigiain]

I have an 01 m750 w/ arrow slip on's & open airbox. 
I am having a little bit of trouble in the 3-4000 rpm range. It is very sluggish and misfire's if I try and cruise in that range. sometime's, not all the time, as I accelarate through that range it does it also. I know for  a fact that she is running rich. is this a carb problem?

Classic symptoms of worn needle jets. Lemme guess, you've got 20 or 30k miles or more on it?

I also should mention that I do have a minor, minor oil leak at the base of vertical cylinder. it is the gasket on the back end of the engine. Could that be causing a loss of compression.

Spectacularly unlikely.

If it does turn out to be the carbs that would be an easy fix if it is because of the richness. I don't know. please help.....

My '99 M750 gets like this every 50,000km or so (~30k miles) and a pair of needle jets ($25 ea from CA Cycleworks) and an afternoon fitting them (or a couple of hours at a workshop) will not only have it running sweet at 80kmh (~50mph) cruise, but it'll likely drop your fuel consumption by 20% or more (mine goes up to 6.5L/100km when it's bad and drops down near 5L/100km when it's running well - so from 36mpg up to 50mpg).

big

[Howie]

I would suspect your running problems are either from improper jetting or worn needle jets.  Partially cover your airbox or borrow an airbox cover and go for a ride.  If the bike runs better you need jetting.  Worse, you need needle jets.

Your leak is probably either the cylinder base gasket or the breather.  Clean the area well, ride, check.  Still can't tell where it is coming from?  Clean area well, spray with aerosol powder, ride, check.  The stain in the powder will point you towards the leak.  A base gasket leak  will not cause a loss of compression and repair can be delayed if the leak is not too bad

[Joshua]

Spectacularly unlikely.

My '99 M750 gets like this every 50,000km or so (~30k miles) and a pair of needle jets ($25 ea from CA Cycleworks) and an afternoon fitting them (or a couple of hours at a workshop) will not only have it running sweet at 80kmh (~50mph) cruise, but it'll likely drop your fuel consumption by 20% or more (mine goes up to 6.5L/100km when it's bad and drops down near 5L/100km when it's running well - so from 36mpg up to 50mpg).

big
[/quote]

I am only getting about 35 mpg which I know I can be doing better. I have about 15000 on it now. And I'm pretty sure that they are the original needle jets. I need to take them out and find out for sure though. I have taken them out before, the weren't exactly needle point on the tip. Should they be?

I would suspect your running problems are either from improper jetting or worn needle jets.  Partially cover your airbox or borrow an airbox cover and go for a ride.  If the bike runs better you need jetting.  Worse, you need needle jets.

Your leak is probably either the cylinder base gasket or the breather.  Clean the area well, ride, check.  Still can't tell where it is coming from?  Clean area well, spray with aerosol powder, ride, check.  The stain in the powder will point you towards the leak.  A base gasket leak  will not cause a loss of compression and repair can be delayed if the leak is not too bad

How would covering the airbox make it run better. Wouldn't that make it run richer?

i am positive that it is the base gasket. I cleaned it this weekend and none of the oil is from the crankcase breather. it is small and I don't seem to have low oil either. I'm hoping if I can be viligante about it I can keep it under control until the fall but I should take care of it as soon as possible.
one more question. Can you get away with replacing the gasket without removing the engine.

[bigiain]

I am only getting about 35 mpg which I know I can be doing better. I have about 15000 on it now. And I'm pretty sure that they are the original needle jets. I need to take them out and find out for sure though.

They'll be the problem for sure. FactoryPro (the jetkit manufacturer) say not to bother trying to tune a bike with more than 5000miles on the needle jets 'cause you'll never get it to work right. If I was you I'd just order a pair and stick them in (in fact, I'm gonna order a pair myself 'cause mines not running badly yet, but has dropped down over 6L/100km (~40mpg) which is a sure sign they're on the way out).

I have taken them out before, the weren't exactly needle point on the tip. Should they be?

Wrong end - you're talking about the needles, and no, they're not sharp at the tips. The needle _jets_ are the brass tubes those needles run in. You get at them from the opposite side of the carbs.

How would covering the airbox make it run better. Wouldn't that make it run richer?

Yep, he's suggesting that it might be running lean, in which case covering the airbox will richen it up enough so you notice it running better, but if it's already running rich, covering the airbox will confirm this by making it run worse.

Can you get away with replacing the gasket without removing the engine.

I've seen pics of it being done, but I've not done it myself so I'm not sure how fiddly it is... (Brad Black tells me you can replace the needle jets without removing the carbs, but I'm pretty sure that's impossible if you've got hands as big (and clumsy) as mine.)

big