I have a 2000 m750, which is carbureted. When I purchased it used, the airbox lid had been chopped and it had Conti Replica Trumpets. I recently installed a Quat-D Ex-Box and now the mixture is lean. (White spark plugs, "backfires" from exhaust when I chop the throttle, correct me if I'm wrong)
As I understand it, I have 2 options: 1) re-jet to increase fuel, or 2) restrict the air coming into the airbox.
Is there a reason I should pick one option over the other? Is there a better option I'm forgetting?
I'm hoping restricting the airbox, because it would be something I could do myself.
Quote from: cloud2blue on January 16, 2009, 07:06:39 PM
I have a 2000 m750, which is carbureted. When I purchased it used, the airbox lid had been chopped and it had Conti Replica Trumpets. I recently installed a Quat-D Ex-Box and now the mixture is lean. (White spark plugs, "backfires" from exhaust when I chop the throttle, correct me if I'm wrong)
As I understand it, I have 2 options: 1) re-jet to increase fuel, or 2) restrict the air coming into the airbox.
Is there a reason I should pick one option over the other? Is there a better option I'm forgetting?
I'm hoping restricting the airbox, because it would be something I could do myself.
Either way you are richening the mixture.
Restricting air to the airbox will reduce power...theoretically.
The more air you can ingest, the more fuel and more power. Less air = less fuel = less power.
I think the ratio is about 14:1, but tuning is usually done by feel and plug readings.
Quote from: Norm on January 17, 2009, 07:04:06 AM
The more air you can ingest, the more fuel and more power. Less air = less fuel = less power.
I think the ratio is about 14:1, but tuning is usually done by feel and plug readings.
Or a dyno with an A/F probe. ;)
Before re-jetting take a second look at the new exhaust I have had more than a few bikes come in with leaky exhausts backfiring up a storm.
Ideally you would get it dynoed after checking for leaks, checking air fuel ratios.
For a quick test throw a stock lid on and see how she runs.
With an open air box lid, you can take a roll of duct tape with you and add strips of it to cover the filter until you get the best throttle response. I usually do this before I start the plug reading process because unleaded fuels can be a pregnant dog to read.
Of course, I ain't got one of them new fangded dino units you speak of.
Norm
you don't always need a dyno but it sure speeds up the process.
I have seen bikes de-tuned because the dyno tuner tuned the bike to run great when sitting in a pressurized room. [laugh]