Too much air???
Feb 3, 2003 | 12:29 PM
#1
Thread Starter
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Pro Rider
Joined: Sep 2002
Posts: 1,205
Likes: 0
From: NL
Too much air???
I was out in the garage the other night, and out of curiosity I tried running my '98 450 Forman with K&N without the airbox lid installed. Well it idled OK, but was super boggy upon applying throttle. Is it possible that engine gets too much air???
Main reason for asking is that I plan on replacing my worn out muffler with a supertrapp IDS II, and adding a 2nd intake box snorkle (as someone else here has done) for better airflow. Would I need to change jets??? Is this why engine runs boggy when lid removed??
BTW: I don't ride with it off - too much water, dirt and debris, just a garage experiment.
Note: K&N filter is the only engine mod right now.
Main reason for asking is that I plan on replacing my worn out muffler with a supertrapp IDS II, and adding a 2nd intake box snorkle (as someone else here has done) for better airflow. Would I need to change jets??? Is this why engine runs boggy when lid removed??
BTW: I don't ride with it off - too much water, dirt and debris, just a garage experiment.
Note: K&N filter is the only engine mod right now.
Feb 3, 2003 | 01:22 PM
#2
Range Rover
Joined: Sep 2002
Posts: 114
Likes: 0
Too much air???
Yes you will have to rejet. Stock jetting on my 03 Foreman is #130, I am putting in a #140 Main, and raising the Jet Neddle clip to the 6th position. If you get two much air (expecially 20 degees F) air the quad will fall on its face, because it is running to lean. You could get the K&N power up kit which would address this, or just try the cheaper method like I am by experimenting with jets.
Feb 12, 2003 | 04:09 PM
#4
Trailblazer
Joined: Jan 2003
Posts: 90
Likes: 0
Too much air???
You'd better rejet, otherwise running too lean will burn your piston. The small amount of fuel in your combustion chamber actually cools the head. The generally accepted correct ratio of air to fuel is 14.7 to 1. That information is really irrelevant unless you have access to an exhaust gas analyzer. But, going too rich, or too lean, will affect performance.
In general, your too lean if pulling the choke helps. Too lean and you'll be able to idle and power will decline, with engine missing and back firing, the closer you get to full throttle.
Too rich, and you'll foul the plug and idle and low RPM will be compromised.
This lean condition will be more pronounced with your after market pipe installed. As exhaust capability increases, so too does the leaning affect on the fuel / air ratio as the engine's ability to asperate increases. Get the pipe, get the correct jets, and install to the pipe manufacturer's specs for your riding altitude range. Make sure your air filter element is clean and properly oiled before starting the rejetting process.
In general, your too lean if pulling the choke helps. Too lean and you'll be able to idle and power will decline, with engine missing and back firing, the closer you get to full throttle.
Too rich, and you'll foul the plug and idle and low RPM will be compromised.
This lean condition will be more pronounced with your after market pipe installed. As exhaust capability increases, so too does the leaning affect on the fuel / air ratio as the engine's ability to asperate increases. Get the pipe, get the correct jets, and install to the pipe manufacturer's specs for your riding altitude range. Make sure your air filter element is clean and properly oiled before starting the rejetting process.
