I was wondering what you recomend i should do to see how my bike is running. Should i just put a new spark plug in it and ride it for awhile, then pull it to see what it looks like? Or should i put the plug in it, run it wide open till top speed ,then shut it off while its wide open and then pull the plug? Thanks for the help.




Nez

 

run it 1/4 then check it and then 1/2,3/4 and wot

 

And use the kill switch to shut it off

 

What kind of quad are you working on ?


Plug checking is highly over rated . So many other things are better tell tale signs of richness or leanness than looking at sparkplugs .

If a quad is deadly lean you will destroy the engine before looking at the sparkplug color will ever let you know you have a problem .

Rick

 

i was also wondering this. i have a 250 trailblazer. how should i go about checking for richness and leaness?

 

Rick tell your thoughts on this subject.

 

Thanks for the fast responses everyone. Its a 2003 polaris scrambler 500. I have a Pro-Circuit t4 full system on it and a kn fileter with kn precharger. Its still the stock jetting and i think amazingly, its running rich (theres tons of carbon build up in the tip of the pipe). I have a hpd air box lid on the way. I was just wanting to know how to check that plug to see if it was black, tan, or white. The bike seems to run great with the new pipe and the stock jet. The jet is a .155.




Thanks for the help,


Nez

 

I wouldn worry to much if you have the HPD air box/carb mod coming. It will bump you up to a 170 main jet and a few other things to get the carb right. Run it for a little bit. If it seems to be running fine at all throttle positions, then just pull to plug and look for a nice tan color

 

So instead of leaving us hanging on the "right" way to setup hows about telling us how we're supposed to do it? Not quite right to come in and tell someone they're doing it all wrong, but leave keeping them in the dark.....

 

I always start out with a 2-stroke set at settings that will make the bike run to rich as a starting point . Then as needed I start taking fuel away small adjustments at a time . Modified Polaris 2 strokers can be very finicky. The quarter and half throttle tests are fine , but equally important is the amount of RPM the engine is turning at these different throttle settings .

For example , and , I am tossing out numbers just for example .

At 3500 RPM the engine may only be able to handle a fuel to air ratio of 16-1.

At 6000 RPM the engine may want a ratio of 14-1.

The problem is the carburetor has no idea the wants of the engine , fuel injection takes into concideration the engine RPM and can be programed to deliver the right amount of fuel not only by throttle opening but by monitoring RPM as well .

NOW , couple this problem with a clutch kit and extra horse power .

To cruise at 35 mph the clutch kit has the motor singing allong at 6000 or so RPM , the modified engine can do this with ease , to maintain this speed the rider doesn't have to apply much throttle at all . The thumb throttle is at a low opening and if the needle is not set properly (about as rich as you can get it and still keep the bike from not stumbling off of the bottom) the quad can lean right out at a cruise and burn itself up .
A normal shifter bike doen't have this problem as much because most riders would have shifted into a higher gear , loaded the engine more , and applied more throttle .

If I had two identical modified polaris 400's , one to be used for running in the desert , one to be used for playing in tight woods I would have different settings on each machine , the desert bike would be up higher in the RPM band more of the time and requiring more fuel than the woods quad . If we took this quad in the tight woods it is likely it would begining to load up and stumble in the woods and require me to reset the needle most likely to cut some fuel back so that its lower apetitie for fuel due to the lower RPM it is at in the woods as a general rule .

If we took the properly jetted woods bike to the desert , it would run fantastic , BUT , we would possibly be at risk for seizure due to the rider being able to stay up higher in the higher RPM while the needle setting was in a position not to flood the motor in the woods where you are on and off the throttle.

I would recommend one learns to tune the carburetor by cause and effect by understanding what a rich bike feels like and sounds like and run your quad by setting the carb so that you are just below the *to rich* threshhold . The area you ride in and the way you ride will have an effect on where this point is , it varys .

Try this method I have prescribed and when you are able to do this , your sparkplugs will be the right color .

Rick