Power Issues

[MadMudder]

Hey guys I got another question about my bike. Its a suzuki 250 quadrunner and im getting some new tires for it soon. There 26x12x10 mudbugs. I currently have 25x11x10 mudlites. What I want to know is this. I ride mud allot and I want a little more power to turn the tires without worry. I dont have a problem with my mudlites but the mudbugs are more aggressive and im sure weigh more. The tread is also allot bigger and they are an inch wider. So what can I do without going overboard to get a little more power. The engine has over 3,000 miles on it but it runs good. I dont have the cheese to spend on a slip on exhaust and nobody makes one for my bike. I was thinking mabye a jet kit or something like that? Im not sure so thats why im asking you guys. Thanks

[MedicMudder]

Set it fire,It will go fast then!!!! LOL     Ha Ha ....    DAD!!!

[jayman]

I just put a DG Accellator exhaust, ltz400 foam filter and jetted my sons ltz250 quadrunner and that made a big difference.  I know you said you do not have the coin but I got the full exhaust off from ebay for like $100.00.  The guy sells them on there all of the time.  The filter kit cost me $85.00 and the jets were like $2.00

[Toomey]

So you want to increase the power with just jetting, no pipe or anything.  Here's what I can think of with jetting for mudding with big tires.

Well, the more load you put on an engine, the leaner it's gonna run, so you need to richen up the jetting to make it run well under load.  It works like this...

You've got the throttle pegged all the way open, and the engine is turning low RPMs because of the high load, being deep in the mud for example.  The cylinder is filling more completely with air, because there is a lot of time for it to fill (low RPMs) and plenty of air supply (wide open throttle).  So now you've got more air in the cylinder (with same jets in the carb), causing a lean condition.  On top of that, since there's so much air supply to the slow moving engine, there's much less vacuum or "suck" in the intake.  The air is kinda just strolling along through the intake.  Opposite holds true for when you're blasting along and shut the throttle, that's really high vacuum because you're got high RPMs and not much air supply.  Carbs work using this suck to pull gas up through the jets and into the intake.  The more suck, the more gas you can get out of the same size jet.  Since this is going to be a very low suck/vacuum condition (wide open in the mud), you'll need bigger jets to supply more gas with less vacuum pulling that gas. 

This really doesn't matter too much, just kinda the theory behind it all.  If you jet correctly for serious mudding, on a machine that's jetted on the lean side for trail riding to start with from the factory, then you could get an extra horsepower or two while in the mud, and the machine will run a little cooler too because of the extra fuel. 

I don't know what sizes you need to increase to, and I'm sure it's a pain to access the carb on a utility bike, but maybe hit up some mudding forums and ask.