hey all,
i did a muffler mod for my grizzly, to get more bottom end out of it. it was just the typical boring holes in the baffles, and opening up the exhaust exit hole.
here is what i have found.
1.) it runs too lean when doing this, and is real hard to dial in.
2.) gain in off the line power, but a major loss in top end.
3.) used to go 65, now maxed out at 55.
4.) 4 stroke engines are designed to use alot of back pressure to work properly.

1.) alot more off the line power.
2.) seemed to run alittle cooler, as long as i wasn't opening it up at high speeds, then it ran hotter.
3.) no replacement for designed aftermarket exhaust systems.

i did this to avoid the loudness and the cost of aftermarket exhaust systems, and the jetting and filter nedded to complete the upgrade. i have had a change of thought, and have now ordered a jet kit, air filter, and exhaust system. i want the hole package, and want it to be right.
i still recommend the exhaust mod though, if you just cant afford the upgrade power kit though, it has helped me climb, and get through stuff with more power than stock.


my pictures

 

Mich~

You'll be happy with the after market exhaust. If you don't like the loudness, you can always get a quiet core and start modifying that..I've actually got two quiet cores completely difference. 'Course I only ride with a quiet core in the woods, otherwise, it's the race core...far too much power increase.

SilverBear

 

hey silverbear,
i know you put on the jet kit, filter, and aftermarket exhaust. i bought the supertrapp exhaust, do to its adjustable plates, and previous experiances. what i am curious about it the total power gain you got from it?
after i put on my aftermarket tires, i lost ALOT of power. i did the exhaust mod, to get some back, but only to loose even more on top end. with the jet kit, filter,(leaving the air box in tact,) and the exhaust, will i feel a power increase over even stock?
my brother bought a new grizzly, and just spanked me in a race. i lost by 4 quad lenths, just by installing the new tires. have you lost top end? is your bottom end better than with stock tires and engine?
i have my quad in pieces on the garage floor, just waiting for parts, lol. i figure, while i'm there, i will also readjust my valves, having done it 15 hours ago.
Thanks, Ron


my pictures

 

Mich~

Total power gain, honestly I can't show you a dyno sheet and tell you...but I can tell you the company I bought it from dyno'd their quad, and they got 6 HP from the jet kit, K&N & HMF. It is substantial, and you do notice it....now I went alittle furthor and modified my airbox, so it's breathing alot easier as well..I have to suspect that has made a difference. For real world comparison purposes...when in was bone stock, it would run neck and neck with a SP700. When I put the 27" tires on, the SP700 would beat me in quickness...I don't really think you loose any top end with just the tires, you have to remember the speedo will be reading slower then your actual speed because you went up in size on the tires. After the pipe/jetting/airbox mods it would beat the SP700, and I know I gained top end as well, because I could pass the SP700 when he was WOT and maxed..'course with the top end rev limiter...I don't think you'd get a grizzly to go over 70mph no matter what you did to it...gonna have to remove that limiter to go faster, (should anyone actually want to on a 'ute)...so not counting the 686, with just the pipe/jets/airbox/27" tires...it gained back more than it was bone stock...you should be happy with the outcome. [img]i/expressions/face-icon-small-wink.gif[/img]

SilverBear

 

I did the muffler mod a while ago and I found that I lost about 6-7mph on the top end, but the lower end gains where great. My jetting was still pretty good after the mod, and heat and temp where never an issue.

This week I put on the High Lifter HP kit with the Supertrapp IDS-X, K&N, Dynojet kit, and NGK Iridium plug. It sounds great, and the low end power seems to be good....but I haven't really had the chance to fully test it. The sound is slightly louder then stock, but it is alot deeper and a nice rumble to it.

I am running a 155 main jet with the needle on 4th groove with stock airbox lid. I am debating going to a 160 main with a drilled airbox lid....but I am afraid of water getting into the airbox.

Good Luck,

Steve

http://www.angelfire.com/me4/grizzly