Need Advice PLEASE!

[tony97gt]

Okay, I'm looking for advice from anybody who has some mechanical expertise here. I recently purchased my first ATV last weekend, through Ebay. I bought a 2005 Polaris Sportsman 800, with approx 200 hours and 1800 miles. The bike has a full Muzzy exhaust, and a few other non-engine mods. The previous owner has the bike fully serviced to include a new belt and battery, a month before I bought it.

I took it for my first ride last Saturday and had no problems at all. The previous owner told me to make sure I run AV Gas (106) thru it, or it would spit/sputter. I don't have easy access to AV Gas, so I refueled with 92 octane after last week's ride. I went riding last night, and started to experience problems. When running wide-open, the bike would either misfire or skip. After about an hour or two of riding, I believe I hit the connector on the left handlebar which leads to the cut-off switch,because the bike died after I did a donut. After about 30 minutes of trying to diagnose the problem, I determined it was the loose connection and pushed it back in and the bike fired up. I continued riding and the bike would intermittently shut off. As I was rolling to a stop, I would mess with the wire and it would fire back up again.

After about 30 minutes of this, the bike started to bog down and shut off. I would let it sit for a few minutes, and then it would start again. As I continued riding, it got to the point where I couldn't go more than a few hundred feet without it bogging down. One time I was riding and when I went wide-open, it started to make a knocking noise. My buddy towed me back to our trucks, and when I tried to drive the bike onto the trailer, it wouldn't move. The bike would crank up, but the transmission wouldn't engage. The gearshift would move, and the indicator showed it in gear.

This is my first bike, and I need some help. Thanks.

[Bruce!]

First off, welcome to the board!

[4getful2]

you need to wait for some of the twin owners to chime in,but until they do. i am almost positive that your machine is not required to use AV. GAS. 87,even 89 should work.
you should take that connection apart that you messed with and clean it real good ,then use die-electric grease on the connectors. should look at other connectors too.

[tony97gt]

UPDATE- I took the belt cover off today. Old belt was wet, and had a chunk missing of about 3 teeth. Replaced that.
Took spark plugs out, the diodes were cracked and plugs looked bad.

My guess is the previous owner dumped the AV Gas in there to compensate for the reduced performance when adding the exhaust. The AV Gas runs much hotter, so it probably cooked the plugs which is why they looked like crap. This is probably why the bike would shut off once the plugs got nice and hot.

Going out for a ride in a bit to test it all out. Still think I will need to order the optimizer to compensate for the exhaust. I'm hoping that once I add the optimizer, it will compliment the exhaust and the bike should run great on regular fuel.

Thanks for your advice guys.

[chopper89]

Originally Posted by 4getful2

you need to wait for some of the twin owners to chime in,but until they do. i am almost positive that your machine is not required to use AV. GAS. 87,even 89 should work.
you should take that connection apart that you messed with and clean it real good ,then use die-electric grease on the connectors. should look at other connectors too.

4getful is right on the money and with what you said on your update i think your on the right track . your manual will tell you 87 octane is all you need.

[Spitfire79]

Originally Posted by tony97gt

UPDATE- I took the belt cover off today. Old belt was wet, and had a chunk missing of about 3 teeth. Replaced that.
Took spark plugs out, the diodes were cracked and plugs looked bad.

My guess is the previous owner dumped the AV Gas in there to compensate for the reduced performance when adding the exhaust. The AV Gas runs much hotter, so it probably cooked the plugs which is why they looked like crap. This is probably why the bike would shut off once the plugs got nice and hot.

Going out for a ride in a bit to test it all out. Still think I will need to order the optimizer to compensate for the exhaust. I'm hoping that once I add the optimizer, it will compliment the exhaust and the bike should run great on regular fuel.

Thanks for your advice guys.

AV Gas doesnt run hotter. The higher octane allows you to run advanced timing because the fuel burns slower. It also helps with increased compression to alleviate the issue of pre-ignition. Lower octane burns very quickly in comparison. Most machines ( sleds, quads, cars, etc) are designed to burn 87-89 octane. As performance mods are added, the need for higher octane is increased due to compression, timing advance, engine speed, etc. Most of the time premium, race or AV fuel is not necessary.

[tony97gt]

Spitfire, I was just going off what the mechanic at the shop was telling me about the AV Gas running hotter. I ran race fuel the other night, which I believe it 110 octane. It ran great on that stuff. No hesitation, no shutting down, and at WOT it didn't skip. Do you guys have any reccomendations for an optimizer? I'm think of ordering the power commander, found one new for $265. I like it over the HMF one because it is almost the same price, and you can adjust it on the laptop or by using the buttons on the unit itself. My problem is that I don't see a map on the dynojet website that would fit my needs, so for now I guess I would have to do it manually.

As far as the switch goes, we removed it, shot some brake parts cleaner in it, and reinserted it with some spark plug boot protectant to keep the moisture out. Worked fine on the ride the other night.

The new belt worked great too, along with the RTV sealant we used to help with the seal. After going through some deep water, there were no signs of any water in there from what I could "hear."

Thanks for your advice guys. Please respond with your thoughts on the power commander.

[Spitfire79]

No problem Tony. What can happen with AV gas or high octane fuel is that without advanced timing or higher compression to make use of the slower burning fuel, it can still be burning as it goes through the exhaust. This would raise your EGT ( Exhaust gas temp). If it runs bettter for you then maybe someone put in a timing key to advance the timing. You mentioned a knocking noise with lower octane fuel. This could be pre=ignition, where the fuel is self igniting from hot spots or detonation where the fuel is burning off too fast and its trying to push the piston down on the power stroke before its reached TDC.
Good luck

Jeff

[tony97gt]

Guys, I'm thinking of adding this optimizer from Muzzy. I want something that will be as close as possible to being tuned for my application, without having to pay someone to dyno it. I'm not trying to squeeze every hp out of it, just want it to run smooth. Power Commander was going ot be my first choice, but they don't have a map that is specific to my application. Advice?

ATV Digi-Tune Fuel Injection Controller

[tony97gt]

Found out on last nights ride that I have a small exhaust leak at the head, where the pipe bolts up to the head. I believe this is what was causing the knocking noise. As I was cruising at 30mph around 4500 rpm, the noise was getting progressively worse, and if I tried to add throttle, it started to cough and bog. Eventually I began to lose speed, the noise got louder, and performance declined. Luckily, I made it back to my truck and up on my trailer before it died. Further inspection revealed some soot on the top of the pipe where the leak is, and I could feel the exhaust spitting out from the leak. I called my local dealer to try and get a new gasket, but they said unless it is the same one as factory, they can't order it. So I emailed Muzzy and they said I need to get it from the dealer.