OK guys I need some input. I am fairly good at tuning and always use the plug reading. I have used AMSOIL and swear by it but all the times I tuned was before I switch the machine to AMSOIL. So my problem is I recently installed a UFO (Ultimate Flow Optimizer) in a friends 400 Sport and am in the process of doing the fine tuning. The problem is AMSOIL burns so clean I can't get a good plug reading. It is still oil injected, so it is still 50:1 at full throttle and 100:1 at idle. I have used 6 different jet sizes 230, 240, 250, 260, 300, and 320. All 6 plugs look identical. Finally at 320 the machine did not rev cleanly (just like the "big carb" theory on cars). I believe I will be safe at a 250, what do all of you think? Anyone out ever install a UFO on a stock machine?

By the way it was about 55 degrees when tested and we experience temp ranges from -10 to 90.

 

Where are you taking your readings on the plug? With a fresh plug; you should ride the bike for a couple of miles to start getting some color on the plug. This will also get the bike up to operating temps. It's not the clean burning oil that colors your plug so much as the actual fuel/air mixture. Beware of those UFO's. I had terrible jetting problems running these on stock machines. Many people have burnt their pistons down trying to jet the machine with a UFO. The gains aren't worth it. A three cylindered sled with 800cc gained 3-5 h.p. using three UFO's. I don't think we stand to gain much with one. The sled magazines reviewed this product with mixed feelings about it's use. One magazine suggested only the most experienced tuners should try the UFO's.

 

Fasterthangas,
I am glad for your reply, you have done serious mods to your quad and I like to hear your opinions.

I am taking the readings on the plug at the outer electrode like you should on a ES plug. I am getting the unit up to operating temps before I make my actual full throttle runs. I do know that the color comes from the air/fuel mixture, but when running an oil that burns very clean it will cause the color to change slighlty. Another reason it may be hard to read is the cleaner burning the fuel is the less deposits that are made. Tear down identical machines, one that has been run on conventional oil, one that has been run on synthetic oil. The one on synthetic will look like it has hardly ever been run. As far as worrying about the UFO's, I love them. They are one of my biggest sellers for Snowmobiles and ATV's. I have personnally installed 3 of them (and know of many others in various machines) and have not had one problem.

 

There's definately a cleaner throttle response from the UFO's. I dislike the leaning out of the bottom end.
Try reading your plugs on the center porcelain. The farther down in that you read the higher the throttle opening. All the way down the white porcelain is wide open. The outer electrode readings work great for race fuel. This is the "old way" of reading a plug, but it has worked flawlessly for me. Now alcohol; that's a different story...

 

I also watch the center electrode when I tune. The plug has never lied to me either.

 

OK one out of several UFOs finally is giving me problems. Fasterthangas, I think you jinxed me, LOL. I ran a 290 for about 20 minutes (at all throttle positions) and it was a little rich. so going with my first instinct I went with the 250 and it read "on the edge". So I decided instead of burning down my friends machine I would go with the 290. I thought of playing with 260, 270, and 280s, but winter is soon to be here and it will be about 40 degrees cooler soon. So I reinstalled the 290 ran it for about 20 mins again and now the dang thing looks like the 250. I don't think the tuning gods are on my side today.

 

Been there; done that! The Polaris is quite different than anything I've ever tuned. I now rely on an EGT guage and plug readings for accuracy. The EGT is a must. Good luck!

 

uflg95,

When I installed the UFO in Celeste's Trailblazer, I only went up one jet size on the main and had to go down on the pilot jet by 1/2. (i.e. 40 to a 20) It's my understanding that the UFO doesn't affect the throttle in the wide open position, but it does affect it every where else. Fasterthangas is right though, to do a proper reading you'll need a EGT.

 

Fasterthangas and Mike,

1)Which is the best EGT for the money, and what temps should I look for in the different ranges? Thanks.

uflg95,

I have read about jetting with amsoil, and it is harder, due to the burning charactaristics (from what I read). This one guy had his bike jetted correctly, then changed to amsoil, and freaked out due to the plug being white. He went up several jet sizes, and even though the bike was obviously running very rich (blubbering), the plug still showed white. So, he went back to the main jet he had used with the other oil, and no problems. He attributed it to the amsoil. The place you may want to look is at www.macdizzy.com, on the message board. I don't know the full link, as the message board (forum) has been down lately. It would be under the "250R engine" folder. Those guys with geared machines have an easier time jetting, in my opinion, since they are not dealing with the CVT. Unless you want to use an EGT to jet it properly, you may want to change oils to the polaris petroleum....just for jetting.

2)I've also got a question for all: I took the stock piston out of my xplorer after about 10 tanks of gas or so, and it had about 1/16" of carbon over the entire surface of the piston. What does the carbon buildup mean? I had been running the Polaris Gold Synthetic oil, and 87 octane gas.

Waylan

 

walexa,

I'd go with HPD. They have forgotten more on the subject of tuning Polaris machines than just about all of us will ever know. They make a really good EGT kit.