I was rejetting my Raptor because of the warmer weather using an EGT gauge and I installed Dynojet 148/150 main jets and set the needle to the first slot from the top.

I am running at 8500 feet above sea level and am using a foam filter with a Graydon aluminum airbox and a Graydon pipe.

At full throttle, I reached a maximum EGT temperature of 1420 F and a top speed of 71.4 MPH according to my GPS - not bad at 8500 feet above. The maximum exhaust temperature for a four stroke should be 1450 F.

I just wanted to post this information because I see many posts about jettting, and the EGT unit pretty much takes out all of the guessing in the jetting process.

 

Glad to hear it's working for your. Did you mount the probe in your head pipe our into the head?

 

Usually....the sensor itself is a restriction. Next, I have found aftermarket EGT guages too be very erratic and hard too jet by. For a stocker at your elevation, thats pretty fast. 70 on a quad feels like 100 don't it?Tell me about the racepak unit....if you don't mind. Welcome bro!

 

I have always been intrested in the EGT sensors, but like Gary said I don't want the restriction.

 

An EGT probe is hardly a restriction. The probe itself is 1/8" usually. The racepak EGT is an extremely high quality gauge for snowmobiles/atv's. It's meant to take a beating.

 

I have the Avenger II Racepak, and it is extremely accurate and consistent. I have a temperature probe in each exhaust header, and the Raptor runs like a beast; I have not noticed any restriction at all in the performance.

As I said before, the EGT is very accurate, but I do not set my jets in order to achieve the maximum temperature of 1450 degrees F. I set the maximum temperature at 1400 F in order to compensate for possible variation in my probe locations and for changes in temperature. Who wants to be changing jets all day.

I spent some money for the unit - 525.00, which included the probes, but the piece of mind was well worth the investment as well as the ability to jet the Raptor perfectly. Also, when I consider how much money I have spent so far on my Raptor, the investment was minimal.

When I compare my Raptor's jetting to the jetting of others in this forum, I have noticed that many people are running their Raptor too lean - and many people have told me that I am running "fat". My response is that the data speaks for itself, and that my Raptor climbs hills and tears up the trails like a "raped ape".

 

If you don't have that probe right in the center and not at the exact point of the hottest point of the exhaust flame.....you could be off a few hundred degrees. With that you could jet it one size too low and be lean and hotter than what your EGT is showing.

 

You are definitely right. The engineers at Racepack told me to place the probes three inches away from the exhaust flange. From their experience, this was the most accurate location in order to get the center point of the flame.

I still did a plug check in order to validate the system; the EGT should be used as a tool in conjunction with the other checks.

 

10-4 that.....don't want you cooking your motor [img]i/expressions/face-icon-small-smile.gif[/img]