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Discussion Starter #1
Has anyone experimented with a pyrometer to performance tune a quad, or even heard tail of such things. I'm not even sure if some ATV exhausts are big enough for the probe?
 

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sounds like decent idea but does how do you know what the proper temp. should be?? The probe has to be close to the exhaust port right??
 

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I have a 2002 sportsman 700 that I bought with a hydro locked motor (crankshaft is toast). I plan to up grade to an 800 crank and 12:1 pistons(i can save $200 on an 800 crank vs. 700). So now I wonder about the carb, I think I will start with a keihin 38 pwk, jet it rich, and use the pyrometer to help me jet it properly. As for proper temp, my research indicates that I should have temps. of around 200F at unloaded idle, and no more than 1400F for throttle full throttle under heavy load. I think I will jet it so the temp never exceeds 1200F, that way I have some cushion for changes in air temp and altitude. Any input would be very welcome as I am uncertain on several areas of this plan. Lastly the probe should be no more than 5 inches from the exhaust valve where possible.

Regards
James
 

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i dont know alot about exhaust temp gases on gasoline engines, but i think you would be better off using a wide band O2 sensor. that way you would get a reading of the exact air/fuel ratio and be able to make minor adjustments to the carb... with an O2 sensor know the exact number to shoot for instead of a range just my .02
 

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I do like the idea, but the size I don't, it would take up a large portion of the exhaust pipe. I am not aware of any O2 sensors small enough? Do they exist? I am familiar with how to read a pyrometer but not an O2 (something I would learn),would an O2 sensor give info too fast to read and comprehend? Sounds like I should do some research.

Thanks
James
 

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i am almost postive that hotseat performance makes an O2 sensor for atv exhaust and it comings with a digital screen for the reading so you can mount it where you want. basicly with a wide band O2 senosr it will be reading the air fuel/ratio...in a car the perfect air fuel/ratio is 14.7:1 at idle and from there it changes when wide open throdle 12.6:1 and decel conditions are met, i really think you would be happier with a wide O2 sensor based on the air/fuel ratio you can adjust and make it run perfect... im excited to here what you think, and yeah the reading is going to jump around but you will be able to see an average as you adjust the carb...
 

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Discussion Starter #7
I googled "atv o2 sensor gauge", narrowed the search to shopping and found some promising results, thank you for the heads up. It will be several weeks before I receive all the parts I have, and will be ordering.Then I'll have to install everything, but I will update everyone when its done.

P.S. Anyone have an opinion on dial-a-jet?

Regards
James
 

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All the wideband o2 use the same sensor, Bosch 5 wire heated. The difference is in the way each manufacturer analyze's the info from the sensor. I personally use the innovate lm-1 digital wideband and it works awesome. Just have to weld on a bung into the exhaust and sample away...As far as I know they don't make a atv specific one, but they work for all engines...
 

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You should be able to get an EGT setup for a quad. Digatronusa.com is a great company to work with. You can lean out the jetting efficiently and safely by watching your egts. A budy of mine used a dialjet and really liked it.
 

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Discussion Starter #10
I was at my local small engine machine shop today and was talking with the boys. They have and build drag race sleds. They have installed O2s and pyros for customers and their own machines as well as the shop race sleds. They said the O2s are more expensive and more accurate, but not so good on 2 strokes (they fowl to easy even with the adapter). On their race sled (2 stroke)they use a pyro and a dial-a-jet and are very please with the setup. The pyro probe is only an eighth of an inch thick so does not obstruct the exhaust much, so I will put the pyro + dial-a-jet a my 88 250 trail boss 4x2 (cyclone cylinder jug, keihin 38 pwk, aaen exhaust) and an O2 + dial-a-jet on my 02 sportsman 4x4.

Regards
James
 

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I would use a wideband before a pyro for tuning 4 stroke engines, especially if you can't adjust your timing. The wideband will tell you the ratio your at and you can advance or retard your timing to get the correct temperature of exhaust your aiming for...I think pyro is a great secondary tuning aid after wideband..
 

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perfect! i agree 2 stroke=pyrometer, 4 stroke=O2 sensor i like that idea sounds like you found a good shop for the little tips and mainly they have had experience with them! good luck and let us know how the tuning goes...
 

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I use a wideband on my tunes. Works great, I put the sensor in the muffler clean out plug. You can really make some big power.
 

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Discussion Starter #14
Thanks for the input 821, I know 14.7-1 is the ideal ratio for a clean burn, fuel economy and emissions but what do you find makes power?
Regards
James
 

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Thanks for the input 821, I know 14.7-1 is the ideal ratio for a clean burn, fuel economy and emissions but what do you find makes power?
Regards
James
Thats true for idle conditions in a vehichle with emissions. I personally have my idle set at 13.9-1 and approx. 12.5-1 for WOT. Normally around high 12's to low 13's for part throttle running.. Although to make peak power, every engine will like a little different ratio depending on alot of things like compression, camshaft, quench, plug heat range etc...
 

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Thanks for the input 821, I know 14.7-1 is the ideal ratio for a clean burn, fuel economy and emissions but what do you find makes power?
Regards
James
Thats true for idle conditions in a vehichle with emissions. I personally have my idle set at 13.9-1 and approx. 12.5-1 for WOT. Normally around high 12's to low 13's for part throttle running.. Although to make peak power, every engine will like a little different ratio depending on alot of things like compression, camshaft, quench, plug heat range etc...
Yeah I second that, I'm running about 13.2 WOT and mid 13's crusie. 14.7 idle.:veryhappy:
 

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Thanks for the input 821, I know 14.7-1 is the ideal ratio for a clean burn, fuel economy and emissions but what do you find makes power?
Regards
James
Thats true for idle conditions in a vehichle with emissions. I personally have my idle set at 13.9-1 and approx. 12.5-1 for WOT. Normally around high 12's to low 13's for part throttle running.. Although to make peak power, every engine will like a little different ratio depending on alot of things like compression, camshaft, quench, plug heat range etc...
Yeah I second that, I'm running about 13.2 WOT and mid 13's crusie. 14.7 idle.:veryhappy:

I think you could pick up some more power if you richen up a bit at each level....
 
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