I dont THINK its just me...but my ds seems to run the fan ALL THE TIME. I just got back from a trip to Colorado/Wyoming/and Utah (lil sahara) and i was for sure running really FAT, and even running with probably 75% HP of what i should have it still got really hot.

One of the people i sometimes ride with (the father of a few riding buddies) has a used DS that also runs the fan a lot[he has no engine mods on the quad and ran stock jetting so he went from 800ft to around 5k-9k feet and his fan was still on a lot as well.
Ive never really run with many other DS's before so i dont know if most of them are like this or if i have a problem.

With my DS running pretty accurate jetting, a billet aluminum inline water cooler, 60/40 water/coolant, water wetter, and 10w40 valoline oil my fan seems to run quite often(engine mods are listed in my profile if that makes any difference)

i have also noticed (might be that im just noticing it more now that im paying attention...) but i seem to feel a lot of heat coming from the engine/headers on my leg (almost really cant wear shorts as it is so hot)

i dont want to run rich all the time as running that rich obviously kills some power, but i also dont want my engine to burn up or overheat.

what does the engine do when it over heats? shuts down? i have noticed a few times the ds will just quit all of a sudden and the tach will jump to like 9k (engine dosnt rev up but the needle goes up and i cant start it till i turn the key on/off again)

let me know how often your fans run. (either im paranoid or my engine is running hot lol)

 

I ride with lots of DS's and even some Baja X's and all their fans come on a lot compared to my Raptor. I think its normal and nothing to worry about.

The reason why I want to post this update is to set something right with jetting. Rich jetting does not always rob power. It actually gives you more HP than the preferred air to fuel ratio of 14.7:1. The best ratio for power is 12.7:1. It also helps to keep the motor running a bit cooler. Do not run the motor richer than 12.1:1, or you’ll just be dumping fuel

Nearly everyone on these forums will tell you if you have a plug that burns brown, your set up right. Yes, they are, but it’s not the best jetting for power. You need a slightly black plug. An air to fuel ratio of 12.7:1 will give you a black plug, not a brown one.

If you have an air to fuel ratio meter set it to 12.7 or around 13. You’ll get more power and help the motor to run cooler.

PS. the fan still comes on a lot, even with the right jetting for power.


I see you have a K&N (Dynojet) jet kit. What is your altitude, and what jet sizes are you running.

The guys here run dynojet 180 to 190. I am at 5000" above sea level. They also have modified intakes on the airbox with K&N's, so the jets are a bit larger than normal.

 

I had read here that that nice brown is for two strokes and four stroke more of a whitish/ gray color? this is the first time Ive heard of a little bit black plug. [img]i/expressions/face-icon-small-confused.gif[/img] can any one else verifie this? maybe I need to find a A/F ratio meter get it diald in. Im not doubting Freez Im just a little [img]i/expressions/face-icon-small-confused.gif[/img]
thanks
Sam

 

No offence taken Sam. By now I am use to fighting with these so called tuners. They are like sheep. They follow things blindly, without asking why. Most people will tell you that a black plug is to rich. A brownish plug is correct, and they are right. A whitish plug means it is to lean.

An air to fuel ratio of 14.7:1 is the best ratio to set for cars and motor wanting to get the best performance and fuel economy. It’s a bit of a trade between power and fuel used.

For best power, a ratio of 12.7:1 is the best. This ratio however do not burn all the supplied fuel and is therefore not commonly used in tuning, as it waist fuel. 12:7 is seen as a rich condition to most people, hence the blackish plug.

The plug is not a dark black. If it is dark black and start showing carbon deposits it is to rich. If done right the plug should have a blackish dark grey look, without deposits. Not brown, Not white, not dark black.

I never use the so called plug test, everyone seem to believe in. It is useless and give confusing information. The only time I look at it is when I get in a new bike to see what sort of state the carb is in. Other than that I leave the plug where it should be. Inside the head.

A carb has many different things that determine the mixture. Air screw and pilot jet takes care of things below 1/4 throttle. The needle does most of the work between 1/8 and 7/8 and the main jet only work between 1/2 to full throttle. The plug cannot tell you where the fuel delivery is rich or lean. The plug will show an AVERAGE condition. People never ride at only 3000 RPM, yet they believe by looking at the plug they can see if it is lean or rich. It is the stupidest thing in the world. The only time a plug color can be used correctly is in a motor that work day in and day out at the same RPM. Something like a generator motor. Quad riders use the motor all the way from the bottom to the top. You can be rich at the low end... lean in the midrange and rich again at the top. The plug will not show this. Some people will look at this condition and go even leaner, causing problems as they go along. You need to run a ratio of 12:7 all the way thru the RPM range.

It is never possible to get it 100% correct all the time, but anything between 12:1 and 13.5 is acceptable for best power.

If I can teach you one thing, please forget about that stupid plug test. You might as well work in the dark if you are going to use it.

I am not a 2 stroke expert, but with the oil in the mixture I believe a two stroke will almost always run more black than a 4 stroke.

 

got it, good info. For mesuring the air fuel ratio do you set the rpm level per the adjustment needed? example 1800-2500rpm for the pilot 5000 rpm for needle possision and full throttle for main jet.
Sam

 

the whole plug thing never did make sense. when i first started jetting everyone said to do plug chops... but i thought my motor was running lean on the bottom and rich on top, but yet i still had a really black plug so i was told i needed to lean everything out.

i made a post awhile back about measuring exhaust gas temp to aid with jetting, is this the method used to read you true state of tune? (or is whats known as an exhaust sniffer what is used [same thing?} )

when i was running out in the dunes i know i was runnin rich as i had a 165 (stock mikuni) main in running pipe/filter. (most said they ran as low as a 145 mikuni main.

I have both dynojets and mkiuni jets (basically a full set of each, buti usually run the mikunis )

**edit**

I always thought that if you ran too rich, besides waisting a ton of fuel, your engine will run like a pig... i decided i would leave my engine with whati thought was pretty damn rich as i wanted to be sure i was rich rather than lean.

i almost think its impossible...but couldi have been running LEAN which caused what fealt like weak power? i know if you run way too lean your engine has a los of power as well...

sorry for all the questions just trying to finally figure this crap out... lol

thanks for the help

 

ROOST,
what did you finely settle on for jetting? This is where I was at when ihad my stock carb, 172.5 main Mikuni, 45 pilot ,clip on bottom grove, air box lid on. this ran great for me all year long. had no troble starting in the winter or other wise. I know your elevation cant be to different than mine so that shouldnt be a factor. My fan came on at times but my cuz 02 baja seemed to come on more, he ran dynojet 180 needle clip in middle grove stock pilot, fmf pipe. I had schrouds though those seem to help. mine or his never just up and quit so im kinda miffed on that.
where do you do most of your riding? I did notice the more I rode in the woods the more my fan came on, it ran hotter, if Im on the track or field it hardly comes on, just a thought.
sam

 

well before i left i was running a 175 mikuni with a 45 pilot (seemed pretty rich on the bottom) with needle in 2nd from top clip.
i usually ride around here where it is 800ft.

im still considering getting a 46hv.... someone had posted awhile back they went out west for riding and didnt have to do much on the 46.... (im going to search up the 46hv as i was told they dont use main jets...but power jets)

 

Really good post Freez!!!
I only take exception with a few points. What kind of fuel a person burns makes a big difference in plug color. If you are running pump gas the plug color could brown to black for the most power. Just like you said, around 12.5 to 1. If you are running race gas, the plug will look an off white for the most power, and that magic 12.5 number. Race fuel burns extrememly clean, and the plug will look extrememly clean. If you are burning something like C12 and see either brown or black you are WAY too rich.
I do plug checks in all circuits of the carb unless I'm drag racing, then I really don't care that much about getting each circuit perfect. If you do a plug check on each circuit you can tell what each circuit is doing, and whether you are rich or lean with that circuit. It's time consuming and a pain, but it really helps with performance.

 

In the summer you can drain your radiator and put water and a corrosion inhibitor. Don't need coolant. The glycol in the coolant reduces the heat transfer by at least 5%.

Get some air in the radiator.

Also, what octane are you running? Pre-detonation produces excess heat.