A properly tuned stock carb at 5000ft is going to be very lean at sea level. Just my opinion.

Man all this talk about tuning carbs has got me even more interested in EFI!

 

EFI is where it is at. In the next month I will have a complete third generation fuel injected system courtesy of KMS. No more messing with the computer. If ya want to add nos. Just do it. No tweaking with the system. no more worrying about running lean.

Duneme, the power up kit is the only garage item that no one cares to list cause they feel so bad selling it to someone. I would gladly sale one to you for a huge savings. (only cause I appreciate all your help) With a new needle and some jets you will have that 730 screaming. LOL

 

I ride at 0-500ft. one time a year we make a st. anthony trip. my ds runs fine without rejetting. it just loses big power. I geuss I shouldnt be so lazy when we go over there. and take the time to drop down a main jet size or 2.

 

Normally unless your needle is in the richest (lowest slot) all you have to do is move the clip a spot or two. I would go from st anthony to glamis and move the needle from the middle slot to the lowest on the needle and it ran great. I didn't have to change the main jet. I tried one trip and it did not run as well with the larger jet. Only takes a couple minutes to change the needle. Try it. Its the idaho in ya that makes ya lazy busmechanic. I would know.

 

I live in a valley at approx. 5000ft but because I am surrounded by mountain ranges I frequently am riding above 8000 ft. I have found a simple way to keep the power up. Just remove the airbox lid when it starts to lose power and sputter then I pop the lid off and it runs fine! So my suggestion is to set it up at the lowest altitude you ride with the lid on. Then when you gain altitude (2000 feet seems about the right time) take the lid off. Just my 2 cents.

 

you can take the man out of Idaho. but, you cant take Idaho out of the man.

 

Crackerjack, where did I say they went down to sea level with the exact same jetting as what I am running at 5000 ft. I said they took the quads down and it run without any problems. I took it for granted that you guys will realise that you have to to use larger main jets for sea level. The guys where told to install one size larger main jet before they went down, to enrich the mixture.

Everywhere I posted in this topic I state I am at 5000 ft and that the jetting spec I gave was for this altitude. I even stated that at sea level the jetting should use larger main jets, compared to my setup. But as you guys want to prove me wrong, I guess you will try any way possible to prove your point and disprove mine.

Why are you thinking I am saying they went down with the same jets? Most guys tune their quads for a mixture of 14.7:1. This is fine for a good clean burn and will give you good power. Taking a quad down with this jetting setup will not run correctly at the coast, I agree. Now for the guys that know their mixtures, you can us a mixture of 12.7:1 for most power output. You can actually even go richer to around 12:1. It is much richer than the 14.7:1 most people use. I set the bikes up to use 12.7:1 for the guys looking for the most power and is not concerned with saving a little fuel. Taking a quad with a mixture setting of 12.7:1 down to the coast will mean that it might very likely run real well with the same jets as used for the 5000 ft altitude. The mixture at the coast will move from a richer 12.7 to a leaner 15:1, maybe 16:1. Closer to a spec most people set thier quads up as a default. At 15.5:1 it is still fine to run, but not the best possible setup and leaning towards lean. I always tell them that if they pick up problems with the 5000 ft jetting at the coast, to pop in a larger main jet. The guys used the 5000 ft jetting for a trip we call the desert run. They start at 4000 to 5000 ft and travel for hundreds of miles down toward the coast where they get very close to sea level. They run the quad at max RPM with full throttle for hours on end. They run dirt road and full on desert dunes for miles and miles. This goes on for more than a week or riding hundreds of miles each day. 2 guys done this trip with the 5000 ft jetting and the DS run very well. If it was out of spec, they would have had blown motors. The guys I work with don't argue with me, nor are they afraid to mention they had to change jetting. They simply do not need to change it that often, even when travelling down to the coast. They even try their own jetting and play with the jets themselves. They always give feedback about their findings. Further proof was that the same guys went on a race we call the Roof of Africa. It is up and down mountains, changing altitude and temperature ranging from searing heat to ice cold. The DS's run perfect once again and finished the race. Not a stutter or bog anywhere in the RPM range, no matter the temperature or the altitude. If you tune then for 12.7:1 they have a large margin of mixture to play with, before they get the motor to run badly.

If you look at the dynojet spec for altitude below 3000 ft and above 3000 ft, they ONLY tell you to change main jets. Needles are not to be touched. The only dynojet kits that tell you to change needle spec for altitude are on 2 strokes and some of the smaller 250cc quads. 450’s, DS’ raptor, you name it. Needle are not to be changed for altitude.

When are you guys going to realise that needles only change mixture between 1/4 and 3/4 throttle. Using the same size main jet for sea level and higher than 3000 ft is stupid. Stop messing with the WRONG parts. The main jet effect power mostly from 1/2 to full throttle. It does play a small part below 1/2 throttle, but nothing major. So, what you guys are actually doing each time you change altitude is fix the midrange by moving the needle, while your top RPM mixture is messed up. You change the wrong parts, yet you see yourself in a position to give advice like you are a pro.

I find it amazing that individuals without a dyno or air to fuel ratio meter will argue with companies like Dynojet that spend hundreds of hours on dynos and other people like me that actually have the test equipment. We tested this and have the test equipment to prove it. Is your butt dyno better than that a dyno and other test equipment?

Cammer, nice to see a man with an understanding of jetting around here. You have the right idea there, keep it up.

 

IMO yes. Normally I would vouch for the dyno jet kit but it seems alot of us clame it as junk in regards to the DS. A guy I ride with had a dyno jet kit, fmf pipe in his DS mine was mikuni jetting stock pipe w/ end cap. if you had a blind fold on when you rode these two bikes you would sware they were two totaly differnt bikes. Mine had alot more tourqe it was grabbie it would lung foward. his was smooth took off w/ out any real authority still fast but it didnt make you go wow.

Freez it seems that if anyone doesnt agree w/ your dyno time or any of your findings because they dont match ours, they must be stupid not to agree w/ you as if your word is the ultimit authority. The Dyno is not the final word in building a bike to suit your style and enviroment.

your comments are welcome but dont try to portray us that have diffrent findings than yours like were dopes.

 

Well, I for one believe seeing results on something I can measure. Dragging or racing another DS is pointless, unless you can race yourself. No single bike is set up exactly like the rest. Beating another guy with a different setup is proving one thing. Your DS is faster, that’s it. The reason why you beat him can be jetting, mods or driver skill. Lots of lots of things are different. Even tyres play a big role on how well a quad accelerate.

When you but a bike on a dyno it is like racing yourself. You compare your own bike from a previous run to the exact same bike with one extra mod. You see the results and you can prove it.

Does this other DS you talking about have exactly the same mods, tyres, sprockets, exhaust mods, air cleaner and the list goes on. IS the only difference the dynojet kit you claim is crap. If not, how can you say it’s the dynojet kit's fault. No single DS makes the same power so even if you have the same mods, one bike will be faster than the other one. There are just so many variables.

Again variables you don’t have while using the exact same quad on the dyno.

You know what, I just might have a theory about why the stock needle might be working for some of you guys.

Sam, you remember that we had a long chat about lid or no lid setup. Your a big lid on fan and I have explained that the lid on will cause massive amounts of vacuum. You have to agree, the thing sucks the rubber pipe to deform. The dynojet needle might not work well with that vacuum, since the carb flow less air and need less fuel than what the dynojet needle provides. You also cut the spring on the slider, now what does that do. Hell and behold it helps the slider to open quicker or larger which means that the stock needle supply more fuel. Combine the dynojet needle with your cut spring mod and the thing might deliver to too much fuel.

Now you guys blame dynojet for it, yet, they never built the thing to work with a modified slider spring.

The cause of this problem can go on for ever. MrHP has his way of tuning and then he finds ways of getting the stuff to work well with his mods, but when you work with aftermarket stuff that are made to work with "stock" parts, like dynojet kits, they might not work well with MrHP mods. Then they run out and throw away the kit and say its crap.

Us guys that do not follow the MrHP mods, might have a completely different view of things and mods might work for us, that will not work for your setup.

I am getting upset and I will call people dopes if they give bogus advice. The changing the needle for altitude is a perfect example. IT IS WRONG, period. This can be proven by any old air fuel ratio meter. The days of people tuning carbs blindfolded is long gone.

Now people actually read this stuff and go try it on their own DS's. They take things people say n here as fact. I have a problem with people believing incorrect "facts". When you help people help them right, 1st time.

 

Freez, you are definitely an interesting guy. All the facts in the world but I wonder how much knowledge. Bombardier are the guys who built the motor. What do you think they say to do if you are at an altitude above the 0-3000ft. You got it, Move the needle. I personally read it at our local bomb shop. If Shmee reads this post or another bomb dealer he can confirm so you don't argue with a dope of a DS owner like myself. I had not changed anything with my spring and I did not take the lid off either when trying the dynojet kit. The almighty dynojet team, ( the only people as smart as you) did not recommend taking the lid off. they give you different stages and where to place the needle clip and the size of the main jet for each. I followed the instructions for a slip on exhaust and it ran like "CRAP!". If I had a dyno it would have shown the exact same thing. (I am going to have to buy one obviously before anyone or someone will take what I say seriously) When I get one I can just refer to "my dyno time" and "Extensive testing" without any proof of it.

Camds650 is coming out of a corner the rpm's are low and he punches it. It feels really boggy. He shifts down the rpms come up and it pulls like a raped ape. The whole 1/4to 3/4 and so on with the throttle position is not just throttle dependant it is also dependant on the air flow especially on a vacuum slide carb. Maybee taking the lid of the box with work. Try it. If you want to leave the lid on then move the needle down. It will then be leaner when you get on it at lower rpms and when the needle raises you will have the same top end.

Freez, you started your post with "of course they changed the jetting" and then later said they didn't have to change anything and it ran great. Which is it?