Moto-Fast vs. LRD pipes
#1
05-31-2000, 04:20 PM
Well I just got the Moto-Fast pipes on, but don't have the jetting completely tweaked yet.
I bought the LRD jet kit to match the pipes (suposedly), but it never did run like it should have and they (LRD Staff)weren't too helpful in nailing down the correct jet sizes (It was always, check this or check that on your bike). It would pull fairly well on top end, but was sluggish elsewhere. I was using 290s/30s jets as they said that should've been right on.
Today I put the Moto-Fast pipe on and just did a quick jet change. I kept the 30s and dropped down to 200s. It seemed super responsive compared to the LRD pipes. I didn't get a chance to run it through the gears because I wanted to drop the 30s down to the lower 20s and needed to raise the 200s up to about 210 or 220s.
Just running it in 1st gear, I can't tell that it tamed the powerband down that much, but I guess it could be because the LRDs never had a fair chance?
Also, has anyone ever dynoed either of these pipes? I'm thinking about setting them on a local shops dyno just for comparison, but would just as soon save the money if somebody else has already done it.
I bought the LRD jet kit to match the pipes (suposedly), but it never did run like it should have and they (LRD Staff)weren't too helpful in nailing down the correct jet sizes (It was always, check this or check that on your bike). It would pull fairly well on top end, but was sluggish elsewhere. I was using 290s/30s jets as they said that should've been right on.
Today I put the Moto-Fast pipe on and just did a quick jet change. I kept the 30s and dropped down to 200s. It seemed super responsive compared to the LRD pipes. I didn't get a chance to run it through the gears because I wanted to drop the 30s down to the lower 20s and needed to raise the 200s up to about 210 or 220s.
Just running it in 1st gear, I can't tell that it tamed the powerband down that much, but I guess it could be because the LRDs never had a fair chance?
Also, has anyone ever dynoed either of these pipes? I'm thinking about setting them on a local shops dyno just for comparison, but would just as soon save the money if somebody else has already done it.
#2
06-01-2000, 01:29 PM
#3
06-01-2000, 01:50 PM
I am not familiar with either the motofast of the LRD pipes, but 200's seem really lean. When i was running stock gas carbs with toomeys, i was running a 280. I would check your specs and remember to start rich and lean out one circuit at a time. And waymod is right, your main jet only effects about 3/4 and up throttle. Your pilot and air jet and then the needle should be adjusted for the low end.
#4
06-01-2000, 01:54 PM
#5
06-01-2000, 02:21 PM
When most people feel that their ATV is not jetted properly, they switch the main jet. However, 90% of the time that's not the problem. You have to pinpoint the problem, area and make adjustments accordingly.
The jetting sequence goes like this: The pilot jet determines how the bike runs from zero to 1/8 throttle: from 1/8 to 1/4 the slide cutaway is working: the needle and needle jet ( mikuni TMXs and Keihins have fixed needle jets( can be changed to affect response from 1/4 to 3/4 throttle mix is regulated be the main jet.
Of all the jetting components, the needle has the most variables-length, diameter and taper all play part in the machine's response. Changing the length is comparable to moving the clip on the needle, that is, a longer needle will be slightly leaner, such as when moving the clip upwards. The diameter affects 1/4 to 1/2 (fatter is leaner). Finally, the taper affects 1/2 to 3/4 throttle(fatter is leaner).
Most of the nations top tuners have their own way of jetting a bike, here is just 1 method. Run the bike in 3rd, under a load (like up a hill). Without a load on the engine, it will tend to require larger jets, and you'll lose performance when you actually get riding. These notes pertain to both 2 and 4 stroke engines.
PILOT JET: turn the air screw all the way in and the engine should die, if it doesn't die the jet is too lean GO to the next size larger. As you back the air screw out, the engine rpm will increase. If you've gone out past 21/2 turns and the rpm is still increasing, go to the next size leaner pilot jet. It is imperative that the air screw and pilot jet be dialled in together for optimum response. Once you determine that you have the proper size pilot jet, back the air screw out from fully seated until the rpm quits increasing, then turn it back in just a touch.
SLIDE: The slide is lean (too much cutaway) if you're experiencing a hesitation at 1/8 to 1/4 throttle. If the engine sounds like it is breaking up, it too rich.
NEEDLE: Your ATV spends most of its time being ridden "on the needle" so this part is most important. The needle is too lean the engine feels flat, or the rpm fluctuates at a steady throttle setting between 1/4 to 3/4 throttle. If the engine breaks up (stutters) or won't pull through to the top, it's too rich. The needle is adjustable by a clip and a series of grooves in the top of the needle. Moving the clip up ( dropping the needle) will make the bike run leaner and vice versa.
MAIN JET: The main jet is too rich if your bike blubbers and breaks up at full throttle, under a load. If it is too lean, the engine will "lay down" or feel like its just not making power on top.
When making jetting changes, be careful, and don't make any radical adjustments. Take the time to make changes in small steps, because on mistake could mean an engine rebuild.
The jetting sequence goes like this: The pilot jet determines how the bike runs from zero to 1/8 throttle: from 1/8 to 1/4 the slide cutaway is working: the needle and needle jet ( mikuni TMXs and Keihins have fixed needle jets( can be changed to affect response from 1/4 to 3/4 throttle mix is regulated be the main jet.
Of all the jetting components, the needle has the most variables-length, diameter and taper all play part in the machine's response. Changing the length is comparable to moving the clip on the needle, that is, a longer needle will be slightly leaner, such as when moving the clip upwards. The diameter affects 1/4 to 1/2 (fatter is leaner). Finally, the taper affects 1/2 to 3/4 throttle(fatter is leaner).
Most of the nations top tuners have their own way of jetting a bike, here is just 1 method. Run the bike in 3rd, under a load (like up a hill). Without a load on the engine, it will tend to require larger jets, and you'll lose performance when you actually get riding. These notes pertain to both 2 and 4 stroke engines.
PILOT JET: turn the air screw all the way in and the engine should die, if it doesn't die the jet is too lean GO to the next size larger. As you back the air screw out, the engine rpm will increase. If you've gone out past 21/2 turns and the rpm is still increasing, go to the next size leaner pilot jet. It is imperative that the air screw and pilot jet be dialled in together for optimum response. Once you determine that you have the proper size pilot jet, back the air screw out from fully seated until the rpm quits increasing, then turn it back in just a touch.
SLIDE: The slide is lean (too much cutaway) if you're experiencing a hesitation at 1/8 to 1/4 throttle. If the engine sounds like it is breaking up, it too rich.
NEEDLE: Your ATV spends most of its time being ridden "on the needle" so this part is most important. The needle is too lean the engine feels flat, or the rpm fluctuates at a steady throttle setting between 1/4 to 3/4 throttle. If the engine breaks up (stutters) or won't pull through to the top, it's too rich. The needle is adjustable by a clip and a series of grooves in the top of the needle. Moving the clip up ( dropping the needle) will make the bike run leaner and vice versa.
MAIN JET: The main jet is too rich if your bike blubbers and breaks up at full throttle, under a load. If it is too lean, the engine will "lay down" or feel like its just not making power on top.
When making jetting changes, be careful, and don't make any radical adjustments. Take the time to make changes in small steps, because on mistake could mean an engine rebuild.
#6
06-05-2000, 10:17 AM
I am running the MotoFast pipe and head mod. I am using a 22.5 pilot and a 210 main at 850Ft above sea level. Mixture screw is at 1.5 turns out. I am running with the airbox lid ON and I am using a foam filter with a proflow type adapter plate. I love the Moto fast mods. I can lug my Banshee around in the woods as good as any 4 stroke and still have the top end to really smoke 'em. Mine seems to be just a little flat in the mid range. I have experimented with moving the clip positions on the needle. The stock middle setting seems a bit rich, and raising the clip one notch seems too lean. Someday I'll experiment with different needles to see if a different taper on the needle will help the midrange without losing my bottom end or top end. I also have the Moto fast head mod to boost compression. Hope this helps.
Bruce
2000 Banshee
99 400EX
99 wolverine
Bruce
2000 Banshee
99 400EX
99 wolverine
#7
06-05-2000, 10:33 AM
Thanks, 22.5 is what Jimmy (Moto-Fast owner) recommended for the airbox lid on, snorkel on.
I took the snorkel off and put in a 25 pilot, and 220 main. It doesn't load up with the 25s, but some of the bikes seem to like the 22.5 in the hot weather here at about 400ft. elev.
Here is a short sound clip of what it sounds like now http://www.vci.net/~bash/tuned_moto_fast.wav Sounds about right, huh?
Did you get the head mod at the same time? I was just wondering how much difference it made above and beyond just the pipe.
I took the snorkel off and put in a 25 pilot, and 220 main. It doesn't load up with the 25s, but some of the bikes seem to like the 22.5 in the hot weather here at about 400ft. elev.
Here is a short sound clip of what it sounds like now http://www.vci.net/~bash/tuned_moto_fast.wav Sounds about right, huh?
Did you get the head mod at the same time? I was just wondering how much difference it made above and beyond just the pipe.
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#9
06-05-2000, 05:36 PM
#10
06-06-2000, 11:36 PM
i have the same setup as bruce but i did the pipe first then head mod. i started with the pipe, boost bottle(question any gain with bottle),22.5 pilot, 200 mains, and no snorkle.i couldn't get it to clean out with stock snorkle. then i got head mods and noticed a gain about half of what the pipe gave me, with the same jetting. i got tired of sucking water and the throtle sticking so i took a 3" street 90 sdr 35 sewer fitting(ask a plumbing supply house they will know what you want) heated it up with a heat gun and formed it to fit frame and airbox. use welding gloves to hold it til it cools, mine didn't even need a clamp to hold it on, then applied silicon around it. now it runs the same as no snorkle but doesn't suck water. everything else is stock on pump gas. hope this helps, shane