Question About Jetting!!! Help Please

[250RGUY]

OK, I just got my R here the other day. Its running like crap at the moment. I just had the top end rebuilt. Its got an ESR low end pipe and silencer, think its the TRX6. 38mm air stryker carb with a 158 main jet. Its running like crap. Bogging in the beginning then winding out a bit as it gets up to speed or hits the powerband. 3rd gear sounds,feels, and is horrible until its full throttle. Should I bump up to a 162 main and what should be my needle setting? Thanks.

[250RGUY]

JUST GOT OFF THE PHONE WITH ESR. THEY SAID THAT IT SHOULD START AT A 170 MAIN AND ABOUT A 50 PILOT AND WORK MY WAY DOWN FROM THERE. 158 IS WAY TO LEAN OBVIOUSLY BUT I DIDN'T KNOW IT WAS THIS MUCH TO LEAN. YOU ALL AGREE?

[Scott-300ex]

Stock jets are 158, 45 3rd clip on needle for some years and 155 42 4th clip on needle for others.


If you got good top end then you just need a richer pilot, I'd say 50 is a good starting point

Mixture
Pilot
Needle
Main

I belive thats low to high rpms on wut to adjust. Good luck.

[250RGUY]

I tried bumping the jet up a few and it ran worse. Checked the plug and it was dark and wet. Put a new plug in, tossed the 158 main back in and it runs alot better but still not perfect. It misses a bit in first and second until its wide open then it runs great. I'll try a pilot adjustment maybe that will straighten it out.

[hang1p]

do you have your airbox lid off that will make all the difference in the world also your running a 38mm so you shouldn't be running close to your stock jetting bigger carb bigger jets more air and don't for get the air screw I run atleast a 180mj on mine in the summer 50 pilot 4th from the top on the clip and about 1 to 1/1/4 on the screw yes mine is a 350 but I'm running a 38mm and your running a 38mm the same amount of air is going threw mine as yours i just have a little more cylinder volume

[250RGUY]

I'm fouling plugs even running it full throttle non stop with a 158, no possible way I could put a bigger jet in it, seems like I need to go down a few. The cylinder is only 1 over stock bore.

[hang1p]

do you have your airbox lid on,if so what i said would not apply but if you do not then I'm not far off my buddy jon 370 is running a 38mm on his stock cylinder and he has a 180 mj in his what is you elevation were are under 1000ft around here maybe you have weak spark or somthing just given you my 2 cents

[250RGUY]

YES, My lid has to stay on. I ride basically GNCC type trails all the time and there is alot of mud and water.

[hang1p]

i got yhea

[86250rrider]

im running open box,178 main,3rd clip .030. over. i would guess in a similar altitude as mine with lid on a 170-174 main would be close.

[250RGUY]

The machine has been bored over twice. I have a 158 main in it with a 38mm air stryker carb. My gas is mixed 32.1 perfectly. Its running rich as can be so going up to 170's, etc is going to make my problem worse. I tried taking the airbox lid off and it runs alot better in 1st and 2nd gear but its a bit boggy and slower in 3,4,5,6 then when the lids on. You think a better air filter would help, this ones pretty messed up.

[jon370r]

Put a new spark plug in with the gap at .018 to .020. May be a weak spark that just makes it feel like its to rich.

[250RGUY]

I had a BR9ES in it when I got it so I put a new BR9ES in it. It didn't help. I thought maybe I need a hotter plug so I but a BR8EG racing plug in it and it runs a bit better but still missing in the bottem end. If you've ever ridden a quad with a reverse rev limiter thats what 1st and 2nd gear feel like on this R right now with the airbox lid on.

[TheFontMaster]

What is the smallest main jet that you have tryed? You said your filter is lookin crapy, that would be a good start, but just keep goin lower on the main untill you get it running right. It might seem odd having a jet smaller than 158 or so with the mods that you have, but whatever works. I would also switch over to amsoil 50:1 oils. That will lean it up a little more, and when I switched from 32:1 to the amsoil 50:1 I got a little better power all around, it was less boggy(my jetting wasn't perfect at the time), reved better, and sounded better too.

[Scott-300ex]

86 and 89 plugs are BR8ES

87 and 88 plugs are BR9ES

[TheFontMaster]

Originally posted by Scott-300ex
86 and 89 plugs are BR8ES

87 and 88 plugs are BR9ES

That's what they are from the factory, but it doesn't make a diffence, ether of those plugs can go in any 250r motor. Personaly I run the BR9 plugs, they are a little hotter plug. More specificaly I run the BR9eya instead of the BR9es. It has I think a V-grove electrode or something like that, I have had good luck with these plugs.

[beerock]

Originally posted by TheFontMaster
That's what they are from the factory, but it doesn't make a diffence, ether of those plugs can go in any 250r motor. Personaly I run the BR9 plugs, they are a little hotter plug. More specificaly I run the BR9eya instead of the BR9es. It has I think a V-grove electrode or something like that, I have had good luck with these plugs.

bro, the 8 is a hotter plug.....

250r guy, it does sound like you have some sort of electrical issue. so check that out, it still could be fuel delivery though, when is the last time you checked your reeds? they could be busted?

are you sure its a wet fuel plug and not a black oil film on the plug ? could be a bad right main seal? i doubt it but who knows?

maybe it has to do with your needle?

what needle is in it????? even if this isnt a problem i reccomend a CEL needle for all 265's and 310's it will boost your bottom and mid like a new port job...

lastly, the trx6 pipe SUX *** maybe your port work doesnt agree with the pipe?

[TheFontMaster]

Originally posted by beerock
bro, the 8 is a hotter plug.....


O my mistake, for some reason I thought the higher the number the hotter the plug.

[250RGUY]

Originally posted by beerock
bro, the 8 is a hotter plug.....

250r guy, it does sound like you have some sort of electrical issue. so check that out, it still could be fuel delivery though, when is the last time you checked your reeds? they could be busted?

are you sure its a wet fuel plug and not a black oil film on the plug ? could be a bad right main seal? i doubt it but who knows?

maybe it has to do with your needle?

what needle is in it????? even if this isnt a problem i reccomend a CEL needle for all 265's and 310's it will boost your bottom and mid like a new port job...

lastly, the trx6 pipe SUX *** maybe your port work doesnt agree with the pipe?

The bike didn't miss before it blew up. lol I dont think its electrical because it seriously runs great from 3rd gear on. The plug was soaked, actually probably dripping wet. The motor was just rebuilt and I dont see anything leaking from any seals except where the header meets the motor there is a bit of black coming out there. I dont know what needle is in it but its set on the 3rd setting. Why does the TR6 pipe suck? I need a low to midrange woods pipe up here in the sticks of PA. I'll get a new one if it sux.

[250RGUY]

I have gone as low as the 158 Main that came in it. The guy I bought it from suspected it was too lean and thats why it blew up so I only bought bigger jets. 162,165 and 168. Tossed a 165 in it and it was 10 times worse, totally bogged down. I rode for an hour the other day without fouling a plug but I was running it hard the entire time, not much 1st and 2nd gear use. I'm going to get a new air filter and see what happens.

[beerock]

Originally posted by 250RGUY
I have gone as low as the 158 Main that came in it. The guy I bought it from suspected it was too lean and thats why it blew up so I only bought bigger jets. 162,165 and 168. Tossed a 165 in it and it was 10 times worse, totally bogged down. I rode for an hour the other day without fouling a plug but I was running it hard the entire time, not much 1st and 2nd gear use. I'm going to get a new air filter and see what happens.

ok, simple way to see why its so boggy is go buy the CEL needle i told you about..

sounds like when you run it hard its fine but when your not on it wot it fouls the plug, get the CEL needle for that 38 a/s carb and run a br8es in it.

take the slide out and check what needle is in it before you buy the CEL needle, but it def soudns like thats your problem to an extent.


the whole thing about the motor running fine in 3rd gear or higher just sounds weird

[250r4life]

whats so great about the CEL needle, and what about on a 36 pwk carb?

[86250rrider]

check to make sure the floats are set correct. you would get those symptoms if you were overly rich until it burned up after running through the gears. if your float were to stay open the jetting would need to be leaned out to compensate.i live in the same region and im using a 178 main and my plug is tan and it runs crisp. dont overlook anything.:D

[86265r]

I HAD I SIMILAR PROBLEM AND IT WAS MY ELECTRICAL SYSTEM. HAD TO PUT NEW COIL & MAIN UNIT BOX-[ WHAT EVER IT'S CALLED]. NOW IT RUNS PERFECT. I DID AS YOU DID, I WAS TRYING EVERYTHING!!! NOTHING WORKED.. FINNALY HAD TO SPEND SOME MONEY & TAKE IT TO A SHOP TO FIND OUT IT WAS ALL AN ELECTRICAL PROBLEM..

[beerock]

Originally posted by 86265r
I HAD I SIMILAR PROBLEM AND IT WAS MY ELECTRICAL SYSTEM. HAD TO PUT NEW COIL & MAIN UNIT BOX-[ WHAT EVER IT'S CALLED]. NOW IT RUNS PERFECT. I DID AS YOU DID, I WAS TRYING EVERYTHING!!! NOTHING WORKED.. FINNALY HAD TO SPEND SOME MONEY & TAKE IT TO A SHOP TO FIND OUT IT WAS ALL AN ELECTRICAL PROBLEM..

if its electrical, which i havent ruled out yet, check the ignition in my how to thread if everything checks out and you tried all your carb adjustments, then it could be the CDI

[250r4life]

hey B- so whats up with that CEL needle?

[beerock]

Originally posted by 250r4life
hey B- so whats up with that CEL needle? i dunno about on a 36, but i bet on a 38pwk or 39 pwk you would still have the snappiness with the cel needle...

[86265r]

IT'S REALLY NOT A BAD IDEA TO CHANGE OUT THE DCI BOX ANY WAY, IT'S ALMOST 20 YEARS OLD! YOU'RE SURE YOU DID NOT OVER LOOK ANY SMALL CRACK IN THE COIL WIRE. THAT WAS ONE OF MY PROBLEMS..AND IT DID NOT ALWAYS EFFECT IT'S PERFORMANCE???

[250RGUY]

My CDI isn't 20 years old, its some sort of newer racing CDI box. I have the stock CDI still, should I try putting that on?

[TheFontMaster]

Originally posted by 250RGUY
My CDI isn't 20 years old, its some sort of newer racing CDI box. I have the stock CDI still, should I try putting that on?

It wouldn't hurt to try.

[250RGUY]

Well, a friend of mine who helped me put a new sprocket on the other day decided that hand tightening my lug nuts would be enough. While I was in the house looking at a picture of an anti-fade locknut they were outside riding the R too see if our fixes worked. So naturally I assume they tighted all of my lugnuts. I then park it for two days, work on the house and tear down a swimming pool and send it to another unfortunate owner. Well last night I finally got a chance to go riding and after about 5 minutes of just flat out tearing the trails up my back left tire falls off and goes about 200 feet out through a field. Luckily I wasn't hurt and I actually got leaned over enough on the right side to keep my hub up out of the dirt and came to a stop. I think it ruined the threads on the hub however and I'm out of lugnuts and the things are stinking hard to come by around here unless I goto a dealer which is an hour away. Needless to say none of my motor fixes will be noticable until I get this tire back on, just hoping I dont need a new hub.

[86265r]

WHEN I HAD MY CDI BOX REPLACED THE SHOP HIGHLY RECOMENDED NOT USING A RACE CDI BOX - FOR SOME REASON! THEY SAID THE HAD MUCH BETTER LUCK WITH OEM PART..

[beerock]

Originally posted by 86265r
WHEN I HAD MY CDI BOX REPLACED THE SHOP HIGHLY RECOMENDED NOT USING A RACE CDI BOX - FOR SOME REASON! THEY SAID THE HAD MUCH BETTER LUCK WITH OEM PART..

dude, CHILL WITH THE CAPS LOCKS

take it off

[cook65xc]

That bike has a new lrd ignition box on it,that is not the problem.I talked to a guy who said it could be the stator,does that make sense beerock.250r guy give me a call.

[250RGUY]

I'll call tomorrow some time. I cant get the fuggin lock nut to stay tight and its basically causing me a ton of rear end problems. The tire fell off, the clip that holds the sprocket on came off again and that dang locknut wont stay tight. lol I'm going to end up gettin the anti-fade I guess. I will say this is the fastest R i've owned though, its just too bad I cant get it running somewhere close to right.

[86265r]

what does it matter if the the cap lock on!!!

[Scott-300ex]

Yeh, 8 is hotter, I just read it the other day in the manual cuz I was working on mine.

And buddy it sounds like locktite would be your best friend right now. My axle nut came loose, then it came loose again like a year later, use locktite, you can also run electrical tape up along the nut on the threads so it makes it harder to back off. Also it has reverse threads. You can use locktite on the lugnuts too but you have to take them off it you want the tire off, I say, in this case a TOURQE WRENCH can do wonders.

[86250rrider]

you don't use a torque wrench to remove lugnuts!

[beerock]

def get the anti fade, but for the time being, the pros use to use DUCT TAP on the stock nuts to keep them from backing off....

[Scott-300ex]

Originally posted by 86250rrider
you don't use a torque wrench to remove lugnuts!

Point out to me where I said REMOVE.

I did not.

And they use Electrical Tape too. Not Tap by the way.

[Grizzlytrap]

Originally posted by 250RGUY
Well, a friend of mine who helped me put a new sprocket on the other day decided that hand tightening my lug nuts would be enough. While I was in the house looking at a picture of an anti-fade locknut they were outside riding the R too see if our fixes worked. So naturally I assume they tighted all of my lugnuts. I then park it for two days, work on the house and tear down a swimming pool and send it to another unfortunate owner. Well last night I finally got a chance to go riding and after about 5 minutes of just flat out tearing the trails up my back left tire falls off and goes about 200 feet out through a field.



Need to find smarter friends, and never assume.

[wilkin250r]

:huh :confused: :huh

I'm confused about the original question. And, frankly, beerock, I'm kind of dissapointed in you for not pointing it out.

The motor can't possibly "run great from 3rd gear up". The motor, carb, and CDI don't run off the gearbox. They don't care what gear it's in. The only thing they know is throttle position and RPM. You can't possibly run fine in 4th gear, but not fine in 1st gear. That's impossible.

Now, it might be possible the gears are causing something else. You might be running certain combinations of throttle position and RPM in certain gears. For example, if you generally use low-mid throttle in 1st and 2nd gear, but more mid-WOT in 4th-6th gear, then THAT might be useful information. Maybe the engine doesn't like WOT at low RPMs. Or vice-versa, maybe it doesn't like high RPMs at low throttle. Both of those are jetting issues that can be fixed, and neither of them have ANYTHING to do with what gear you're in. It's just that possibly you only see those combinations when you're in certain gears, so you associate them with your gears.

Bottom line is, your problems cannot be associated with your gears. You can't run fine in one gear, but not fine in another. It's impossible (unless you have transmission problems).

So, when you get back to your motor, forget the gears. Describe the problems in terms of RPM and throttle position. For example, low RPM and 3/4 throttle bogging, or high RPMs popping and stumble when you let off the throttle. It doesn't matter what gear you're in, the tranny doesn't affect the fuel path.

[cook65xc]

Have you checked the reeds in it that could be your problem or maybe the stator:(

[250RGUY]

I'm wide open in all the gears. When I hit powerband in 3rd gear it turns into a whole new quad and never misses a beat after that in any gear. 1st and 2nd sound and feel like a 4 stroke in reverse with the dang rev limiter. Its strange. I know its jetting but I dont know how the original owner can be too lean and blow it up and I am too rich with the same jetting. Doesn't make any sense to me. I'm baffled, still haven't changed the pilots though.

Didn't check the reeds or stator.

sounds like your motors cursed, sell it and get a new one haha jk

[cook65xc]

Maybe the original owner was running it too rich and he was a dummy:D Check those reeds and i hope that is it.It ran fine when i had it except for running hot.Between beerock and wilkin you will get it figured out.Good luck.

[250RGUY]

I'm sure I'll figure it out, it would be nice to go riding but what are ya gonna do ya know. Anyway, i'm amazed at all the 170 and up mains I see people running on this site when I have a 158 in and it seems like its running rich. Maybe its because its a new motor I dont know. I just missed an anti-fade on ebay for 58 bucks, like to kick myself for that one.

[beerock]

wilkin, my first post says how 3rd gear up sonds weird.


got a question for ya 250rguy, have you tried getting it WOT in 1st and second?

[250RGUY]

Yes, but only until I need to shift obviously. It bogs like crazy, skips and misses until its wound out, however when the airbox lid is off it runs much better/smoother in first and second. I dont know what else to tell everyone. If you've ever ridden a z 400 and had to use reverse and didn't hit that rev limiter button then you know how it runs, thats how this R runs in 1st and 2nd gear.

[beerock]

sounds like its to rich man go one or two stages down on your main

and check your reeds you havent have you?

[250RGUY]

Nope, haven't checked the reeds yet. The 158 main scares me though, everyone I talk to is up close to 170 and I'm going down from 158? I'll check the reeds tonight.

[GPracer2500]

These are factory Keihin jets and not Dynojet jets, correct?

[250RGUY]

I dont know, I got them from my Honda dealer. I told him I had a 38 mm AS carb and I needed jets.

[beerock]

listen, if you take the airbox cover off and it runs better then its RICH its simple....

do your friends have the lid on or off? that lid really its like a 2-3 main jet difference


what sparkplug are you using? really, if your jug isnt ported much and your running a larger carb your main will be lower then stock....

what elevation are you at also?

you know we dont post on here for fun, when the post gets this long and your not trying to see whats wrong and keep posting i dont know whats wrong, but we tell you what to check......

im pretty sure that before you even take the intake off and check your reeds and waste a intake gasket you really ne3ed to check the needle in the carb and tell us what it is....

if your nto ported much(or ported a certain way) the motor will bog until high rpms thats just the nature of a
R motor with certain variables..... and throwing in a 38mm carb doesnt help BUT if you checked the needle like i asked i would be able to help more, and i already said go buy a CEL needle......

your killin me here...

[250RGUY]

In a previous post I stated the axle problems I'm having. I cant run this thing at the moment to find out if jet changes are working. If durablue ever gets my posi-lok axle nut sent I'll be able to answer better. Right now its a garage ornament. I'm just collecting info so when I do get it rolling again I wont have to come here and ask, i'll already have the answer. I didn't know they made different types of needles, the needle that came with the 38mm carb is still in it. I have the stock carb so maybe i'll toss it back on if you think it will help. The motor is bored once over maybe twice at the most I cant remember, PJCOOK can answer that question if he see's this. Too bad nobody with R knowledge lives around here so they could see how its running, i'm sure most of you could figure it out in a few minutes. I'll try dropping the main but what should I do with the pilot?

[beerock]

Originally posted by 250RGUY
In a previous post I stated the axle problems I'm having. I cant run this thing at the moment to find out if jet changes are working. If durablue ever gets my posi-lok axle nut sent I'll be able to answer better. Right now its a garage ornament. I'm just collecting info so when I do get it rolling again I wont have to come here and ask, i'll already have the answer. I didn't know they made different types of needles, the needle that came with the 38mm carb is still in it. I have the stock carb so maybe i'll toss it back on if you think it will help. The motor is bored once over maybe twice at the most I cant remember, PJCOOK can answer that question if he see's this. Too bad nobody with R knowledge lives around here so they could see how its running, i'm sure most of you could figure it out in a few minutes. I'll try dropping the main but what should I do with the pilot?


please oh please go take the top of your carb of take the slide out and check to see what needle is in it. if its not a CEL order ONE!

i know you want mroe bottom mid and im trying to help ya! you dont need the durablue posi lock to check yout needle right?:blah:

[250RGUY]

The R is put back together, rear end is in tip top shape once again. I'll say that the durablue posi-lok nut is worth its weight in gold and for 45 bucks you cant beat it. Ok on to the jetting.

Jetting!!! - Everyone, I have been giving false info on here so no wonder everyone was baffled. I rode this thing hard for the first time today because its finally back together. 1st and 2nd gear run ok at low rpms but at WOT they are like a reverse rev limiter. 3rd gear on still runs like a champ. I'm dropping the Main down 6 thousanths to see what that does tomorrow. I thought the new K&N filter would make it better but it didn't. Beerock - I'll check that needle tomorrow when the carbs apart.

Thanks everyone.

[slick250]

I am sure the effect of the engine running better in certain gears has something to do with the load placed on the engine being greater the higher gear you are in. This will actually affect the air/fuel ratio and efficiency of the engine. It sounds like you are running rich, but if the air filter is plugged, it will make it run rich.
As for the jetting. Dont feel bad about the 158. I have a 330PV engine with a 38MM Airstryker and mine runs best with a 162 jet, and I could probably run a 158 and still be OK. I am at 1900 feet, but run the same jet at the dunes around 1100-1200 feet.

Try a .018 gap on the plug, check the reeds, and.....this may sound dumb, but make sure the choke is not on....I have seen that too....LOL

[wilkin250r]

Originally posted by slick250
I am sure the effect of the engine running better in certain gears has something to do with the load placed on the engine being greater the higher gear you are in. This will actually affect the air/fuel ratio

No, it won't. It can't. It's physically impossible.

The piston draws in air through the carburetor and reeds. The piston motion is EXACTLY the same whether you are in 1st gear or 5th gear, whether you are going uphill or downhill.

The load and gear will affect YOU, and what throttle postion you're riding at. If you're going uphill in 4th gear, you're probably not at 1/4 throttle. Likewise, if you're going downhill in 1st gear, you're probably not at WOT. But it can still all be boiled down to throttle position and RPM. There is nothing at all in the fuel/air pathway that is connected or dependent upon the transmission.

It's like saying your quad runs good in the sand, but it runs rich and bogs on pavement. It's not possible.

[cook65xc]

250r guy it has been bored once and i dont think any porting has been done to it.CHECK THOSE REEDS:D

[250RGUY]

Hello,
I dropped the main down to 152. Took the uni-filter out and put in a brand new K&N. The results!!! NONE. Same exact atv, if anything the bogging at high rpms in 1st and 2nd gear was worse. Thing smokes so bad its amazing. Should I not be mixing this thing 32 to 1? Thats what I always mixed my last R and it ran like a champ. When and why would you mess with a pilot jet?

Beerock - I never took the top of the carb off, just changed the jet and took it out to see what it was like, hoping that would fix my problems. Got back to the garage and a bunch of friends were there asking to go for a ride so I went riding for about 5 hours with them and parked it. Never fouled a plug and didn't really run it that hard.

PJ - Dont even know what to look for. How will I know the reeds are bad? I think I'll check the needle before getting into that.

PS - did you get a chance to mail that other top end to me yet?

[slick250]

Originally posted by wilkin250r
No, it won't. It can't. It's physically impossible.

The piston draws in air through the carburetor and reeds. The piston motion is EXACTLY the same whether you are in 1st gear or 5th gear, whether you are going uphill or downhill.

The load and gear will affect YOU, and what throttle postion you're riding at. If you're going uphill in 4th gear, you're probably not at 1/4 throttle. Likewise, if you're going downhill in 1st gear, you're probably not at WOT. But it can still all be boiled down to throttle position and RPM. There is nothing at all in the fuel/air pathway that is connected or dependent upon the transmission.

It's like saying your quad runs good in the sand, but it runs rich and bogs on pavement. It's not possible.

I wondered if I would get any heat over this one. I have worked as an auto tech for 17 years and own my own shop now. I have seen a few things. This theory applies to all engines. I have seen many vehicles that have either fuel or ignition misfires that only show up in high gear (absolutely no sign of trouble in lower gears). The engine will require different fuel management in a higher geared situation. This can been seen in fuel injection mapping sequences. Take a scanner with a vehicle and moniter RPM, MAF, and MAP data in first or second gear, then get that thing up to highway speed in fourth at same RPM and throttle position and notice the difference in MAF and/or MAP readings. This difference requires a difference in injector pulse width mapping.
I realize I am comparing a fuel injected engine to carbuerated, but the principle is the same.

[250RGUY]

Yeah, I'm about as much as a machanic as Andy Dick, so how about we keep it simple. lol Oh, and I cant get the dang needle out of its housing.

[beerock]

im not helping anymore, i asked ya to check your needle and reeds, you still didnt, i dunno why but good luck

[250RGUY]

Thanks for trying to help me anyway. I told you I cant get the stinkin needle out of its housing. I took the lid off, needle and housing pull up. Cant read what kind it is, cant get the needle out, cant even see what setting its on. What does the brand of needle have to do with anything anyway, the stock needle for a 38mm AS carb is no good? I've never checked reeds so I wouldn't know if they are in good shape or not, how can I tell? Whats the best reeds to buy if these are shot?

[wilkin250r]

Originally posted by slick250
I The engine will require different fuel management in a higher geared situation. This can been seen in fuel injection mapping sequences...

...I realize I am comparing a fuel injected engine to carbuerated, but the principle is the same.

It's not a fuel-injected vs carbureted issue, it's more of a Automobile vs ATV issue.

You are looking at designed and INTENTIONAL differences. The engineers specifically designed the fuel mapping to optimize desired characteristics. In lower gears, they optimize power delivery for acceleration, but the higher gears are optimized for long-term running, reliability, heat, and fuel management.

A fuel-injected automobile is infinitely more complex than your ATV engine. In a car, those adjustments are possible, changing fuel mapping, ignition advance, ect ect. The designers intentionally added those adjustments so they can use them. I would venture to say it's those adjusements that are giving you differences in your readings, not the gears.

Your ATV engine doesn't HAVE those adjustments. It doesn't adjust spark advance based on your gear, or injector pulse mapping. It's all about airflow through the carb. At any given throttle position, there are two and ONLY two factors that determine how air is pulled through the carb. That is the piston motion, and the pipe effect, and these factors are not dependent upon the transmission. Whether 1st gear or 5th gear, the piston motion is identical, as are the pressure waves bouncing around the pipe.

[slick250]

I know what you are trying to say, however, I never said the transmission was directly related other than the load stress accomplished with a higher gear.
A quad will NEVER see the load stress in 1st gear that will be accomplished at 6th gear pinned.
It is this relationship that I am trying to establish.

Also the fuel mapping is designed special for any gear/load situation for one goal....to maximize efficiency.

[slick250]

Originally posted by 250RGUY
Thanks for trying to help me anyway. I told you I cant get the stinkin needle out of its housing. I took the lid off, needle and housing pull up. Cant read what kind it is, cant get the needle out, cant even see what setting its on. What does the brand of needle have to do with anything anyway, the stock needle for a 38mm AS carb is no good? I've never checked reeds so I wouldn't know if they are in good shape or not, how can I tell? Whats the best reeds to buy if these are shot?

There may be better needles out there, but the factory needle is just fine for most engines. You will have to pull back the spring to get the needle loose....very simple.
As for the reeds, if you can see very much daylight coming in around the edges when you hold the cage up to the light, replace them. The petals should be tight to the cage.

[250RGUY]

Ok I'm back on this dang issue. I bought this thing 2 months ago and yesterday was my 2nd time riding it. I seriously have no time to do anything having just got married and building this house. Anyway. I took the main jet all the way down to a 152, didn't check the pilot. Thing still smokes like crazy. We went to the local drag strip and rode it WOT about 5 trips. I fouled 2 plugs. WTF?? 152 is still too rich???? Rainy day tomorrow, not much planned. The Reeds and Needle will get checked. I cant believe its running rich with a 152 main.

[wilkin250r]

What kind of diagnostics have you done on this thing? Did you check compression? Leak-down test? And we still haven't heard any results on checking those reeds...

[250RGUY]

No diagnostics because this motor is brand new, top and bottem. I said I'm taking the reeds out today, i'll let ya know.

[slick250]

Check the float level in the carb. If it is too high, it will run rich even with a smaller than normal jet.

[250RGUY]

The float looks fine, seems to be perfect actually.

The reeds actually had dirt and stuff in them from the guy I bought it from racing in this red clay crap. I cleaned them up as best I could. The space looks ok, no daylight. I put them back in and took it for a ride, still bogging in 1st and 2nd when WOT until powerband. I guess I could go lower on the jet but that will put me in the high 140's, which seems way to small. Its running like a champ otherwise. I just really want that 2 stroke snap and i'm not getting it until 3rd gear powerband, which is pizzin me off.