Jetting and Premix Questions

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kingsxjt

Member
Dec 7, 2003
116
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Been reading a bunch of posts here about jetting. I ride an 01 KDX200 and live in TN and ride from about 40 degrees up to the 90's. The bike appears to be jetted stock (no airbox lid, stock pipe and silencer with 160main, 48 pilot) based on its spooge and smoke level. I've been running 40:1 premix (Maxima Super M). I plan on going to 155 main and 45 pilot (seems to be what most everyone starts out with). I'd like to be on the safe side of things though and I am wondering about going to 32:1 when I rejet so as to have a little more lubrication to protect. Any thought comments or derragatory remarks would be appreciated. Thanks!
 
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Rhodester

Member
May 17, 2003
549
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I would stick with 40:1. What mods are you running? 155/45 might be slightly lean at 40 Degrees with a stock 200. It should be fine when things warm up a bit. If you have mods (reeds, pipe) it may be slightly rich still when it gets hot outside. 32:1 will lean your air/fuel mixture more than 40:1. More oil means less gas in the mixture, hence leaner.
 
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kingsxjt

Member
Dec 7, 2003
116
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I understand that rich and lean are referring to gas and not oil, but won't more oil mean more protection against seizing. Clip position should be 3rd from the top right? Several other guys that ride at my temps and altitudes run 155/45 with aftermarket pipes. I only have the aibox lid removed, stock pipe and stock silencer with Twin Air Filter.
 
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Braahp

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Jan 20, 2001
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Super M is a good oil. You could and should use it at 40:1 with it offering plenty of lubrication. Try this first...........raise needle clip one position up and use BR8EG plug. Shoud run pefect.
 
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yz250flash

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Aug 8, 2003
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Braap - so are you saying he should raise the needle or the clip? If he is currently at the third from the top are you saying he should go to the fourth from the top or second from the top?

Going to the 4th position would make it richer and the 2nd leaner


I am asking because I have the same jetting and I am going to try these suggestions also. I am in florida so I should be okay with these also correct?
 
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yz250flash

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Aug 8, 2003
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I am glad that you pointed that out. I was actually going to set it where it ran like crap. :laugh:
 
K

Kwakasaki

Member
Aug 22, 2004
167
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King,
I ride alot in Memphis TN is the same type temps. I do have a 220 with the smaller carb if this makes any difference. Ran 40:1 until broke in. Went to Klotz Techniplate at 32:1, fmf desert series pipe, made a frisbee out of the air box lid and went to a 155 main. Rode it like it was stolen, :ride: no spooge and plug looks great, check it during the first 10 minutes of every ride. I might have some more hidden power if I play with the clip and all the stuff you read but why, its screaming now. And with my luck, If I change the clip position, a tire will blow out :nener:
 
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John Harris

Member
Apr 15, 2002
552
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KDX's always seem to run better with the clip in the next to top position on the needle, thus making the needle lower down in the main jet to let in less mix=leaner. Leave your oil mix at 40 to one, but you probably will be happier with 100% synthetic oil (Maxima makes a great one). Based on my experience the 155 will be about right on the top end and will keep you from seizure problems. Again, based solely on what I have learned from my KDX you will be happier with about a 42 pilot jet. Everyone's engine is different and so are the conditions, but get close and you will be amazed at the difference. Cheers John
 
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Braahp

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Jan 20, 2001
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Raise the clip which would lower needle.
 
K

kingsxjt

Member
Dec 7, 2003
116
0
Haven't checked needle position yet. I am still confused about what you guys are saying about premix ratio. I think Maxima Super M is full synthetic. It's supposed to be smokeless...not!Kwakasaki said he ran 40:1 until he got it broken in and then went to 32:1. That seems bass ackwards to me? I would think you should run 32:1 at first and then 40:1 after you get everything settled in. I was trying to get more of a pro's and con's answer to running either ratio. I kinda think 32:1 is safer though. Hey Braahp, what's so special about the BR8EG vs. the ES (besides $4.99 a pop)? I kinda like your ideas about trying the needle position and the plug first and have used a good bit of what you said when respringing my front end. I used your and CC's advice in that area. Thanks again everyone!
 
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R

Rhodester

Member
May 17, 2003
549
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I use Mobil MX2T @ 40:1 (full synthetic). When I did my top end everything had a nice film of oil on it and no pooling anywhere. There was no excessive gunk build up on the KIPS or any of the other parts. It was pretty much what I expected to see from an engine jetted in the ball park of where it should be and running a proper oil ratio. If your oil is of good quality and jetting is close any more oil than what you need is just wasted in my view. I don't think it will offer any more significant protection to run more oil in the gas. Your jetting being off will add more complications to the quality of the combustion and lubrication then the difference between 32:1 and 40:1 in the oil ratio. However, you should fine tune your jetting to a specific oil ratio. 32:1 is a leaner fuel to air ratio than 40:1. Does this make sense?
 
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kingsxjt

Member
Dec 7, 2003
116
0
Rhodester, Yes. I fully understand that rich refers to fuel and not oil. Yes, 40:1 is richer (we're talking fuel not oil) than 32:1, but does not contain more lubrication. So you think 40:1 jetted properly will protect just as well as 32:1? I see what you're saying about proper jetting and a given oil ratio combusting properly being able to lubricate better. I was just trying to figure out which premix ratio would be safe(r). Sounds like 40:1 is the most popular ratio anyway, so that's what I'll go with. I'm still wanting to hear from Braahp about the BR8EG and simply raising the clip position (dropping the jet needle). Thanks for the great input! :)
 
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Braahp

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Jan 20, 2001
641
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The EG series are racing plugs with a fine wire center electrode of 1.3mm. ES regular plugs have something like a 2.0 to 2.5 mm electrode. The fine wire improves ignitability and acceleration. A smaller center electrode requires less voltage to jump the gap which means fewer misfires. This all according to NGK.........All according to me---they simply work better in my KDX. I'm in TN also and figure we might ride at same altitudes and humidity. I run stock jetting except for clip up one and the EG plug. I can foul ES plugs but with EG the jetting becomes spot on. I use lid off in summer but have to put it back on (it has holes drilled) in winter because its a tad on the lean side. I do use a FMF KG35 pipe and powercore 2. Stock reeds. Amsoil at 40:1 I change plug once a year just for the heck of it. Shows little wear but not much even after a year. I finally broke down and repacked my silencer after 3 years. I know...3 years is too long. I was pleasantly surprised to see very little oil in packing. Quite a bit of carbon but no spooge. Wow! Boy does it run noticeably better with fresh packing. I'll do this more often for sure now. I just suggested this because its simple. It might not be the answer for anyone else but this setup makes my KDX a fire breather! Give it a try. Its much easier than changing jets. According to all I've ever seen I must be only one in world that uses stock jetting. I've tried to go down thinking it might run better.......it didn't......too lean. Call me crazy but there is something special about the EG plug in a KDX.
 

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kingsxjt

Member
Dec 7, 2003
116
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Braahp great info! What position is your clip in? 2nd from the top? Is the BR8EG is "safer" than the BR7ES. I know it's a hotter plug than the BR8ES. Also, does adding an aftermarket pipe generally mean you flow better and require richer jetting?
 
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Braahp

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Jan 20, 2001
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Yep....2nd from top. The 7ES was a tad hot with my bike. Yeah the 8EG would be safer. The pipe.......yeah I'd say so.
 
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kingsxjt

Member
Dec 7, 2003
116
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Thanks Braahp. I'll give it a go today and let you know. For all who read this, I was wrong about the Maxima Super M. It is a synthetic blend. Which Amsoil premix are you running Braahp? I found a good place to mail order from and I really like their gearbox and fork oil, may try their full synthetic premix too. :cool:
 
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Rhodester

Member
May 17, 2003
549
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Going to an aftermarket pipe (and/or reeds for that matter) will mean that you'll need to jet even leaner than if you stay stock. In a 4-stroke if you improved the exhaust scavenging effect you'd need to go richer. In a 2-stroke other variables come into play because of the complexity of how the exhaust interacts with the combustion process.
 
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Braahp

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Jan 20, 2001
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Rhodester said:
Going to an aftermarket pipe (and/or reeds for that matter) will mean that you'll need to jet even leaner than if you stay stock.
Click to expand...

No......richer
 
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Braahp

~SPONSOR~
Jan 20, 2001
641
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Kingsxjt............I use Amsoil Dominator or series 2000 is what it was called. Same stuff new name.
 
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Rhodester

Member
May 17, 2003
549
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Braahp, I'm more than happy to be corrected if I'm in error, but this time I don't think that's the case.
 
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kingsxjt

Member
Dec 7, 2003
116
0
Richer makes more sense. Didn't get to fool with my bike yesterday, but will this week and try to post my findings. "Update"- Insatlled BR8EG tonight after checking float level and checking what jets were actually in the bike (bought it used). Saw that it had 160 main and didn't mess with pulling the pilot out (figure it's stock too based on no mods when bought except for the airbox lid gone). Also checked the clip position (2nd from the top). Is that stock clip position? Let me know if anyone knows.Fired it up and I immediately noticed a difference with throttle response. Definitely promising. Much crisper, but no ride yet due to the rain and muddy conditions here in God's country. Will give her a test ride A.S.A.P. Thanks!
 
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kingsxjt

Member
Dec 7, 2003
116
0
Gave the bike a test ride today. I just installed XR 400 springs and put in the BR8EG. I ran it in my yard (kinda soft from the rain Sunday) and all I can is say is that I'm Pleasantly surprised. Did a hard run from 1st and all I did was aeroate the yard from first to second and when I hit 3rd I was on it hard. :ride: Funny thing was the front end came up quick in 3rd! Before the bike would not come up in 3rd unless I REALLY tried. Man I wasn't expecting that! I think I'll be sticking with stock jetting and the BR8EG. I also order some Amsoil Interceptor premix from The Lubrication Specialists today. I liked the specs on the oil and the fact that it boasts keeping the powervalves really clean. Thanks Braahp for the heads up on that plug. :cool:
 
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O

OldTimer

Member
Feb 3, 2005
475
0
????? I'm like Kingsxjt, I don't understand the problem with leaner air/fuel mixture as long as you have richer fuel/oil mixture or vice/versa seems like a trade off? Which do you choose and why?
A little spooge is better than a little aluminum right?

BTW Kwak, I live in Olive Branch and am looking for places to ride. Got any 'honeyholes'?
It's hard as can be to get any kind of riding information around here if you're not in the loop, so to speak. :bang:
I too have little ones in tow, 7yr old on a CR50 and a 5 yr old on a JR50.
Around here, you can't get off the pavement unless you have a 'Bridgeforth connection'! :worship:
 
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