What's this all about?

[XR100rRida]

I just bought my 2002 kx100 two days agoe (10/30/02) and it ran good in teh begging. Like first hour/half i rode it (for the break in). Now it takes off good but right before it hits the powerpand it starts to sputter and feels like there is absolutely no power at all. We're gonna try a hotter plug tomarrow. I think it's a little rich. Would a new plug fix this or do i HAVE to rejet it? I really don't know how to jet. My dad is a mechanic and can do it with instructions. Prolly doesn't even need any though. Would a hotter plug fix this or do i have to rejet it? Lean it out or richen it up?

P.S. the riding conditions are between 35-50 degrees. Barely rarely does it get to 50 though. so in actuality abou 35-45 degrees.

 

[cr25096er]

yes there is a br10.5evx or something plug in it and unless your jetting is right on it will foul if not completely it will just run crappy at high rpms. my friends did it(lasted like 2 rides) then he put a b9es and has been trouble free since.

 

[XR100rRida]

io bought some new plugs. a new standard and a 9. It says NGK BR9EVX. I bought a NGK BPR9EVX. It says platinum on hte box. Is that what the p stands for. Will this plug work fine/ is it the same as a BR9EVX?

 

[RanMan]

Sounds like your plug is loading up. It can possibly do this even if jetting is on if you lug it too much. Need to let her rip every now and then to clean out.
Could also be too rich. They are very sensitive to jetting. In a sense, you need to jet it according to what and how you ride it. If you are gonna be on trails mostly and be lugging it alot, then you need to jet it leaner than you would if you are gonna be on the track to where you are wide open most of the time. I had to lean my son's YZ85 down alot and go to one hooter plug because of this. I still think I need to go a little leaner. Better on engine if you can stay just a tad on the rich side, but not too much. Keep us posted.

 

[Fred T]

I'm the guy that bought your XR for my daughter. What you describe can be one of 2 things. I want to be cautious here so I don't give you bad information.

1. Your bike may be running rich causing it to run poorly just before the midband hit occur. Loosen the carb boot clamps on both d\sides and spin the carb so the top is pointing toward you and unscrew the top where the cable go's in. Pullout the slide and drop the needle jet 1 notch (Raise the clip) That will cure it if it's rich. BUT!>>>>>
2. If you are suffering from a lean bog the above will make it worse. If it gets worse then move the needle the other way. (Raise the clip 1 spot from stock -take note of where stock setting is)

Cold weather tends to lean out the jetting from warmer because the air is more dense and the bike gets more air. So you got to be careful with leaning it out when it's cold. When it sputters did you look at the spark plug to see if it's black?

 

[whyzee]

To be certain that your problem is lean, pull on the choke and see if the problem gets better or worse. This will affect ALL circuits.
If better, your problem is a lean condition.

 

[XR100rRida]

Hey fred My carb hits my frame when i try and twist it. any way around this??

 

[23jayhawk]

If you're having trouble getting at the top of the carb, you might want to slip the tank & seat off. That way you will have an open look at what you're doing, and how it all goes back together.

Without having a KX to look at, can't tell you if you need to remove the carb to get the top off. Wouldn't expect that to be the case, though.

 

[XR100rRida]

ok i got the slide out. How do i know when i moved it? will it click? It's in the 4 stock. So to move the click leaner i move the clip to 5 right? How do i know when it clicks? Please hurry. I wanna get it done by the end of tonight.

 

[XR100rRida]

ok now all i need to know is how to move it?

 

[minifig-phil]

XR100rRida you now should change your user name to KX100Rida

 

[XR100rRida]

ok i did what fred said (the first thing) and since i fouled 2 plugs. 1 stock plug and one hotter plug. should i move the jet bakc to stock or what.

 

[23jayhawk]

You may not have done exactly what Fred was suggesting. He said lower the needle, by raising the clip up one notch (toward the top of the needle). One of your posts indicated you were planning on moving from #4 to #5, and with the standard numbering convention that would mean you went from the second from the bottom to the bottom notch, which will raise your needle. If you were rich before, you'll be going in wrong direction. So you may want to first clarify that situation.

Also, where and how were you riding when you fouled the plugs? Slow idling, part throttle in the woods? Or more wide open stuff? You're in Michigan, and I know you guy's have some high speed trail up there. Did you foul the second plug soon after installing it, before the end of that ride? Or after the engine had cooled off & during your next ride? Possibly you're cold fouling the plugs on start up, which would indicate a very rich pilot jet.

If you bought your bike new (you mentioned break-in riding), ask your dealer for a suggested main & pilot jet. And also have him tell you what came stock in your bike.

 

[XR100rRida]

ok i moved it to the 3rd postion not the 5th. someone from db.com told me that. Well the first plug i started it up the night after i rejeted it and after letting it warm up i went down the street and back and well did make it back before i foulde it. then the second one i installed it and ran it 5 minutes after rewrming it up and ran fine. then i took it out on the trails and we rode for about 2 hours. since i have a 10.5 plug in i ran it in a gear lower than normal so it's in the higher rpms. well we came back for a rest then went back out. on the way out i forgot to put my goggles on and stoped put them on and went to take off. when i took of it died right away and i fouled my plug. so i put another one in and rode andother 30-45 minutes and did fine. should i run a 9. that's the first plug that i fouled. would an 8 be ok. we picked an 8 up for my dads bike in case and could i use that.

 

[XR100rRida]

o yea my dad has a 2002 kdx200

 

[23jayhawk]

Well, if you rode 2 hours in the woods with no problems, you're probably fairly close on the needle position. Sounds like you fouled 2 plugs either during startup, or idling, so the pilot may be the suspect.

The reason I suggested getting the jetting combo from your dealer, is that gives other KX100 riders a baseline for where you're at. You can also take your carb off & remove the float bowl to find out yourself.

I'm not a big fan of chasing jetting issues with heat ranges; again, other KX100 owners may have suggestions there.

 

[nikki]

XR100 - If you're not revving the heck out of the KX100 - go ahead and try an 8 plug. Especially since you're riding trails. It is a hotter plug and will reduce your fouling problems. I fouled two of the stock R6252K-105 plugs in my last KX80 and switched to BR8ES's and never fouled another plug again. I went to an 8 because I was not running the bike at high rpms.

Now if you start riding more wide open riding (like MX or open fields or whatever) and having the bike at higher rpms for a longer amount of time, you might want to switch to a 9 plug.

 

[KelvinKDX]

Originally posted by nikki
XR100 - If you're not revving the heck out of the KX100 - go ahead and try an 8 plug. Especially since you're riding trails. It is a hotter plug and will reduce your fouling problems. I fouled two of the stock R6252K-105 plugs in my last KX80 and switched to BR8ES's and never fouled another plug again. I went to an 8 because I was not running the bike at high rpms.

Now if you start riding more wide open riding (like MX or open fields or whatever) and having the bike at higher rpms for a longer amount of time, you might want to switch to a 9 plug.

I've done the same thing that nikki mentioned with Wendy's KX100 - since she foulded one of her R6252K-105 plugs and all i had were pulgs for my KDX (BR8ES). Ever since then she has not fouled a plug. :) She rides mostly woods.

 

[CJ Rider]

Hey XR100- The needle doesn't affect your bike's performance at full throttle; your MAIN JET is your key to full throttle performance (refer to your manual). Since you mentioned that yer KX sputters (usually means rich) in the power band (close to or at full throttle), my guess is that you really need to change your main jet.

I ride a KX100 too and typically change the MAIN JET every time I change from a lower altitude (bigger jet) to higher altitude (smaller jet), or every time the weather gets significantly colder (bigger jet) or warmer (smaller jet). It's EASY and takes only five minutes tops.

Here's what you need: I got a small jet tool for under $5 at the bike shop to so that I don't even have to move the carb at all. That tool is simply a short stumpy-looking 6mm hex socket. Nuthin' special. You'll also need a 17mm closed or box end wrench and a 10 mm box end wrench. You'll also want a couple of extra main jets from the bike shop. The stock main jet is 138 typically for sea level. I carry that, plus a couple larger (for my aftermarket pipe) and a few smaller (for mountain riding).

Here's how: Turn your gas off. Take your 17mm wrench and unscrew and remove that thingy (technical term) on the bottom of your carb. Some gas will leak out of your carb for a minute or so. Stick that 6mm hex socket up into the bottom of your carb and unscrew the jet. The long-ish brass thingy that comes loose is your main jet and needle jet. Take that long thingy completely out into your hand. Now, put the 6mm socket over the main jet and use the little 10mm wrench separate the main jet from the needle jet. Replace the main jet with another one (I'm guessing smaller size to fix your problem). Then do the steps backwards. One note, don't tighten the brass peices too tight (just nice and snug) since they are very soft metal. Try to keep the parts dirt free (could cause carb clogging later). Remember to turn your gas back on (I forget all the time).

To check to see if the jetting is correct: Put in a new spark plug (I do use one that's a little hotter than stock). Ride around like a banshee for five or ten minutes. Stop the engine quickly after reving it up a bit more. Remove the spark plug and take a look. If the end is black and oily wet, this is too rich so try a smaller main jet. If it's white and flaky, this is BAD and too lean so try a larger main jet. If it's a nice brown carmel color and dry, they you GOT it! Note, it's better for your engine to run a little rich than to run lean. You could seize your engine by running it too lean.

I'll add this too: I started with a 32:1 pre-mix at first. Since I ride at altitude and my bike's broken in, I changed to a 36:1 or 40:1. It may not be as good for the engine, but I get better performance and less exhaust spooge. It's probably not the smartest thing to do.

I REALLY found that changing my main jet is THE KEY to keeping my KX100 running like a TOP! I also try to keep my (aftermarket for better airflow) air filter clean, change the gear oil often, and repack the pipe more often than you'd think (because it gets real spoogy in there and constricts airflow).

Sorry for the length of this.