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01 RM125 No Top End Bogging

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Well I just got an 01 RM125 from a co worker. He purchased it about a year ago and it has never really ran right.

He replaced the piston and rings and had the cylinder replated as well as new v-Force reeds. It still didn't run right.

It starts up great and idles great. You can ride it around slowly with no problems at all. And then when you get on it it acts like its going to take off and then it just doesn't. I assumed it had to be the Main Jet and I thought it would be an easy fix. He was tired of it being in the garage and didn't want to put any more money into it so I bought it.

I brought it home and bought a brand new filter for it picked up a few jets and went from there.

It as the following.

Brand New Uni Air filter

FMF Fatty Pipe I think can't remember which one for sure right this second

Factory Silencer

430 Main Jet stock is 460

27.5 Pilot Jet stock is 27.5

Needle in second clip

130 Compression

BR9ES Plug Came in the bike

I'm not sure where to go form here. It seems like its just to rich but I can't imagine that I would need to go much leaner on the main but I am getting dripping spooge out of the pipe.

I've read that maybe it could be a crank case seal but is there anyway that I can verify this before pulling it apart? Or is there anything else that anyone can suggest to check. I don't know if its using oil because I haven't riden it long enough to tell. When I took the plug out the other day it was dripping but when I wiped it off it was the perfect mocha color that I would expect from a great running bike.

So any suggestions?

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Power valve seems to be working as when the bike is reved you can see the arm rotate when the cover is off.

and the needle is a 6BGY23-75 not sure if this is stock or not

slide is a 5.75 which I not sure what stock is on this either

Float height level looks to be ok but I haven't measured it

V Force Carbon Fiber Reeds appear to be brand new

I do not have a manual yet.

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Maybe the carb...holes ...are blocked and need to be blown out ( with compressed air).

Like take out the main jet ...blow out the hole...until you feel it come out somewhere.

Same with the pilot jet...and anything else.

If it is a r/s crank seal...............then...it will lose oil from the transmission. The crank will pull it in........you could lose 250ml in an hour worth of riding......also have someone follow you or at least watch you ...when you ride..........and they can tell you if you are smoking excessively.

Dissassemble the petcock....and check for clogged or fouled up areas.

good luck.

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I'll definitely check both of those things but it seems like both would make it run leaner and it seems as if it is running way too rich.

One interesting thing though is for some reason the petcock is on the tank backwards which I planned on fixing as soon as the tank was out but since it isn't running I may just dump it and turn it around and start with some fresh gas. I guess though it maybe could have something to do with it. I'll check that tomorrow.

Thanks for the suggestion. It definitely doesn't seem to smoke that bad. I may try to put together a little video of it running to make sure.

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On suzuki's the petcock lever is facing the inside....not outside, like a cr/f honda.

I also have a 05 rm-125.....it has the mikuni.......it leaks gas....out the overflow...I don't know why. Sporadically....but not constantly.

But it has the pro-circuit pipe....on it when I bought it......I checked jetting....went leaned on the main....similar to your jetting.....and left the pilot the way it was....not sure what stock is...or what size is in there currently.

But will start....with choke....and will idle...after warmed up. But not choke to idle..and sit....without blipping throttle.

So , that being said , I am no expert on the mikuni's ........just throwing out some ideas...

out.

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Thanks for the info. I really appreciate all of the help you can get here on TT. I'll post an update once I get to mess with it some more.

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The plug your bike came with is not the right plug. The original plug is about $28, but it is worth it. It can last 2 seasons easy if jetted right. Also, the compression seems to be on the low side. My 2001 was reading 155 cold. Start with making sure that the carb is clean. Also, try a 25 pilot. The float level should be 5mm. If that does not help, check to make sure that the exhaust valve is functioning properly.

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One thing that I forgot to mention was that the cylinder piston and rings were sent off to have the cylinder replated and fitted to the piston and rings and the bike has barely been ran since. I replaced the right side crank seal. I ran the bike only for a few minutes afterwards and it still seemed to be lacking top end power. It doesn't really bog down it just doesn't take off. It sounds like it's getting on the pipe (if that's what you call it).

Also it seems to run a little better up top when the choke is on. Which leads me to think that maybe I have an air leak somewhere. There are two things that I have noticed about the bike which I think could definitely contribute to the problem.

1. After shutting it off tonight it sat in the garage for about 10 minutes and I noticed a puddle of gas underneath the bike and after further inspection it seems to be coming from where the bowl comes off of the carb. So I'm going to order a new seal for that.

2. The throttle cable has now come off of the slide twice. The first time I just fixed it because I had just put the carb back on the bike and I figured I just didn't get it in there well enough. Now the second time I now that it was in there and then I noticed that there is quite a bit of slack in between the top of the carb where the cable enters and the end of the cable housing. There is not enough adjustment to take this up and then I started looking at how it connected to the carb and something seems like it may be missing. Is it possible that I'm sucking extra air in there as well?

Here is a pic of what the plug looked like after a few minutes of riding. Granted it wasn't brand new before I started but it almost looks lean if you look at the insulator but the outside threads are dripping wet. I'm not sure what to think of it.

IMG_20111116202049.jpg

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