1997 RM125 - Rebuild (lots of pictures)

[Bumperlt]

I can describe it real easy. Comes out almost dripping with spooge.

[Pyramid Kid]

Well then your way too rich. Order up some main jets probably like 3 or 4 sizes smaller than what is in the bike currently and start going down in size one at a time. Plus like I mentioned before you will need to adjust your jet needle or at least pull it out to see where its at. But if you pull it out you may as well adjust it.

[Bumperlt]

High throttle is when it runs good, so it's not the main jet. I pulled the needle and it was on the 3rd clip, im moved it to the 4th. That made the throttle response sooo much better.

I also got some slow jets. It had a 55 in there, and I bought a 52 and 50, the 52 made it a little better, the 50 made even better, but it still has a little bit of a hesitation at low throttle, but i havent ridden a lot of two strokes, I know they needs to be revved a little mroe and I have a feeling im riding it a little like my 250f. Plastics also came today, hooray. There is a lot less spooge and the spark plugs look real good. But I havent had enough time to ride it around to really see.

Is it unheard of to drop below a 50 slow jet on a 125?

[mihylo33]

High throttle is when it runs good, so it's not the main jet. I pulled the needle and it was on the 3rd clip, im moved it to the 4th. That made the throttle response sooo much better.

I also got some slow jets. It had a 55 in there, and I bought a 52 and 50, the 52 made it a little better, the 50 made even better, but it still has a little bit of a hesitation at low throttle, but i havent ridden a lot of two strokes, I know they needs to be revved a little mroe and I have a feeling im riding it a little like my 250f. Plastics also came today, hooray. There is a lot less spooge and the spark plugs look real good. But I havent had enough time to ride it around to really see.

Is it unheard of to drop below a 50 slow jet on a 125?

Print this out.

It should be around 100* and 6000' ASL for a 50 pilot.....

IS the carb clean and the float height set properly???

[Bumperlt]

Interesting I have not seen that chart before. Where is it from?

As far as elevation and temp, its no where near 100 degrees and im no where near 6000ft. More like 50 degrees and 1000ft max.

That said, It's just flat out running a lot better after the adjustments I made. Id like to get a 48 slow jet just to see what kind of defference it would make.

The float hight is set properly and I have cleaned the carb mutliple times. I'm gong to pull it off agan tomorrow and clean it again cause it's not idleing again.

Ive said it a couple times before but I had to bore it out to 56mm (stock is 54) so I don't know what kind of difference that is making.

[aakmetz]

Interesting I have not seen that chart before. Where is it from?

As far as elevation and temp, its no where near 100 degrees and im no where near 6000ft. More like 50 degrees and 1000ft max.

That said, It's just flat out running a lot better after the adjustments I made. Id like to get a 48 slow jet just to see what kind of defference it would make.

The float hight is set properly and I have cleaned the carb mutliple times. I'm gong to pull it off agan tomorrow and clean it again cause it's not idleing again.

Ive said it a couple times before but I had to bore it out to 56mm (stock is 54) so I don't know what kind of difference that is making.

if you have to keep cleaning your carb, maybe there's crap in your tank, did you ever pull the petcock and check the screen? plastic tanks shed small fibers.

[mihylo33]

if you have to keep cleaning your carb, maybe there's crap in your tank, did you ever pull the petcock and check the screen? plastic tanks shed small fibers.

Good thinking:thumbsup:

[mihylo33]

Interesting I have not seen that chart before. Where is it from?

As far as elevation and temp, its no where near 100 degrees and im no where near 6000ft. More like 50 degrees and 1000ft max.

That said, It's just flat out running a lot better after the adjustments I made. Id like to get a 48 slow jet just to see what kind of defference it would make.

The float hight is set properly and I have cleaned the carb mutliple times. I'm gong to pull it off agan tomorrow and clean it again cause it's not idleing again.

Ive said it a couple times before but I had to bore it out to 56mm (stock is 54) so I don't know what kind of difference that is making.

2nd page of the FAQs sticky is where the charts are.

I would think that with boring out you would need to be fatter in the jets.

Maybe you have an air leak and don't know it.

[2strokecrazy]

High throttle is when it runs good, so it's not the main jet. I pulled the needle and it was on the 3rd clip, im moved it to the 4th. That made the throttle response sooo much better.

I also got some slow jets. It had a 55 in there, and I bought a 52 and 50, the 52 made it a little better, the 50 made even better, but it still has a little bit of a hesitation at low throttle, but i havent ridden a lot of two strokes, I know they needs to be revved a little mroe and I have a feeling im riding it a little like my 250f. Plastics also came today, hooray. There is a lot less spooge and the spark plugs look real good. But I havent had enough time to ride it around to really see.

Is it unheard of to drop below a 50 slow jet on a 125?

my stock jets on my kx 125 are 40 /160 so i would think 50 is not too low...

[Bumperlt]

At one point there was a lot of crap in the gas tank, I noticed after some got sucked into the carb, So i took the petcock out and blew air through the filter, and also cleaned the gas tank out.

I guess it feesable that there could be an air leak but I don't see where. Ill investigate.

As far as jetting, FMF's jetting for a 98 rm125 is 50 slow and I think 165 main, which is what I've got in there now. I don't know how big of a difference it makes in jetting but I've got a fmf fatty and a fmf shorty.

[Pyramid Kid]

An air leak would cause a lean condition

[mihylo33]

An air leak would cause a lean condition

Yes Normally it would. Airleak as in bad rightside crank seal or bad reeds. I should be more clear when I answer. Thanks for pointing that out:thumbsup:

[Bumperlt]

crank seals are brand new, but i did reuse the reeds. They looked pretty good although I don't know what bad ones look like.

I let it sit yesterday for about 5 minutes with the throttle at about 1/8th leaned against the wall and the silencer had a stream of spooge going down it, so even with the 50 slow jet, it seems to still be running lean. I am going to try and move the clip up the needle another spot and see if that helps, if not I guess im going to get a few smaller size slow jets.

[mihylo33]

crank seals are brand new, but i did reuse the reeds. They looked pretty good although I don't know what bad ones look like.

I let it sit yesterday for about 5 minutes with the throttle at about 1/8th leaned against the wall and the silencer had a stream of spooge going down it, so even with the 50 slow jet, it seems to still be running lean. I am going to try and move the clip up the needle another spot and see if that helps, if not I guess im going to get a few smaller size slow jets.

Rattle me off a list of mods to the bike, the premix brand (pump gas?), current temp real quick

[Bumperlt]

Off the top of my head-

FMF Fatty

FMF Shorty

98 Carb (choke/idle in one)

UNI air filter

~40 degrees

Fuel is 91 pump 32:1 mixed with Maxima castor 927

Another thing i keep meaning to mention is that from what ive read, a properly jetted two stroke wont smoke much after it's warmed up. This is not the case with my bike, it smokes all the time. Sometimes more than others, but theres always smoke.

[mihylo33]

Has the pipe been cleaned and the packing replaced?

Very weird I bet the Jetting would be leaner with the mods you have.

[Bumperlt]

No and no. Hadnt thought of that. I will look into it.

I moved it to the 5th clip and it seems to do even better than it was. i still need to jump on a different 125 so i know what its suppose to feel like.

Here's how she sits now, getting closer to ridable. (need rear fender, rear sprocket, rear tire)

EDIT: Im suprized, it look s a lot better in that picture than in person. Ha.

[aakmetz]

No and no. Hadnt thought of that. I will look into it.

I moved it to the 5th clip and it seems to do even better than it was. i still need to jump on a different 125 so i know what its suppose to feel like.

Here's how she sits now, getting closer to ridable. (need rear fender, rear sprocket, rear tire)

EDIT: Im suprized, it look s a lot better in that picture than in person. Ha.

if you're in the 5th clip, then its time to change needle size.

[Bumperlt]

If i needed to go richer than the 5th clip then I need a new needle, but if its kosher on the 5th why replace the needle?

[aakmetz]

If i needed to go richer than the 5th clip then I need a new needle, but if its kosher on the 5th why replace the needle?

because having a more gradiual pull on the needle will transition the mixture over a broader width of the throttle, in the 5th position you're lifting it right away, and your needle taper is all used up, in a higher position the taper will feed gradiually through the throttle, making it a smoother feed from idle to WOT. Just a guess, you need 1 or 2 richer on the needle size and put the clip in the center, But, before making any jetting change, i'd suggest new reeds, check out Boyesen, they have the jet specs to match the bike and reed type. and their set up is pretty much dead on.