Jetting Change

[f14rio]

I made a one clip change to lean out my fuel as I was going through fouled plugs every 20 minutes or so.

Can you guys tell me if the pictures of the spark plug look good? Before they were very wet and totally black. Now they are light and dry... I want to make sure that it isn't too lean...

http://www.rv7x.com/sparkplugs.htm

Thanks!!

 

[dank]

didnt look at the pics, but ideally they should be golden brown. think marshmallow.

 

[f14rio]

didnt look at the pics, but ideally they should be golden brown. think marshmallow.

Link not work dank? I didn't realize that I could just post the pics so I did that now and hopefully no link issues.

Well an update on this saga... as I noted in my first post that I made a clip change to lean it out, i then rode the bike for a good 30 minutes without issue. Took the pics that can be seen below. Plenty of crisp power except low end was kind of weak. Took it to the track today and my boy gets on it for no less than 2 minutes and the plug fouls!!

We are going to tear down the carb and clean it out and probably buy some new jets. Anybody have any advice?? I'm certainly no expert on this stuff... 1st time having 2 stroke bikes in 15-20 years

 

[dank]

i am no expert either, this is my first bike period, and im 17, but what ive heard is that there supposed to have a light golden color, whereas yours look darkish on one side and kindof wet.

 

[stainlesscycle]

is that a fresh plug? color doesn't look bad , but the ground strap looks beat up. is the electrode still square - or are the edges rounding?

 

[f14rio]

is that a fresh plug? color doesn't look bad , but the ground strap looks beat up. is the electrode still square - or are the edges rounding?

Yep fresh plug with about 30 minutes of time on it. Electrode is still square.

Funny thing is ... 24 hours later and 2 minutes into riding the plug fouls. Also... plenty of oil dripping from the exit of the silencer and runs the down the length of the pipe.

I am running 42:1 whereas the previous owner ran it at 32:1 without problems until recently.

I don't think I mentioned this earlier but it is a 125cc. Main jet is a 180 (manual says standard is 185). Got the clip on the needle on the 2nd notch from the top.

Any suggestions?

 

[cbutler]

I have a MC 250 that fouled plugs unless I road it "like I stole it" my problem was the float reset it and haven't put a plug in since.

 

[roostafish]

I'd advise to make sure the float is set correctly. If it drools with the bike leaned over on the stand, it needs to be reset.

Next I'd look at the airscrew. Turn it in all the way and see how many turns out it is set. A good starting point is 1.5 turns out from fully seated.

Check where your needle clip is. If it is in one of the lower settings, move it up. The needle will make the most dramatic changes in the way the bike runs, and it's simple to check.

I wouldn't think your main jet would be the source of your issues unless you're always running around WFO. The pilot might be a bit rich, but if it's fouling out in a half an hour, I don't think that's it either. You could easily lean it out a couple of steps to see if you don't get good results with the others.

There is a possibility that it's not jetting at all, but electrical, but with your description of the exhaust, likely not.

Another possibility, and this is an ugly one: If your right side crank bearing is leaking, transmission oil will leak into the engine as it runs, creating lots of smoke out the exhaust, and the smelliest, nasty, gross scent ever, not typical two stroke smell. That would be your clue on this option.

 

[wence]

Do what I did and check by riding not plug colour.
Put a 170 in and ride it on a flat open area, rev from closed to fully open, fast and slow to check for bogging etc.
Change main to 185 and recheck.
If nothing else you will get the feel for a too rich or too lean bike and you should be able to get it close by feel.
I did this and found it to be very good in the determination of the main jet.
All the best ,
Mark

 

[f14rio]

Well I think I will start with a rebuild kit and then buy some jets as well. It was leaking gas from somewhere yesterday after the haul home and then when I put it up on the stand so hopefully it's just the float thing. We shall see!

Next question... I can't find a data plate on the bike itself. It is a 2003 125cc and I am assuming it is a MC125. Looks just like an EC but doesn't have any lights... Am I right in my assumption? If so... is the carb the same as the EC which is a Keihin 38mm PWK??

Thanks for all your help everyone!!

 

[stainlesscycle]

the only difference would be ignition/flywheel and possibly rear wheel size i believe. carb should be the same.
seems to me 180 is a big main for a 125. what's the pilot at?

 

[f14rio]

the only difference would be ignition/flywheel and possibly rear wheel size i believe. carb should be the same.
seems to me 180 is a big main for a 125. what's the pilot at?

According to the 2003 EC124 manual on page 104 the standard main is 185 and the slow jet is a 38....

Mine are 180 and 45 respectively. Is the slow jet the one you are asking about?

 

[marjastaja]

Today I was on a local mx track and I was conserned about how hot my Gasser runs. Radiators were pretty hot compared to Yz 125 I rode yesterday.
The plug is dry and coloured black, looks like "dry fouled", the highest plug in the picture http://www.atlanticjetsports.com/TechTalk_Images/spKPlg_colorchart1.jpg
I tried to rise the needle 1clip from the 3rd to 4th clip from top. It didn't take rpm and was too rich to run good so I lowered it back to 3rd clip.

Should I be worry about? Last summer it was also like that and it runs good always. I just don't like it gets so hot. I run with 2,5 to 3% oil/fuel mixture.
I'm not sure about the jets, remember like the main jet is 160
Almost forgotten.. Gasser ec 250 2003 is my bike