[Joeb1983]

Yeah, I’m not sure and don’t mean to make a mountain out of a molehill here, but I just thought it was odd… Like I said, I’ve never run it before, so I guess I expected something different.

I spoke with a vender of Sunoco race fuels and he said it will start smelling like regular gasoline as it ages and that this could also have a lot to do with the way it was stored as well like Gif stated.

I purchased it from a Simons Petroleum here in Oklahoma City that is also supplied by Pilot Logistics. They supply race fuel for a vast majority of local and non-local racers. Although they did change the name to Simons recently if I recall… Still the same place, just a different name. (The company has since been purchased by Maxum Petroleum and gone public)

I spoke with them on the  phone with them and they said it should definitely have a race gas smell to it, but seeing how its leaded, it definitely wont be as sweet as my unleaded 101 due to the lead.

I threw some in my blower and the exhaust had a faint hint of race gas, but nothing that stood out like my 101. It ran perfectly fine and was actually easier to start. (Usually it is a PITA) Who knows… We will have to see I guess… Maybe Ill stick with the 101 and pay the extra $.

 

 

 

[Joeb1983]

I think I’ll hold onto the yz, but appreciate the suggestion. Thing is a blast banging through the gears! Plus I just threw a Hinson clutch kit in.

Just pulled all the RTV out and found the power valves were JB welded in place… Slowly chiseled them out. Ill clean it up even more with the dremel.

The push rod is still there and connected, so I ordered a excellent used power valve assembly/set with all the hardware.

Hopefully I’ll get it by this weekend and throw it in while rebuilding the carb. (Keihin 72R/39mm)

[Joeb1983]

Well, I am stationed in Oklahoma and the individual I purchased the kart from may or may not fit that description to the “T”… Haha!

I see plug kits all day long for the CR125, but nothing for the YZ125 (Probably why all the RTV) any out there that you (or anyone else) know of?..

I’d feel more comfortable with an actual R&D’d kit installed or seeing about the process of re-installing the power valve setup.

I know its a 2-stroke kart and not a dirt bike, but I was wondering why it had little to no low-mid power and the “light switch” effect was so drastic. (again, first shifter kart and learning)

 

 

 

[Joeb1983]

Update: ordered a JD kit. ended up installing a 55 pilot, 175 main, blue needle with the clip in the 3rd notch. Air screw 1-1/2 out.

(Kit didn’t have a 168 main, but came with a 162,170, 175 & 180)

17O was a little lean up top my buddy said according to the plug and 180 was a little rich.

She idles now and the idle screw actually works!

Low end cleared up nicely. No more bogging/hesitation. It’s now acting like a typical light switch 2-stroke. Lol!

Plugs is a light tan color after a WOT pull.

Thanks again for all the help guys!

[Joeb1983]

I really do appreciate it. I’ll head to the shop and grab the jets you recommended or order them if they don’t and a few other close in that range.

Thanks again. I’ll let you know how she runs. I’ll run through the carb again as well.

I should stay with the 3rd clip setting right?

I installed a new pump, lines and filter as well last week.

[Joeb1983]

The jets in it now are brand new (60 & 160) and I cleaned the carb.

I’m about ready to just order a OEM carb seeing how I know nothing about the history of this one.

Is the PWK 72 39mm to big for a 125? Also, are karts jetted differently than bikes?

Sorry for being a PITA. Just trying to figure this all out… Kinda frustrating. Lol!

All I know is it has a big carb on it, it doesn’t want to idle, the idle screw does nothing, it bogs hard when you first get on it, and it’s a rocket ship up top in the band.

I can bang gears all day long tbat way and it pulls hard. Just that horrible bogging down low when your not ripping it.

101 octane @ 32:1

[Joeb1983]

45 is lean for the pilot?. Most have been 42’s and 45’s I’ve came across for 125’s running Keihins (38 & 39mm)

The richest I’ve seen the main was 185, most were 170 – 180.

It’s apperant I’m confused… haha!

The 60 in it now I know is too rich. Even with the 50 it had in it before seemed a little rich as well.

It doesn’t like to idle and the idle screw seems to do nothing.

It bogs out of a corner for sure. Falls flat on its face… However, up top in the band it rips like I said.

I sent JD jetting an email as well, and I also know every kart/Bike setup is different.

Just trying to get it running right.

It’s been one thing after another and this is the LAST step. Everything else is paractically brand new…

[Joeb1983]

From all I gathered from the past few days of reading kart & bike forums, articles and sites for both the yz125 and cr125; is I should be in this ballpark:

Main: 170 – 180
Pilot: 40 – 45
Clip: 2nd or 3rd slot
Air screw: 1-1/2 to 2 turns out.

Like Matt said, fat on the pilot with the 60.

I’m throwing in a 170 and 45, 3rd clip, 1-1/2 turns out and see how that goes.

Like I said, the 160 and 60 was just a starting point seeing how that’s what the Keihin PWK 72 came with out the box.

[Joeb1983]

I’m stationed in Oklahoma and our field elevation is roughly 1,200 ft.

Just throwing that out there if that helps. Thanks for the replies!

[Joeb1983]

The clip on the needle was in the lowest/richest slot out of the 5.

It’s now in the 3rd/middle and I will just go from there.

I’m not sure why it was setup to run so dang rich…

Maybe it was a carb off something else and he just threw it on to sell it… Who knows?

Learning a lot though! So that’s a plus.

[Joeb1983]

Yeah, if been reading all about it the past couple days.

Did a compression test and it was good.

Dropped the jets down to Kehin OEM specs. 160 main and a 60 pilot.

This things top end now is a beast and pulls the front wheels off the ground!

Off idle it’s a dog though… Stuttering and bogging. Need to mess with the Air adjustment screw and if that’s not the case start looking into the pilot more.

[Joeb1983]

Just double checked. It actually has a #180 main and a #50 pilot…

[Joeb1983]

I kept the old pump and did exactly as you said by putting the new pumps caps on the old.

There was a small tear on one of the rubber discs.

Just finished running new coolant hoses and installed a new radiator and overflow. The guy who had it before had a Frankenstein job going on.

Throwing in a Hinson clutch kit tomorrow as the old is locked up. After that, it should be ready to rip again.

[Joeb1983]

It was the pump. Installed new lines, filter, pump and plug. Runs like a champ! Thanks all

[Joeb1983]

No plugs anywhere around; so I had to order them… (NGK 3530 B9EG)

I got it started again. It dies even while nursing the throttle after a while, but not more runaway idle!

Pulled the plug after it dies and it was wet (reason why it wouldn’t start before I’d take it) , cleaned the plug and started it again, same outcome – wet plug… Rinse and repeat.

So now at least now it looks to me its a fuel issue and not a bad gasket, seal, boot, crack, etc.

Could it just be that the carb was jetted for the pump style fuel system and that is why the gravity feed is causing it to run rich? (I would think the carb would only pull what it needed…)

Feel like I am on the right track though!

[Joeb1983]

Made a makeshift  gravity feed system out of the top of a 2 liter and drilled a hole in the cap a tad smaller than the line and wedged it in.

Added some fuel and the carb took in quite a bit.  (assuming it was filling the bowl)

Started it up as usual and noticed I actually had to burp the throttle periodically to keep it running, but I didn’t get to it quick enough due to having to add more fuel and it died.

Haven’t been able to get it to start since… I’m taking a break. Haha!

On a lighter note I did not see any indication of increased idle for the short time I did get to run it; so hopefully that’s a real good sign!

I did not have enough fuel line to on hand to run to a container from the pump however.

I capped the vacuum line that went tot the pump as well during this test and the carb was being fed a solid stream of fuel.

Ill try again here in a few with my brother in law and see how long I can run it having him on refuel duty… That is if I can get it to start again. I’m running out to grab a box of spark plugs.

 

 

 

 

 

[Joeb1983]

I got to thinking, since there are bubbles in the fuel line feeding the carb from the pump, air has the be being introduced somewhere…

Could these be a possibility:

1) Pump bad; causing air to be introduced via the pump housing or allowing it to somehow suck from the carb.

2) Vacuum port from the case; either not pulling enough vacuum to allow the pump to operate properly or actually intermittently allowing the opposite to happen  where air is being introduced from the port to the pump

The last possibility would lead me to believe crank seals or something along those lines… Just spit balling here as this has me puzzled. Sorry if I am being a pain.

I also thought about bypassing the fuel system all together and setting up a temporary gravity feed system and see how that plays out.

Like I said, I will mess more with it tomorrow. Pick up a gauge and some T-fittings.

 

 

[Joeb1983]

^ Oh, I pulled the air filter off as well and the slide is staying down and not creeping up. Ive checked the throttle cable tension, needle and seat.

I also only have one pump with 3 connections. Fuel in, fuel out and the vacuum line.

Throughout my Google research I am coming to the conclusion it is leaning out obviously; whether It be related to lack of fuel or an air leak.

Ive read about everything from as simple as a carb boot to more in-depth crank seals. I sure hope its something simple such as  a pump or float adjustment.

[Joeb1983]

Thank you for the response!

I just started it again today after work. Started on the 4th pull. As usual idle crept up. I tried to let it run like that for longer than I usually do to see if things would calm down, but It did not and I ended up killing it.

I tried spraying carb cleaner around the carb, boot, reed area and both sides of the engine in hopes of a change in RPM but there was not.

I checked all the fuel and vacuum lines for any holes or chafing. There was some chafing on the vacuum line from the pump to the case due to it resting on the chain gaurd, but nothing was chaffed through.

I also tried restricting the the return (just because) with no difference as well and the gas tank is well vented.

If I blow in the vent tube from the gas tank and pressurize the system I can see fuel come out of the pump and feed into the carb in a MUCH better stream of fuel… It still crept up.

On another run I pulled the choke up and it amplified the effect 10-fold. I talked to a buddy at work and he said I might need to adjust the float. (he’s a big MX guy)

I do not see a fuel shut off valve anywhere, other than the choke lever on the carb. I definitely need to install a kill switch as I am just pulling the plug boot.

I will tackle it more tomorrow with all the tips you pointed out. Always something. Haha!

Like I said, this is all new to me and the only 2-strokes Ive ever had was a moped when I was a teenager and lawn equipment. All bikes, Atv’s etc. have all been 4-strokes.

Thanks again!

 

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