Coolster 125 Pitbike bogging issues - Page 3

dirtbkr188 · 10-02-2019, 08:35 AM

It probably won't hurt to pull the carb apart and clean it as well, if the debris was in the bowl, chances are it could still be in the carb passageways too.

Douglass · 10-03-2019, 10:22 AM

I had a similar problem on my 125cc Apollo ATV. You will need 5mm sized fuel line, and go to autozone or orileys to get a new filter. Take the carb apart, and blow everything out with carb cleaner. What I do after EVERY time I finish running the bike for the day is while the engine is running I drain the fuel bowl.

Hope this helps

Douglass

Here is the link for the fuel line I replaced the factory lines with.

https://www.ebay.com/itm/Motion-Pro-...72.m2749.l2649

dirtbkr188 · 11-16-2019, 08:46 PM

Were you ever able to get this sorted out?

Dusman · 11-16-2019, 10:21 PM

I’m sorry I haven’t gotten back on here. Been busy dealing with some health issues in the family. I’m currently rebuilding/cleaning the old PZ22 carb, putting new lines on, & cleaning out the tank. I should have it running by the end of the week. I’ll let you know how she goes.
Thanks so much for inquiring about what’s going on with this little bike. Y’all have been such a big help!

MooDog · 11-17-2019, 06:37 AM

I'm sorry if I missed it, but you got this bike new in a crate?
I've seen where people get these bikes out of box to find hella metal shavings in the fuel tank..

Dusman · 11-24-2019, 08:35 AM

Really? That’s just crazy. I didn’t get my bike in a crate, but bought it from a friend who’s grandson drove it for 2 minutes, wrecked it, and said it scared him and he didn’t want to get back on it. I think the bike sat for a long time before I bought it, and as you know, motorcycles sitting for extended periods of time and not being ran will totally screw up carburetors, especially if you’re using regular fuel. Moreover, I don’t think this bike was ever properly prepped, so I’m left going back and doing that. The valves alone were so tight I’m surprised the thing ran!

motoracerx · 01-21-2020, 08:10 PM

@Dusman....any updates?

Dusman · 03-07-2020, 09:01 PM

FINALLY the weather is decent enough here to get the 125 Coolster pitbike back together today (I don't have a garage). Here's what I did and here's what happened:

1. Ultrasonically cleaned the carb and rebuilt her. I left the 98 main jet in.

2. I rebuilt the entire fuel system (i.e., new lines, new inline fuel filter) and cleaned the tank thoroughly. The dang line out from the tank had a pine needle in it! No wonder the thing was behaving like it was starving for fuel at times! The tank was filthy and had various junk in it. The kid that owned it before apparently, at some point, left the gas cap off or something and some trash got in that tank. The old fuel filter was filthy. I'm amazed the thing ran at all.

3. I got her all back together, got her fired up, adjusted the air/fuel mixture screw, the idle screw, and she starts right up now.

HOWEVER, she still seems to want to bog down a little when you get to 3/4 to full throttle. When I ran her up the street tonight, again after running her full throttle, she ran well, but she didn't run long. She started bogging down and just wanted to cut off and then finally did, even when I let up on the throttle.

It is indeed as if the valves swelled (or something expanded) and the internal engine dynamics changed. That's quite weird considering right before I wintered her I adjusted the valves to spec. I even double-checked them to make sure I did it correctly.

She'll run ok for the 11 year old, but if you really want to open her up, she's just gonna act funny until I can get this figured out.

Dusman · 03-29-2020, 09:39 AM

I wanted to post a final update here on the Coolster 125cc Pitbike.

With the extensive help from dirtbkr188, I adjusted the Xjoy carburetor (a Molkt PZ22 Keihin/Mikuni mix clone) up one side and down the other and just never could get it to run correctly. I purchased a genuine Mikuni back in October, but really wanted to try to get this cheaper carb to run right for the purposes of getting a better carburetor education.

However, after cleaning, rebuilding, rejetting the Molkt every which way but loose, and trying just about everything, I simply couldn't get it to run right after hours of working on it.

Yesterday, after working on it for a few more hours, I took a break, got some lunch, and said, "I've worked enough with this clone; I'm putting the Mikuni on."

The Mikuni came factory jetted at a 95 main and 15 pilot, which should have been about right for our elevation.

I put her on, gave the bowl time to fill up, and she fired up on the first kick. The idle was *ridiculously* high, so I turned the idle screw out and it still didn't seem to want to idle at a proper rate. I took the Mikuni off and made sure that the jets were seated properly, the needle wasn't floating around, and that there wasn't something I overlooked, such as a vacuum leak at the intake manifold or the pod filter. I tightened everything back down, fiddled with the idle screw a bit more (it's a weird one, never seen anything like it), and finally she started to settle down.

She runs like a top now and will get up to @ 42 mph (GPS confirmed). No bogging, no hesitating once she's warmed up, and she truly runs like a champ with that Mikuni on. I'm not exaggerating when I say this, but if you buy a Coolster 125cc pit bike and you're having bogging issues, I'd recommend just going ahead and purchasing a PZ22 Mikuni or getting this kit from t-boltusa.com:

https://tboltusa.com/store/mikuni-22...nis-p-107.html

Below are a few videos of the information and some seat-time action. In these videos, I put them together to update dirtbkr188, who has been a *tremendous* help through these last 6 months. That dude has given me a "college education" on carb tuning! Seek him out if you are serious about tuning your bike. He is a huge help and enjoys teaching other folks how to do this:

03-07-2020, 09:01 PM	#38
Dusman Join Date: Jan 2018 Location: NC Posts: 203	Update FINALLY the weather is decent enough here to get the 125 Coolster pitbike back together today (I don't have a garage). Here's what I did and here's what happened: 1. Ultrasonically cleaned the carb and rebuilt her. I left the 98 main jet in. 2. I rebuilt the entire fuel system (i.e., new lines, new inline fuel filter) and cleaned the tank thoroughly. The dang line out from the tank had a pine needle in it! No wonder the thing was behaving like it was starving for fuel at times! The tank was filthy and had various junk in it. The kid that owned it before apparently, at some point, left the gas cap off or something and some trash got in that tank. The old fuel filter was filthy. I'm amazed the thing ran at all. 3. I got her all back together, got her fired up, adjusted the air/fuel mixture screw, the idle screw, and she starts right up now. HOWEVER, she still seems to want to bog down a little when you get to 3/4 to full throttle. When I ran her up the street tonight, again after running her full throttle, she ran well, but she didn't run long. She started bogging down and just wanted to cut off and then finally did, even when I let up on the throttle. It is indeed as if the valves swelled (or something expanded) and the internal engine dynamics changed. That's quite weird considering right before I wintered her I adjusted the valves to spec. I even double-checked them to make sure I did it correctly. She'll run ok for the 11 year old, but if you really want to open her up, she's just gonna act funny until I can get this figured out.
	0

03-29-2020, 09:39 AM	#39
Dusman Join Date: Jan 2018 Location: NC Posts: 203	Finally...Mikuni PZ22 success! I wanted to post a final update here on the Coolster 125cc Pitbike. With the extensive help from dirtbkr188, I adjusted the Xjoy carburetor (a Molkt PZ22 Keihin/Mikuni mix clone) up one side and down the other and just never could get it to run correctly. I purchased a genuine Mikuni back in October, but really wanted to try to get this cheaper carb to run right for the purposes of getting a better carburetor education. However, after cleaning, rebuilding, rejetting the Molkt every which way but loose, and trying just about everything, I simply couldn't get it to run right after hours of working on it. Yesterday, after working on it for a few more hours, I took a break, got some lunch, and said, "I've worked enough with this clone; I'm putting the Mikuni on." The Mikuni came factory jetted at a 95 main and 15 pilot, which should have been about right for our elevation. I put her on, gave the bowl time to fill up, and she fired up on the first kick. The idle was ridiculously high, so I turned the idle screw out and it still didn't seem to want to idle at a proper rate. I took the Mikuni off and made sure that the jets were seated properly, the needle wasn't floating around, and that there wasn't something I overlooked, such as a vacuum leak at the intake manifold or the pod filter. I tightened everything back down, fiddled with the idle screw a bit more (it's a weird one, never seen anything like it), and finally she started to settle down. She runs like a top now and will get up to @ 42 mph (GPS confirmed). No bogging, no hesitating once she's warmed up, and she truly runs like a champ with that Mikuni on. I'm not exaggerating when I say this, but if you buy a Coolster 125cc pit bike and you're having bogging issues, I'd recommend just going ahead and purchasing a PZ22 Mikuni or getting this kit from t-boltusa.com: https://tboltusa.com/store/mikuni-22...nis-p-107.html Below are a few videos of the information and some seat-time action. In these videos, I put them together to update dirtbkr188, who has been a tremendous help through these last 6 months. That dude has given me a "college education" on carb tuning! Seek him out if you are serious about tuning your bike. He is a huge help and enjoys teaching other folks how to do this:
	0

10-02-2019, 08:35 AM	#31
dirtbkr188 Join Date: Aug 2009 Posts: 498	It probably won't hurt to pull the carb apart and clean it as well, if the debris was in the bowl, chances are it could still be in the carb passageways too.
	1

10-03-2019, 10:22 AM	#32
Douglass Join Date: Aug 2017 Location: Bay Area, CA Posts: 375	I had a similar problem on my 125cc Apollo ATV. You will need 5mm sized fuel line, and go to autozone or orileys to get a new filter. Take the carb apart, and blow everything out with carb cleaner. What I do after EVERY time I finish running the bike for the day is while the engine is running I drain the fuel bowl. Hope this helps Douglass Here is the link for the fuel line I replaced the factory lines with. https://www.ebay.com/itm/Motion-Pro-...72.m2749.l2649
	0

11-16-2019, 08:46 PM	#33
dirtbkr188 Join Date: Aug 2009 Posts: 498	Were you ever able to get this sorted out?
	0

11-16-2019, 10:21 PM	#34
Dusman Join Date: Jan 2018 Location: NC Posts: 203	I’m sorry I haven’t gotten back on here. Been busy dealing with some health issues in the family. I’m currently rebuilding/cleaning the old PZ22 carb, putting new lines on, & cleaning out the tank. I should have it running by the end of the week. I’ll let you know how she goes. Thanks so much for inquiring about what’s going on with this little bike. Y’all have been such a big help!
	0

11-17-2019, 06:37 AM	#35
MooDog Join Date: Oct 2019 Location: Wisco Posts: 58	I'm sorry if I missed it, but you got this bike new in a crate? I've seen where people get these bikes out of box to find hella metal shavings in the fuel tank..
	0

11-24-2019, 08:35 AM	#36
Dusman Join Date: Jan 2018 Location: NC Posts: 203	Really? That’s just crazy. I didn’t get my bike in a crate, but bought it from a friend who’s grandson drove it for 2 minutes, wrecked it, and said it scared him and he didn’t want to get back on it. I think the bike sat for a long time before I bought it, and as you know, motorcycles sitting for extended periods of time and not being ran will totally screw up carburetors, especially if you’re using regular fuel. Moreover, I don’t think this bike was ever properly prepped, so I’m left going back and doing that. The valves alone were so tight I’m surprised the thing ran!
	1

01-21-2020, 08:10 PM	#37
motoracerx Join Date: Feb 2019 Posts: 5	@Dusman....any updates?
	1