Coolster 125 bogging out when hitting throttle

VirtualWheeler · 08-12-2018, 09:40 AM

I have a couple of Coolster 125 with the same problem...

They start fine and idle fine. If I bring the throttle up at a moderate speed they have plenty of power and speed.

But if I hit the throttle fast, they die out.

Is this normal? I've tried adjusting the idle and a/f using these instructions https://atvconnection.com/forums/1-e...-sunl-etc.html without success.

The only way I can get it not to do it, is if I put the idle up a little high, which of course then it's idling too fast and causing clutch engagement.

Is this behavior typical?

Douglass · 08-12-2018, 11:28 AM

I have a 2017 Coolster, and it had the same problem. I purchased the new lever choke style carb, and moved needle clip down to the number 4 or 5 position. It solved the bog problem, but I ended up with some surging when cruising.

I ended up changing to a different style Carb. I can't remember the settngs, but I was able to get the ATV to run pretty good with it.

This is the one that I purchased, but if you buy this unit it will most likely ship from China, and take about two weeks to receive. It will also require a new air filter. The opening is much larger, and the stock air filter will not fit. Here is the one that I purchased.

https://www.ebay.com/itm/EPA-Approve...item25ff57b6a5

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

This one looks to be the same, and ships from California.

https://www.ebay.com/itm/PZ22-Carbur....H0.Xpz22.TRS0

Bruces · 08-12-2018, 04:54 PM

You might just want to try lifting the needle all the way to the top ,not sure if you have any more slots or if a few washers are needed .

08-12-2018, 09:40 AM	#1
VirtualWheeler Join Date: Aug 2018 Posts: 14	Coolster 125 bogging out when hitting throttle I have a couple of Coolster 125 with the same problem... They start fine and idle fine. If I bring the throttle up at a moderate speed they have plenty of power and speed. But if I hit the throttle fast, they die out. Is this normal? I've tried adjusting the idle and a/f using these instructions https://atvconnection.com/forums/1-e...-sunl-etc.html without success. The only way I can get it not to do it, is if I put the idle up a little high, which of course then it's idling too fast and causing clutch engagement. Is this behavior typical?
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08-12-2018, 11:28 AM	#2
Douglass Join Date: Aug 2017 Location: Bay Area, CA Posts: 375	I have a 2017 Coolster, and it had the same problem. I purchased the new lever choke style carb, and moved needle clip down to the number 4 or 5 position. It solved the bog problem, but I ended up with some surging when cruising. I ended up changing to a different style Carb. I can't remember the settngs, but I was able to get the ATV to run pretty good with it. This is the one that I purchased, but if you buy this unit it will most likely ship from China, and take about two weeks to receive. It will also require a new air filter. The opening is much larger, and the stock air filter will not fit. Here is the one that I purchased. https://www.ebay.com/itm/EPA-Approve...item25ff57b6a5 https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 This one looks to be the same, and ships from California. https://www.ebay.com/itm/PZ22-Carbur....H0.Xpz22.TRS0
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08-12-2018, 04:54 PM	#3
Bruces Join Date: May 2018 Posts: 1,648	You might just want to try lifting the needle all the way to the top ,not sure if you have any more slots or if a few washers are needed .
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