I have a 01 scrambler 90 I bought for my son last year. It runs fine when he first rides it, but after 5 minutes or so it seems to lose power. He has the throttle wide open but it only runs like you have it at half throttle. It doesn't die when you let off or anything, just putters around. Sometimes it comes out of it and sometimes it doesn't. But if you let it sit it will run just fine and does the same thing. I have changed spark plug, air filter, fuel filter and checked for kinked fuel lines etc. Last year I cleaned the carb. It just started doing this last week.

looking for some help

 

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Hi Lung. Welcome to this forum.

You may have to clean the carb again. It only takes a little grain of dirt to make a 2 stroke run terrible.

Also, you may want to perform a compression test on the engine. A fresh "stock" Polaris 90 has between 120 - 90 compression. 100 PSI to 90 is average. If anything below 80, then start ordering the parts. When an engine warms up, its cylinder expands. When it expands, air "can" sneek past worn out rings. If you can, check the compression to eliminate (or identify) this situation.

Note: Check the compression with COLD, then with warm engine. Sometimes, their PSI value is dramatically different.

Hope this helps...

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We had a very simialr problem with our ac 90 we had to remove the petcock to preven the carb bowl from running dry, if cleaning the carb doesn't help like spike suggested try bypassing the petcockadn runnig straight to the carb.