Troy T
06-11-2022, 10:11 PM
I will start by saying that I've never had an issue I couldn't figure out and resolve on a motor until now.
Background;
I have a 1985 ATC 200m that started to run poorly one day a couple months ago. I put it in my shop and ran a compression test I got around 50psi of compression AKA not a good result. I then replaced the piston and rings with a new WYSCO 10.25 to 1 piston. I put everything back together and started my trike, it ran poorly.
I then performed another compression test and found that my compression was now at 200psi. With compression fixed by replacing the rings a and piston I moved on to the ignition.
I replaced every ignition part, coil, cdi box even though my old stuff tested fine I thought this is all fairly cheep just replace it. replacing all of the electronics in the ignition system and set my timing correctly it made no difference, it still runs poorly.
I then replaced the carburetor with two different carburetors both cleaned, inspected and working properly and still it runs poorly.
I then performed a leak down test and at 100psi there is less than 1% leak I say less than 1%.
I may be misinterpreting what my machine is doing but to me my machine acts like the intake valve isn't sealing even though my leak down test would say it's sealing fine so I replaced the head with a known good head. I then ran the leak down test again. My results were the same little to no leak, less than 1% at 100 psi.
I started my machine and it runs exactly the way it did when I started working on it, poorly.
Description of "poorly"
my machine is running poorly in a very particular way.
It starts fantastic, one revolution and bam she's running. It only runs poorly when you start rolling on some throttle. I would say it runs not that bad up to a quarter throttle but anything more than that it makes more noise but makes no more power and doesn't really increase in RPM's. It also seems to mist some air/fuel back out of the carburetor onto my air filter when you give it throttle. It acts like it has a bad intake valve seal but my tests would say other wise.
Any and all help would be appreciated because this one has me stumped.
Background;
I have a 1985 ATC 200m that started to run poorly one day a couple months ago. I put it in my shop and ran a compression test I got around 50psi of compression AKA not a good result. I then replaced the piston and rings with a new WYSCO 10.25 to 1 piston. I put everything back together and started my trike, it ran poorly.
I then performed another compression test and found that my compression was now at 200psi. With compression fixed by replacing the rings a and piston I moved on to the ignition.
I replaced every ignition part, coil, cdi box even though my old stuff tested fine I thought this is all fairly cheep just replace it. replacing all of the electronics in the ignition system and set my timing correctly it made no difference, it still runs poorly.
I then replaced the carburetor with two different carburetors both cleaned, inspected and working properly and still it runs poorly.
I then performed a leak down test and at 100psi there is less than 1% leak I say less than 1%.
I may be misinterpreting what my machine is doing but to me my machine acts like the intake valve isn't sealing even though my leak down test would say it's sealing fine so I replaced the head with a known good head. I then ran the leak down test again. My results were the same little to no leak, less than 1% at 100 psi.
I started my machine and it runs exactly the way it did when I started working on it, poorly.
Description of "poorly"
my machine is running poorly in a very particular way.
It starts fantastic, one revolution and bam she's running. It only runs poorly when you start rolling on some throttle. I would say it runs not that bad up to a quarter throttle but anything more than that it makes more noise but makes no more power and doesn't really increase in RPM's. It also seems to mist some air/fuel back out of the carburetor onto my air filter when you give it throttle. It acts like it has a bad intake valve seal but my tests would say other wise.
Any and all help would be appreciated because this one has me stumped.