Wburton
New member
Hiya,
Got a "good" Mantis that's driving me nuts!! I bought it new and it's always been 'good' but temperamental. Usually a slight carb tweak and off I go. I'm good on small engines (2&4 stroke) but I'm stumped.
This one is a 10 yr old 2 stroke. Starts on 2 pulls and runs great- for about 2 minutes then quits. Starts right back up with a pull. Throttles up and down fine. I rebuilt the carb. No help and no change. I swapped it with another Mantis Zama carb. No change. All new fuel lines, vent, plug, cleaned air filter, cleaned muffler. No change. Bought a whole new OEM carb. No change. Compression is great. Visual inspection thru the muffler port and the piston and rings look fine. I only burn non-eth 93octane, 50/1 mix fresh.
So today I heard the vent line might not be working right. Ran 2 hours of tests with a stop watch. I can crack the gas cap open and leave it on fast idle (via the throttle cable adjustment screw) and run a half tank of gas. But when I screw the cap tight it will 'stall' in about 4 minutes. I swapped the brand new vent line with 2 others I have on hand. All are spotless and clean. I get the same results.
I've got tractors, gas and diesel, 6 chainsaws, a '70s cast iron Ariens Rocket 7 tiller, Shindaiwa blowers, weadeaters, push mowers, 4 riding mowers and a big JD 0-turn. I maintain and do all the repairs on all of them!
But- this tiny little thing is killing me
Got a "good" Mantis that's driving me nuts!! I bought it new and it's always been 'good' but temperamental. Usually a slight carb tweak and off I go. I'm good on small engines (2&4 stroke) but I'm stumped.
This one is a 10 yr old 2 stroke. Starts on 2 pulls and runs great- for about 2 minutes then quits. Starts right back up with a pull. Throttles up and down fine. I rebuilt the carb. No help and no change. I swapped it with another Mantis Zama carb. No change. All new fuel lines, vent, plug, cleaned air filter, cleaned muffler. No change. Bought a whole new OEM carb. No change. Compression is great. Visual inspection thru the muffler port and the piston and rings look fine. I only burn non-eth 93octane, 50/1 mix fresh.
So today I heard the vent line might not be working right. Ran 2 hours of tests with a stop watch. I can crack the gas cap open and leave it on fast idle (via the throttle cable adjustment screw) and run a half tank of gas. But when I screw the cap tight it will 'stall' in about 4 minutes. I swapped the brand new vent line with 2 others I have on hand. All are spotless and clean. I get the same results.
I've got tractors, gas and diesel, 6 chainsaws, a '70s cast iron Ariens Rocket 7 tiller, Shindaiwa blowers, weadeaters, push mowers, 4 riding mowers and a big JD 0-turn. I maintain and do all the repairs on all of them!
But- this tiny little thing is killing me