Mantis won't start- cylinder scored?

[AlbionWood]

Picked up (for free) an older Mantis tiller that won't run, hoping it was just a carb full of goo. The carb was indeed badly fouled, but after cleaning it and reinstalling, the engine still won't even cough when I add fuel to the cylinder. Spark tester shows juice getting to plug, which looks fine. SO I am wondering if the cylinder/piston might be scored from running with unmixed gas.... Took the muffler off and there is indeed a groove running down the length of the piston, and it looks like a corresponding groove in the cylinder wall. I presume that should not be there and is preventing compression. Anybody here know for sure?

 

[Travelover]

Some times the scoring on the piston traps the piston rings in the piston lands and then you don't have enough compression to start. The right way to fix it is to take it apart and hone the cylinder and maybe replace the piston and rings.

Sometimes you can squirt 30 weight motor oil in the cylinder, which will temporarily seal the piston enough to start. Then run it on a rich oil / gas mixture until the rings work loose.

Given what you paid for, I'd try the cheap way first.

 

[Craig Clayton]

You could try squirting some gas mix into the carb and see if it might fire.
Craig Clayton

 

[AlbionWood]

Interesting tip about injecting oil; I might try that, as I have nothing to lose. It's pretty clear there isn't enough compression, and I just showed it to a repair guy and he confirmed the cyliner and piston are both damaged. Now looking for a short block.

 

[Molerj]

Go to the Mantis site, you can buy whatever you need. They should have pricing for replacement engines etc. Mantis Tiller Parts - Official Site

 

[Bird]

The first time my Mantis wouldn't start, I finally discovered the in tank fuel filter wasn't letting fuel through the filter. I've bought a new filter, but all I needed to do was give it a short blast of air in the reverse direction and the old filter worked fine. The second time it wouldn't start, I simply re-adjusted the carb according to the manual, and all was well.

Your problem could be similar . . . or entirely different.

Another odd thing I've learned with mine is that when it does start, you MUST allow it to just sit there and idle until it warms up. No matter how you go about it, if it hasn't warmed up good, trying to give it the gas will kill the engine. Of course, if that happens, it restarts very easily.

 

[Jim Thompson]

I just Googled for info on Mantis engines and found a thread that suggested that it had an Echo engine. Might be cheaper to replace with a suitable used Echo if such an animal exists.

Jim

 

[Molerj]

Another odd thing I've learned with mine is that when it does start, you MUST allow it to just sit there and idle until it warms up. No matter how you go about it, if it hasn't warmed up good, trying to give it the gas will kill the engine. Of course, if that happens, it restarts very easily.

I have found that if you work the choke on & off a few times while revving it up, it will not stall. I do the same to some of the weed trimmers that want to stall when cold.

 

[Bird]

Ron, that might work for mine, too, except it's a bit awkward to try to reach and hold the throttle lock out button and throttle back on the handle while reaching the choke on the front of the engine, especially if the tines start turning when you give it some gas. And the manual does say to let it warm up two to three minutes before using.

 

[Jim Thompson]

The carburetors on many of the newer 2 cycle engines that no longer have the two mixture screws can in still be adjusted. You have to know what you're looking for. Some have a small plug that must be removed before the adjustment can be made. Takes a very small screw driver. Others just require a special tool. All carbs come from the factory set very lean

Jim