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Discussion Starter #1
Just got a mantis rotiller will start and only run when choked or 80% chocked any ideas what I need to do ?
 

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80% closed or open? 4 cycle? if its 80% open thats all right. if its 80% closed it may be harder/easier to start depending on your model of tiller. is the the type with an motor that u can take off?
 

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salarmi said:
Just got a mantis rotiller will start and only run when choked or 80% chocked any ideas what I need to do ?
i am guessing that is a Kioritz engine with a Walbro diaphragm carb. If it has been sitting for long, the fuel has gummed up the carb. The first short cut to try is to back out both mixture screws if present, and you may need to remove limit caps, and start it and run it wide open popping the choke open and closed to try to flush out the carb with fresh fuel. If it will stay running after doing this, then readjust by setting the idle screw and low speed screw, which is the one closest to the engine, until you have a smooth idle, and the engine will accelerate smoothly. Sometimes that means setting the L screw a tad rich (open) to help the engine accelerate. The mixture screws are needles that regulate fuel flow, so unscrewing a mixture screw, or opening it up, will let more fuel flow, making the mixture richer. If you can tune the idle to run smooth, then hold the engine WOT (wide open throttle) and adjust the H screw, which is closest to the air filter, for max RPM, which will be found by turning it in slowly and listening very carefully to the engine. This is best done with a tachometer. Be very careful here as you can run the engine to lean and damage it. As you screw in the H screw the aRPM will go up until it gets too lean, and then start to fall of as there is not enough fuel. Back it out until it runs smooth again, then back it out rich another 1/4 to 1/2 of a turn rich to provide adequate fuel for horsepower and cooling.
If the carb has no mixture screws on the side it is a fixed jet carb and the only way to fix it is to take it apart. There is a thread on that that is current you can look at.
HTH
 

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The low and high speed adjustments on the carb. have a white [low] and red [high] plastic limiter.
I assume not all carbs have this I have seen a number of carbs that do.
 

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Discussion Starter #8
Hi thanks for your help!! It is running so much better now, but it real hard to start cold
is there a way I can correct that? Yes it has a primer bulb and the red & white screw covers

Thanks!
 

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limiter caps

Most manufacturers now use limiter caps to prevent the end user (you) form adjusting the carb too rich. Remember I said that as you screw in the screw you take away fuel, leaning out the mixture, and the opposite the other way. This is an EPA thing since emissions standards are now in effect for small engines. Before 1990 or so the screws had springs to keep the screws from vibrating out of adjustment. STIHL, which I am most familiar with, adjusts each engine for the best tune when it is built, then sets the limit cap in place against the rich stop, meaning your only option is to be able to lean it slightly. This would happen if the engine was taken to a higher altitude: less oxygen, so adjust for less fuel.
If the carb gets gummed up from old fuel, it will be lean, in most cases, and sometimes you can get it to flush out by opening up the screws, then re-adjusting for proper tune. I have special tools for removing the caps, that usually will not damage the mixture screws. I have seen them get bent from trying to pry off the cap with needle nose pliers or some other tool. Just be careful getting them off, flush out the carb and try to get it running and tune it, then if successful, put them back, so the screws stay in adjustment.
Salarmi, regarding the hard start, that would imply that the choke isn't closing all the way, so take off the air filter and make sure it closes with a tight fit. If that is OK, then I would think you still aern't getting enough fuel, so give it a squirt of choke spray in the carb, as starting fluid, and if the engine starts on that, then the carb is still restricted and needs to be cleaned.
 

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Discussion Starter #10
Thanks Stil

You are a wealth ofo information, my problem now is hard starting cold, the choke looks closed and I removed bioth needle valves and tried to clean those and put them back, what else can I do help the hard cold start?
And also just want to say once it warmes up it starts with a 1/2 pull
 

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squirt some gas , carb cleaner, or starter fluid in the carb and watch it start =) today 50 degrees and i got mine to start in 1/2 pull with a few squirts from da carb cleaner. just wondering, how cold is it there? if its around 0 or lower, gas and diesel usually freeze around that point and cause either no start or hard starting. good luck!

PS ya can get the stuff at walmart or just your local gas station shop
 

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Your best bet is probably to take the carburetor apart and clean it thoroughly, inspect the diaphragms (especially the metering diaphragm) to see if it might be stiff or hard, if it is then you might want to install a rebuild kit. Check the inlet needle if it has a ridge around the end of the tip or is pink then replace it as it could be sticking closed.

oscaryu1 -- gas does not freeze at 0 degrees, so even if it's very cold that should not be the problem, and you should not be using diesel fuel in a 2-cycle engine.
 

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You'll have a hard time getting gasoline to freeze at 0, gasoline doesn't freeze until roughly -120F. That's 120 degrees Farenheit below zero.

Also, it's not advisable to use Ether or Starting Fluid in a cold 2-cycle engine, as it doesn't have any lubricating properties.
 

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Hi
Stihl #1 mentioned that he had a special tool for removing the limiter caps on a two stroke engine. Where can you get this special remover tool? Thanks
 

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hey, RK,
I mainly work on STIHL, and they use Walbro and ZAMA.
These pics show the tool and how it is used. I would think other manufacturers may use something similar. I worked on an Echo blower recently, and they were different than these, and came off easily by gently prying them up with needle nose pliers. Always re-install them to prevent the screws from vibrating out of adjustment. I usually set them in the middle of the range so I can have a little room to tweak them later if needed.
HTH
 

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