Picked up a eton 90 fourstroke second hand....wouldn't start so got a deal. Anyways ended up being a bad break lever switch. Fired right up idle excellent. Tried to rev it up and died everytime. Will start right back up. So I took the carb off to it to a shop and they super cleaned the carb, also put a new plug and have very good fire.still does the same thing. So I noticed that the plunger wasn't moving works off vacume. Took carb apart again and had a good look at diaphragma. Looks fine. So what I did is lifted plunger while operating throttle and it revs out great when I do that. Checked throttle body boot for leaks with a visual inspection and used propane around to see if idle changed...no leaks.so I'm assuming it isn't pulling enough vacume for some reason. So I'm at a loss now and hope someone can point me in another direction. Valve adjustments maybe???? Again need help!!!

 

It won't be lack of engine vacuum that stops the piston from rising, either it is loosing the vacuum due to an air leak in the dashpot chamber, (holed diaphragm, incorrectly seated lid, vac pipe off, etc,) or the piston is sticking, not allowing it to rise.

 

I'm at a loss then due to the fact I have triple checked the chamber for leaks and the piston doesn't seem stiff or sticky

 

Is there another carburetor other then the factory that will work with the eton 90 4 stroke

 

I have done a trawl of Google, as I assumed the engine would be Honda cub clone, which usually use a slide carb (like Honda). Anyway, apparently Eton used the Yamaha Raptor engine, or more likely, Yamaha used the Eton engine. So Raptor carbs of 2009 to 12 are the same, and expensive. Found this on a Raptor forum, haven't viewed the videos, but it may help you overhaul your existing carb. https://www.raptorforum.com/forums/7...ent-video.html

 

I've had that damn carb off ten times and completely disassembled it and blew All air passages and jets out. I've taking the carb to 2 different local small engine shops and had them clean it and still acts the same. Idles fine and still dies when throttle is touched. If I lift on slide with flathead and control throttle it'll rev up excellant. Ready to baseball carb in the woods.

 

Had the same problem on a Honda 500 but you could feel it stick at the bottom of it's slide, tried metal polish on the piston but that didn't work, so fitted a new piston assembly (expensive) and it worked fine after that.

Could be worth checking if the 90 is a bored out Raptor 80 engine, as you can get Raptor 80 slide carbs for $22, it would probably need a different throttle cable, and no guarantee it would fit.