A couple of months ago I had a post about how my 90 yamaha 2 stroke was idling rough, sometimes cutting out (and at the worst possible times, ie near landing,etc.). I suspected that it was likely related to old gas/resin in carbs and gave it the Sea Foam try. Well, after multiple cans of Sea Foam and Sta-bil the thing is still not running right. I also tried couple tanks of premium and new spark plugs. It cranks and runs for about 20 seconds, shutters, then cuts out; however, sometimes it will run decent and not shut off in idle but when I go to put it in gear it then shuts off. If I’m able to get it to 1500-2000 rpms it runs just fine. Truly think it is low flow carb jets (Chris V’s assessment from original post). Is there anything else I can do at home as a rookie mechanic short of carb soak/rebuild? Also, if I take it to have it looked at, what is typical $ for carb clean and rebuild on that motor?
Thanks
Pull the carbs off and do it yourself. It really is easy. A buddy’s 70 2 stroke was having some of the same problems. I used an air compressor and a guitar string and went through every hole I could find. I used to be deathly afraid of carbs. After you do one though, you will fly through the other two.
And one other thing, seafoam or any magical additive is not going to fix it. You have have to manually remove whatever has the jet clogged. And chrisv will have the parts you need or get them quickly.
If I remove the carbs should I just go ahead and buy a full rebuild kit?
If I were you, I would. My buddy didn’t because he had them rebuilt by a supposed mechanic that works for him a few months prior and he used a rebuild kit. All the o-rings were fine. If it hasn’t been done in a while, I definitely would.
Thanks, Local. At the advice of mechanic friend of mine, I tried one last thing before going to full rebuild - power tune. When putting the power tune in the carbs, I noticed that when I squeezed the primer bulb gas was flowing from the middle carb in between carb and flame arrestor. Could this mean a bad gasket, needle valve gummed open, float somehow open, etc? Also, would this cause it to run rich and possibly cause rough idle and run okay at top end? Lastly, is this a sign I should just bite the bullet and rebuild?