8N Carb issues - dies when accelerating

[tin soldier]

I just rebuilt the carb and it dies on acceleration. I have no idea what's going on. I have new fuel, clean lines and it can't get up to 2000 rpm, separate from the gov even. I've adjusted all the needle valves to specs in the book. (main adjustment 1.5 to 2 turns off bottom, idle needle 1.25 turns of bottom). For some reason when you open the thottle plate, the engine dies and I think it's being starved of fuel, but I suppose it could be the other way, too rich. I've taken apart the carb and blown out all holes and cleaned it thoroughly several times. I'm using a temporary fuel jug at ambient pressure/ventable and fuel line (1/8 inch ID). My compression is about 70 psi on each cylinder, but when the engine idles, it can suck my hand into the intake on the carb. I think that's enough vacuum to atomize and mix fuel and air in the carb.

Its driving me nuts.

 

[whodat526]

check and make sure u have the two jets set in the right place it may take a few tries of just turning the two jets the get the fuel mixter just right put that most likely what it is but if that doesn't do it u might have to take it back apart and clean the jets on the inside of the carb again

 

[Soundguy]

sounds way lean.

big downpointing mainjet try an initial setting of about 2 turns out. Out to enrich.

small side pointing idle air jet, try a setting of 1.5 turns out, IN to enrich.

adjust idle jet for fastest idle, not smoothest idle.

adjust 1/8 a turn at a time than check.

good way to check main is to goose throttle.. adjsut till it does not hesitate on acceleration.. or stumble and doesn't make black sooty smoke out the tail pipe.

soundguy

 

[whodat526]

and if all else fails they have aftermarket carbs for about 100 dollars

 

[Soundguy]

and if all else fails they have aftermarket carbs for about 100 dollars

and worth every penny too...

soundguy

 

[whodat526]

yep cause i found some of them old carbs just will not take a rebuild kit for some reason and they can drive u crazy cause just when u think u got it fixed it starts messing up again

 

[Soundguy]

yep cause i found some of them old carbs just will not take a rebuild kit for some reason and they can drive u crazy cause just when u think u got it fixed it starts messing up again

yep.. I have a nice ( had a nice) ms carb on my 660. when that 'new' gas stuff cane out, a few months later my 660 died.. fuel issues.

pulled the carb down, and rebuilt it like I've done to so many other carbs over the years. except this one was pitted inside.. pitted so bad that the new jets and seals wouldn't seal good... tried it twice.. new gaskets.. new seats.. tried a NOS set of brass valves not the viton ones.. nada...

in the end, the high end rebuild kit and a new float ( old one disintegrated ) just wouldn't make her go without choke.. I had to throw in the towel and buy another carb.

sometimes it's money ahead to do that then fight them.

soundguy

 

[whodat526]

thats right cause be time u buy a float and a major carb kit u just about got as much in it as a aftermarket carb cost

 

[Soundguy]

thats right cause be time u buy a float and a major carb kit u just about got as much in it as a aftermarket carb cost

yep.. good kit can be as high as 40-45$.. floats 15-19$ depending..

soundguy

 

[whodat526]

and if that dont work thats about 60 dollars wasted