MS660 spewing fuel out exhaust

[altair]

Just bought an assembled Farmertec MS660 big bore bottom end.
Assembled it using an old Ms660. got it to run,but it spews black oil/fuel mix out around behind the exhaust, and either revs at about 4000rpm, or floods out. Either way it dies, and won't rev out.
Have replaced carb twice, one known good Walbro, one chink copy Farmetec new
all rubbers, intake,impulse new.
New plug, fuel mix, filters, muffler clear and opened up a little.
Even tried a different tank in desperation..any clues?
Tried lowering the metering lever in one carb, wasnt high anyway.
Got me beat.
Does this sound like a faulty bottom end?
Cheers

 

[earlthegoat2]

Is the ignition module Stihl or FarmerTec?

 

[altair]

Stihl coil, off an old MS660

 

[TreeswingerPerth]

Mine did this , 1st time the carb needle valve had a lump of dirt sticking it , second time the flywheel key sheared and it refused to start and dumped fuel .

 

[earlthegoat2]

...second time the flywheel key sheared and it refused to start and dumped fuel .

This is what my follow up question was going to be.

The coil could possibly be bad. Do you have a spark tester or a way of reliably checking for spark.

 

[Derrick Sawyer]

Make sure the throttle plate isn't sticking after you release the choke, sometimes the spacing on the carb gasket and air filter plate can cause it to bind and keep the throttle plate closed so its choked and gas comes out the muffler

 

[bikemike]

Yeah buddy. Flame thrower of you can get it fired up

 

[alexcagle]

+1 on ignition or timing .
*
Set the piston on TDC, and check how much the magnets on the flywheel lead the coil counterclockwise.
*
I know this sounds rudimentary, but did you try a different plug?
We've all been duped by the fabled "bad" brand new spark plug a time or two.
I just had one the other day.

 

[TreeswingerPerth]

This is what my follow up question was going to be.

The coil could possibly be bad. Do you have a spark tester or a way of reliably checking for spark.

I just earth the plug and check for a strong spark , probably not the best method .

 

[alexcagle]

Use one of these, and watch it while it's running with it in line to the plug. Harbor freight has them too.
Yes they will run with a tester on them.
When it acts up see if the spark quits before the saw does.
Even if you have spark at plug, and everything else is good, if it's got a sheared flywheel key, the spark plug will not be at the right time.

 

[rd35]

Last time this happened to me I discovered (after getting a hint from one of the members of this forum) that I had my H needle opened up WAY too much as a starting point after a carb rebuild. Turned it in one full round and had me a nice running saw. And this was not my first carb rebuild....had done many before this, but I had never made this mistake before. I was pretty embarrassed when I realized what I had done!

 

[bayard]

View attachment 603033
Use one of these, and watch it while it's running with it in line to the plug. Harbor freight has them too.
Yes they will run with a tester on them.
When it acts up see if the spark quits before the saw does.
Even if you have spark at plug, and everything else is good, if it's got a sheared flywheel the spark is not at the right time.

reminds me of sparkies we put on the plug wires of our harley choppers . back in the 80,s

 

[altair]

Cheers guys, seller has asked for it back, he will put new seals in it. I have stated I'm happy with a non big bore kit, seems the big bore kits can be slightly more challenging to tune.
Tried 2 plugs, 2 carbs, throttle plates not sticking, only have one coil though...when it does run well briefly its responsive and powerful...I reckon its some sort of seal problem, and seller thinks it is too.
Flywheel key not sheared..has the poly flywheel. Have an old 066 flywheel but they are all alloy and different?
If the replacement isn't up to scratch running wise I'll have to throw $60 at a chinese coil I guess. After that I'm stumped. Have ordered a new AM tank/throttle setup today too, just in case, plus the MS660 AM filter covers won't fit over the old 066 on/off lever.
Thanks guys for any ideas, very much appreciated. Maybe I should get the chink spark plug out of the bag and try that.....lol

Off to drop a few trees with my 661 now...now thats a proper saw!

 

[altair]

Yeah the h and L screws are out one turn from seated on this rebuild, and thats where it runs its best...which is still terrible.
One carb Walbro, one AM, seating seems the same but the Walbro seating feels much more precise.

If I win the lottery I'll buy my mate a proper 661..and set fire to this bloody 660 copy!