mac pro 10-10 auto gas in exhaust

[poppiecarver15]

hi guys,question i rebuild the carb.on my mac pro 10-10 auto sdc carb. it was running ok but i bought it new in the mid 70's and have done nothing to it before this .it will start and run now but is getting lots of gas in the exhaust. had the carb. apart again and it looks ok but not sure why i am getting the gas in the exhaust,plug does not seem overly wet like it is flooding.aslo installed a new intake gasket as the origonal one was torn. this i really a fun saw to use and hope i can get it running right,wish i had left it alone now.any help or advise would be greatly appreciated.thanks in advance. Jim

 

[lostone]

what ratio are you mixing at? You said the plug looked good, is it coated with oil?
Just wondering if you have a heavy oil mix ratio or either have the carb set to rich.

 

[poppiecarver15]

what ratio are you mixing at? You said the plug looked good, is it coated with oil?
Just wondering if you have a heavy oil mix ratio or either have the carb set to rich.

i am running 50 to 1,plug does not look overly we like it is flooding i have high and low at 1 1/2 turns

 

[MacAttack]

Good chance it's the inlet needle in the carb leaking or the metering diaphragm lever is out of adjustment and flooding it.

 

[poppiecarver15]

thanks i think i will but back in the old metering lever and see if that helps

 

[MacAttack]

I would for sure check the adjustment, if an SDC is like an MDC the metering lever should be flush with the carb body.
In my experience, extreme flooding and gas in the exhaust were due to the metering lever / diaphragm / needle.

 

[poppiecarver15]

ok thanks will check to make sure it is l it level might be a bit high,flush with the carb.body and not flush where it fits in?? thanks

 

[MacAttack]

From Walbro:

 

[poppiecarver15]

thanks for the diagram, i think i might be a bit high will check in the morning,thanks again,will post how i make out

 

[SteveSr]

thanks for the diagram, i think i might be a bit high will check in the morning,thanks again,will post how i make out

NEW metering levers ALWAYS need adjustment!

 

[lostone]

SDC are good carbs once you get them dialed in, hopefully it's just a lever adjustment. Are you tuning the saw by ear?

 

[giver]

Did you make sure to put the gasket against the body of the carb and the diaphragm against the plate? If the diaphragm is against the body it will make the saw super rich.

 

[vizette]

Had a 10-10 that drove me crazy with this. It would run at first and then flood out, dribble gas out the muffer, etc. I must've had that carb apart 100 times. Turned out to be a multitude of issues. Some of it was adjustment, but it also had some gunk stuck down in the seat. After replacing the needle, triple checking the arm, and cleaning out the seat REALLY well with q-tips, it hasn't given me any issues. I think I also stretched the spring a hair to give it more seat pressure.
I have read that some people had success cleaning up a damaged seat with a mildly abrasive rubbing compound.

Also have a little homelite that did this to me. I almost dropped a match in the gas tank one day I was so mad at that saw! That turned out to be some very small bits of dirt that found their way in there, and like my 10-10 were causing the needle not to seal on the seat intermittently. Glad I didn't burn it up, it turned out to be a lot of fun and is now one of my go-to saws for smaller stuff.

Also, I assume it's the diaphragm style that hooks on to the arm? Make sure the button is hooked in there and not sitting on top of the arm. Voice of experience.
One more "also"; make sure the diaphragm gasket is on the carb body side and not on the cover side.

 

[MacAttack]

Did you make sure to put the gasket against the body of the carb and the diaphragm against the plate? If the diaphragm is against the body it will make the saw super rich.

This is very true....ask me how I know! Haha

The worst part was that it wasn't entirely my fault, I was following a diagram from a Clymer manual, that had a misprint and showed the diaphragm and gasket in the wrong order!

 

[poppiecarver15]

well thanks ,i missed the gasket under the diaphragm i put the gasket them the diaphragm then the cover ,metering leer is just touching a st.edge. it now runs with no gas in exhaust but will not rev up .high and low jets were out 1 1/2 turns each but nothing happened with the high speed. it is cold here so will wait till it warms up some before i do any more but am open to more ideas and thanks for all the help so far.

 

[vizette]

well thanks ,i missed the gasket under the diaphragm i put the gasket them the diaphragm then the cover ,metering leer is just touching a st.edge. it now runs with no gas in exhaust but will not rev up .high and low jets were out 1 1/2 turns each but nothing happened with the high speed. it is cold here so will wait till it warms up some before i do any more but am open to more ideas and thanks for all the help so far.

What does it do when you hit the throttle?
Out 1-1/2 is just a basic starting point and will need some adjustment. Without knowing more, I'd say start testing changes with the high needle. 1-1/2 might be too much, some of them are good with as little as 3/4 out, just be careful going lean lest you burn it up. Too fat will just run like crap and carbon up. Too lean will quickly put you in "burned up and need a rebuild" territory.

 

[poppiecarver15]

when it was running ,WOT it did not rev. up leaned the high jet but did not help ,maybe need to lean more,before the carb.rebuild the high and low were not quit 1 1/2 turns.this is a dumb question but need to ask,this saw to choke the choke knob is pulled out and pushed in to run,i have seen videos where the knob is pulled out to run.this saw has the sdc warbro card, just wondering. i am running the saw also without a bar and chain which i think is OK.hope to get it going good and put on a 20 inch bar and chain need something a bit bigger,maybe 24 inch.thanks for any help

 

[poppiecarver15]

well ready to give up on the old girl ,thought i got the gas in the exhaust fixed ,none when i put the gasket i missed on under diaphragm it it ran with no gas in exhaust but not to WOT removed high speed jet cleaned again and set to just over a turn but now hard to start and getting gas back in exhaust.next thing i guess is to go back and check the whole rebuild of the carb. funny it ran kind of ok before the rebuild so i am guessing i did something wrong or a bad rebuild kid,any thoughts?? thanks in advance . jim

 

[MacAttack]

It's awful hard to diagnose over the internet but if the metering diaphragm / lever / needle are working and installed correctly you should not be getting gas in the exhaust. If they aren't correct it also makes it impossible to tune the saw correctly. I'd start at square one with how the carb is assembled and making sure everything is in the right order and orientation. Are you sure you have the metering diaphragm in the right way?
When I had a Mini Mac giving me hell to tune, it was the metering lever the whole time out of adjustment.

 

[poppiecarver15]

i know it is tough to trouble shoot over the internet but i really appreciate all the help so far,i will take carb. off and go through it again but i was real careful about getting the little notch on diaphragm hooked to the pin but i am going back to sq. one a check everything again.getting good at removing the carb. tanks again for the help and thing to check,will keep posted.