Smoking 2 stroke ?

Post by **madog99** » Sun Sep 02, 2007 1:12 pm

My 7.5hp Johnson (mid 80's)seems to be smoking a lot more this year , I'm mixing the oil right on and have used various brands . I noiticed that the shaft of the motor is getting covered in black soot under the exhaust port. Any ideas what would be the cause of this ?
thanks again

Post by **jiggy2006** » Sun Sep 02, 2007 10:19 pm

when was it last tuned up!? it may need a tune up!
Assuming you are using 50:1 gas/oil mix. ie 25L tank you put 500mL oil.

Tune up:
- new spark plugs (you can get them at canadian tire, champion spark plugs), make sure you have good spark (can do a spark test and find out)..
- new carburator kit!?
- do a de-carb [carbon] (look up on the internet), to clean the combustion chambers ..sounds like you may need to do this

Post by **mikemicropterus** » Wed Sep 05, 2007 5:07 pm

how does a tune-up stop it from smoking??????How does a set of new plugs stop an engine from smoking???????

You need a thermostat, the engine if the carb adjustments are not disturbed should be runniog at the same mixture that hasn't changed.
Why didn't it smoke more last year, because it was the year of the goat NO, because it ran hotter, thermostat worked.

Most nobody checks the thermostat and if the motor is running to cool it will not produce enough heat to complete the fuel burning process. This is SOMETIMES compensated for by richneing up the mixture because a cold engine will run lean.

The symptoms are USUALLY excessive smoking and rough idle. A tune-up(wrong expression)will not fix that problem because like I said earlier most everybody forgets the thermostat. If the motor is running hot enough you should not be able to keep you hand on the head for more than a few seconds as it is suppossed to run at 143 degrees F.

See if that helps and don't waste your money on plugs and a tune-up. and don't get a carb rebuilt unless the motor does not run properly.

A tune-up should make a good running motor to run great not fix problems. Problems need to be fixed not tuned-up.

Post by **madog99** » Sat Sep 08, 2007 5:20 pm

thanks for the advice , I have never de-carbed a 2 stroke but it seems like a good thing to do after reading on the net . the thermostat sounds like a great idea also , I'll try both actually and report back . One other thing that someone mentioned is the old gas tank could be sludgy ?
thanks for the advice boys !