d17 series IV

[k wolff]

Hate to bother everyone again, but I need help with carburator adjustment on a D17 gas. At full rpm I am getting a light blue smoke and a slight backfire when idling back down. The sparkplugs look like they have been around awhile as the outside housing is rusty. They also blacken up rather quickly. They are autolight 64. Would changing plugs help or is the problem in the carburator. Thanks for the help.

 

[Jeff Z.]

Sounds like you have a little oil being burnt with the blue smoke and maybe some unburnt full with the backfire. Try some Autolite 303 spark plugs and see if that helps any.

 

[Hurst]

When you say the plugs blacken up, is it a glossy/wet black or a sooty/dry black? If running rich, you will have a sooty black (unless it's running so rich you have raw fuel on the plug, but that will evaporate rather quickly, still leaving a sooty look). If you have a wet/glossy black, that's oil. The blue sounds like you have an oil burning problem (rings or valve stems).

Hurst

 

[k wolff]

The black is a sooty dry black, however the threads on the sparkplugs seem to be wet, but not oily. Last night is the first time I noticed the smoke. Normally I don't run the tractor in the garage and outside I have never noticed any smoke. In the garage I didn't notice any until I ran at high idle. I know the tractor hasn't been used for much other than raking hay the last few years.