Suzuki DT40 fouling plugs

[jafa]

My Dt40 s/n 04003-011046 is wet fouling both plugs. Both are equally wet so I'm assuming its not a water problem. I'm pretty sure that the engine is running rich for the following reasons , wet plugs , warms up but certainly not hot , adjusting the pilot air screw in to the correct number of turns causes it to stall , adjusting the air pilot screw out to acheive correct rpm means that the idle speed adjustment screw is backed off so that it is not touching the throttle control. <br />I'm reasonably confident that the float level is set wrong , even more so as my clymer manual shows the carb I have fitted should , according to clymer be on a DT 55/65. The info from Browns Point does show the correct carb.<br />My Clymer says the dt40 pre92 should have a float level of 17 mm to 19mm and the 55 should be 10 to 14 mm. I think mine has been set to 17 to 19 mm and its possibly a bit high, could somebody please cross check from another source what the float level should be.<br />Thanks

 

[jafa]

Re: Suzuki DT40 fouling plugs

Bump Could somebody please have a look at a seloc manual for me and give me the float height. Carb has pilot jet on the top and the adjustment screw is in the throat behind the silencer.<br />Thanks

 

[jafa]

Re: Suzuki DT40 fouling plugs

After reading hundreds of posts about this and similar I made an educated guess and removed the thermostat housing and sure enough the stat was jammed halfway open. I dont know how long its been like this as i've only had the motor a couple of months but there is a "moderate " amount of carbon buildup on the piston heads. No scuffing in the bores that I can see. Blast it with ringfree or simiar or pull the head off. Can you remove the head without taking the whole power head out ?

 

[rodbolt]

Re: Suzuki DT40 fouling plugs

hello<br /> I would try the chemical decarb first.<br /> as long as the rings arnt stuck dont sweat it to bad. did ya ever find the carb specs you were looking for?

 

[jafa]

Re: Suzuki DT40 fouling plugs

The advise I got for the decarb was somewhat contradictory from what you read in the forums. Under no circustances should a decarb agent be left in the engine for more than 30 mins and use 1/3 of the can a week over three weeks. I thought one good tip was to spray a small amount into the plug holes and use compressed air to drive it back down the sides of the pistons.<br />Still no joy on the float height though

 

[clanton]

Re: Suzuki DT40 fouling plugs

If I have manual at shop, I will post setting Tuesday. I see a lot of floats set incorrectly here in South Florida on Johnson,Evinrude, Suz, Merc, Force. Dont work on the other brands. It is the age of shoddy work.

 

[clanton]

Re: Suzuki DT40 fouling plugs

Sorry no manual for this engine.