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300U plugs

D

Dave H (MI)

Well-known Member
Wondering can I get a quick heads up. The 300U is not wanting to start this year. Been going thru the usual (fuel, air, spark). Want to clean and regap the plugs as there is spark and fuel and this is a good running tractor. Plugs have a good bit of carbon on them. Has Champion D21 plugs. Remind me...what is the correct gap?
 
When you say the plugs have carbon build up on them, I would just go buy a new set of plugs and put them in and if the tractor starts, warm it up and then put the old plugs back in the warm engine and see if it will start. I have had plugs that got had set for a spell and would not work, changed plugs and it started right up. run the engine till it is warm and change plugs right away and the plugs worked great after that. Your mileage may vary.

Bob
 
21s are the hot plug. designed for light use and, usually, not for field work. If the 21s are old, and have hours of light use they could be fouled enough to be causing hard starting. Heating them up with a propane torch till the tips of the center porcelain is glowing red (not oxy acetylene) they might serve again. If they carbon up in a few hours, the load screw might be a bit too rich for the work it is doing. Jim
 
Ah...you anticipated my next question! I am thinking I need to adjust the carb also. Appreciate the responses. I bought a new set of matching plugs. A couple of these look like they have been around a while and one was a mismatch. Left the key on while I was gone today and drained the battery...and hopefully that is all, so I don't know if she is ready to go. Think I will pull the small drill with it next week.
 
A few years back I was having a lot of trouble with both 300 utilities. One would not start and the other would foul plugs in a few days. I was told to try the autolite plugs and they both run great now.
 
I was not able to get those, but I will be watching the tractor for problems and see if it wants to foul plugs. It will be working a bit harder from here on out. That always seems to work out better than sitting in the barn.
 
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