So, I stop at the dealership today to get a larger main and pilot jet for the winter snowplowing season, and the parts manager says not to bother with the jetting and just put a hotter plug in there.

First of all, I've tuned/jetted snowmobiles and motorcycle for years, and have always done so by way of carburetor jets and needle clip position, never by spark plug heat range. The mechanic comes out front and verifies what the manager said, that I should put a hotter plug in. I asked him how the hotter plug compensates for the leaner mixture produced by cold temps, and he told me that it will allow less fuel to burn thereby fooling the engine into thinking it's running richer.

Okay, so I tell them I'll buy jets on a different day and proceed to scratch my head all the way home about this spark plug heat range/ jetting issue. I still don't understand how a hotter spark plug will compensate for a lean mixture.

Can anyone enlighten me on this. Personally, I think those guys were full of it.

 

Sounds like you need a new dealer,

I have a '03 400 Trail Blazer 2-stroke, and put on a HPD race pipe, V-Force Reeds, 44mm flat slide carb and open air filter and a 300 main jet, well it was to fat, I didn't have any main jets on hand so I went from a BR 8ES to a hotter BR 6ES and ran a temp probe in exhaust. The #8 plug ran 800-900 degrees WOT and the #6 runs 1100 WOT, hot plug hotter temp it is simple math.

If you only keep your ride for a couple of years don't rejet, just put a little duct tape on 1/3 of air filter for a rich mix. If you keep your ride forever then rejet.

My Trail Blazer has factory recomendation of jet sizing for alt. and temp from 175 to 290 and where I live at 1000' elevation my original jet was a 250 for 40-80 deg. a 230 for above 80 deg. and a 290 for below 0 deg.

Hotter plug in winter without jet change will fool the piston, and when the piston isn't looking a big hole in his top will apear.

good luck.................handycap

 

well you nick name is suitable. ya handycap the motor and give less power ya that's solution. sounds you need a new brain and he needs a different dealer

 

well, heres my 2 cents and lets see if i need a new brain. i would not change heat ranges on the plug more then 1 up or down in any reasons. the duck tape theroy is correct in it will change the air flow cutting off it off and making it run rich. unless you run alot in cold wheather 20 to -20 degrees i wouldnt rejet my slf. as far as a 2 stroke is concerned if you run a hotter plug w/ out rejetting in cold wheather you are asking for a hole in the piston. just a side note if you did what the dealer suggested and it was still under warranty and had a engine failure, i would bet you money when they found that hotter plug you would be srewed w/ no warranty and pay to fix it your self. i have dealt w/ alot of dealers over the yrs and never had one say put hotter plug to compensate for jetting.

 

The jetting that comes in them is more than rich enough for winter running. I dropped two main jet sizes to a 147.5 and ran last winter with no problems....

 

use a NGK platinum spark plug for a 2 stroker its a very good plug i have it in all my 2 strokes. it made a big difference in my 01 xplorer 250

 

Thanks to all except mrtwostroke.

Stendori, I do appreciate your input, and I always read every post you make. You are an asset to this group, always giving good advice and being respectful of those less knowledgable.

 

for a peformance tuner your suggestion was the stupidest thing i have ever heard of. but ya it might work with a severe drop in power. which other wise you should gain power in the cold if you rejet

but nb sportsman is right normally they are jetted to rich from factory to save their ***.