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1992 Honda 300 spark plug reading

908 Views 9 Replies 6 Participants Last post by  SlammedRanger
Sorry if my grammar is bad, but I have a 1992 Honda 300 that I installed a thrush glass pack on yes bring the hate it was cheap.

Anyways I figured I would have to jet my carb but thought I'd check the plug first I ain't no mechanic checking the plug isn't my thing. Thought I'd ask for you opinions first, I have ran the engine for about 15 to 20 hours after putting the pipe on many heat cycles.

Quad runs good but backfires quite a bit around mid range rpms while engine braking. Although after riding for about 45 minutes and the engine is hot the back firing seems to stop so I don't know. Doesn't ever bog I mostly ride at WOT for best engine braking since it has very not existing brakes lol

I live on a farm so I do use this quad for chores and moving cattle as well so it does do alot of idling and low throttle riding. But anyways enough rambling if you could please look at my pictures and tell me your input that would be really helpful. Thanks

P.s it sounds damn good and I'd say has alittle more top end power still pops a wheelie as well

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Richen the mixture (screw out) 1/4 turn at a time, definitely lean IMO. @SlammedRanger helped me with my carb issues and he was absolutely spot on!
You may need to talk to some of the utility quad guys on here on how to properly do the test. I do it on sport quads with a clutch. And when i hit 4th gear and wind it out to just before rev limit i pull the clutch while flipping the kill switch and roll to a stop. Thats the proper way to do the test. I havent the slightest clue how to do that on a quad with no clutch lol. But you will want to warm the quad up on your current plug. Then slap in a new one and go real hard on the throttle through the whole test.
Similar procedure except hold the gear lever up until you’ve come to a stop, holding the lever up (or down) will keep clutches engaged :)
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