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70's model Suzuki RM80 WON'T START!!

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Alright folks, I've recently purchased an older Suzuki RM80 it's a late 70's model. The bike would start with starting fluid when I got it and after it ran for a bit would start without. It was running a little sluggish so I was adjusting the carb, (bike was rebuilt when I purchased just needed tuning), had it running nicely at the end of the day. Went out the next day and now it won't start. It will backfire every other kick, but won't turn over.... Any help would be greatly appreciated... 

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Sounds like it may have fouled the spark plug.

I recall my 79 RM100 being a bit fussy with regard to starting it from cold. Technique that worked for me was full choke with no throttle and 2 to 3 kicks, then as soon as it fired up feather the throttle for a short time then get the choke off, then continue to feather the throttle revving it moderately to warm the engine up.

If it didn't fire after those initial first 2 to 3 kicks it would wet the plug.

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Yes I believe it did.. After reading your reply and a few other forums, I pulled the plug and checked the spark, it's not a fat blue, it's a weak blue spark and occasionally orange... Thanks for the reply. 

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OK... I have went and purchased a NGK plug instead of the knock off I was using.. My RM80 now has more kick and power lol... I'm having trouble getting the gas to lean though.. What would you recommend on jets? I currently have the factory jets in the carb. I live in Colorado so I'm high altitude.. 

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Have you done a compression test? Just because it was rebuilt doesn't mean it was rebuilt correctly. Putting a brand-new piston in a worn out cylinder will do exactly what you are describing

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On 5/28/2017 at 9:00 AM, Abraham Lee Warnick said:

OK... I have went and purchased a NGK plug instead of the knock off I was using.. My RM80 now has more kick and power lol... I'm having trouble getting the gas to lean though.. What would you recommend on jets? I currently have the factory jets in the carb. I live in Colorado so I'm high altitude.. 

Now that it is running, run it out through the gears until it is wide open in the top gear.  The hit the kill switch and coast to a stop, remove the spark plug and check the color of the ceramic insulator of the center conductor.  If the main jet is the correct size and the fuel/oil ratio is also correct the spark plug should be light to medium brown.

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