Thread: 3 questions
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Old 05-27-2014, 03:49 PM
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mapbike mapbike is offline
Motorized Bicycle Elite Member
Join Date: Mar 2010
Location: Central Texas
Posts: 5,379
Default Re: 3 questions

#1. Leaner/less oil means more fuel in the mix which = a richer mix relating to the amount of fuel in the mix, a smaller jet will lean the fuel mix or a larger jet will richen the mix, all of the china girls I have had come with a jet that is way big and needs to be reduced for the engine to run right in my climate and altitude in Texas which is 1242 ft above sea level if I remember right.

#2. sprocket size only affects power for pulling the bike along and top speed at a set rpm, smaller 36T sprocket at 4000 rpm for example you will be traveling at several mph faster than at that same rpm when using the 44T, so engine revs lower rpms at say 25mph when running a 36T sprocket verses if you are running the 44T which is fine but will limit top cruising speed a little normally and causes the engine to increase its rpms at the same 25 mph.

#3. If your engine 4 strokes all the time (makes a constant blubbering sound) and never smooths out and makes a steady purrring sound you are likely running to rich on fuel, yes a jet change will remedy this problem, you can put the #65 jet in the carb, pull the sprak plug and clean it well with some brake parts cleaner and a wire brush, then dry it off and reinstall it in the head, start the bike and go for a couple mile ride and on the way back you need to cruise it for a while at the high end of what you plan to cruise the bike around, get back home, let the engine cool down for 10-15 minutes and then remove that spark plug again and look to see what color the electrode is, if it is a nice medium brown color and the engine was purrring along real nice then I say you are in business, if the plug color is sorta white looking or very light tan you probably need to go up one jet size so that you don't run the engine to lean which makes then run to hot, if the plug color is a very dark brown or blackish color and the engine is blubbering and not purring at cruise speeds then you should go down one jet size and do the test again.

Hope this helps ya out.

I dont always ride WOT, but when I do..I do my best to keep the rubber side down..Ride safely my friends!

Last edited by mapbike; 05-27-2014 at 03:52 PM.
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