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Old 06-29-2009, 01:35 PM
Ocean7 Ocean7 is offline
Motorized Bicycle Newbie
Join Date: Jun 2009
Location: USA
Posts: 15
Smile Quest to restore lost horse power…

So after my first china girl died, I decided to order another kit (from a different company) to see if that would make any difference. Well, the kit arrived and I got it on the bike the same afternoon. Straight away I could feel a HUGE improvement. This kit seemed to be of much better quality and the engine had more horse power from day one, and made no rattling noises when riding.

So anyways, I was taking it easy during the break in period, and was mixing 16:1. A strange thing was happening though.

After getting through the break in period, the engine seemed to have lost horse power. It could reach speeds of around 25 mile/h but the acceleration was terrible!

So these are the steps I went through to finally rectify the problem…

1) I first suspected the gas was too rich with oil. Leaned it out from 16:1 to 30:1 (and used 100% synthetic 2-cycle oil) but made no difference.

2) pulled out the spark plug and it was coated with crap. So I cleaned it up, reset the gap and tested for spark. The spark seemed to be very weak so tried a new spark plug (NGK B6HS). Test drove the bike and it was still lacking power, almost seemed to have gotten worse.

3) thought maybe it was an electrical problem so tested the magneto and CDI with a multimeter. The resistance readings on the magneto were comparable to those quoted in this forum. :-) The readings on the CDI were not, so I was thinking Ahh Haa it’s the CDI. Ordered a new CDI, installed it, and it did not help one bit. Oh Crap! Now really wondering?

4) Carb maybe? I pulled it apart to see if the float was sticking or anything, but all looked fine. I had a spare carb so I tried it, but it didn’t help. I tried different fuel/air mixtures by adjusting the needle, but all were much worse.

5) Lastly I was thinking maybe a blocked exhaust? Not letting the gasses out quick enough? So I removed to muffler and gave the bike a test drive. Holy crap, when I accelerated, there was so much power I almost popped a wheelie! Darn loud too! I had a brand new muffler in my garage so replaced the old for the new. Wow, it made all the difference! The bike has so much power again! I would never have imagined replacing the exhaust would make that much of a difference, and such a simple problem to fix. I kicked myself once I found out.

Needless to say I’m smiling again!

Just thought I should share this with any other newbies (being a newbie myself) and any other skill level I guess. It seemed there were similar accounts of this happening. Especially when running rich during break in?

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