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Old 06-13-2013, 01:10 AM
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mapbike mapbike is offline
Motorized Bicycle Elite Member
Join Date: Mar 2010
Location: Central Texas
Posts: 5,379
Default Re: She Just Ain't Climbing Like She Used To - Standard China Girl 66cc

Russ, first off I would like to say that some of the HT/China Girl engines last a long time and some dont I have an older 2009 engine that has 1600+ miles on it and still runs like a champ, no mods accept a well tuned carb and a free flowing exhaust.
This bike cruises at 30mph all day long without a glitch.

Russ, I think you have already answered you own question here, you removed the end cap of the exhaust and you got your low end torque back for pulling those hills, seem the obvious problem is that over time you have developed some flow restriction in the exhaust, I would take a long steel rod and by hitting it with a hammer I would punch several larger paths through the honey comb looking stuff you will see up inside your exhaust muffler and then put the end cap back on and give it a try.

NOTE: remove the exhaust before doing the mod to open it up more through the catalytic part that has a honey comb look to it, the stock exhaust are to restrictive for these engines from my experience and freeing them up using the method I described is a bit crude but it works and will allow the engine to breath better.
I did this very thing on one of mine one time and it allowed the exhaust to start flowing better and it made a noticeable difference on the hills, be sure and clean the spark plug really good and use a wire brush to knock the soot off of it and then after a nice run do a plug check to make sure the aded air flow hasn't caused a lean run condition.

if you are using a really high quality oil you may even consider going with a 40:1 mix and see what that does as well, sounds to me like you just have some simple tuning issues from a plugged up exhaust that need to be done and then you'll likely be good to go again and maybe even better than before.

Best wishes and I hope you get it back to good on the hills asap.
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; 06-13-2013 at 01:16 AM.
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