China girl motorized bicycle first startup - loud noise from motor

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brett7777

brett7777

New Member
Aug 19, 2011
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Auckland, New Zealand
Have done first test ride. Motor makes a loud kind of metallic high pitched sound, some of the time, (probably most of the time) sounds a bit like metal against metal, most noticeable when you begin to take off from idle & let the clutch out with the engine under load. But happens sometimes also at idle or at about half revs while running, or also sometimes when revving while idling.
Im running 25:1 with BP 98 & Motul synthetic 2 stroke oil TC grade.
 
GearNut

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
Re: China girl first startup - loud noise from motor

That sounds like the transmission gears. They are inherently noisy. They will quiet down a little over time.
Look up "noisy gears" on this site for more info.
Folks glue custom cut computer mouse pads to the outside of the clutch cover.
Folks glue cardboard to the inside of the clutch cover. (I did that and it definitely helped).
SBP also sells specialized sound deadening material pre-cut to fit inside the clutch cover and the other covers. Sick Bike Parts
 
2door

2door

Moderator
Staff member
Sep 15, 2008
16,302
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Littleton, Colorado
Re: China girl first startup - loud noise from motor

And part of the noise is just normal for these little Chinese wonders. Screeching, high pitched metallic sounds are just something you come to expect and live with them.

As Gearnut said, some of the noise is from the square cut gears. A small dab of a good quality grease should be applied to the gear teeth occasionally but don't go overboard or you'll end up with a greasy, slipping clutch. Use the search feature as suggested and type in 'Engine Noise'. You'll have plenty to read on the subject. http://www.google.com/cse?cx=partne...hina-girl-first-startup-loud-noise-34787.html
Tom
 
B

buhz

New Member
Mar 16, 2011
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clearwater fl.
Re: China girl first startup - loud noise from motor

expect all sorts of sounds they quiet a little over time. it will wear in or wear out,as allways. ride safe Bob
 
brett7777

brett7777

New Member
Aug 19, 2011
619
1
0
Auckland, New Zealand
Re: China girl first startup - loud noise from motor

This is what the vendor said:
"It sounds like the big clutch gear is scraping on the cover. Remove the 5 screws on the clutch cover, take the cover off and take a look inside. You may see a tell tale mark or two. The clutch gears like a bit of grease on the teeth. It helps keep it quiet. Loosely mount the cover and screws back on, and hold the cover back so there is the most clearance for the large gear, then tighten up. Hopefully this will stop the noise."
 
GearNut

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
Re: China girl first startup - loud noise from motor

After hearing that, I say it very well could be the clutch flower nut screw is scraping the inside of the cover. I have one engine (now dead) that had that problem. The scraping screw problem did not cause the death of it mind you, a failed piston ring locating pin killed it.
The scraping screw eventually scraped the cover until clearance was good enough to stop making the awful noise. It never scraped all the way through.
I suppose an extra gasket or an extra thick gasket would have fixed it properly, but oh well, it fixed itself....

While it is hard to diagnose the sound over the internet, it also sounded like there was something rattling around inside the muffler? You decide on that one......

Follow thew advice of your vendor and remove the cover. You most likely will need an hand held impact driver to loosen up the screws for the first time as the factories are notorious for over tightening them.
Impact Screwdriver Set with Case

You never know what you may find, but it is the best first thing to check.
 
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