Loud screeching noise

pyromancy5

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Jun 24, 2008
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I have a generic Chinese 2 stroke, and my motor screeches with the drive engaged. I do not have clutch slip, but it goes away with clutch in at idle, and does not make a sound when revved at a stop. it is more noticeable during acceleration, but never goes away while driving. the bike runs good, keeps a low idle, and has less than 10 hours on the engine, has wonderfull pickup, and i feel it wants to go faster. I have been babying it, i have a 44 tooth sprocket, and it does 15 or 20 like it was born to do 40.


Any ideas on how to make it stop screeching?
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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The screeching you describe sounds like it's from the gears....pop off the right side cover and grease the gears with a little wheel bearing or lithium grease. Some bikes, the sound never goes away.

Don't baby it too much. More important during break in is to vary the throttle and engine speed, don't be afraid to run it up once in awhile. Avoid long periods of downhill coasting with the throttle off, it starves the engine of oil.
 
Last edited:

Dave31

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Mar 1, 2008
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This is just for practice for copy & paste...figured I practice here..

1. How to Adjust Clutch if signs of slipping or squealing are encountered :

A) Disengage clutch by pulling handle bar clutch lever inward and lock into catch lock.

B) Remove right side engine clutch cover and remove small locking screw on center *Clutch Adjust Nut.

C) Pull clutch arm on left rear engine inward. Back off *Clutch Adjust Nut ¼ turn counterclockwise.

D) Release clutch lever and check for slight clutch arm 1/16” free-play on opposite side of engine. Readjust *Clutch Adjust Nut as required to get required 1/6” clutch arm free play.

E) Tighten *Clutch Adjust Nut on clutch plate clockwise until just snug.

F) Then re-install small locking screw in outer edge of *Clutch Adjust Nut.

G) Good idea to place a small gob of grease at gear mesh area. Use grease sparingly! Then replace cover.

H) Squirt light grade oil down clutch cable sheathing to reduce friction and make for easy lever pull.

Yeah, it worked....:D
 

Pablo

Master Bike Builder & Forum Sponsor
Dec 28, 2007
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Easiest stuff (as in lubing the gears):

Indeed have you had the clutch cover off?

Remove the cover and inspect the inside of the cover for contact marks. Clean it (the inside of the cover) and inspect again.

Then wipe all the black crap and black nasty stock grease out around and on the large (flyweel) and small engine gear. You'l want the old grease out because you want to lube it fresh - with nice new very sticky grease. Use boat axle grease if you can find it. Use about the amount you would brush your teeth with....:p maybe a hair more, but that's it. Put the cover back on and ride. If that doesn't help we'll go from there....(as in checking clutch pucks, etc because you said it doesn't do it when you are sitting there with clutch handle pulled in, right? )....see post above!!
 

pyromancy5

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hey thanks for the advice! all this is great stuff. Sounds like I'll be working on it for a good part of the afternoon. One question though, am i going to have to replace the gasket for the clutch cover cover? and is black gasket maker ok to use instead?
I don't know if I'm going to be able to get a hold of boat grease, but I've heard the synthetic green grease is really sticky.
 

Pablo

Master Bike Builder & Forum Sponsor
Dec 28, 2007
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I've never replaced the gasket on mine!! :eek:(^) It's not a wet gasket so unless it somehow gets destroyed, keep using it. OR any gasket maker sealant goop stuff should work.

Not sure what "synthetic green grease" is but it should work fine if it's "shsticky"....I use Amsoil racing grease with a tackifier I add myself, because while a great super fast good grease, the racing grease is not sticky enough for such a gear set up.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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up north now
Maybe you should mix up a batch of "Pablo's Magic Gear elixer for Motorized bicycles".

Sell it in 4 oz. mini tubs.

I agree that the gasket is mostly there for show. Even if it tears, glue it back together with nail polish, superglue, RTV or?????
 

pyromancy5

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Jun 24, 2008
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i pulled off the cover, there was very little some black grease on the gears, added some more and tightened the clutch a notch, to make the play correct in the clutch lever. a fair amount to dust from clutch pucks was lying around, and pucks looked like they were frayed. what are the best ones to replace these with?

Still has the same sound :(
 

pyromancy5

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Jun 24, 2008
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good to know! today i opened er up all the way for the first time. The vibrations were increasing untill at full speed, and then a very smooth ride. I don't intend to do it ever again. (Have lost the chain once on my coaster break only bike, and had to "Fred Flinstone it" to a stop) kept up with traffic going 40!! any idea on ow to cut down vibrations in between 55% and 90% throttle? Would rubber bushings make the motor unstable?
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
236
63
up north now
People have tried that, never heard back about them, so 'm guessing it didn't work too well.

The engine will get smoother with miles...how many do you have? You can buy a smaller sprocket (36T) to help with the vibes too. These engines vibrate, that's just how it is.
 

Norman

LORD VADER Moderator
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Jan 16, 2008
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36 tooth sprocket will get you lower engine speed/ vibs. and when wide open you will be able to hit at least 40mph and it gets a little hairy at that speed on a bicycle.
I don't recommend rubber mounting but I do endorse a good tight engine mount front and rear along with foam handlebar grips and a good spring seat.
Norman
 

pyromancy5

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I hit 40 with a 44T sprocket. if not darn close. It was wide open at that point, and really smoothed out (vibes around the 15 mile an hour range) ran into a new problem today, the pin that holds the clutch lever in place came out. the metal on the case cover looks like it may have broken off. is that a screw or a pin? i never took a close look at it while it was attached. any one know where to get a new one or a good make-shift replacement?

I dont have springs, and I'm not going 40 again, like i said, Im running a coaster break, but i have intentions of putting on standard front break pads. maybe ill get a springer fork too.