Did my china girl motor blow up??

fall_down_stand_up

fall_down_stand_up

New Member
I had a spare 66cc engine laying around and mounted it last week....I had about 11 miles on it and was staying around 15mph for break in....As I was going down the road I heard a "cling" sound like my tire picked up a peace of metal on the road and threw it up into my fender....My first thought was here comes a flat,well about 20 seconds later I hear the "cling"again and thought man that had to have come from my motor,whats the chances of hitting 2 peaces of metal on the road with the same sound....The whole time thought my engine sounded great,then about 10 seconds after the second cling the engine started making all kinds of clinging and clanging noises,so I pulled the clutch in and the engine stalled....After coasting for 15 seconds I dumped the clutch and the back tire was locked up but if I pull the clutch in it coastes fine....With the clutch in it does have a slight sandpaper rubbing sound,but mabe im hearing things.....What was really strange with this engine was when I went to mount it I could not believe how far the clutch lever set in....of all the engines I have had I have never seen one ajusted so far in....It made for a perfect straight shot were there was no angle or bind in the cable....It was the smoothest clutch I had ever had....Could it be something in my clutch?
John-John
 
Re: Did my china girl blow up??

granbury_man said:
Could it be something in my clutch?
John-John
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I think the question may be is there something missing from your clutch. From what you describe the difference in angle on the clutch arm may just be the width of a missing ball bearing?
 
Re: Did my china girl blow up??

Kevlarr said:
I think the question may be is there something missing from your clutch. From what you describe the difference in angle on the clutch arm may just be the width of a missing ball bearing?
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I pulled the rod and ball bearing out and greased it and put them back in....
 
Re: Did my china girl blow up??

hm. clutch id say. especially if it runs fine still.... well. aside from not anymore if its that fubar.

pull that **** apart and take pictures for us
 
Re: Did my china girl blow up??

Dan said:
any news GM?
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Yes I have some news and its all bad....Pulled the head today and the head gasket was hitting the piston and got shavings all down the cylinder....Its strange how the gasket was off center(only one side of the gasket was beat up),but whats really strange is the cylinder walls are smooth as silk....You would think I would have been able to hear the piston hitting the gasket,but It ran quiet and smooth as a sewing machine until it clanged and stopped....The only thing I can think happened is some of the shavings got down in the crank and messed up the bearings....tomorrow I will put some oil mixed with gas or some wd 40 in the cylinder to see if it will free the piston up so I can take the cylinder off....I have been to busy with a new engine today....
John-John
(aka GM),no wait that wont work im a Mopar man lol.... No GM will work lol.....shft. Oh one more thing dan,I showed my girlfriend your bicycle video and she laughed her butt off....I dig the mega phone ductaped to the helmet....
 
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Re: Did my china girl blow up??

Got an update....At closer inspection looking down in the cylinder I noticed that a small shaving was wedged at the very top of the pison....If I can get a sharp object like an ice pick or something to flip it out....or a tooth pick mabe?The cylinder walls are super smooth the motor only had 11 miles on it when the head gasket shavings got on top of the piston....If I get it out,do you think the engine will be fine if it turns over ok?I mean it is a very small shaving....I figure I just put a new head gasket on it and it will be rocking.....shft.
 
Re: Did my china girl blow up??

If I understand you correctly, the engine is seized and the crank will not turn? If that's the case I doubt a small sliver / shaving, as you describe it, would be enough to bind it that much. If its bound tight enough to stop your rear wheel from turning I'm thinking you have more serious issues than a small piece of gasket material wedged. Keep us posted; this is an interesting problem.
Tom
 
Re: Did my china girl blow up??

2door said:
If I understand you correctly, the engine is seized and the crank will not turn? If that's the case I doubt a small sliver / shaving, as you describe it, would be enough to bind it that much. If its bound tight enough to stop your rear wheel from turning I'm thinking you have more serious issues than a small piece of gasket material wedged. Keep us posted; this is an interesting problem.
Tom
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I took a peice of wood and hit the top of the piston with a hammer and it moved down 1 inch to the bottom stroke....I still cant get it to turn by using a screw driver on the sprocket....Im going to take the srocket cover off and put a wrench on it and see what it does....I will get back to you shortly
John-John
 
Re: Did my china girl blow up??

Humsuckler said:
have yo taken a gander at the clutch yet?
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When I push the clutch lever in the sprocket turns smoothly,but when I release it the piston wont move....Im convinced it has to do with the aluminum head gasket being off center and getting chewed up and peices down in the cyclinder,unless you know of something that could be causing the clutch to lock it up?....
John-John
aka granbury_man
 
Re: Did my china girl blow up??

hm. nope cant say i do.... i missed that earlier even tho i remember reading that the clutch works freely.
pull the jug off i guess and give it a good inspection. sounds like a bummed crankshaft. i had one spin on me once... actually put the crank out of round. Id almost put money on the crank being out of wack. Or possibbly something simple like the magneto chewed up. check under there before you go splitting your bottom end
 
Re: Did my china girl blow up??

fall_down_stand_up said:
When I push the clutch lever in the sprocket turns smoothly,but when I release it the piston wont move....Im convinced it has to do with the aluminum head gasket being off center and getting chewed up and peices down in the cyclinder,unless you know of something that could be causing the clutch to lock it up?....
John-John
aka granbury_man
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sounds like the needle bearings went...i had same problem....broke engine in with the best syn oil...wont mension name...not one engine..2 engines....both went down at 200 miles...now i use basic 2 stroke oil...good luck...Dennis
 
Re: Did my china girl blow up??

drhofferber said:
sounds like the needle bearings went...i had same problem....broke engine in with the best syn oil...wont mension name...not one engine..2 engines....both went down at 200 miles...now i use basic 2 stroke oil...good luck...Dennis
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You were right,the upper needle bearing went and the piston flopped and busted off a peice of exaust port on the side of the cylinder wall and fell down and got wedged on the side of the crank(locked it up)....Had 11 miles on it with non synthetic oil....Oh well,I put a new engine on my bike a couple of days ago and have 30 miles on it so far....Hope this one lasts....
John-John
 
Re: Did my china girl blow up??

Dan said:
Sorry to hear she is that bad off John-John. Really is great to have spare parts on hand though. That won't help until you need em.




Cool about the vid, Thanks. Fairracing did a bunch. Some great stuff.

http://motorbicycling.com/f15/video-photo-montage-8035.html
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Thanks Dan,I already have 6 spare engines laying around for parts,they have all seemed to loose compression over the years....Im thinking about selling all the engines and and keeping the rest of the parts for spares....Know anyone that would be intrested in bunch of engines with good clutches and still running when I took them off(just had little compression)?....for the cheap price of these engines I really havent thought about rebuilding any of them...
John-John
 
Re: Did my china girl blow up??

LOL, dang. Got me beat! (I have one spare that now looks nothing like a CG) Dunno why, but I thought this was your first build and was trying to ease the loss.

Just a thought, can almost always get more life out of em. Kinda like toothpaste tubes. snork. I bet a bunch of folks would want to buy em. Post in the swap section? You would be doing a service. There are folks saving up that can't afford new.
 
Re: Did my china girl blow up??

Dan said:
LOL, dang. Got me beat! (I have one spare that now looks nothing like a CG) Dunno why, but I thought this was your first build and was trying to ease the loss.

Just a thought, can almost always get more life out of em. Kinda like toothpaste tubes. snork. I bet a bunch of folks would want to buy em. Post in the swap section? You would be doing a service. There are folks saving up that can't afford new.
Click to expand...
I built a many,just never tore them down until this one that locked up on me....I have taken the heads off and replaced the cyclinder gasket and such,just never tried to do a complete rebuild....I was thinking about posting them on the swap and shop but didnt know if anyone would even want them....wonder how much it would be to just ship 4 of them and keep the rest for the heads and clutches and such?Would give 4 up for 50bucks or less,they pay the shipping....
 
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