Engine Trouble Another power loss story

[Fabian]

The connecting rod small end bushing failure is the cause of your power loss, not to mention the connecting rod big end bearing would have also failed or be at the point where it is no longer usable.

Time to split the cases and install a new crankshaft and connecting rod assembly.

 

[jeffuehrer]

Now I need to replace the drive sprocket!

I have figured out by now that nothing in the MB world is an easy fix (mostly). I decided to "throw" on my new motor and got some things in advance of the new venture i.e., new wider mounting plates for the wider size front mounting bolts. I finally got my back mounting nice and flush top to bottom on the back tube. My front mounting plates picked up the slack of the unfavorable angles (pictures to come). The crack in my frame hasn't worsened. I got to putting my chain on and discovered that my chain would not fit. DOH! I had a spare large chain that didn't fit my other sprocket so I tried that and it fit the drive sprocket but it wasn't flowing freely as a wheeled it so I had to learn a new thing. Drive sprocket removal. I used a chain as my binder (chain.jpg) to unscrew the nut with a 3/4" socket (counter-clockwise). I flipped the chain around (chain_clockwise.jpg) to screw in the sprocket puller with a crescent wrench since I don't have a 7/8" wrench (sprocket_puller.jpg). I got the sprocket off pretty easily (sprocket_off.jpg). I threw it back on the drive shaft and put the chain on counter-clockwise to unscrew the sprocket puller (sprocket.jpg). Here is my new sprocket (new_sprocket.jpg). Don't forget to take the bucking bar out (new_sprocket2.jpg). I was able to use my spark plug remover to remove the drive procket nut (spark_plug_remover.jpg). To my dismay my new sprocket would not tap on because the ?rocker pin? was slightly thicker (rocker_pins.jpg) than the pin on the other drive shaft. Figures. I turned the shaft so the pin groove was on top (pin_groove.jpg). I then filled the groove half way with super glue to hold it in place (pin_groove_filled.jpg) so I could tap on the sprocket (sprocket_attached.jpg). I tightened the sprocket nut (nut_attached) by holding a screwdriver in the clutch gears (screwdriver.jpg) to prevent the gear from spinning. Reverse the orientation of the screwdriver when unscrewing the sprocket nut. I've never had two builds that were exactly alike...on the SAME BIKE! Well, after all I'm only going to be three years old in this field. I've had no prior experience in automotive or motorcycles. Kinda sucks when you didn't have gear heads around you while you were growing up. Tomorrow I'll be finishing up and getting her started if at all possible. 2-3 hour build my ass. Well, at least for me that is.

 

[jeffuehrer]

The connecting rod small end bushing failure is the cause of your power loss, not to mention the connecting rod big end bearing would have also failed or be at the point where it is no longer usable.

Time to split the cases and install a new crankshaft and connecting rod assembly.

LOL. That's funny. I think I'll save that after I have a little more experience.

 

[jeffuehrer]

Got the new engine up and running!

I took her out yesterday for the maiden voyage (blue_lightning.jpg) and she worked the very first try. I let her idle for about two minutes to warm up then I ran her for twenty minutes varying the rpms but not going above 20mph. My mix is 7oz. Amsoil two-cycle to one gallon which comes out to 18.28 to 1 which is higher than most of you would say to go (20:1) and lower than the seller (16:1) so I split the difference somewhat. I'll use that ratio for three gallons than go to it's permanent ratio of 36.57 to 1. I finally got the mount where I want it (flush to back tube) upper_mount.jpg & lower_mount.jpg. The one thing I did notice was some resistence every revolution. At first it would kind of lock up the rear wheel. Now it seems to be going away...like maybe one of the clutch pads was a little thicker or the magnet was causing it. I'm not sure. I seem to remember it doing that with the last engine I had at break-in. Do the senior members have any input or suggestions to add to my break-in procedure? The most I've gotten out of these engines was 2,500 miles. (49cc) the least was 600 miles (66cc). This is my fourth engine in about three years. Thanks in advance.

 

[crassius]

To my dismay my new sprocket would not tap on because the ?rocker pin? was slightly thicker.

Lately, there have been two sizes of these woodruff keys - either thick or thin.

If the motor hasn't been worked on since leaving the factory, all 4 keys will be the same & all 4 slots on the 2 shafts will be the same & all 4 units that fit onto the shafts will be the same. This make ordering rotors & clutches and stuff from the inet REAL hard Lots of filing & blacksmithing needed sometimes nowadays : (

 

[jeffuehrer]

Lately, there have been two sizes of these woodruff keys - either thick or thin.

If the motor hasn't been worked on since leaving the factory, all 4 keys will be the same & all 4 slots on the 2 shafts will be the same & all 4 units that fit onto the shafts will be the same. This make ordering rotors & clutches and stuff from the inet REAL hard Lots of filing & blacksmithing needed sometimes nowadays : (

Thanks for the definition of the woodruff key. Are you saying they're four different sizes? Or two? Thick and thin. Because if there are four different key sizes than there would be four different shaft sizes (four different size woodruff key slots). I agree with choice but if one thing works why change it? That's why you don't see several different types of p.u.s.s.y.

 

[BchCruizer]

I took her out yesterday for the maiden voyage (blue_lightning.jpg) and she worked the very first try. I let her idle for about two minutes to warm up then I ran her for twenty minutes varying the rpms but not going above 20mph. My mix is 7oz. Amsoil two-cycle to one gallon which comes out to 18.28 to 1 which is higher than most of you would say to go (20:1) and lower than the seller (16:1) so I split the difference somewhat. I'll use that ratio for three gallons than go to it's permanent ratio of 36.57 to 1. I finally got the mount where I want it (flush to back tube) upper_mount.jpg & lower_mount.jpg. The one thing I did notice was some resistence every revolution. At first it would kind of lock up the rear wheel. Now it seems to be going away...like maybe one of the clutch pads was a little thicker or the magnet was causing it. I'm not sure. I seem to remember it doing that with the last engine I had at break-in. Do the senior members have any input or suggestions to add to my break-in procedure? The most I've gotten out of these engines was 2,500 miles. (49cc) the least was 600 miles (66cc). This is my fourth engine in about three years. Thanks in advance.

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Bummer dude! Only 2500miles and 600 miles..i have 6,000 on my kit. Whatta expect for 179bucks though..You pay for what ya get! I spent $279. worth every penny..i ride friction though there just more reliable..they dont look as cool though. Im sure fabian will have plenty of helpful tips. he's like the chain drive guru for sure!

 

[danmarjon]

I have the same problem at only 1500 mi, bushing almost gone, had loss of power and rattling sound. I just want to purchase a new bushing, but I can't find one anywhere!! ant help on this would be greatly appreciated

 

[BchCruizer]

I have the same problem at only 1500 mi, bushing almost gone, had loss of power and rattling sound. I just want to purchase a new bushing, but I can't find one anywhere!! ant help on this would be greatly appreciated

Try contacting the company you bought it from. they might now. They make everything so disposable now days! i looked around and couldn't locate one either..good luck and if ya do find one let us know..im gonna keep on looking to..

 

[BchCruizer]

I have the same problem at only 1500 mi, bushing almost gone, had loss of power and rattling sound. I just want to purchase a new bushing, but I can't find one anywhere!! ant help on this would be greatly appreciated

Check these guys out they can probally help ya...
http://www.shop.motorizedbikeparts.com/product.sc?productId=32