Pop goes the Motorized Bicycle.

GoldenMotor.com
S

spit_fire

New Member
Aug 28, 2009
207
0
0
Brampton
Re: Pop goes the MB.

i was thinking of doing that where do you think i can get the crankshaft ballanced maybe a machine shop such as were i send my flywheels to be machined? you think they would have the right equipment??? and as far as throwing out the ballance the crank shaft arent ballanced to begin with right? so they would already b out of ballance you really think removing that little bit of alluminum would make that much of a diffrence and even so i would be removing weight from the object causing the inballance (the piston along with connecting rod) so wouldnt that bring it that much closer to being ballanced???
 
S

stv1jzgte

New Member
Feb 11, 2009
489
0
0
australia
Re: Pop goes the MB.

spit_fire said:
its wut i figured i mean when it comes to cars ill c anywhere between 90-110 maybe 120 psi so i figured if this little engine can do that it must be good and it was done ith a MAC tools compression tester not some cheap pos
Click to expand...
In a car 90 - 120psi is bad, a std corolla will see 190psi new.
 
S

spit_fire

New Member
Aug 28, 2009
207
0
0
Brampton
Re: Pop goes the MB.

i havent performed a copmpression tests on any new motor just used and i wasnt refering to anything high output or high compression motors i was generally speaking of your typical caravan or some gms its all i find myself doin compression tests on its all that comes in with missifres that arent related to ignition problems, any how even in school they told us we should be looking at anything between 90-120 i dont doubt theyrer are motors with way higher compression as theres tons of diffrent engine with diffrent outputs, its why some car dont run on regular and you need to use higher octane fuels to keep them from predetonating, so with that said 90-120 for most engines is perfectly acceptable and is not bad
 
R

rcflier500

New Member
Nov 15, 2009
50
0
0
Upland, Ca
Re: Pop goes the MB.

ok guys so im back with an update. I took the bike out to no avail again and after getting back i took the plug out, plugged it into the cdi wire and then pushed the bike, no spark. Even with the plug contacts completely cleaned there was no spark. Is the cdi dead already?
 
Blakenstein

Blakenstein

Member
Sep 15, 2009
561
2
16
Alta. Canada.
Re: Pop goes the MB.

rcflier500 said:
ok guys so im back with an update. I took the bike out to no avail again and after getting back i took the plug out, plugged it into the cdi wire and then pushed the bike, no spark. Even with the plug contacts completely cleaned there was no spark. Is the cdi dead already?
Click to expand...
Yea, that's what I said way back on page one. "be 1oo% sure that u got spark. don't just assume"
Then u can start your trouble shootin from there.
Once again, I rest my case.
 
R

rcflier500

New Member
Nov 15, 2009
50
0
0
Upland, Ca
Re: Pop goes the MB.

I definitely underestimated you blkenstein :) Is there a thread on here about how to test the cdi for troubleshooting purposes?
 
Blakenstein

Blakenstein

Member
Sep 15, 2009
561
2
16
Alta. Canada.
Re: Pop goes the MB.

rcflier500 said:
I definitely underestimated you blkenstein :) Is there a thread on here about how to test the cdi for troubleshooting purposes?
Click to expand...
Yes there is,try asking one of the moderators, and check out Norms repair center ,he can be a big help to u on that, as well as many others such as bairdo, motorbike mike, bikeguyjoe, 2door,venice,barely awake, and many others. P.S.-your kill switch might be shorted out,-It happend to me.
 
E

exavid

New Member
Dec 12, 2009
163
0
0
Medford, OR
Re: Pop goes the MB.

spit_fire said:
i was thinking of doing that where do you think i can get the crankshaft ballanced maybe a machine shop such as were i send my flywheels to be machined? you think they would have the right equipment??? and as far as throwing out the ballance the crank shaft arent ballanced to begin with right? so they would already b out of ballance you really think removing that little bit of alluminum would make that much of a diffrence and even so i would be removing weight from the object causing the inballance (the piston along with connecting rod) so wouldnt that bring it that much closer to being ballanced???
Click to expand...
I can't say positively that these engines are balanced but find it unlikely they aren't. I haven't disassembled any of these little engines but it's pretty rare to find one that doesn't have counter balances cast or forged in to the crank shaft. The easiest way to check a crankshaft and piston assembly on a small engine is to take the crankshaft with the piston and rod attached and set the crank across a couple pieces of steel straight edges that are level. With the crank throw positioned at 0300 or 0900 the shaft shouldn't show any tendency to roll. If it does the metal is taken off the piston or crankshaft as needed to prevent the assembly from rolling on the straight edges.
 
S

spit_fire

New Member
Aug 28, 2009
207
0
0
Brampton
Re: Pop goes the MB.

i have taken this engine apart i put in skf main bearing before the engine was even ran just for s hits and gigles firgured it def couldnt hurt it and i can tell you there are no counterweights they are just 2 round plates maybe 3/4 inch thick (dont really remmber it was almost 6 months ago) and a whole as to were the pin that connects the bottom of the connecting rod to the crank shaft (it would be the throw but just a pin presses into the two round plates) and they are perfectly semetrical and even in weight except for the whole i just mentioned, i agree with you that all engines should be ballanced asspecially a single cyclinder where it doesnt have another one to counter ballance it but for the price you pick up these kits does it really surprize you?
 
E

exavid

New Member
Dec 12, 2009
163
0
0
Medford, OR
Re: Pop goes the MB.

It does surprise me because it's simple and cheap to do a rudimentry balancing. I might check out my engine one of these days and balance the crank and piston. It can't help but reduce vibration. I should have suspected these weren't balanced when I saw someone post about changing a 49cc to an 66/80 just by replacing the piston and cylinder.
 
S

spit_fire

New Member
Aug 28, 2009
207
0
0
Brampton
Re: Pop goes the MB.

apparently in another thread it was mentioned that there is a mathematical formula that according to the weight of the piston and connecting rod it tells you exactly how much weight to remove and from where but somebody mentioned they tried it and it made the engine worse either they didint do a good job or it doesnt work, i like your idea better you think you can take some pics of your setup when you get around to doing it and let me know how well it works and if it does wonders i will gladly follow in your footsteps
 
E

exavid

New Member
Dec 12, 2009
163
0
0
Medford, OR
Re: Pop goes the MB.

It probably won't do wonders. The Grubee I have runs fairly smoothly for a one lunger. The vibration level isn't bad at all. If it goes bad so I have to tear it down I will try balancing it. Basically it's pretty much the same as bench balancing a wheel, except you have to drill out metal instead of sticking on weights.
 
R

rcflier500

New Member
Nov 15, 2009
50
0
0
Upland, Ca
Re: Pop goes the MB.

PROBLEM SOLVED! It ended up being a broken solder joint where the coil in the magneto connects to the ground. I can post pictures if wanted
 
GearNut

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
Re: Pop goes the MB.

Congratulations! Now you can enjoy the fruits of your own expertise.
Well done.

Pictures could help the un-initiated, if you want to share them.
 
Last edited:
You must log in or register to reply here.
Top Bottom