can't find an answer then ask here someone may be able to help!!

GearNut- I believe I've mentioned to you that my bike is up and running!
To update here, at 5,500' I had to turn the air/fuel mixture screw out 3 full turns. There was a lag in the engine between say 3mph and 10mph, it was being starved. That problem has nearly gone away. I intend to experiement a little more to dial it in, but so far I could'nt ask for more. It is possible that re-jetting the carb would be an overall improvement...
 
Hi Norman,
I bought a new 60cc engine for my son who before I can get home to help, took the top end off to 'lubricate" it before he put on bike and start it up. When he was putting the top end back on, the top piston ring broke. I got two new rings, but before we put them on, would like to get any information to help us to put them on and avoiding them to break when put on the engine top end. I have read some stuff, like to sand them, but dont know where to do that, and how to keep them in place for the head to go over them without breaking....
Thanks!:-||

Here's some info on rings.
This may or may not help you. Install a set of rings I don't have any info on the side gap of the ring or the end gap on the rings. You can push the ring into the cylinder and the ends should not butt up, should be around 0.002 or more end gap on the rings. You can use the piston to gentle push the ring into the cylinder around halfway then measure the end gap. Side gap is measured with the ring help in the piston's groove and measured with a feeler gauge side gap I'm guessing should be around 0.002. For more help you might want to google rebuilding a 2 stroke engine, or even a 4 stroke engine just for the ring install info. Remember the 2 stroke engine has keeper pins installed in the piston's ring groove to keep the ring from rotating around on the piston. The ring keeper is where the split on the ring will be.

here is a link for the top end it's old and don't have a bunch of info but might help some.
http://motorbicycling.com/showthread.php?t=297
Norman
 
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Okay so I had a bad night went riding to a friends house and when almost there throttle cable broke at the throttle! Kind of a far ride but the things I needed to fix this were not available there so I used one hand on the bars and one on the cable at the carb was working great a lil hard on the hands but hey me and my bike were both going to make it home ! But when I was on the last leg just at the bottom of the biggest hill and having to go up the chain comes off for some reason so I put it back on did any re adjusting that it needed and it would not fire up thinking that it had something to do with fuel I decided to just pop the clutch in and peddle home up the hill! Get home and fix cable problem and go for test ride but still not starting so I think it has to be spark ! Pull plug and test for spark and nothing so I think maybe the chain went through the case and sent some fragments into magneto ? pull case off and there was lil bits all over as well as the magneto magnet the round piece that spins on the shaft to generate the electricity is no longer connected to the rest of the shaft the shaft broke ! Can someone please tell me if they have done a repair on this and how difficult and time consuming it is ? and any tips would be great as well I have a 66cc SkyHawk Thank you !
 
If you have the tools and the knowledge on how to take the engine apart and put it back together again then you should be able to fix it. Getting the proper parts that fit may be a problem.

Would I want to fix it?.......... Nope, I can buy a replacement engine cheaper than fixing the broken one.
 
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anonymouspimp said:
Okay so I had a bad night went riding to a friends house and when almost there throttle cable broke at the throttle! Kind of a far ride but the things I needed to fix this were not available there so I used one hand on the bars and one on the cable at the carb was working great a lil hard on the hands but hey me and my bike were both going to make it home ! But when I was on the last leg just at the bottom of the biggest hill and having to go up the chain comes off for some reason so I put it back on did any re adjusting that it needed and it would not fire up thinking that it had something to do with fuel I decided to just pop the clutch in and peddle home up the hill! Get home and fix cable problem and go for test ride but still not starting so I think it has to be spark ! Pull plug and test for spark and nothing so I think maybe the chain went through the case and sent some fragments into magneto ? pull case off and there was lil bits all over as well as the magneto magnet the round piece that spins on the shaft to generate the electricity is no longer connected to the rest of the shaft the shaft broke ! Can someone please tell me if they have done a repair on this and how difficult and time consuming it is ? and any tips would be great as well I have a 66cc SkyHawk Thank you !
Click to expand...

This sounds like a broken crankshaft to me. It is a major failure but you can easily replace it yourself if you do a bit of research. Take your time and replace all the bearings and seals when you re-assemble the block. Search here for lots of tips on how to replace cranks and the related parts. These engines are very easy to work on if you take it easy and use the proper tools. I'd suggest you invest in a good hand impact driver to avoid stripping the cheap hardware when disassembling the cases. The china phillips-head hardware is cheese hardened at best.
 
Hey NORM
I built my bike a year ago been running perfect today it just quite running and cant restart it, checked gas for water, checked ohms on the cdi and the magneto everything checks out but it still wont start.
Any suggestions ?
 
I'm not norm, but I'd stick with the basics. Fuel, spark, and air. You checked spark, so.....
 
I mostly work with 4 stroke, but much the same applies. I sort of forgot about air. Like vacuum leaks too. But three things always I think are necessary are fuel air mixture, compression, & spark.

For spark, discounting timing temporarily, taking the spark plug out and shielding from sun or bright light, have its threads touching ground and with high tension connected, keep yourself away from high tension and turn the crank to see if it sparks.

Clean plug and gap if necessary and also look to see if it is wet with fuel. You would have to dry it if wet, but at least you would know you got fuel.

Some where some one should know on this site the list of things already like I mentioned. See if you can find it.

MT
 
Hey guys, didnt read all 35 pages, but my question is this. I currently have a mountain bike build going on, and im having some trouble with the mounting on the front tube of the bike. Not the seat tube, ive got that sorted out, the other tube you mount to. Its far to wide for the engine mounting studs to fit around. Anyone have advice on what I can do? Maybe link me to another thread where this has been talked about before? thanks
 
I copied this from another guy, it was real easy. All you need is a hockey puck, a flat piece of metal, and a u bolt. I cut the piece of metal and drilled holes for the frnt mount and ubolt. Then I measured and cut hockey puck and drilled holes for the ubolt. Bolted it on and the motor is solid. Check out the pics, let me know if you have any questions.
http://motorbicycling.com/showpost.php?p=456311&postcount=17
 
Frogster said:
Hey guys, didnt read all 35 pages, but my question is this. I currently have a mountain bike build going on, and im having some trouble with the mounting on the front tube of the bike. Not the seat tube, ive got that sorted out, the other tube you mount to. Its far to wide for the engine mounting studs to fit around. Anyone have advice on what I can do? Maybe link me to another thread where this has been talked about before? thanks
Click to expand...

http://spookytoothcycles.com/component/virtuemart/?page=shop.product_details&product_id=460
Easy to copy locally with a steel plate, a drill, and a u-bolt.
 
engine problems

i have a gt5 skyhawk with pc high compresion head, sbp exhaust, jaguar ignition jnx header port billeet intake and a nt carb. it starts fine runs find and is able to get up to top speed for a couple minutes and then it sputters and wont hardley get above an idle and wont rev back up pls help. keeps foul'n plugs and im runin a 40 to 1 ratio . pls help :-||
 
It could be a number if things. Start with the basics.
Fouling plugs = too cold of a spark plug heat range and/ or too big of a fuel jet in the carb.
My guess is to big of a fuel jet which is fouling the plug and a poorly vented fuel tank which starves the fuel flow after a few minutes.
Next time is acts up, crack the fuel cap (twist it open and tighten it again) and see if the engine picks up again.

I have never heard of JNX and a quick web search comes up with alot of non motorized bicycle related stuff
What spark plug are you running?
 
I'm kinda stumped...I also haven't checked everything yet. I'm just asking this question now so maybe there will be a helpful response right around the time I get frustrated as **** trying to fix it lol zpt. I just put on a NT Speed Carb yesterday and the bike ran great during a quick test run (FYI -only had half an extended exhaust pipe and no muffler) Then today I went for a ride (now with about 10 inches of an exhaust pipe left because the weld wasn't done correctly due to the metal constantly burning through and thinning out) and for a couple min I couldn't accelerate past the low end. When reaching top end the engine would want to die, the more gas I gave it the faster it would want to die. Well after a couple min it ran fine until I reached my destination. Upon returning to my home the same thing happened but hasn't gone away. So far I've checked for blockage, leaks, opened gas cap, checked the throttle linkage and the float isn't stuck but that's as far as I got and still no change. Oh yeah and I've run the bike b4 several times with the exhaust as it is now(with the stock carb) and no issues I haven't checked the forum completely due to lack of time so I apologize if there's already a thread about this and thank you very much for your time and thank you everyone, especially the most dedicated, .flg. for making this site possible. If it wasnt for this resource I think there would be a #!*$load of chinagirl 2strokes pilling up in landfills everywhere....Thanks (^)
 
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So I dismantled the carb and made sure all is well and took it for a spin...same thing happened...so i removed the air filter thinking its not getting enough air...well acceleration improved to an extent and would drop out when almost at peak speed (id say 3/4 of the way. During this i noticed gas spitting out of the carb through the air filter port, so im thinking too much gas...but I have the neeedle at the leanest setting #1 top indent. Going to investigate further, just thought this info might be helpful in some way...thx
 
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