NO IDLE 80cc skyhawk bicycle

jkflyer

New Member
Jan 4, 2014
11
0
0
bakersfield
Hi there, I'm new to moto bicycling, I've recently purchased a couple of used bicycles both with 80cc Skyhawk motors from what I was told. Well I'm sure I'll have tons of questions to come i was wondering why my girls bike doesn't idle and how would I go about adjusting it?
As she comes to a stop it kills the motor until of course she starts pedaling again. How do I get her bike to idle as mine does? From what I've researched both bikes have an NT carb.
 

rohmell

Active Member
Jun 2, 2010
1,533
1
38
New York
Have you tried to adjust the idle screw that is in the side of the NT carburetor?
Clockwise rotation of the screw will raise the carb slide, and thus the idle.
 

Donavan321

New Member
Sep 27, 2012
238
0
0
Appleton, Wisconsin
Sometimes the clutch doesn't disengage entirely and that can also kill the engine as well. First adjust the idle as mentioned above. If there's anyone in your area who has built several of these and know about them, you should consult with them and get to learn them. They are a HUGE learning curve, once you learn them though........everything's a breeze for the most part. Good luck and keep us posted!
 

il_10

New Member
May 6, 2013
10
0
1
VA
Check a couple of the threads on the nt carb, there are plenty around:
http://motorbicycling.com/showthread.php?t=31260

An air leak usually results in a racing idle, but could prevent idling altogether, so check the connection between the carb and the intake manifold.

Once you get the carb worked out, I'd start focusing on the clutch. When you get the bike started and rolling around, pull the clutch all the way in and keep riding for a second to see what happens with the throttle OFF. If it dies and the bike is still moving, the clutch is fine and you still need to mess with the carb. If it idles while moving, but dies when you stop, then the clutch is probably still engaged a little bit even when you pull the lever. You can adjust this either via the star nut inside the clutch cover, or by adjusting the length of the clutch cable at the clutch lever (either the one on the bars or the one on the engine, I usually adjust this engine side)

Good luck! As Donovan321 said, even though these are simple little engines, there's a steep learning curve to getting them to act right. Most of that learning comes when you're assembling the kit and getting it running initially, so you've got some work to do to get up to speed, but this forum is a great resource and everything you need should be here somewhere.
 

jkflyer

New Member
Jan 4, 2014
11
0
0
bakersfield
Thank you all, and yes the idle simply needed adjusting as I assumed. To be honest I have a little history in mechanics but as I've said I'm new to this sort of thing. From what I've heard these things can be a blast but require some know how and up keep. So I figured best to consult some experience before turning screws :) I'll be repainting one of the bikes so I'll get some hands on the dismount and remount. From what I can see it all seems fairly simple by design but I'm certain I'll be back with tons more question until I get it down. Thanks again
 

Donavan321

New Member
Sep 27, 2012
238
0
0
Appleton, Wisconsin
You're welcome! They are pretty simple for the most part and lack reed valves which most two stroke engines have. These do NOT. You can get a reed kit which boosts your performance, but starting out? I don't think you want to mess with upgrades yet! I like crusing between 30-35mph, maybe I'll push 40 once in awhile. Also, be sure to check nuts and bolts every so often as they DO tend to come loose. I've mentioned before I've noticed this more as a problem with the 66/80's compared to the 49/50's I like the 49's over the 66's anyday beacause they vibrate less and I/you can build them up and change the gear ratio to achieve the speeds of a 66/80 while having a far much smoother ride!When you compare them stock, the speeds aren't that far apart. Good luck! looking forward to seeing some great pictures!
 

Jumpa

New Member
Aug 12, 2011
607
1
0
Cape Cod
get the NT speed carb by far the best carb I've had, and the short aluminum intake that ends the carb issues for a good long time .. At least it did for me
 

Agreen

Member
Feb 10, 2013
792
11
18
Southeastern GA
I like the 49's over the 66's anyday beacause they vibrate less and I/you can build them up and change the gear ratio to achieve the speeds of a 66/80 while having a far much smoother ride!
Absolutely. I couldn't agree more. And what's strange is that my 48cc hit faster than my 66/80cc ever did! No idea why, but I can zoom easily over 40 mph on the 48cc. The highest I ever hit on the 66cc was 33 mph. Probably because the engine is somehow balanced better?