HELP!! Grubee Skyhawk 66cc Bogging down, desperate - Motorized Bicycle

ILoveVTEC · #1 03-03-2011, 05:57 PM

I am new to motorizing bikes, and this is my first project. For some reason, whenever I start my bike, it idles at a VERY high RPM, and when I start to accelerate (10+MPH) it bogs down until I release the throttle. When I engage the clutch, it idles at a very high RPM. I've made sure my carburater is airtight around the intake valve, and I've also played with my adjustment screw.. It's running at a 24:1 fuel ratio at the moment. I've also found that playing with the clutch lowers the RPMs when idling. Sometimes it idles at such a high RPM that the curburater is thrown off the intake valve.

If you can offer any tips, that would be great. I'm desperate to get this thing working after several trips to home depot and power equipment stores. It's been almost a week-long project.

Bike Monster · #2 03-03-2011, 06:42 PM

There is a screw on your carb... (it has a spring) this screw will lower or raise your idle depending on which way you turn it try fooling around with it... okay

matthurd · #3 03-03-2011, 06:50 PM

if you're using the grubee CNS carb, screw your fuel air mix screw in all the way, and start adjusting your idle screw from there

this thread has a good picture labeling what i'm talking about http://motorbicycling.com/f34/inside...arb-25062.html

ILoveVTEC · #4 03-03-2011, 10:13 PM

Thanks all 3. My intake valve was leaking, which I remedied by coving the plastic ring holding the carbureter onto the intake pipe with heat-resistant electrical tape. I have tried playing with the fuel mixture screw.. but the engine still keeps bogging down when I lay out on the throttle. Should I try a less rich mixture? (currently 24:1)

ILoveVTEC · #5 03-04-2011, 10:52 AM

How do I raise the carb needle? It's an aftermarket CNS carb.

Goat Herder · #6 03-04-2011, 10:59 AM

In this link will give you a brief over view of a carb and how to adjust the needle. AKA fuel metering rod. While not the same carb the over all principles here are the same. Scroll through this link will help

http://www.google.com/url?q=http://m...FrCesayi21NGBw

Mac · #7 03-04-2011, 11:12 AM

Check "Norm's 2 stroke repair center"

http://motorbicycling.com/f39/motori...build-302.html

notshy77 · #8 05-11-2011, 01:46 PM

check ur trhottle cable, by the handle adjust it, that happen to me also.

Greg58 · #9 05-11-2011, 08:12 PM

I see that you are in Alabama i am in Ga. I had to change the e-clip on my cns 48cc grubee to get it to run past idle, it would just spit back through the carb. I tried first moving the clip to the top and doing all the adjustments, I did try all five slots with the bottom working the best. elevation makes a big difference on these engines.

Greg58 · #10 05-13-2011, 08:48 PM

I was working on mine today and noticed the air filter was oily, started thinking why came in and found a old thread about the vent tube. it turns out I needed to remove the tube from the air intake, at half throttle sometimes it would bogg. It was drawing gas from the bowl, I pluged the hole behind the air cleaner and put a six inch piece of fuel line on the vent and ran it over the carb in between the filter and barrel. It increase my mid. range power, if you look around this site enough you can find the fix for most problems.