Grubee Skyhawk, Engine Won't Go

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thejdoe

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Apr 29, 2011
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Here is my issue: I pedal down the street, release the clutch, engine starts. Then I give it gas, the engine revs a little, but then it just dies out.

To me, it sounds just like a weed eater if the choke isn't adjusted properly. I've tried tightening the cable that connects to the throttle thinking maybe I'm just not pulling it tight enough when I twist the throttle, but that doesn't help. I don't know what the problem is.

I bought this kit about 6 months ago, and it has had this problem from the beginning. I lost motivation to try to fix it, so my bike has just been sitting there. But now I'd like to fix it. Any ideas???

I've applied the rubber silcon sealant around key areas where air leaks might affect the engine power, but that hasn't helped. Maybe I didn't apply the sealant everywhere I should have. And yes, there's gas in the tank.

The fuel was mixed with 18:1 ratio, which was the recommended amount for the initial ride. Could that be my problem??

This is my kit:
GRUBEE SkyHawk GT5 66cc/80cc Slant Head Bike Motor Kit (Standard Finish)
 
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LaLongueCarabine

New Member
Aug 15, 2011
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Is your fuel petcock open?

Don't laugh, I've seen it more than you would believe.

What about debris in your tank, did you clean it before you poured fuel into it?
Lasty hows your spark? Possible it looses connection for a bit?
 
Greg58

Greg58

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May 1, 2011
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These little engines are tough to get right when new, what I run in a new build is 24 to 1 for a couple of tanks then lean the fuel mixture out to 32 to 1 on my bike I run lucas semi-synthetic at 40 to 1. I am on my sixth build and have found that if I get to run at around 12 to 15mph and be patient it will get better, the more you run these engines the better they get.
 
Ditchrider

Ditchrider

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Jun 25, 2011
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Is it a new motor? If so look in the exhaust port and see if its open, try it with the exhaust and air filter off. There could be trash or something in the needle valve passage.
Hope it works out ok. I'm sure someone out there has had the same problem.
 
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thejdoe

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Apr 29, 2011
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Ok guys I’m reviving this thread. Someone hopefully can help me. I’ve had a very frustrating experience with my Grubee Skyhawk. I ordered this back in May 2011 from gasbike.net, and I’ve never gotten it up and running (needless to say customer service sucks, and they haven’t helped me). I’ll try to recap in a nutshell.

I can get the engine to start (peddling down street and release clutch). But as I give it gas, the engine never gains power and just fizzles out in about 2 seconds after starting. I’ve followed suggestions found in this forum: I’ve tried different gas to oil fuel ratios, I’ve adjusted the float, and I’ve adjusted the E clip on the plunger, and I’ve used rubber silicone sealant around where the carb mounts. What the heck else is there to do??

Please someone help. Why can I not give the engine gas without it dying? I’d really like to ride this thing.
 
Greg58

Greg58

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May 1, 2011
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I can't tell from the pic. which carb you are running, if the top is held on by two screws and you have a remote choke it is a cns if not it is a nt. When you get it running let it idle till it warms up, on one of my bikes with the nt it takes a good while before I can turn off the choke. Some of these engines will barely run when new till they get hot. Take some pics maybe someone else may be able to help.
 
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thejdoe

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Apr 29, 2011
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Well, perhaps that's my problem. As far as I can tell, it probably would, but every time I've tried to start it, it's been on flat land, so it will idle until the bike comes to a stop. I try to build up a speed then release clutch.

As soon as the engine starts, I stop peddling (or else I'll break my chain, which has happened several times until i figured out I need to stop peddling once engine starts).

I'm going to try to find a long hill to try it out on, and maybe like Greg is saying, it needs to be able to run longer and it might kick in stronger. I'll report back later tonight.
 
Greg58

Greg58

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I noticed on the listing where you bought your kit that it came with the standard 410 chain, thats why it is breaking on you when you pedal. It would be a good idea to replace it with a 415 or a 41, both are much heavier and will work on most kits. I can buy the 41 at tractor supply for 18$ for 10 ft, enough to make two chains.
 
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thejdoe

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Apr 29, 2011
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Ok epic fail tonight. Found a hill, and it definitely kept idling while I was going downhill, but if I gave it gas, it didn't do anything. I mean, the engine revved a little, but quickly just died out as I came back down to flat land. I'm really frustrated.

I'm not a quitter, but im fed up with this kit. I got it from gasbike.net. Can anyone personally recommend somewhere else to buy an engine from that WORKS?? Mine is a Grubee Skyhawk.
 
Rocky_Motor

Rocky_Motor

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Nov 14, 2011
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My engine has so far been very strong and starts up real quick. Got it from bike berry. 66cc flying horse.. They shipped the wrong color though. But I wouldn't give up yet. Your engine I imagine is fine.

The important question is still, what carburator do you have? CNS or NT. I believe the CNS has a red cap over the air intake. The NT has a black one facing down.
If you have a CNS then that's more than likely the problem. If you don't want to mess with it then I would suggest getting an NT carburator. A bunch of the kit sites sell them.

I'm not very experienced yet but from what I have read over the months so far, the CNS has a lot of issues and requires a fair amount of attention to get tuned correctly.
 
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thejdoe

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Apr 29, 2011
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I have the one with a red cap. So I guess that's my problem. That stupid site I ordered it from claims a 6 month warranty, but I called several times within the 6 months and they just kept suggesting things for me to try.

I don't really want to have to buy a new one but oh well I guess.
 
Rocky_Motor

Rocky_Motor

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ENGINE_KIT_PARTS_PAGE_2

There's an NT carb there. They are typically only 20 bucks.
Thatsdax is one of the reputable venders out there. They also have an "RT carb". Supposuvly is quite good, dunno how well it fits from motor to motor though. If you get the NT I would get the O-ring he has there too. I have one and my motor has been working great so I assume it's a + but never tried without it. Couldn't hurt.

Maybe see what other members think, but it's a better alternative than a whole new kit I would say. btw, if you're wondering, why make a crappy CNS carb? It's because of our emission regulations. They didn't try and make them bad.. to an extent..
 
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young grease monkey

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Sep 20, 2011
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take the carb apart, check that it isn't clogged. then check if there is junk in the tank. you can detach the fuel line from the carb, shutting off the valve first, and then turn it back on and see if fuel runs out. play with the choke when trying to start it.
 
Flight Risk

Flight Risk

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Jan 25, 2010
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I'm wondering why the chain breaks if you keep pedaling? Are you talking the bike chain, or the engine chain?
After it starts do you tweak the choke slightly open a bit at a time, or just go full on and off?
If it won't even even sputter and run rough going down hill it would seem you aren't getting fuel. Or spark.
Remember there are probably two fuel shut offs, on the tank and on the carb.
Can you verify that fuel is going through? If you have adjusted anything on the carb, you may want to reset to original settings.
It may be possible that you don't have a good ground, or other problem with the ignition.
Who knows, there may even be a chop stick in the crankcase!
If you do give up and want a new engine, I'll take the old one off your hands.
 
Allen_Wrench

Allen_Wrench

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Feb 6, 2010
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Thejdoe, I don't know if this has much bearing on the problem at hand, but are you using the stock spark plug? I know, I know, some of you have had no problems with the stock plug. That's great news. But for me, I had to find an NGK in the correct heat range for my problems to go away. (Champions are good ones too.) No matter how I cleaned it or gapped it, the little stock plug wasn't going to cut it.
Once I had a good plug, I gapped it at (I think) .25, I'd have to look at my feeler gauges to make sure. (When I walk away from my work bench, I leave the memory of what the heck I'm doing behind.) But then I held the plug against the block and cranked, opening and closing the gap a little each time, until I got the right size spark. Too weak, and she won't run. But you don't want your electrodes almost touching either. Just a strong enough spark to touch off the air-fuel. You don't need much more than that.

So, how's your spark plug?
 
Allen_Wrench

Allen_Wrench

Resident Mad Scientist
Feb 6, 2010
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thejdoe said:
I have the one with a red cap. So I guess that's my problem. That stupid site I ordered it from claims a 6 month warranty, but I called several times within the 6 months and they just kept suggesting things for me to try.

I don't really want to have to buy a new one but oh well I guess.
Click to expand...
I just got to this post. So, you have a CNS carb, eh? I really, really, really, really wish I could help you there. I have read posts in this forum where people have figured them out, and got them working well. You'll need to do some serious digging with the 'search' tab up top there. It'll be work, but there's tips on how to get a CNS carb in proper shape.
I run an NT, and I can't complain about it. The NTs are simple and easy to tinker with. I can't claim to thoroughly understand the CNS.
 
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