Starts and runs..but pulling clutch cable kills engine

Motorbikenewb · Mar 19, 2013

Hi everyone... I'm new to this. Bought and installed an engine from gasbike.net. It started right up but I can't seem to keep the engine running, when I slow down or stop.

More specifically, pulling on the clutch cable to (to disengage the engine from the chain) kills the engine.

Any suggestions?

Thanks in advance.

2door · Mar 19, 2013

Welcome to the forum.
We're assuming you have a 2 stroke, in frame engine.
Have you tried increasing the idle speed of the engine? Idle speed screw on the carburetor?
It helps to tell us what engine and carburetor you have when asking for advice.

Tom

Motorbikenewb · Mar 19, 2013

Yes, a two stroke, in frame engine 60/80cc air cooled engine, using 16:1 gas

il mixture (GRUBEE 2012 SkyHawk GT5 66cc/80cc Slant Head Bike Motor Kit). I figured the engine would need some fine tuning, and I intended to adjust the idle speed screw on the carburetor... but my plan was to do that while the engine is idle... but since I can't seem to keep the engine running at standstill I figured I'd consult the experts first. Would a messed up choke cable also be an issue???? Also, how much rotating would I need on the idle speed screw (full turn, half turn, etc).... I'm assuming clockwise increases idle speed. Again, thanks....

2door · Mar 19, 2013

Correct. Turn the screw in to increase idle speed and out to decrease it. The engine doesn't even have to be running to screw the idle speed screw in but it helps. The engine should be warm, at least operating temperature though.

I'm not sure what you mean by a "messed up choke cable". This tells me however that you have a CNS carburetor. Technically it is a fuel enrichment control and not a choke or air inlet restrictor as is used on the other more common NT carbs.
There is a lot of information on your carb here. Use the search feature at the top of this page, type in 'CNS carburetor' and you'll have plenty to read on tuning and getting the most from that particular carb. http://www.google.com/cse?cx=partne...j14#gsc.tab=0&gsc.q=cns carburetor&gsc.page=1

Good luck.

Tom

maniac57 · Mar 19, 2013

Again, 16:1 is FAR too much oil for your engine to ever run good. I use 40:1 and have had great results for over 40 years.

Motorbikenewb · Mar 22, 2013

Update: I've been increasing the idle and that seems to be giving better results. Only now the engine chain is locking up on the master link. This can be dangerous so I'm going to fix this issue first.

Motorbikenewb · Mar 22, 2013

Perhaps... but I'm just following instructions that came with the engine. It says to break in with a richer mixture. Seems to make sense

2door · Mar 22, 2013

Motorbikenewb said:
Perhaps... but I'm just following instructions that came with the engine. It says to break in with a richer mixture. Seems to make sense

The instructions that come with most kits are wrong on many points. The most glaring is their oil ratio recommendations. 16:1 is too much oil and will cause spark plug and exhaust system fouling, poor performance and tuning problems. Take the advice of the people here who have been building and riding these bikes for a number of years. Reduce your oil content to at least a 24:1 mix and preferably 32:1. Your engine will thank you for it and you'll be more pleased with the way it runs.

Some kit instructions tell you to put the two rubber parts of the rag joint (sprocket attachment) on one side of the sprocket. Some say to "finger tighten the spark plug".
Sometimes things get lost in translation. Oil ratio is one of them.

Best advice? Throw the instructions in the trash. They're not always reliable.

Tom

Motorbikenewb · Mar 23, 2013

THanks Tom, and you're right.....I finally got it to idle in place and there was oil everywhere. I wound up swapping out the spark plug, and replacing fuel filter with an inline fuel filter. A few more quick questions..... the engine chain appears to splash against the fender. I'm guessing removing the fender would be wise... thoughts? Also, I know have close to a gallon of 16:1 fuel...... should I just toss it and start over or attempt to dilute to the proper ratio... if so, any recommendations on how to compute what volume of what I have with pure gasoline.

Thanks for the tips.

2door · Mar 23, 2013

Sheet metal snips or a Dremel tool with a cutoff wheel will trim your fender for chain clearance. I would suggest you do a little reading here on the hazards and fixes for fenders. Many factory fender braces are not up to the task of keeping things in place on a motorized bicycle. They can look great but they can also get you hurt if not properly attached. That usually means either new braces or reinforcing the originals.

As for calculating your fuel mix? I'm a math dummy. If it was me I'd dump what you have left of the 16:1 in your car and mix up a new batch.
Maybe some of our math gurus will speak up. But "close to a gallon" is going to complicate the issue

Tom

crassius · Mar 23, 2013

rear fenders keep crap from being thrown right at your air filter

Motorbikenewb · Mar 23, 2013

Well I figured out that if I add 1 part of 16:1 to 1 part pure gas I'll get 32:1. So therefore, If I add 1 part 16:1 to half part pure gas I will get 24:1. I also googled that I can safely add the 16:1 gas to my car. As for the loose chain, I just moved the tensioner down a couple inches and its nice and taught.

However I noticed that just before I emptied the bike tank of the little gas I put in, it would accelerate by itself to a pretty high RPM. COuld it be I had the idle too high (like what you said before concerning the rich oil gas mixture?

2door · Mar 23, 2013

The increase in RPMs when you were running the tank dry was because you momentarily ran a very lean condition. Yes, it will show up as high revs and a little more power but that isn't where you want to run continously. That lean and you'll cook something.

Tom

Motorbikenewb · Mar 25, 2013

That's what I figured. I noticed you seem to be an expert on the matter... I've seen your posts in other threads. I created a new thread in the general discussion asking about the risk of using the stock chain that comes in the kit. Would love to hear your thoughts on the matter.

maniac57 · Mar 26, 2013

2door said:
Sheet metal snips or a Dremel tool with a cutoff wheel will trim your fender for chain clearance. I would suggest you do a little reading here on the hazards and fixes for fenders. Many factory fender braces are not up to the task of keeping things in place on a motorized bicycle. They can look great but they can also get you hurt if not properly attached. That usually means either new braces or reinforcing the originals.

As for calculating your fuel mix? I'm a math dummy. If it was me I'd dump what you have left of the 16:1 in your car and mix up a new batch.
Maybe some of our math gurus will speak up. But "close to a gallon" is going to complicate the issue

Tom

I'm a math dummy too. After all these years mixing fuel for ring-dingers, I just dump it in till it looks right. I check myself every once in a while and my usual mix is around 40:1. Just comes natural after so long.
I have to get a little bottle to show new customers how much oil to use because I can never remember the oz.!

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Starts and runs..but pulling clutch cable kills engine

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