Brand new motor questions

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anthonytheflirt

New Member
May 17, 2014
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dekalb, il
I just purchased a new motor for my bike :) I've had one before, but sadly it was stolen :-( Now I have a few questions. The first bike was already used, so im just wondering if what im experiencing is normal for a new motor. Installation was relatively easy, but the large chain seems to catch in the motor every so often. I figure the sprocket teeth just need to be worn down a bit from use? The carburetor is my biggest question. My idle was not preset to 3.5 turns from closed position. After tweaking it, I've got it almost closed, but it does finally idle. Is it normal to be so closed on a new motor? And the throttle cable going into the carburetor. What should the nut be set at? All the way in? Up? Halfway? Any ideas on what the settings should be for the idle screw and throttle cable would be great!!!!
It's an 80cc 2 stroke
 
2door

2door

Moderator
Staff member
Sep 15, 2008
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Littleton, Colorado
We need to know what carburetor you have. If it is the NT then the idle screw does not have a particular 'setting'. It is simply a mechanical way of keeping the throttle from closing completely, keeping it open slightly. Turns in or out doesn't mean anything.
You set it to give you the best idle. turning it in, clockwise will increase the idle speed, turning it out or counterclockwise will decrease the idle.

If the chain is hitting or binding at the engine drive sprocket that is an indication of the chain beeing too loose or not aligned properly. You want 1/2" to 3/4" of slack. No more, no less. If the rear or driven sprocket is not aligned with the engine sprocket the chain can be pulled off to one side or the other and can have interference with the engine case.

Tom
 
massdrive

massdrive

New Member
Oct 3, 2013
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Las Vegas
Another cause for the chain to bind up is that it may be rubbing on the inside front of the drive sprocket cover. You mentioned "the large chain", I run a 410 drive chain and had to relieve the cover for chain clearance. Make sure your chain, tensioner and rear sprocket are all in a straight line too.
Also since your engine (motor's are electric, engine's are internal combustion) is new it may idle rough until you put some mile in it, and if you are running a rich premix like 16:1, or 20:1 for breaking in the engine (I hope you are) it will idle rough until you change your premix ratio.
Oh and just one more thing, if your engine is a "china engine" than it is either 49cc or 66cc. There are no 80cc china girls
 
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anthonytheflirt

New Member
May 17, 2014
3
0
0
dekalb, il
Thank you for the replies :)
My carb is a NT, so thanks for the idle screw info. On my previous bike, it had the same carb, but the screw was REALLY touchy. Could almost never find a sweet spot :-(
As for the chain, I was just talking about pre-threading it through the motor. I'd get it over the sprocket, then the next links would stay straight, like they were just a hair too big. I just sprayed it with white lithium grease and got it to work. I still hear/feel a catch every so often, but like I mentioned, it's a new motor, know it'll work itself out.
What about the throttle cable and screw on top of the carb? I know it makes your cruising speed faster, but can I extend it out too far that I'll ruin the engine?
Lastly, to avoid an future problem, what would cause a bog down? My previous motor some days would go at top speed, and only loose little power at max throttle, and other days I'd get close, but then loose a ton of speed. And no, I changed neither idle or throttle screws before changes occurred. Figured it was a old motor/constant bad gas-oil mix
 
Greg58

Greg58

Well-Known Member
May 1, 2011
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Newnan,Georgia
Welcome to the forum, the adjuster on the top of the carburetor is used to take the slack out of the cable housing. I like to adjust it out till the cable housing has just a small amount of slack when I move it up and down by hand, that way you get maximum cable travel without pulling the cable to tight causing a raised idle. You will need to do a plug chop to tune the carb after the engine is broken in, I like to run a couple of tanks of 24/1 mix before I start tuning the carb. 32/1 is a good ratio with these engines. These are 66cc or 69cc depending on the crankshaft stroke, 80cc is used because they measure the engine differently. And it makes a new buyer think its bigger than it is!
 
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RGZWS6

New Member
May 26, 2011
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Illinois
anthonytheflirt said:
Lastly, to avoid an future problem, what would cause a bog down? My previous motor some days would go at top speed, and only loose little power at max throttle, and other days I'd get close, but then loose a ton of speed. And no, I changed neither idle or throttle screws before changes occurred. Figured it was a old motor/constant bad gas-oil mix
Click to expand...
From my own personal experiences, there could be a couple things going on in your carb. You could have a tiny piece of trash in the bowl preventing the float from operating properly. In addition to running piss poor, it would cough fuel from the air filter. Easy fix for this is to remove carb from engine, drop the bowl, and gently blow some air through it. Make sure the float moves freely while you have it off.

Another issue I had was the actual jet nozzle had worked its way loose! It would bog down really bad at wide open throttle, but would run really well at part throttle. Really confused me until, again, I removed the carb bowl and the piece actually dropped off with the bowl. As a pre-assemble practice, I always take apart the carb, clean it, and make sure the jet and the piece it screws into (emulsion tube) are nice and tight.

Good luck!

PS: Here is a very good step-by-step with pictures and proper terminology for all the parts on the carb
http://motorbicycling.com/showthread.php?t=195
 
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