80cc stalling out after 10 mins

njkl44

New Member
Sep 1, 2012
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Durango
I just built this new bike. I got everything from motovelo and I got it running and it runs fine. The prob is that I can ride it for about 5-10 mins then it just cuts out all of a sudden. The sparkplug is still firing too. I can pull the clutch in the motor will idle and I can ride it at idle but after a bit that cuts out completely and now its not starting. Really need some help with this!

Thank you
 

tooljunkie

Member
Apr 4, 2012
663
5
16
Manitoba,Canada
Probably starving for fuel.dirt in filter,the intank screen is dirty.
Fuel cap may not be venting,allowing air in to replace fuel that has burned.
 

2door

Moderator
Staff member
Sep 15, 2008
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Littleton, Colorado
Probably starving for fuel.dirt in filter,the intank screen is dirty.
Fuel cap may not be venting,allowing air in to replace fuel that has burned.
Ditto:

Check for fuel flowing to the carburetor. Did you clean the fuel tank before installing it? Do you have an in-line fuel filter?

Try riding the bike with the fuel tank cap loose. If the problem goes away the cap isn't venting.
If it keeps stalling with the cap loose the filter in the tank is probably plugged with dirt and rust from inside the tank.

Tom
 
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socialdistortionkid

New Member
May 14, 2011
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Orange County, CA
Hey try tearing apart the carburetor and checking the float level.

I was riding my yamaha 2 stroke dirt bike a month ago and it was doing the same thing and the float level needed to be adjusted
 

njkl44

New Member
Sep 1, 2012
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Durango
Well easy fix!!! just the gas tank cap. Thank you for everyone who contributed to all of this. Sorry for not getting back to you guys sooner I have been working on the bike all day and well... more problems. I guess ill just ask on here.

So I bought a 80cc motovelo high performance engine, an expansion chamber muffler with silencer and a Jaguar CDI pack. The engine sounds good when it runs but sadly i top out at 20.... This was a huge disappointment to me! I bought all of this for about $500 and my other motor bike that i only put about $150 into tops out at 25. I really expected around 35 with all of this. I do have a 44 tooth but i still expect more than 20 on it. I have been adjusting the carb as I am at 7,000 feet but still no difference. I really want to get this thing going! Any help with be appreciated.

Thank you!!!
 

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2door

Moderator
Staff member
Sep 15, 2008
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Littleton, Colorado
What fuel/oil ratio are you running?
Have you checked your spark plug color?
How new is this engine?

They run better with miles. Don't expect top performance for the first hundred miles or so. Burn through a couple of gallons of fuel before trying for better performance.

As for your aftermarket "speed" parts, we always suggest to get the bike running and well broken in before adding performance parts. That way you'll have a baseline to work from. Starting out with pipes and questionable ignition parts make it hard to suggest where you need to go as far as tuning is concerned. Expansion chambers require some tweaking of jet size to realize their potential. Stock carbs and jets usually don't work well with pipes.

My advice, put some miles on the engine and see where you're at a little later. Also 7000' MSL will have a profound effect on performance. You'll need to go lean on jetting but watch the plug color.

Tom
 

njkl44

New Member
Sep 1, 2012
9
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Durango
What fuel/oil ratio are you running?
Have you checked your spark plug color?
How new is this engine?

They run better with miles. Don't expect top performance for the first hundred miles or so. Burn through a couple of gallons of fuel before trying for better performance.

As for your aftermarket "speed" parts, we always suggest to get the bike running and well broken in before adding performance parts. That way you'll have a baseline to work from. Starting out with pipes and questionable ignition parts make it hard to suggest where you need to go as far as tuning is concerned. Expansion chambers require some tweaking of jet size to realize their potential. Stock carbs and jets usually don't work well with pipes.

My advice, put some miles on the engine and see where you're at a little later. Also 7000' MSL will have a profound effect on performance. You'll need to go lean on jetting but watch the plug color.

Tom
the engine only has about 15 miles on it haha. I am running 16:1. I will check the sparkplug soon. I guess i should put the stock muffler back on? How would you adjust the jet size?

Thank you for everything!!
 

2door

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Sep 15, 2008
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Littleton, Colorado
16:1 is way too much oil. You probably read that in the instructions which assume you are using regular 30 weight motor oil and not a good 2 stroke oil. Drop your oil mix down to 24:1 or even lower. Most run a 32:1 mix but some prefer to break in with a little more oil. Either way 16:1 is going to reduce your performance significantly as well as fouling the plug and clogging the exhaust with goop.

Your spark plug color will tell you a lot about what the engine needs. Too dark and you're running rich. Too light, light grey to white, and you're lean. I wouldn't worry about doing any jet changes just yet. You haven't told us what carburetor you have but that would help us make recommendations on tuning.

Tom
 

njkl44

New Member
Sep 1, 2012
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Durango
16:1 is way too much oil. You probably read that in the instructions which assume you are using regular 30 weight motor oil and not a good 2 stroke oil. Drop your oil mix down to 24:1 or even lower. Most run a 32:1 mix but some prefer to break in with a little more oil. Either way 16:1 is going to reduce your performance significantly as well as fouling the plug and clogging the exhaust with goop.

Your spark plug color will tell you a lot about what the engine needs. Too dark and you're running rich. Too light, light grey to white, and you're lean. I wouldn't worry about doing any jet changes just yet. You haven't told us what carburetor you have but that would help us make recommendations on tuning.

Tom
Alright I'll mix some more gas up! I'll go 24:1. Should i just get rid of that gas that's in there now? The carb im using is just the one that came with the kit. It has a black almost skull like plastic piece where the air intake is if that helps. I'll check the sparkplug soon. Your right with that goop in the exhaust! I actually have a few holes in the expansion chamber I need to patch up. Should I leave this muffler on?
 

2door

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Staff member
Sep 15, 2008
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Littleton, Colorado
Start out with the pipe and muffler that came with the engine. From your description of the air cleaner my guess is that your carburetor is probably the old NT style, which I and many others feel is the best option, especially for a beginner.
It is easily tuned and typically performs well under most conditions. There is a lot of good information here about that carburetor but to start with you'll want to have the little clip on the needle on the second notch from the top. That's a good starting point. The clip determines how far the needle is lifted when you twist the throttle grip. The lower the clip, the higher the needle is raised and the richer the fuel/air mix delivered to the engine. Conversely, the higher the clip, the leaner the mix. The needle only controls fuel flow up to about 3/4 throttle and after that the jet orifice size determines fuel flow.

Mix up a new batch of fuel in a serperate container then drain your tank and refill with the new fuel. You can get rid of the old stuff by dumping it in your car's fuel tank. It won't mind a bit.

Tom
 

njkl44

New Member
Sep 1, 2012
9
0
0
Durango
Start out with the pipe and muffler that came with the engine. From your description of the air cleaner my guess is that your carburetor is probably the old NT style, which I and many others feel is the best option, especially for a beginner.
It is easily tuned and typically performs well under most conditions. There is a lot of good information here about that carburetor but to start with you'll want to have the little clip on the needle on the second notch from the top. That's a good starting point. The clip determines how far the needle is lifted when you twist the throttle grip. The lower the clip, the higher the needle is raised and the richer the fuel/air mix delivered to the engine. Conversely, the higher the clip, the leaner the mix. The needle only controls fuel flow up to about 3/4 throttle and after that the jet orifice size determines fuel flow.

Mix up a new batch of fuel in a serperate container then drain your tank and refill with the new fuel. You can get rid of the old stuff by dumping it in your car's fuel tank. It won't mind a bit.

Tom
Yeah I do think it is a NT carb. I will put the other muffler on and should i put the stock CDI back on? About how many miles do I need on it til its the right time to put the performance parts on it? With the 44 tooth and my conditions (7000' and such) should i be able to get to 35mph?
 

biknut

Well-Known Member
Sep 28, 2010
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Dallas
Yeah I do think it is a NT carb. I will put the other muffler on and should i put the stock CDI back on? About how many miles do I need on it til its the right time to put the performance parts on it? With the 44 tooth and my conditions (7000' and such) should i be able to get to 35mph?
The answer to this question is no. A 44 tooth will allow about 30 mph, but it will have to over rev a little to do that. You'll need a 36T to go 35 mph on a level grade, assuming 26" wheels.
 

2door

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Sep 15, 2008
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35mph is humping it for a stock 2 stroke, especially with a 44T sprocket an at your altitude. A more realistic speed will be as Biknut said, in the 28 to 30 range but then only after a few tanks of fuel. As said earlier, these engine run better with miles. Don't expect too much from it right now. Ride it, burn some fuel and enjoy it for a few weeks then start adding your parts but only do one upgrade at a time so you can see and adjust to the change. Install one and ride the bike to see what you need to do to get the most from your modifications.

Tom
 

njkl44

New Member
Sep 1, 2012
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Durango
35mph is humping it for a stock 2 stroke, especially with a 44T sprocket an at your altitude. A more realistic speed will be as Biknut said, in the 28 to 30 range but then only after a few tanks of fuel. As said earlier, these engine run better with miles. Don't expect too much from it right now. Ride it, burn some fuel and enjoy it for a few weeks then start adding your parts but only do one upgrade at a time so you can see and adjust to the change. Install one and ride the bike to see what you need to do to get the most from your modifications.

Tom
So I just went for a little ride and I put the stock muffler back on it and wow its so quiet hahah. I topped out at 20-23. That's still with the 16:1 gas too. Do you have any links for a cheap 32tooth? I have one on my other bike but I hate taking them off and putting them back on.
 

njkl44

New Member
Sep 1, 2012
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Durango
Just went though my stuff and I found a 41 tooth. Should i got for this one or should i got for a 32 tooth?
 

biknut

Well-Known Member
Sep 28, 2010
6,540
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Dallas
Just went though my stuff and I found a 41 tooth. Should i got for this one or should i got for a 32 tooth?
Go with the 41T for now then. 32T is way too tall for a stock motor.

With a 41T you'll be able to do about 31-32 mph.

This is how fast a 40T goes. A 41T will be about 1 mph slower.

26x2.125 tire 81.8" circumference

40T sprocket

RPM MPH

1000 4.7
1200 5.7
1400 6.6
1600 7.6
1800 8.5
2000 9.4
2200 10.4
2400 11.3
2600 12.3
2800 13.2
3000 14.2
3200 15.1
3400 16.1
3600 17.0
3800 17.9
4000 18.9
4200 19.8
4400 20.8
4600 21.7
4800 22.7
5000 23.6
5200 24.6
5400 25.5
5600 26.5
5800 27.4
6000 28.3
6200 29.3
6400 30.2
6600 31.2
6800 32.1
7000 33.1
 
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