A while back I bought a motor off the Wish app, it's supposed to be an 80cc. That's really all I know about it. I finally got around to riding the bike yesterday it ran pretty well, however it just wasn't that quick. The bottom end power was good, but even wide open in neutral it never sounded crisp like it was really revving strong. It seemed to miss and bog at full throttle. Another thing that I don't understand is The Jug and the head are one piece on this engine, so I can't get another cylinder head for more power. Also is it worth trying to gut the muffler? Should I get another carburetor so that the engine will pull harder in the top end? Can anyone help me out here. I have plenty of experience building Ford and Oldsmobile V8's so I probably won't be to lost when you explain it. But I'm not experienced in building 2 cycle engines.
new guy bunch of questions about making power
- Thread starter APRules2
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That type cylinder design has been showing up more and more, I have never seen one but there are some threads here somewhere. Maybe someone will jump in to help. If it runs fairly well you need to put some miles on it till the rings seat, two to three tanks usually. Getting the carb jetted right is the key, that carb has only one jet, I solder and redrill mine but jet kits are available.
Is it better to just swap the carb to a different model? Does anyone make some kind of a 2 barrel carb or something like that? It seems pretty responsive in the bottom end but feels like it's starving for fuel at full throttle.
It seems like the one piece jug would be difficult to do any kind of performance work too. Is there a lot to be had from just port matching the intake to the jug? Also Ive read about 2 stroke porting on a few chainsaw forums and it seems like the big move is to kind of open up the inside of the port where the piston is to match the outside where you would bolt the carb on or exhaust. The port is wide and carb shaped but narrow and round on the inside on the chainsaws. So guys reshape the port to be the same shape inside and out. Is it the same way on these bikes? I thought 66cc on a bicycle would feel a little quicker than it does. I had a KE100 dirt bike when I was younger and it weighed double what my gas bike does if not more and it felt so much more powerful than my bicycle did on this first ride.
These engines are piston port design not reed valve like the motorcycle you’ve had, they will perform if you tune the carb and exhaust correctly. If it runs fairly well it’s best to put a couple of tanks of fuel through it before doing a lot to it, then only do one mod at a time so you can see if it helped of hurt performance.
Ok, I think I get it. Im so used to the V8 world where so may people have tried things that there are like kind of standard recipes for power. Usually a cam, head, compression, carb, and exhaust combo known to make x amount of horse power, rather than just making educated guesses.
From all the posts here and from what I’ve learned with this type of engine a expansion chamber exhaust will show the best improvement, if you will search here or on the web you’ll find the two stroke tuners hand book that will explain a lot.
Greg has given you some good advice... Run the heck out of it before trying to tune it... It's going to run better & better the more it breaks in!
Also... What ratio gas/oil mix are you using?
Also... What ratio gas/oil mix are you using?
Yes Greg & Norm walk before you run, I've had several engines that were so tight that startup was a half day effort and they ran like arthritic, 3 legged dogs for the first 2 or three gallons of fuel...then they came alive & performed well. That's the point mods can be made and evaluated & I've no real problem with one at a time mods either Greg, but most mods don't show their real improvement until other tuning is done to maximize the addition of a particular performance part. I'd suggest reading the spark plug to begin with once you feel the engine "break in" and you know it's not going to improve past the point it's at & you then change fuel mix ratios (less oil to gas mix) & run about a half tank of the new mix ratio fuel through the engine...then read the plug again. If it's too lean or too rich, adjust. You may need a different size jet or a different heat range plug...perhaps a combination of both. It's a process.
When what you got, seems to be running the best it's going to get, is when you can efficiently start adding changes., but even then it's dicey and expensive if you're not certain where to begin & don't know exactly where you're ultimately heading. Study what experienced builders have done and ask questions along the way.
Your question: Yes port matching can improve both intake and exhaust flow. how much it helps depend on how bad these are restricted remember if the exhaust flange inlet of either the exhaust pipe is smaller than the engine jug port (quite common) that is also a restriction....as is a tiny carb air filter that blocks air flow. I've found changing to a high flow air filter from the one that comes with the NT kit carb has required a jet change up because it leaned the fuel mix out. So if you read the plug of your stock engine when it's first broke in and it seems rich simply changing to a high flow K&N style cart filter will bring the mixture back closer to the correct ratio, without a jet change. Again one small performance change either correcting a problem or causing a carb tuning problem that when corrected will make a bigger performance gain than initially experienced by just the addition of a less restrictive air cleaner. A good expansion pipe, motorcycle type, is another bolt on, kind'a, that can make a huge difference in performance, but can create a need for jet change up and or a carb upgrade to a Dellorto or Mikuni carb to furnish enough air flow mix. One example of a performance change that could require further tuning and or additional performance parts to maximize some or all the benefits possible from the exhaust upgrade. These are just basic changes that can build noticeable performance gains.
Lots more performance mods that require internal engine mods are proven to build hp/torque but each mod is enhanced, or should be, with the appropriate corresponding mods. If you don't consider what you've modified or changed along the way future performance mods can actually cut performance. Example piston port work, such as piston ramping and port timing on the intake side is no longer effective when, you convert to a reed port design, third port jug and piston "window" and without at least one of these two upgrades a reed valve addition can actually lessen power by as much as 100% 4 hp down to 2 hp...that's going in the wrong direction! An extreme example for sure, but I've seen it proven on a dyno.
If you are thinking there are performance gains to be realized with these small engines you are correct, and it's a fun process that usually takes time and some insight/experience/experimenting & $$ along the way.
Don't get discouraged by the process, lots of great running high performance 2 strokes on this forum and yours can be one of them!
Have fun.
Rick C.
When what you got, seems to be running the best it's going to get, is when you can efficiently start adding changes., but even then it's dicey and expensive if you're not certain where to begin & don't know exactly where you're ultimately heading. Study what experienced builders have done and ask questions along the way.
Your question: Yes port matching can improve both intake and exhaust flow. how much it helps depend on how bad these are restricted remember if the exhaust flange inlet of either the exhaust pipe is smaller than the engine jug port (quite common) that is also a restriction....as is a tiny carb air filter that blocks air flow. I've found changing to a high flow air filter from the one that comes with the NT kit carb has required a jet change up because it leaned the fuel mix out. So if you read the plug of your stock engine when it's first broke in and it seems rich simply changing to a high flow K&N style cart filter will bring the mixture back closer to the correct ratio, without a jet change. Again one small performance change either correcting a problem or causing a carb tuning problem that when corrected will make a bigger performance gain than initially experienced by just the addition of a less restrictive air cleaner. A good expansion pipe, motorcycle type, is another bolt on, kind'a, that can make a huge difference in performance, but can create a need for jet change up and or a carb upgrade to a Dellorto or Mikuni carb to furnish enough air flow mix. One example of a performance change that could require further tuning and or additional performance parts to maximize some or all the benefits possible from the exhaust upgrade. These are just basic changes that can build noticeable performance gains.
Lots more performance mods that require internal engine mods are proven to build hp/torque but each mod is enhanced, or should be, with the appropriate corresponding mods. If you don't consider what you've modified or changed along the way future performance mods can actually cut performance. Example piston port work, such as piston ramping and port timing on the intake side is no longer effective when, you convert to a reed port design, third port jug and piston "window" and without at least one of these two upgrades a reed valve addition can actually lessen power by as much as 100% 4 hp down to 2 hp...that's going in the wrong direction! An extreme example for sure, but I've seen it proven on a dyno.
If you are thinking there are performance gains to be realized with these small engines you are correct, and it's a fun process that usually takes time and some insight/experience/experimenting & $$ along the way.
Don't get discouraged by the process, lots of great running high performance 2 strokes on this forum and yours can be one of them!
Have fun.
Rick C.
I have that exact same engine, off the wish app and all. After my 4th tank, 2nd gallon, she woke up.
