NT Speed Carb vs Racing Carb

[Sharif]

I would say that the stock NT carb is not really that bad. There are more important upgrades from stock to do for sure. I would say some good upgrades to get are:

(1) An expansion exhaust pipe is one of the best performance upgrades you can get, just get a good one, the bigger it is the better it will be.
(2) A high compression head really helps make the engine run much cooler, the large fins and heat sink really help with temps and no doubt makes the engine last much longer.
(3) A sprocket adapter can save you a lot of headaches from dealing with broken spokes or the rear sprocket becoming loose. Also, It's better to drive the rear wheel hub rather than the spokes anyway. A rear wheel hub with a disc brake mount is even better, you can screw the sprocket screws right to the disc brake mounts.
(4) A double leg kickstand. This might sound like a strange upgrade to list but it will make it much easier to work on your bike and keep it from falling over. You can even put it up on the kickstand and kick start your bike by using the peddles without having to get on and ride it.

I pretty much have everything you mentioned and the last one being a compression head.

It should arrive sometime next week (Generic Fred clone off ebay), wanted to ask about few things
Will my current spark plug fit? it's a champion rc12yc
Will I need to rejet the carb first?
Current expansion chamber is straight piped because the muffler fell off, is that going to be an issue as well?

 

[Tyler6357]

I pretty much have everything you mentioned and the last one being a compression head.

It should arrive sometime next week (Generic Fred clone off ebay), wanted to ask about few things
Will my current spark plug fit? it's a champion rc12yc
Will I need to rejet the carb first?
Current expansion chamber is straight piped because the muffler fell off, is that going to be an issue as well?

Spark plugs have standard threads, you don't have to change the spark plug if you are happy with the one you are using. You most likely won't have to rejet if you got a 6cc head. If the muffler fell off it's going to be loud and might increase vibration. Which expansion pipe do you have??

 

[Sharif]

Spark plugs have standard threads, you don't have to change the spark plug if you are happy with the one you are using. You most likely won't have to rejet if you got a 6cc head. If the muffler fell off it's going to be loud and might increase vibration. Which expansion pipe do you have??

I hope it's the 6cc one, this is completely for better cooling (Reduce my paranoia to turn the engine off without any active cooling at idle) and aesthetics to be honest. I read somewhere the spark plug hole is a different diameter and deeper on the fred head?

It's also a generic banana exhaust I added a lawn mower muffler that fell apart

The head in question, it's a 13mm spark plug hole
https://www.ebay.ca/itm/39238692672...04&_trkparms=gh1g=I392386926725.N41.S2.R2.TR2

 

[extremeodd]

To be entirely honest it's not fair to use "banana exhaust" and "expansion chamber" in the same sentence without the words "is not a".

They have the approximate appearance of an expansion chamber if someone was told what an expansion chamber was without ever seeing one and was asked to draw it. However, that is where the similarities between an expansion chamber and those banana pipes end. Most of them are just 2 metal tubes that nearly meet in the middle and have the signature banana metal bubble around them.

A proper expansion chamber doesn't do that

 

[Sharif]

To be entirely honest it's not fair to use "banana exhaust" and "expansion chamber" in the same sentence without the words "is not a".

They have the approximate appearance of an expansion chamber if someone was told what an expansion chamber was without ever seeing one and was asked to draw it. However, that is where the similarities between an expansion chamber and those banana pipes end. Most of them are just 2 metal tubes that nearly meet in the middle and have the signature banana metal bubble around them.
View attachment 90152

A proper expansion chamber doesn't do that

Hold on then, are these just a glorified noise maker?
Is the smoother running just placebo?

 

[extremeodd]

They are a small improvement over a factory pipe but most vendors severely overstate the benefits it'll deliver. If it runs better for you, then it's obviously helping some however do be aware that even the complete trash CDH66/ZEDA88 "expansion chamber" (it's a visual copy of the mz65 pipe without any of the performance the mz65 gives) will help quite a bit more than one of those banana pipes.

It's something to just keep in the back of your mind and if you ever get the itch to get a nice bump in power for $100-120, try to pick up an MZ65 pipe (youll probably have to find one used if you dont get one from mzmiami in the next week, they only show up like once a year) or if you stumble across one, a dirtbike pipe modified to fit on these engines like a cr80. They will require you to bump up your carb jetting a touch but you'll gain anywhere from 50-100% power once your tuning is correct with a solid expansion chamber.

Here is the mz65 I'm talking about, their kinda spendy but do keep in mind they don't lose their value as they are a limited commodity in a market that will quickly consume them. So you can always resell it down the road for little to no loss.
https://www.ebay.com/itm/MOTORIZED-BICYCLE-MZ-65-High-Performance-Pipe-BLACK/283579679386

 

[Sharif]

They are a small improvement over a factory pipe but most vendors severely overstate the benefits it'll deliver. If it runs better for you, then it's obviously helping some however do be aware that even the complete trash CDH66/ZEDA88 "expansion chamber" (it's a visual copy of the mz65 pipe without any of the performance the mz65 gives) will help quite a bit more than one of those banana pipes.

It's something to just keep in the back of your mind and if you ever get the itch to get a nice bump in power for $100-120, try to pick up an MZ65 pipe (youll probably have to find one used if you dont get one from mzmiami in the next week, they only show up like once a year) or if you stumble across one, a dirtbike pipe modified to fit on these engines like a cr80. They will require you to bump up your carb jetting a touch but you'll gain anywhere from 50-100% power once your tuning is correct with a solid expansion chamber.

Here is the mz65 I'm talking about, their kinda spendy but do keep in mind they don't lose their value as they are a limited commodity in a market that will quickly consume them. So you can always resell it down the road for little to no loss.
https://www.ebay.com/itm/MOTORIZED-BICYCLE-MZ-65-High-Performance-Pipe-BLACK/283579679386

Appreciate the load of information, it's a good thing I am at least aware of it now.

I guess the improvement I am seeing is the fact that anything is better than stock hahaha. I will be riding it with the current setup and new head that should be coming soon and if it serves me well till end of this year, will pull trigger on one of those 100%.
With how often I needed to work on it the last 4 months, still have trouble completely trusting it to invest more money into it, if this kit was made by Toyota instead I would place an order for that exhaust right now lol

 

[extremeodd]

I don't blame you there, if I had a dollar for every time my damn bike has let me down, I could build a beautiful electric setup or straight up buy a solid motorcycle. These engines, even the "good ones" are manufactured to the bottom dollar as the average motorized bicyclist consumer is anything but a big spender. Many of the people that I've met/talked to that use these bikes do so out of necessity because of either serious offenses that got their license revoked, exfelons who literally cannot afford anything else, retirees that didn't plan for retirement and are scraping by, etc.

For every one person who would be willing to purchase a really good, quality kit you have easily 50-100 that would only ever get the $80 bottom dollar kit, even if something better was available.

 

[Sharif]

I don't blame you there, if I had a dollar for every time my damn bike has let me down, I could build a beautiful electric setup or straight up buy a solid motorcycle. These engines, even the "good ones" are manufactured to the bottom dollar as the average motorized bicyclist consumer is anything but a big spender. Many of the people that I've met/talked to that use these bikes do so out of necessity because of either serious offenses that got their license revoked, exfelons who literally cannot afford anything else, retirees that didn't plan for retirement and are scraping by, etc.

For every one person who would be willing to purchase a really good, quality kit you have easily 50-100 that would only ever get the $80 bottom dollar kit, even if something better was available.

Extremely true!
The only reason I got into this was that electric kits came out to be double of these (On hindsight, should have gone electric instead) and the actual reason is because at the moment I can not afford to pay insurance for a car with a part time job. With that said, putting all the inconvenience I went through aside, I learned a bucket ton about simple combustion engines and carburetors!

It's a little goal of mine to work on my own car someday, i'd say this was a good starter kit haha

 

[Chop-chop]

I think it's all lucky-dip. I swapped the stock NT with a 'Racing carb' and ended up going back to the NT, even if it meant I've had to throwing on a pile of silicone to make it seal properly onto the manifold. The NT gave me the best transition from idle to WOT and overall power. My next induction upgrade will be a Reed- Dellorto chainsaw type carb with it's mixture adjustments on-the-fly ability.... great piece of gear and they're not that expensive either.