I have just finished breaking in my stock bikeberry 66 cc kit and have around $50-$60 I could put into it. I mostly use it for short trips and I wouldn't mind having a higher top speed, I'm ok with it's current sound level, wouldn't mind it being quieter. Engine seems to get a really good vibration/rythm that has more power, but only when giving it gas going uphill. I'm pretty big 325#'s so I don't want to further abuse the bike with a smaller gear. I was thinking of either carb, exhaust, or cylinder head upgrade. CCI seems to be a bit out of my range. Thoughts?
What mod should I get.
- Thread starter JOBAfunky
- Start date
The first mod for a 2 stroke is usually an exhaust. An expansion chamber exhaust usually offers the most bang for the buck on a 2 stroke.
not sure how you mean 'short trips' - I find that these aren't warmed up to a stable operating temp until about 8 to 10 miles - the running characteristics are changing all thru that time
some mods that work for 3 to 6 mile trips may disappoint after 12 miles or more
some mods that work for 3 to 6 mile trips may disappoint after 12 miles or more
The reason it runs better uphill is because your carb is jetted too rich. A smaller jet and proper tuning will improve power almost as much as a good tuned pipe.
My preferred mod list:
#1 : Proper jetting
#2 : Tuned pipe
#3 : smaller rear sprocket (I run a 36)
#4 : High-comp head (Puch, Fredhead etc)
#5 : Lightning CDI (No real power gain, just much better running motor, smoother and pulls from idle)
My preferred mod list:
#1 : Proper jetting
#2 : Tuned pipe
#3 : smaller rear sprocket (I run a 36)
#4 : High-comp head (Puch, Fredhead etc)
#5 : Lightning CDI (No real power gain, just much better running motor, smoother and pulls from idle)
Thanks for the advice. I already have the carb needle set to as lean as possible. I was considering the $25 speed carb off bikeberry. Anybody have any experience with that? Or should I just rejet my stock NT carb? Also any opinion on Jaguar vs. Lightning CDI? Oh, and by short trips I mean about a mile.
Big and dave, how does the expansion chamber with muffler compare sound wise to the stock muffler?
Big and dave, how does the expansion chamber with muffler compare sound wise to the stock muffler?
Don't get any mods, save your dough.
When something breaks (and it will) you will have the dough to fix it.
When something breaks (and it will) you will have the dough to fix it.
Speed carb offers no performance gain, only gives an extra fuel shut off valve and allows the use of 1/4" fuel line instead of the 3/16" that works best on the standard NT carb.
The NT carb or speed carb will allow you plenty of fuel and air flow makes good power whan the rest on the engines set up is right, having the needle set at its leanest (highest) setting only affects low to low medium throttle, from about 3/4 throttle to wide open throttle the metering needle does nothing, the factory main jet that comes in the carbs is to big and causes a rich run condition like has already been mentioned, the main jet in the carb has to be reduced in size to solve that issue and make the engine smooth up at lower to mid throttle cruising.
A better flowing exhaust along with a quality spark plug and better quality spark plug boot are what I consider the two best mods that can be done initially to these little engines, one thing to remember is that you should settle on the exhaust you plan to run before jetting down the carb, a better flowing exhaust will cause to engine to run a bit leaner, so I recommend doing everything else first and then re jet the carb to work with the final set up.
Since you're a big fella I would not recommend going any smaller than a 40T rear sprocket so you dont loose all your pulling power for hills.
The sick bike parts expansion exhaust is the best bang for the buck in my opinion if you dont habe a way to build a custom exhaust and need easier bolt on thing to upgrade the bike, its easy to install on most bikes.
Something else that will have an affect on jetting is the oil/fuel mix ratio, you will get many differing opi ions on what people think is best and what oil they like the best, most people run anywhere from a 25:1 mix all the way to a 100:1 mix with oils that are designed for those ratios and all the in between, personally I run a 100:1 mix of Opti2 2 stroke oil and my engines are tuned for that mix, most people agree that with conventional dino oils its a good mix @ 32:1 and with some synthetic blend oils a 50:1 works good like the Echo oil that can be found at an Home Depot.
The main thing to remeber is that the cab must be tuned to everything else and until you have about 100 miles or so on the engine I wouldn't do a lot since it will get better and beyter as it breaks in, I personally dont wait and I jet mine to whete I know from experience is a leaner than stock but safe level and then I ride mine pretty hard for the first 50+ miles and constantly check on things to make sure all is good and then I will start tweaking the tuning as I figure out the exhaust set up I plan to run.
Best wishes on the bike, use the search feature here on the forum and you will find loads of info to help you solve problems and get you china girl tuned in just right.
Map
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NT carb works well when jetted right unless the engine is so heavily re-worked as to handle 50% more flow volume - I can't tell much about an engine in the first mile, as I have none that will ever run well when that cold. Right about at a mile they start to run acceptably, but not like they will farther down the road.
I wouldn't recommend the speed carb either, and if I had one I'd swap out to the NT because the speed carb has the extra fuel valve that I've found to be problematic as there's no filter between that valve and the float needle and seat valve so rubber particles from the fuel valve can shed off the inside of it and clog up the needle and seat valve or the main jet.
The NT carb can perform very well on these engines once jetted and tuned properly, and their simplicity makes them easy to fix and very reliable. Even with some really good mods to your engine like porting or a pipe the NT is still plenty enough carb. The speed carb is pretty much identical except that it has that fuel valve I don't like and I think it may be 1/2mm bigger at the slide, which won't even be noticeable.
A properly tuned NT carb with a good pipe will definitely wake up your engine and I'll also agree about switching over to the Opti2 oil and mixing it at 100:1 as this oil is designed to run at that ratio and plenty safe, you'll need to jet the carb accordingly but you'll also pick up a little more power from the higher mix ratio as well as a cleaner smoke free exhaust and a lot less opportunity to foul the spark plug. I get the Opti2 oil from amazon.com and it comes in single mix packets or you can get it in quart or gallon size bottles but I like the quart size with the metering chamber so getting the mix right every time is easy. http://www.amazon.com/Opti-2-34oz-E...?ie=UTF8&qid=1403306438&sr=8-1&keywords=opti2
The combination of running the Opti2 oil, a better spark plug, an expansion chamber pipe, and tuning the stock NT carb to run with the pipe at the new mix ratio will net you some impressive gains, The SBP pipe is one of the best "off the shelf" pipes out there and costs about $80 but even those cheaper banana pipes will give you a good boost and with that combo you should be able to stay under $60 for everything. Of course, the SBP pipe will make better power if you can get it, but if not, a banana pipe will do the trick, and if you can weld, a modified pocketbike pipe or a modified KTM 50 or 65 pipe will work really well too.
The NT carb can perform very well on these engines once jetted and tuned properly, and their simplicity makes them easy to fix and very reliable. Even with some really good mods to your engine like porting or a pipe the NT is still plenty enough carb. The speed carb is pretty much identical except that it has that fuel valve I don't like and I think it may be 1/2mm bigger at the slide, which won't even be noticeable.
A properly tuned NT carb with a good pipe will definitely wake up your engine and I'll also agree about switching over to the Opti2 oil and mixing it at 100:1 as this oil is designed to run at that ratio and plenty safe, you'll need to jet the carb accordingly but you'll also pick up a little more power from the higher mix ratio as well as a cleaner smoke free exhaust and a lot less opportunity to foul the spark plug. I get the Opti2 oil from amazon.com and it comes in single mix packets or you can get it in quart or gallon size bottles but I like the quart size with the metering chamber so getting the mix right every time is easy. http://www.amazon.com/Opti-2-34oz-E...?ie=UTF8&qid=1403306438&sr=8-1&keywords=opti2
The combination of running the Opti2 oil, a better spark plug, an expansion chamber pipe, and tuning the stock NT carb to run with the pipe at the new mix ratio will net you some impressive gains, The SBP pipe is one of the best "off the shelf" pipes out there and costs about $80 but even those cheaper banana pipes will give you a good boost and with that combo you should be able to stay under $60 for everything. Of course, the SBP pipe will make better power if you can get it, but if not, a banana pipe will do the trick, and if you can weld, a modified pocketbike pipe or a modified KTM 50 or 65 pipe will work really well too.
Mine are the same way, about 3-4 miles before they settle in and start running like they should.
Map
Mine does the same thing, it's all about warming up that crank in there so the fuel evaporates and separates from the oil then everything runs like it's supposed to.
Mine actually warmed up quicker when I was running the stock heads on my engines which is one way I know that both the Puch heads and the Fred Head I currently run allow the engine to run cooler, since I started using the Puch Heads I noticed that it takes a little longer ride before the engine stops the initial 4 stroking and being a bit sluggish, once I do about 3 or so miles at a good clip things are starting to hit like they should.
I guess we better be careful here since we're highjacking the heck outta the fellas thread..LOL!
Map
I guess we better be careful here since we're highjacking the heck outta the fellas thread..LOL!
Map
Oh, I'm eating it all up. All seems like good info. I do have a welder but not much time in on it yet. I used 16:1 for the first 2 gal using Lucas 2 stroke oil. Now I'm down to 20:1
I'll definitely implement the spark plug and oil upgrade this weekend. Let that settle down a week or two and try out re jetting. Still though I wonder what happens to the sound level when going from stock muffler to an expansion chamber with the attached mini muffler.
I'll definitely implement the spark plug and oil upgrade this weekend. Let that settle down a week or two and try out re jetting. Still though I wonder what happens to the sound level when going from stock muffler to an expansion chamber with the attached mini muffler.
Another quick question. Are the spark plugs for these bikes available at an auto parts store, or are they online only?
Lucas makes good products and I know I have seen where others on here are running Lucas 2 stroke oil with good results, 32:1 or 40:1 would most likely be the best mix to run if you wanted to stick with the Lucas oil.
I have bought my plugs at my local motorcycle shop and I have ordered the same plugs from SBP ( sick bike parts ) http://www.sickbikeparts.com/catalog/product_info.php?cPath=22&products_id=142 I run the B6HS but I think many people use the B7HS in the summer since it is a cooler plug, I run the B6HS year around with no issues myself.
With the SBP expansion exhaust the sound level is very good and not to loud at all, this pipe actually helps low to mid range power and may add a couple MPH more top speed to you r bike as well, I have this pipe on my older HUffy bike, I didn't use the silicone tubing to join the pieces together as my final set up though, that tubing will burn out in time so I used simple copper tubing fittings instead and it has been running great for a little over 1,300 miles now, the pic I included here shows how I mounted the pipe on the Huffy bike, the engine on this bike has serious vibes above 34 MPH but this pipe helps it pull really good from about 10mph all the way up to 32-34MPH.
This pipe can be mounted so that it is low down also, this is just the first way I did mine and I liked how it turned out so I have left it this way.
Map
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That pipe does look good mounted high... I need a seat like you got too...
About the spark plugs, the NGK numbers Map mentioned are what I run, but when I need cheap plugs for tuning purposes, the Autolite # 275 plugs also fit perfectly and you can buy a pack of 4 for about $8 or so, they're cheap but also better than the stock plugs which makes them great for tuning and doing plug chops with.
i'm running a modified KTM 50 dirtbike pipe on mine and the performance gain is night and day compared to stock, I noticed it pulled a Lot harder the first time I cracked the throttle and the top speed went up pretty good too, even with a 44 tooth rear sprocket I gained about 2mph. My first pipe was one I made out of an old pocketbike pipe, it worked great on the low end but the muffler was too small and top end was about the same as stock, the difference in acceleration was definitely worth the effort tho.
Here's mine with the modified pocketbike pipe installed...
And this is how it looks now with the modified KTM pipe.. I liked the first pipe I made up for it but it lacked top speed and burned my leg once before so I made this one more forward and out of teh way... this pipe accelerates the bike really nice too, but it gives me the better top speed that the other one couldn't do since it has a bigger stinger diameter... even with no muffler it's not any louder than the pocketbike pipe since it exits down and close to the road.
About the spark plugs, the NGK numbers Map mentioned are what I run, but when I need cheap plugs for tuning purposes, the Autolite # 275 plugs also fit perfectly and you can buy a pack of 4 for about $8 or so, they're cheap but also better than the stock plugs which makes them great for tuning and doing plug chops with.
i'm running a modified KTM 50 dirtbike pipe on mine and the performance gain is night and day compared to stock, I noticed it pulled a Lot harder the first time I cracked the throttle and the top speed went up pretty good too, even with a 44 tooth rear sprocket I gained about 2mph. My first pipe was one I made out of an old pocketbike pipe, it worked great on the low end but the muffler was too small and top end was about the same as stock, the difference in acceleration was definitely worth the effort tho.
Here's mine with the modified pocketbike pipe installed...
And this is how it looks now with the modified KTM pipe.. I liked the first pipe I made up for it but it lacked top speed and burned my leg once before so I made this one more forward and out of teh way... this pipe accelerates the bike really nice too, but it gives me the better top speed that the other one couldn't do since it has a bigger stinger diameter... even with no muffler it's not any louder than the pocketbike pipe since it exits down and close to the road.
You should be able to get the plugs at an auto parts store, the NGK's tend to work best but somewhere someone posted a good cross reference on plugs in here telling a bunch of different brands that fit.
I like the NGK plugs best and run them but use Autolite #275 plugs when I need cheap plugs for tuning.
For the best oil, I sell Amsoil and was using that but I tried Opti2 and like it better now. Amsoil Dominator works great but has to be mixed at 50:1 and they got 2 other 2 cycle oils that can mix at 100:1, they work really good too, but the Opti2 works best in my engine at 100:1 mix.
