Not reaching top speed

T

thirdorangutan

New Member
Recently my friend and I both bought 66cc flying horse motors and put them on micargi panteras. He has a 90 degree billet and a speed nt carb and I have the stock nt carb and billet. We both recently tested our top speeds. My bike reached 23 miles per hour and his reached 37. Do y'all think that this major difference is all from the carb and billet difference or do you think it could be something else about my motor? I feel that it might be more than just the visible differences because mine doesn't seem to be going anywhere near the suggested speed. Thanks in advance.
 
Wow 23mph top speed, that is low, very well could be that modifying the exhaust to get it flowing better and putting a smaller main jet in the carb could be what you need to get yours reving higher and pull8ng better.

Your buddy may have a better flowing exhaust and the speed carbs do have a slightey larger bore, I really think the carb is the issue other than needing to be jetted down a little which is very common.

sounds to me like you may have a very restrictive exhaust which will feally kill the power of these engines.

Remove the end cap of exhaust, there will be a tube the goes up into muffler which is the same.tube that sticks out the end on cap, cut off the part that goes up into muffler and then drill about three 5/16" extra holes in the end cap and replace cap.

Take it for a spin and see what you notice.
 
I'll definitely agree on the mufflers... some of them I've seen on customer's bikes have only a 9 or 10mm outlet and these engines need at least a 15mm or larger outlet just to be able to breathe... Map's advise on the end cap drilling is the same thing I do over here when I get a customer's bike to work on. An expansion chamber pipe also works wonders for these engines and can almost double the power output just by bolting one on. The carb jetting issue is another power restricter because these things are jetted way richer than they need to be... Easiest thing to do here is get a few spare jets and solder them shut then get a micro drill set (these cost about $15 if I remember right) and re drill the jest from size 70 to 74, the larger the number the smaller the hole size, then starting with the largest drilled jet, try it and work your way down on jet sizes until the engine revs clean without any 4 stroking. You can do the same with just one jet by re soldering and drilling until it accelerates cleanly but dialing it in is a lot quicker if you have a few extras pre drilled and ready. Don't trust the jet numbers since you can order 4 jets all the same size and each one will measure differently.
Map also has the link for the micro drill set, I used to have it but it's on the shop's computer, these are cheap so I got 2 sets in case I dropped one and couldn't find it or broke one... these bits are extremely small and range from wire gauge size 60 to 80, most bikes will tune out with a size 72 or 73 hole size in the jet, but each engine is different and will tell you which size works best, you'll know by how well it runs and by doing a plug chop.
 
ill post the link to the bits here shortly when I can get one my computer, dang phone is a lot of trouble to do it on...lol
 
Haha... I know exactly what you're talking about... everytime I'm posting from my Kindle I have to re read it before posting because the space bar is sooo close to the N key it throws N's everywhere and re spells words or changes the words entirely... Sometimes I don't catch all the mistakes then when I look at the posts in the morning from the shop's computer it looks like I spent all night drinking before posting sometimes... lol

Enough on that... I got the link on my computer at the shop since that's where I order my parts from and have everything sent to.. I spend more time there than at home nowadays anyway... I think it was widgetsupply.com or something but they got all kinds of other cool stuff it's easy to get distracted and buying other things then forget to buy the bits so it's definitely convenient to have the link directly to the bit set...lol
 
Thanks for the advice on the exhaust. My only concern is I've heard that making it more open can reduce back pressure and shorten the motors lifespan. Should I be worried about that?
 
Awesome!!! Its currently night here and I don't want to wake up any cranky neighbors but Ill try that tomorrow and get back to y'all with the results!
 
Cheapest and most added speed? Nothing can beat a sprocket swap. Depending on what kind of terrain you have depends on what type of sprocket you'd want to get. Other than that there is tons of free things you can do to up your power like port matching the exhaust and intake manifolds and porting the intake and exhaust ports.
 
Just by drilling a few extra 5/16" holes in the end cap will give you a noticeable difference in top speed as well as more power on top...
I'm running a KTM 50 dirtbike pipe modified to fit the engine and bike and it's stinger outlet diameter is bigger than the stock pipe's header pipe at nearly an inch wide, I run mine at 10,000 rpm on a daily basis to reach 42mph and keep up with traffic on the road I ride on. The traffic on that road usually flows at 35 to 40mph so it's nice to be able to keep up with everyone or pass up that jerk that's going way too slow and holding up traffic in the morning...
 
best all around bang for the buck really is to get a decent expansion chamber pipe, you can make one from an old dirtbike pipe like the kx65 or kx80, or the KTM 50 or 65cc engines, but they do take some welding and cutting to make fit...
For a good pre made pipe, the SBP pipe or the snake pipe is hard to beat.
Sprocket swaps can get you some good speed on the cheap, but at the cost of acceleration. I set my engines up to make a lot of power at higher rpm so I benefit more by keeping the stock 44 tooth sprocket and let the engine rev... One does need a very well balanced engine with the best quality crank and wrist pin bearings to do this tho... I'm hitting between 40 and 42mph with the stock 44 tooth rear sprocket and the stock NT carb rejetted to match the engine as well as the stock CDI. I'm getting the power mainly from LOTS of porting mods and matching up the right pipe for the rpm I'm running at. Most engines will grenade at 10,000 rpm let alone trying to use it daily at those speeds, but a well prepped engine with mild to moderate porting and a good exhaust can get you at least up to 40mph with the stock gearing.
 
mapbike said:
link to bits and pin vise for using bits

http://www.widgetsupply.com/product/WB05.html

http://www.widgetsupply.com/product/SHG3-840.html


best deal I have found on these items and they work great, I get a lot of my tools for doing port work on my cylinders also.
They ship quick also.
Click to expand...

Yup... that's the link I was thinking of... Lots of other cool stuff there too... I bought 2 of those drill bit sets since they're not that expensive and bits this size can be quite fragile.... I have some bits even smaller than in this kit and they will snap just by looking at them wrong...
 
thirdorangutan said:
By the way, I was wondering what performance parts I could add for the most added speed and for the cheapest?
Click to expand...

The two main points that have been made here about either modifying the stock exhaust or adding and good expansion exhaust and then getting the carb tuned properly are actually two of the best banks for the buch when it comes to performance gains.

The one other modification that helps on top of what has already be mentioned is a bit more technical and not recommended if someone doesn't have the proper tools or understand how it all works and that is some work on the engines ports, cleaning cast flashing out of the intake and exhaust port is a good thing that can help with flow and there are mods that can be done to the transfer ports that can improve performance also but these things can be a little tricky if you dont understand how it all works together.

Im gonna say that if you will get the exhaust flowing better and get the carbs main jet reduced to an ideal size for your setup you'll see a nice improvement in performance.
 
mapbike said:
Wow 23mph top speed, that is low, very well could be that modifying the exhaust to get it flowing better and putting a smaller main jet in the carb could be what you need to get yours reving higher and pull8ng better.

Your buddy may have a better flowing exhaust and the speed carbs do have a slightey larger bore, I really think the carb is the issue other than needing to be jetted down a little which is very common.

sounds to me like you may have a very restrictive exhaust which will feally kill the power of these engines.

Remove the end cap of exhaust, there will be a tube the goes up into muffler which is the same.tube that sticks out the end on cap, cut off the part that goes up into muffler and then drill about three 5/16" extra holes in the end cap and replace cap.

Take it for a spin and see what you notice.
Click to expand...
Hey map bike, how far up on the pipe that goes into the muffler should I cut it? Should I cut it right up next to the end cap or farther down? Thanks in advance
 
thirdorangutan said:
Hey map bike, how far up on the pipe that goes into the muffler should I cut it? Should I cut it right up next to the end cap or farther down? Thanks in advance
Click to expand...

as far down as you can is best, but if all you can get of it is flush with edge of cap that is still better than it was and about 3 extra holes drilled in cap will help also.

I think I may have said drill the holes 5/16" in a previous post but actually 3/8" is better.

this mod to the exhaust will make it a little louder but not nearly as loud as just leaving the end cap off completely which I have done and some others do, I live in a rural area and dont have neighbors that ould be bothered by the extra noise but inside a town running without the end cap can get people upset and draw unwanted attention sometimes...lol
 
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