Modern Buddy

in a few weeks i will be putting on a 161cc cylinder kit on my buddy 125. i already have the ncy trans and the prima pipe. i was wondering how much it will increase my top speed by if any?

Milktown wrote:in a few weeks i will be putting on a 161cc cylinder kit on my buddy 125. i already have the ncy trans and the prima pipe. i was wondering how much it will increase my top speed by if any?

It depends a LOT on how you setup the trans and what other mods you have. If you've just done the variator and clutch(Thats all thats in the NCY kit right?) then you'll accelerate faster, but the top speed won't change much. If you've done springs, jets, airbox, etc then its a couple extra MPH. If you've done far more like head and cam, its yet a few more MPH. Its not gonna add a whole lot to your top speed, but its a big jump in acceleration. You can actually get just as much top speed with transmission mods, a cam, and a LOT of tuning.

My bike could do 88MPH when it was still 125cc. Now its 161cc, and it still tops out at 88MPH. It gets there a lot faster, but I didn't gain a single MPH.

yes i put on everything that came in the ncy kit except the roller weights i used dr pully 11g sliders instead. i do long scooter trips with about 50lbs of gear with me every summer(florda, alaska) will the 161cc kit help me sustain higher speeds with more gear? will it overheat?. and pardon my lack of knowledge but i dont really understand all this talk i hear about jets...

Milktown wrote:yes i put on everything that came in the ncy kit except the roller weights i used dr pully 11g sliders instead. i do long scooter trips with about 50lbs of gear with me every summer(florda, alaska) will the 161cc kit help me sustain higher speeds with more gear? will it overheat?. and pardon my lack of knowledge but i dont really understand all this talk i hear about jets...

No, its not likely to increase your chances of overheating. I ride mine 25 miles each way to work year round, and have never had any issues with heat. Yes, it will sustain high speeds more effectively.

Jets control how much fuel gets into the motor at any time, and are the hardest thing to tune on any engine. If you're mechanically enclined, search the forums and google. But beware, its a rough road to learning how to tune a carburetor. If you're not mechanically inclined, most shops can tune it for you, but expect 2-3 hours of shop time.

No top end, whatsoever....tire sure comes off the ground easy though

ScooterTrash wrote:No top end, whatsoever....tire sure comes off the ground easy though

Heh, I'll second that It sure makes the bike a lot more fun

With the trans, a 161 and relatively heavy sliders/rollers, I think you do have a chance of running too hot if you're riding WOT for long stretches.

Fortunately, the loss in MPGs will force you to stop for gas more often and let the engine cool.

For this kind of riding, if you want to eke out as much as you can on the top end, I'd seriously recommend getting a mid-sized windshield.

any mods i can do to the trans to get a bit more on the top end? i am not worried if i loose a bit on acceleration.

Milktown wrote:any mods i can do to the trans to get a bit more on the top end? i am not worried if i loose a bit on acceleration.

The NYC clutch and variator kit gets you both Just order some 11g dr pulley sliders to compliment it

Best way to increase speed is to change the rear tire O.D. or pump um up! – Of course you can’t pump them too high, they will over heat.

ericalm wrote:With the trans, a 161 and relatively heavy sliders/rollers, I think you do have a chance of running too hot if you're riding WOT for long stretches.

I think this might be backwards. Heavier roller weights will work the engine less at higher (maintained) speeds because they'll put the transmission into a higher gear ratio. Lighter weights will spin the engine at higher RPMs to maintain the same speed that heavier weights run at lower RPMs.

Lostmycage wrote:

ericalm wrote:With the trans, a 161 and relatively heavy sliders/rollers, I think you do have a chance of running too hot if you're riding WOT for long stretches.

I think this might be backwards. Heavier roller weights will work the engine less at higher (maintained) speeds because they'll put the transmission into a higher gear ratio. Lighter weights will spin the engine at higher RPMs to maintain the same speed that heavier weights run at lower RPMs.

My thinking on this is that with heavier weights running WOT, you'll be pushing max RPMs at the highest gear ratio—essentially allowing the engine to work harder to maintain a slightly top speed for the duration and generating more heat.

[Aside: That's also really bad for tire longevity!]

I'm thinking (again) of robtaylor's bent crankshaft at the end of the last Cannonball. Of course, that was riding at the very extremes and he rode most of a day with a stuck exhaust valve. But it's always been my theory that an auxiliary gas tank (meaning fewer stops and cool-down periods) and 12g rollers were the primary culprits.

The other bent crankshaft I know of was also probably heat/stress related: it was a Buddy that had been tricked out with all sorts of cheapie performance parts he'd sourced from Asia and crammed in there. This was pre-VooDoo days when good performance parts were scarce. He ran the hell out of his Buddy at high speeds with all that crap in there—bam, bent crankshaft, which he then wanted repaired under warranty!

ericalm wrote: My thinking on this is that with heavier weights running WOT, you'll be pushing max RPMs at the highest gear ratio—essentially allowing the engine to work harder to maintain a slightly top speed for the duration and generating more heat.

[Aside: That's also really bad for tire longevity!]

I'm thinking (again) of robtaylor's bent crankshaft at the end of the last Cannonball. Of course, that was riding at the very extremes and he rode most of a day with a stuck exhaust valve. But it's always been my theory that an auxiliary gas tank (meaning fewer stops and cool-down periods) and 12g rollers were the primary culprits.

The other bent crankshaft I know of was also probably heat/stress related: it was a Buddy that had been tricked out with all sorts of cheapie performance parts he'd sourced from Asia and crammed in there. This was pre-VooDoo days when good performance parts were scarce. He ran the hell out of his Buddy at high speeds with all that crap in there—bam, bent crankshaft, which he then wanted repaired under warranty!

I can see the sense in that thought process. Weight tuning is a slippery slope - every rider/bike/condition is different. It sounds like you're saying that if the bike is able to reach higher speeds, the rider will keep pushing it to those maxes. Weight tuning won't make a difference; that all boils down to rider self control.

What happens is that if the weights are too light, the engine will go at max RPM's with a lower gear ratio and lower speed. That means the rider will be trying to twist it at WOT constantly and still wanting more.

With heavier weights, the engine doesn't have to work as hard to hold onto the max gearing ratio, which means it can hold the same speeds with lower RPMs.

Of course, if the weights are too heavy, the engine will bog which puts excess strain on it. If they're too light, the engine stays over it's power band and over-works itself to acheive only lower speeds.

As to the guy who wanted a warranty replacement with aftermarket parts... "LOL" doesn't do that justice. Is there a way to laugh harder than "ROFLMFAO" Laugh my intestines out?

Let me just add one other point: if the weights are too heavy, the engine may not have the torque to even reach maximum rpms. It will always stay below it's max rpm because as Lostmycage mentioned, it will always be in a "bog" mode. In this case, one would never reach the maximum speed the scooter is capable of.

babblefish wrote:Let me just add one other point: if the weights are too heavy, the engine may not have the torque to even reach maximum rpms. It will always stay below it's max rpm because as Lostmycage mentioned, it will always be in a "bog" mode. In this case, one would never reach the maximum speed the scooter is capable of.

That's a case of bad WOT!

babblefish wrote:Let me just add one other point: if the weights are too heavy, the engine may not have the torque to even reach maximum rpms. It will always stay below it's max rpm because as Lostmycage mentioned, it will always be in a "bog" mode. In this case, one would never reach the maximum speed the scooter is capable of.

What do you think the cylinder kit is for?

ScooterTrash wrote: What do you think the cylinder kit is for?

Actually, that brings up another point of curiosity... why is it that I never heard of people going to a heavier weight after the overbore kit? Has anyone tried heavier weights?

Lostmycage wrote:

ScooterTrash wrote: What do you think the cylinder kit is for?

Actually, that brings up another point of curiosity... why is it that I never heard of people going to a heavier weight after the overbore kit? Has anyone tried heavier weights?

I went to heavier weights when I installed my 161 kit. I also switched from a 1000rpm contra to a 1500rpm contra though, so that might have been more of the reason I needed heavier weights.

I thought you were still using 11g's.

Lostmycage wrote:I thought you were still using 11g's.

No, I did for a bit but I'm on 12g's now. I lost a lot of top end after going to the 1500rpm contra when I had the 11's. It was also really hard to keep the front wheel down. It still likes to bring it up at launch, but its less of a pogo-stick with the heavier weights.