Modern Buddy

If you decide to kit your 125 to a 161.. basically you're going to want to change the oil after 200 miles and check it constantly. I broke mine in at 500 miles and guess what? I ran it out of oil on accident and now my dealer is advising that we replace the kit and crank shaft because it now has a tick that won't go away.

I don't know. I kitted my Buddy 150 and 7000 miles later, I haven't had any significant issues. I wonder if you got a bad part or something like that.

There are quite a few folks running the 161 and, til now, I haven't heard of any significant issues.

Howard

I'm getting a second opinion on whether or not all that work needs to be done, but it's definitely concerning.. my scooter is my primary mode of transportation.

Kitting a motor is not just a plug and play action. You put on a new top end it's like having a new motor that needs to be broken in. That means letting the rings set which keeps oil from passing by.

When breaking in any motor you have to keep a good eye on the oil level. I change the oil after the first 100 miles on a break in.

If your kitted engine exhausted all of its crankcase oil in 500 miles or less, it sounds to me like you have either a bad seal or rings that did not seat.

Ticking (depending on who is actually describing the sound) is often valve related. Check the valves, you may need to replace the top end as well if they weren't set right. The tick could be the valve lash not set correctly, timing chain off, or... and this is a long shot, the piston could be on upside down (with extra spacers installed by mistake keeping it from completely smashing into the head). Long shot and VERY improbable.

Running out of oil... that's suspect. You would have (or at least SHOULD have) noticed smoke in your exhaust along with a horrible smell that no 4 stroke should emit. Likewise with a leak on the ground. Are you positive you filled the oil to spec after the build? Was the engine cycled to displace the oil to the filter and sump?

Live and learn, check your oil. Check it often if you're messing with that stuff.

Good luck!

I've got about 22k miles on my 161 kit. It burns oil but I've never run out. I change it every 2k and top off when I notice it's getting low.

Sounds like it wasn't installed quite right.

Yeah, I'm going to try and have a friend check it out.. I don't exactly know how to ask my dealership who I've become good friends with, "Hey uh, did you install this right?"

Hello Buddyland:

I upgraded my Buddy 125 to 161cc cylinder 5000 miles ago. They put my piston in 180 degreez backwards. There is a directional orientation arrow on the piston that should face the exhaust port when properly installed. Have all engine settings checked first like valve clearances, before you go to the extremes you mentioned.


You do need to check the oil level constantly during the break in period. I would not go as far yet as to change a crankshaft and do another 161 kit. Keep the oil at proper level and keep on riding it for several hundred miles more then see how that goes.

Richard

Hi Richard,

Thank you for your post. I think they already checked the valve clearances, but I think that's all they've checked. I'm going to go in soon to have it completely looked at and ride my Sym HD200 while it's in there getting looked at.

Hello Buddyland:

What is your max speed with the 161 kit installed?

After I installed my 161 kit, my top end speed is still the same as stock 125 at 50MPH actual 60MPH indicated. Even still the same top end speed after changing roller weights from stock 11gs to 14gs.

It has more power, faster acceleration, but top speed unchanged.

Now what if I want more top end speed?

Rick71454

My top speed is usually an indicated 65 and I got it up to 70 once, which before I could only get to 60.

Noticeable changes to top speed will usually require new final drive gears. I am not aware of any readily available gearsets for the Buddy 125, but there could be something available from PGO or the Taiwanese aftermarket. Contact your local shop to see if they have any ideas.

Interesting. Both stock 11.5g rollers and 11g sliders have yielded 65bmph casual driving, 72bmph in a tuck on a long stretch for a top speed run. The likely limiting factor (as it is for most people on these scooters) is the same as it is for motorcycles and even cars - wind resistance. If you have the same low top speed with the BBK; that's a little intriguing. The extra torque should compensate for that. With enough power, and aside from any issue with hitting the rev limiter, I'm assuming this scooter could exceed 75bmph (~64mph actual); it's just a matter of getting there.

Unfortunately the Buddy does not have a large oil capacity so a close watch is always needed.

All vehicles can be subject to oil control issues.

We had a recent model year Corvette that always had blackened and damp exhaust pipes, although the oil level seems to hold.
Our Subaru shows no external sign of oil use but it can fool us by being down more than a quart between changes, so we have to watch that one closely.
Part of it is the ring seal but also how hard the engine is pushed. I suspect that an engine always used in performance mode may generally push some oil.

Yeah, this has been a lesson is understanding my knowledge limitations and perhaps someone with limited mechanical knowledge should not have performance mods beyond their understanding.

Henceforth before I have any performance mods done on my scooter I'm going to do quite a bit more research. This is at least 60% my fault.

In addition to oil consumption issues, has anyone experienced vibration or anything from doing the 161 kit? Are there any changes in how the bike runs besides the obvious torque increase that those of us doing this mod, say, over the winter, should know about?

It all depends on the quality of the kit. Some Big Bore Kits use forged pistons, ceramic coating, all new hardware etc. Others use the cheapest parts they can source and don't include all of the necessary parts needed for the swap.

I have ridden a nice 206cc Yamaha Zuma (125cc stock) that rode great. I have also ridden a couple cheap BBK's done on GY6 based engines that idled rough and sounded like they were about to blow up at any minute.

Stick with a name you know and be sure that everything you need, such as gaskets, new jets and such is purchased at the same time so you don't find yourself waiting for parts that have been back-ordered after you have already pulled the stock engine apart.

Careful inspection and assembly are the key to longevity any time you open up your engine. Rushing or cutting corners will come back to haunt you later every time.

I would definitely plan to feed a worked engine with the best fluids possible after the break-in period is complete and the rings have fully seated. Full synthetic oil costs a bit more, but it protects better and lasts longer. The maintenance interval should be adjusted to account for the increase in performance.

Since your engine will now have more horsepower and torque, but you will still be running the same CVT and gears, it is recommended to inspect the belt, pulley, clutch and replace the gearbox lube on a shorter service interval as well.

That's all good information have handy, sure. I've heard horror stories about people doing BBK's and the bikes not only idling rough, but running rough as well. There's a school of thought that says if you're looking for performance gains to make it "a whole new bike", the best way to do that is to buy a whole new bike. We shall see. The folks at the local scooter shop say they've done a couple of them so I assume they know the good from the bad. The Buddy 125 is their most recommended bike to kit apparently, due to the stroke of the engine.

Even with the best BBK on the market, you will still be using the stock crankshaft and connecting rods etc. If I wanted to have the most reliable and smooth running scooter possible, I would stay away from bolt on power adding parts that the factory engineer's original design specs didn't account for.

Your comment about buying a whole new bike is the only logical answer, since it will then be designed as a complete system with the properly sized brakes, gears, CVT etc.

With all that said, I am fully planning to put a 155cc BBK in my Zuma 125 as soon as I have the time. I like to tinker and often exhibit far more ambition than common sense.

Rusty Shackleford wrote:The Buddy 125 is their most recommended bike to kit apparently, due to the stroke of the engine.

The 125 is already a "stroker" over the 150 by about 2mm. This has advantages and disadvantages.

z20k wrote:I'm getting a second opinion on whether or not all that work needs to be done, but it's definitely concerning.. my scooter is my primary mode of transportation.

Dooglas wrote:If your kitted engine exhausted all of its crankcase oil in 500 miles or less, it sounds to me like you have either a bad seal or rings that did not seat.

I'm sorry about this. If it's a ringing noise then chances are the top end bearings are shot and a new kit is required. I had the same thing happen to my stock motor when it ran dry.

BuddyRaton wrote:The 125 is already a "stroker" over the 150 by about 2mm. This has advantages and disadvantages.

Sorry for the delayed response, ha. What would you say those are? The Buddy 125 has the torque to move the weight but lacks up top? I'm imagining that "all-torque; no-horsepower" effect. Care to share some insight?

The advantages are the increased torque at low rpms...great for climbing hills and better acceleration. The disadvantages are as with any 4T crank. At high rpms the stretch of the crank comes into play. The longer the crank the greater the stretch.

It would be hard to do on a Buddy but with minimal clearance between the piston and the head enough stretch can cause the piston to contact the head...never a good thing.

With the longer crank you can also get higher compression...run higher octane..and run hotter. Remember...these are air cooled motors so it is always a challenge to get rid of the heat. If you seize a pistion on a cvt it is pretty much lights out unless you are lucky enough to snap the belt. Unlike seizing a manual shift there is no clutch to pull. The rear wheel is going to stay locked up...not to mention the other parts of the motor that will be damaged.

Thanks for the reply. Extra torque to overcome hills and wind resistance is what we're going after here. On the flip side, the bike will be running for extended periods at 55mph (gps). I would assume the operating temperature would still be within an acceptable range, else Genuine wouldn't honor the warranty when an authorized dealer did the 161cc kit. Do you know of any potential downside to this? Are bore kits for scooters usually more of an "off the line, around town" kind of mod, or will they also add the benefit we're looking for with country-riding without putting too much stress on the vehicle?

BBK voids the warranty!

http://www.scooterworks.com/prima-58-5m ... s-1027.php

"-Voids your factory warranty"

If doing the BBK I would at a minimum open up the air box, jet it fat for break in (I went to a bigger carb) and put a pipe on.

I used a NCY pipe and I don't notice performance difference between it and a Prima...and the welds don't break.

It's a little louder than stock but no where near 2T expansion chamber type loud!

BuddyRaton wrote:BBK voids the warranty!...

Now, the shop had told me the kit doesn't void the warranty if an authorized dealer does it. I'm with you though, I would've thought there'd be no way in the world Genuine would cover a mod like that. I'll definitely need to double check with the dealer. I know it voids it if anyone else does it, yeah.

BuddyRaton wrote:...If doing the BBK I would at a minimum open up the air box, jet it fat for break in (I went to a bigger carb) and put a pipe on...

That's the thing, we were trying to avoid a pipe since the Buddy 125 is already louder than the CBR250R, believe it or not. I was under the impression that doing the BBK alone, rejetting would be sufficient to balance the A/F. My understanding is that it'll still give a bump in torque, just not as much as with the pipe and head. That's fine though, we just want a little boost in muscle for wind and hills.

Do BBK's make the bikes run rough at all, or is that the result of them not being done properly?

Rusty Shackleford wrote:Do BBK's make the bikes run rough at all, or is that the result of them not being done properly?

I haven't noticed any rough running. As far as running with stock air box and pipe ask around. I don't know of anyone that has gone that route but I'm sure someone has...just remember to jet fat for break in and then you can consider leaning it out.

BuddyRaton wrote:

Rusty Shackleford wrote:Do BBK's make the bikes run rough at all, or is that the result of them not being done properly?

I haven't noticed any rough running. As far as running with stock air box and pipe ask around. I don't know of anyone that has gone that route but I'm sure someone has...just remember to jet fat for break in and then you can consider leaning it out.

Might want to rethink the rich jetting thing.......fat jetting on a four stroke will cause rapid ring wear as the oil on the bore gets washed off.
Just do a normal break in.....as in, be a bit gentle so the rings can settle in gradually.

Rob

Robbie wrote:

BuddyRaton wrote:

Rusty Shackleford wrote:Do BBK's make the bikes run rough at all, or is that the result of them not being done properly?

I haven't noticed any rough running. As far as running with stock air box and pipe ask around. I don't know of anyone that has gone that route but I'm sure someone has...just remember to jet fat for break in and then you can consider leaning it out.

Might want to rethink the rich jetting thing.......fat jetting on a four stroke will cause rapid ring wear as the oil on the bore gets washed off.
Just do a normal break in.....as in, be a bit gentle so the rings can settle in gradually.

Rob

Good point but doesn't running a little rich help it run cooler?

Going a bit rich will make lower cyl temperature on a 2t if it is showing signs of running hot.

On a four stroke, it only runs cooler if it is so rich as to create incomplete combustion.
If a four stroke is too lean it just results in a high speed misfire, and a misfire doesn't make heat.
Since the buddy uses a constant velocity carb the main needle is controlled by a vacuum diaphram.
The diaphram recieves a vacuum signal based on throttle position and manifold vacuum and these type carbs have a main jet that, if were to be used on a mechanical carb, such as found on a 4t Stella, would likely be too large.

Wide open throttle, if too lean, would result in the diaphram getting a irregular vacuum signal and the resultant misfire......meaning, you'd know as soon as you got up to speed it was leaning out.

If you are thinking this could cause piston or cylinder damage......highly unlikely.....the piston is being cooled and lubricated from beneath, on the crankcase side.
So, to re-iterate, a high speed misfire, on a 4t isn't really harmful to the engine unless you get it to knock or ping at speed......this can fracture the piston......sometimes burn a hole right through the middle of it.
But, this means the driver continued to operate it even though the engine was audibly protesting, and the power was falling off.
Same results would happen to a automobile engine under the same circumstances.

So, to get the jetting correct on a four stroke you really should utilize exaust sampling under load (good luck finding someone nowadays to do that).
To further complicate matters, you can't rely on reading the plug much either....unleaded fuel makes plugs always look lean.

Your kinda stuck with the seat of the pants dyno......pulls smooth to top speed....leave it be.......stutters a bit, go a size or two up on the main jet or use a reconfigured needle and see what it does.......all trial and error.....and a royal pita.

Rob

JettaKnight wrote:

z20k wrote:I'm getting a second opinion on whether or not all that work needs to be done, but it's definitely concerning.. my scooter is my primary mode of transportation.

Dooglas wrote:If your kitted engine exhausted all of its crankcase oil in 500 miles or less, it sounds to me like you have either a bad seal or rings that did not seat.

I'm sorry about this. If it's a ringing noise then chances are the top end bearings are shot and a new kit is required. I had the same thing happen to my stock motor when it ran dry.

frak. Yeah, that's kind of what I imagined.. I hope it has a couple more months in it because I'm moving and can't afford to have it out of commission.

Robbie wrote:Going a bit rich will make lower cyl temperature on a 2t if it is showing signs of running hot.

On a four stroke, it only runs cooler if it is so rich as to create incomplete combustion.
If a four stroke is too lean it just results in a high speed misfire, and a misfire doesn't make heat.
Since the buddy uses a constant velocity carb the main needle is controlled by a vacuum diaphram.
The diaphram recieves a vacuum signal based on throttle position and manifold vacuum and these type carbs have a main jet that, if were to be used on a mechanical carb, such as found on a 4t Stella, would likely be too large.

Wide open throttle, if too lean, would result in the diaphram getting a irregular vacuum signal and the resultant misfire......meaning, you'd know as soon as you got up to speed it was leaning out.

If you are thinking this could cause piston or cylinder damage......highly unlikely.....the piston is being cooled and lubricated from beneath, on the crankcase side.
So, to re-iterate, a high speed misfire, on a 4t isn't really harmful to the engine unless you get it to knock or ping at speed......this can fracture the piston......sometimes burn a hole right through the middle of it.
But, this means the driver continued to operate it even though the engine was audibly protesting, and the power was falling off.
Same results would happen to a automobile engine under the same circumstances.

So, to get the jetting correct on a four stroke you really should utilize exaust sampling under load (good luck finding someone nowadays to do that).
To further complicate matters, you can't rely on reading the plug much either....unleaded fuel makes plugs always look lean.

Your kinda stuck with the seat of the pants dyno......pulls smooth to top speed....leave it be.......stutters a bit, go a size or two up on the main jet or use a reconfigured needle and see what it does.......all trial and error.....and a royal pita.

Rob

Thanks for the good info...I will admit that I am much more of a 2T guy

Well.. things went in a new direction..

My 161 buddy kept drinking oil, so I decided to get a second opinion from another shop. I don't want to go into too much detail as people I know locally visit this forum, but the other shop is telling me there's literally nothing wrong with my scooter.

I'm going to give it another 500 miles and see how the oil situation is then.

Hello Buddyland:

Immediately after my upgrade from Buddy 125 stock engine to 161cc, I did notice increased oil consumpution. I checked my oil level amost every couple days. Oil consumption has now slowed down quite a bit. I have over 4000 miles on the 161cc.

Richard

rick71454 wrote:Hello Buddyland:

Immediately after my upgrade from Buddy 125 stock engine to 161cc, I did notice increased oil consumpution. I checked my oil level amost every couple days. Oil consumption has now slowed down quite a bit. I have over 4000 miles on the 161cc.

Richard

Good to know I'm not the only one!

Hello BuddyLand:

Am I the only one with a Buddy 125 that has a shop installed 161cc BBK and got no increase in top speed? I understand the compression on a stock 125cc is around 120-150LBS. I got 117LBS.

Could this be because my connecting rods are stock, stroke is same length, and the resulting compression ratio is the same or lower after BBK install?

Do you believe that a stand alone 161cc BBK install will increase RPM, and or HP, and or or top speed?


rick71454

That's an in depth question.

Did you also do exhaust changes, etc? If not, it seems like it would just be trying to push more air/fuel through a straw.

Did you get increased quickness? Is it faster from stop to top speed? That's really all you should expect from higher ccs without changing the gearing or the CDI to allow higher rpms.

Hello Skully93:

I did no intake and no exhaust changes.

However I did ride my scooter with the air intake opened up as a short distance ride experiment and there was no increase in speed.

Another time, I loosened the exhaust pipe nuts where it connects to the engine, did a short distance ride experiment, and no increase in speed.

Right now, I got my intake & exhaust clearances set to 0.10mm as compare to stock 0.08mm. My carb main jet is at 112 as compared to stock 92.
It does get increased gas miliage, but no increase in top end speed.

Rick71454

Hello Syd:

It does what you say...........
Definitely quicker from stop to top speed, but top speed no better than stock.

Somebody else suggested a CDI change, but how does changing that increase top speed? Do you suggest a particular one?

rick71454

rick71454 wrote:Hello Syd:

It does what you say...........
Definitely quicker from stop to top speed, but top speed no better than stock.

Somebody else suggested a CDI change, but how does changing that increase top speed? Do you suggest a particular one?

rick71454

Among other things, a performance CDI (I'm sure they are available, somewhere) would have a rev limiter set at a higher rpm, which would allow the engine to spin faster, which would run the belt higher on the variator, which would pull the clutch pulley faster, which would turn the wheel faster, which would make the scoot go faster.

But it also might make the belt fly off the top of the variator, so you would need to find out how high the belt runs now. I have read that one way is to open up the variator cover and take a Sharpie or similar and put one line from the center of the variator out to the edge. Button it up, run it to top speed, then open it up again to see if there was any marker left on the variator face at the top edge. The other side effect of higher rpms is more heat, so you'd need to keep an eye on engine heat too.

Probably a better way to improve top speed would be to put taller gears in the back (I'm sure some are available somewhere). That could improve your top end at the expense of torque, which the BBK improved in the first place.

my aftermarket mods change how fast it GETS to top speed, not top speed itself.

There are too many variables that have to be in balance. Air, jetting, fuel mixture, etc. the folks here with 161cc kids have said they climb hills much better, but overall it's similar top speed.

Hello Skully93;Syd:

Thanks for your responses as they are helpful to me.
I will seriously consider a performance CDI.

I have taken of my CVT cover and watched it all operate. I even swapped out my 11G stock roller weights and put in 3 13g & 3 14g ones. Not much throttle and it cruises at mid 2/3 speed. At top speed, the drive belt is at least 4-5mm from the outer edge.

I ordered 18X14MM Dr. Pulley sliders. I even though of adding expoxy or JB Weld to built these sliders into 20X14MM.

Rick71454

rick71454 wrote:I even though of adding expoxy or JB Weld to built these sliders into 20X14MM.

Rick71454

I'm not a physicist, or an applied mathematician, but that variator is spinning at 7-8000 rpms. Not so sure I have the huevos to do that myself.

Syd wrote:

rick71454 wrote:I even though of adding expoxy or JB Weld to built these sliders into 20X14MM.

Rick71454

I'm not a physicist, or an applied mathematician, but that variator is spinning at 7-8000 rpms. Not so sure I have the huevos to do that myself.

Yeah....not something I would try. If not balanced or they don't roll or slide evenly the variator will asplode...probably taking the crank and other related parts with it.

It would be fun to watch! Please take video!

^ Intentionally blowing up your own scoot through mods, now that could be an interesting thread.

Hello BuddyLand:

Below the asterisked line is an entry from almost 3 years ago about the 161cc BBK. I agree with it as it is my results too, when rajron says:

"lost top end after the bore kit, but, it pulls much stronger from stop, and will sustain higher speeds up hills."

I was hoping for more top end speed, which I did not get. If I had known this before, I just would have just kept the stock cylinder or gotten a bigger scooter.

Rick71454

*********************************************************
rajron
Member

Joined: 18 Jul 2006
Posts: 1319
Location: ABQ & PHX
Buddy Sold - Vespa

PostPosted: Tue Sep 29, 2009 1:46 am Post subject: Reply with quote

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I have heard several people say they had lost top end after the bore kit, but, it pulls much stronger from stop, and will sustain higher speeds up hills. I’m running a big main jet, not sure the size, maybe around 0.118mm, I drilled my own and forgot what I ended up with and I am at altitude, running with an unrestricted air box, pipe, sliders etc; still my top end seems the same, or maybe a little lower, whatever the case its about the same. Those running the larger valves, 150 head, maybe getting higher speeds only because they rev higher – I think we are limited by the final gear ratios, not letting us get the higher speeds some want.