ratdog
Scoot Enthusiast
Posts: 342
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Post by ratdog on Aug 18, 2018 7:42:49 GMT -5
A block down the street I live on there is a house that always has a Harley and a black Tao Tao scoot. I must have driven by the place a thousand times on a bike, but have never met him. Well last week when we were doing a bunch of testing and plug chops, he decided to jump on his scoot and see what was up.
after riding the paperboy’s scoot, he said he would love to do a “ full house” build. I offered to help him if he bought the parts. Didn’t think about it until this morning. That’s when he came down and told me he got in the parts! I went down to his house and he showed me what he had. WOW! Has this guy got a set up! In the center of the 20X24 “garage” he has a motorcycle lift! No more bending over! The bike is on the lift, but he has puller the engine out of it, and the engine is on the bench!
He bought a BBK with a 50 mm bore. Came with head, A9 cam, and a 22mm “high flow” carb. He also got a real neat reverse cone megaphone . Like the kits I have used, the top of the piston looks like a gravel road. I mentioned that if I still had my lathe, I would clean that up. To which he replied, I have access to a complete shop! Seems that among other things, he owns a machine shop! This is going to be FUN!
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wahlman
Scoot Enthusiast
Posts: 111
Location: Miami, Florida
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Post by wahlman on Aug 18, 2018 9:35:13 GMT -5
Sounds awesome. Reminds me when I was a teenager and we went to this rich kids house he had a full drum setup, guitars, bass, amplifiers, effects pedals, just EVERYTHING.
We had a blast. Like a kid in a candy store
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ratdog
Scoot Enthusiast
Posts: 342
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Post by ratdog on Aug 18, 2018 10:06:57 GMT -5
Truth is, this guy dosent need my help. He builds big V twins all the time. But he wanted to tap my experience on these little guys
Also found out that just because you own a machine shop, dosent mean you work in a machine shop
So far... we pulled the engine down. I wanted to clean up the top of that piston, so we took the new parts to the shop. Amount the other goodies, he has a CNC lathe. I’m not up to snuff on his cad cam program, but it’s just a Fanuc controller, and it sure isn’t hard to do the G code once we decided on the radius we wanted. We cut a hemispheric top to the piston. The orginal casting was more of a cone with a small flat spot at the top. The cylinder was not totally flat. There was a dip of about .0009” above the exaust port. Easiest thing was to just set it up in a Bridgeport and take a .001 cut. While the head look like it had been machined flat, to a indicator it looked more like a motocross course. We took a .0015 cut to get it flat. Every think else was fine, so it’s time to do a little hand work on the head
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ratdog
Scoot Enthusiast
Posts: 342
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Post by ratdog on Aug 18, 2018 13:37:22 GMT -5
Couple of problems... I wanted to match up the ports for this “22 mm high flo” carb. Only every way I measure this carb, it an 18mm. On top of that, I was curious what they had done to make it “ high flow”. Well, nothing! There is no enlarging of ports or polishing. Just a stock carb with a 78 jet in it! I also have a little problem with the “big bore” head. I have to wonder if it’s new! Of course the ports look like poop but it appears that someone ran a debuting tool around the lip of the port. Someone that had not a clue how to correctly use the tool. The owner is going to have a talk with the people he bought it from. As we guess it will take a week or so to straighten that out, so he would rather buy another head gasket then wait, so we are putting it back together as it sits. Like I said, this guy dosent need my help really, so he had it back ready to go in the bike in about 20 min. OK he did need my fancy valve adjustment tool, but just to save a little time Just eating lunch, and he buzzed the house. Wow is that thing loud! Stopped by and he is a little disappointed. Had him take it “around the block” ( that gives him 2 1/2 mile long stright with no stop signs. We checked the plug and (at least the way he and I read plugs) way lean Tomarrow I’ll take up a selection of jets, and we will re jet it. He is also going to make a new exaust pipe. The stock pipe has about a foot and a half of very small tubing, the joins to a section of tubing with an 1 inch OD. He is also going to make it a little shorter to put the “ram tune” length in the middle of the megaphone.
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ratdog
Scoot Enthusiast
Posts: 342
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Post by ratdog on Aug 18, 2018 19:08:34 GMT -5
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ratdog
Scoot Enthusiast
Posts: 342
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Post by ratdog on Aug 18, 2018 19:35:03 GMT -5
well this guy may not do much in a machine shop, but boy can he weld he made a whole new pipe from head to megaphone. its all 1" OD stainless the bends look great. he told me he packed the pipe full of sand before he started bending and you don't have the flat spots in the bends I'm used to seeing
he also decided to drill out the main jet with a #62 drill. that should be about a #96 jet. He is much more happy with the bike now. even though its not broken in yet, he sz he gets 49 mph at 8900 rpm now. sz it pulls over 8 grand so easy that he has ordered a new final drive for it. we are going where I have never been now. dosent look hard, but it will be my first time.
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Post by magoconnor on Aug 19, 2018 8:13:47 GMT -5
Have you guys tried messing with the cvt yet?
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ratdog
Scoot Enthusiast
Posts: 342
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Post by ratdog on Aug 19, 2018 10:31:13 GMT -5
Have not tried any CVT stuff. My thinking is that this little scoot jumps up to 8200 rpm almost instantly and pretty much stays there up to a bit over 40. Then the rpms slowly increase as the speed increases. To me that would seem to say it has full lockup at a bit over 40 and the only mod I can think of from there is the final drive
I was looking at some of the stuff in the top speed area. I didn’t read all the posts, but it seemed like damn few listed both speed and rpm. I have only juiced up three of these so far, but it seems to me that the stock gearing limits these guys to the mid 40s.
The owner of this latest project found a 12” tire to replace his 10” tire.
As of a few min ago he has a 50 mm BBK that we cleaned up a little. Big bore, big valve, ported head with metal intake runner and 22 mm carb. Exaust is 1 inch SS tube same dia for the whole pipe. “Muffler” is a reverse cone megaphone. He also made a 5” intake horn ( we used to call them “ velocity stacks” currently no air filter 32 polit jet, 95 main jet. 12 inch rear wheel.
He just did a 52 mph run (per GPS) at 10,200 rpm. And oh my God it that thing loud!!! Monday he ordering a different set of final gears. Also found a High performance variator that is supposed to be larger (79 mm) face. I’m guessing he is also ordering a new belt.
We are also going to try a different fan that they say gives more air flow
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ratdog
Scoot Enthusiast
Posts: 342
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Post by ratdog on Aug 20, 2018 8:57:31 GMT -5
The earsplitingloudenboomer is back! Walt (the owner) had a talk with the people that sold him the kit that tncluded the “22mm high flow carb” that looks and measures just like a stock 18 mm carb. Also sent pic of problems with their “new” head. He is not happy! So they tell him that this is the right stuff and he should put it on the bike because it will give him the best preformance possible.
Now for me, I’d just write it off as a bad investment and chuck the stuff. But not Walt. So, we took off my head, intake, and carb, and put on the ones that came in the kit. And he took it for a ride. I didn’t think it was possible, but earsplitingloudenboomer is even loader! Mostly because now it makes big backfires when you back off the throttle.
I will ne honest. If some one told me there would be this much difference, I would tell them they were full of it. Anyway, with the junk head and carb (but still using the A9 cam, the bike starts struggling in the mid 30s. After a very long run ( more then a half mile), the best he can get is 42, and that’s with a small tail wind! In case you haven read about this little guy, he had the bike doing 52 mph yesterday!
Well he came up with a deal to buy my carb, intake, and head. He said I “somehow must have got the combination just right” and he didn’t think he could buy other parts to give him the same preformance. Because I have decided to sell the bike back to stupid ( my Nephew that tore out all the wireing trying to hot wire it, then sold it to me) I made the deal. He is ording a new 23 mm carb and metal intake fore me and giving me the junk head, as well as doing some work for me fabing up some stuff for my real M/C
I did discover a couple of things when we were swapping out the heads. The pick up for the ignition (above the flywheel) normally just has two holes to mount it. It looks like he mounted on a turn table and milled out those holes into carved slots. This allows him to advance the timing. Not sure how much, but I’m guessing he’s getting about 3 more degrees of advance. I also noticed he is running a huge gap on his plug. He has a different coil “adapted” to the bike. I don’t know what it is from, I would guess it might be some part for the Harley’s he builds. When I asked he just said it was something he was seeing if he could get to work. Wouldn’t tell me more. Also has a fatter plug lead . So it appears he is doing ignition mods a little off the charts.
So anyway the earsplitingloudenboomer is back on the road and back hitting those 50 mph speeds. He has a bunch of new stuff on the way. Most important is the new gears for the final drive. Did I mention that bike is way loud?
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Post by AtariGuy on Aug 21, 2018 0:22:10 GMT -5
You can add heavier variator weights to bring the overrev down to a safer rpm while still maintaining those speeds. It might slightly slow down your acceleration times, but with the power you guys are turning, i doubt it'll affect those accel times much at all.
Just a thought
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ratdog
Scoot Enthusiast
Posts: 342
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Post by ratdog on Aug 21, 2018 8:51:11 GMT -5
You are 100% correct until you get to the point that the CVT cant change the gear ratio anymore. I don't think that is the issue. What we are talking about is RPMs at top speed. this is after full lock up, and controlled by the final drive ratio
I'm not an expert on CVTs but maybe it would help if I explained how I think they work. The key is the drive disks. These have a taper and can move closer together of father apart. Because you have a “v” belt, if the drive disks are close together, the belt rides near the outside of the disk. How close together the drive disks are controlled by the variator. As the RPM of the variator goes up, the weights force the drive disks closer together. This effectively makes a larger “pulley”
The belt is a fixed length, so as the belt is forced into a larger “front pulley” the drive disks on the rear (the clutch side) are forced apart, making a smaller “rear pulley”
these are not necessarily the correct numbers, but just used for demonstration.
At idle, the front pulley is as small as it can get, lets say 1”, which makes the rear pulley the largest it can be. Lets say 6” So the front pulley has to turn 6 times to turn the rear pulley But it is the easiest to drive the rear pulley. Our “low gear” now as the bike gets rolling, the front pulley can start turning faster. The variator forces the drive plates closer together. Now we have a 2” front pulley and a 5 inch rear pulley The front pulley only has to turn 2 ½ time to turn the rear pulley so the bike is going faster. The variator is “set” for a certain RPM range (function of the weight of the rollers) so now as the bike is going faster, the front pulley increases in size to 3” causing the rear pulley to shrink to 4” and now the front pulley only has to turn 1 1/3 turns to make the rear go one turn. The bike is going a good clip now. As the engine is able to pull more RPM, the front pulley grows more. Now its 4” in size and the rear is only 3 inches in size so the front pulley only has to turn ¾ of a turn to turn the back pulley a full turn. Of course now it is very hard to turn that front pulley If you hit a hill, the RPMs start dropping, the variator drops in rpm and the weights let the drive plates slide apart a bit to make a small front pulley (and larger back pulley) so its easier to turn the back pulley Result is you keep about the same RPM, but now at a lower speed.
We are flying, down the highway but at some point the front pulley gets the largest it can get with out pushing the belt off. That is what I would call full lock up. We are in as high a gear as the bike has. I can "see" full lockup by watching the tach. while Accelerating the engine is kept, more or less, at the same RPM while the speed increased. after full lock up, the rpms climb as the speed climbs. The only way to go faster is to spin the motor faster. Now the stock engine doesn't have enough HP to increase the rpms against the load anymore. In fact it may never even get to the largest the front pulley can get because it just cant pull the gear. My scoot, when stock, could only get me up to about 32 mph. I'm willing to bet that it had not reached full lock up.
We have our modded engines. When those engines get to “full lock up” they still have the HP to increase the RPMs. But you can only spin these engines so fast. This is where to final drive comes in. by going to a lower final drive, the bike will go faster at any given RPM (while in full lock up), if the engine has the power to pull those RPMs
SO, the only engines that will benefit from a lower final drive are those that have the HP to push very high RPMs at full lock up. If your engine is all in at say 8000 rpm at top speed, don't change your final gear ratio. A lower ratio will actually hurt you. If at top speed, your engine want to climb in the 9000s (or more), then that engine most likely has the HP to benefit from a lower final gear
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Post by magoconnor on Aug 21, 2018 9:33:00 GMT -5
How do you go about breaking in the 80cc cylinder ? Seeing that you have a lengthy experience with bikes, you may do things differently.
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Post by benji on Aug 21, 2018 9:49:53 GMT -5
Technically it's torque that provides the higher top speed, not high RPM. Although "over rev" does help if you have the power and motor to go above 10k (usually considered high RPM). The bike can rev to the moon, but if it doesn't have the torque to push taller gears, the pulleys won't go all the way to "top gear" (variator fully closed, rear pulley fully open) and will actually act like it's going up a hill.
Take my bike for example... If I lighten the rollers, the bike goes to 10.5k+ real fast but won't shift higher so I'm stuck at 55-60. If I use the correct weight rollers, the CVT shifts at the correct RPM for the power band and it only hits 8.5-9k while shifting, and it'll be at 62-65 before I even hit 10k.
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ratdog
Scoot Enthusiast
Posts: 342
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Post by ratdog on Aug 21, 2018 11:48:31 GMT -5
How do you go about breaking in the 80cc cylinder ? Seeing that you have a lengthy experience with bikes, you may do things differently. first, remember I’m building race engines, not engines designed to last the rest of your life. we have sorta a old saying, “break them in fast to go fast, break them in slow to make them last” first i control the fitting of the piston and use a very fine hone. You don’t have control over that so it is not a factor to you. Next, never let a new engine idle! Most engines barely push enough oil for a broken in motor and not enough for a new motor. I set my throttle stop to about 3000 rpm. once your up and running, very the speed! Frankly, this is hard with a CVT, because it wants to keep your engine at about 7000 rpm, but just keep sawing the throttle. Form time to time keep it at WOT and as high of RPMs as you can get, then back off and let it run at reasonable RPMs but almost no load. frankly, we were making full WOT runs with the 3 we build within an hour of first startup. in a bike with a clutch and gears, if much easier to control your break in. With the CVT, it always wants you going the same RPM. So on a CVT, I think of load no load. You want to put a big load on it then go a while with light load. but remember, I’m breaking in fast to go fast. My engine won’t last as long as one with a long break in. i also choose to do an oil change after about 4 or 5 hours. ( don’t care about miles as the CVT will have your bike running lots of rpms even at low speeds)
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ratdog
Scoot Enthusiast
Posts: 342
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Post by ratdog on Aug 21, 2018 12:56:33 GMT -5
Benji, I guess I'm not sure what you mean by "shift". As I understand a CVT, there is no "Shift" That's the whole point of a Continuously Variable Transmission. no shifting. SO if the weights are set correctly, the the engine should be kept at the designed RPM from 0 to full lock up. Once you get full lockup, the only thing that controls your speed is the RPMs your engine has the HP to pull From what you say, I guess your CVT dosen't work that way. I just don't understand what you claim is a "shift". At full lockup, that's all the gear your going to get. there is no additional shift into an overdrive or what ever you are trying to discribe. Are you saying that there is an additional gear? This is a dyno sheet. the top lines are HP, the bottom lines are torque. AS you can see, torque is the most important thing until a little over 5000 rpms from there up, torque is pretty flat and then decreases, while HP increases. torque is what gets you going. frankly, its what you feel when you are taking off. but to go from 7500 to 8000 rpms at full lockup, it HP that gets you there.
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