Sb50p sticker bomb build

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Chubbyfunkmonkey
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Re: Sb50p sticker bomb build

Post by Chubbyfunkmonkey »

I like bacon
1989 sb50p
2005 ruckus 50cc custom
2009 ruckus 125cc 4speed
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Re: Sb50p sticker bomb build

Post by Wheelman-111 »

Greetings:

Nice work so far. That propane tank idea is very clever; wonder why nobody thought of it before! Back pressure is not a factor though. It is the timing of the pressure Wave that stuffs fresh mixture that's trying to escape through the exhaust port back into the cylinder just before the Port closes that increases the intake charge and power. Adjusting the pipe length moves the power band up or down the Rev range.

Have you mounted a Cylinder Head Temp gauge? I recommend one. If you do, you may find the 75 main keeps Temps reasonable on the throttle. What you may also find is that the temp spikes sharply on deceleration, since you have uncorked the intake with a pod filter as well as your exhaust. The pilot circuit is very small on the PA carb. It relies on negative pressure in the tight airbox to suck fuel through the circuit. Without the box, the mix predictably goes very lean on coast-down. Fussy air-cooled 2-strokes have been known to seize under such conditions. Steer into the skid until the clutch releases, then change underwear. :)
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Re: Sb50p sticker bomb build

Post by Chubbyfunkmonkey »

I was hoping to get a temp gauge at some point, I've been keeping the rides short for the moment as a precaution. I had no idea it could overheat to the point of seizing on deceleration. The first time I took it out I couldn't believe how hard engine braking was. I hoped it meant I was getting good compression but never having driven a scooter this small I didn't know what to expect. As far as the pressure wave is concerned I felt the propane tank would be a good place to start. The neck of the bottle actually extends a few inches into the tank, this means as the exhaust exits the pipe the majority of the expanding gas is re directed by the round shape of the tank back at the cylender, now we are half way there. Changing the diameter of the exhaust at the bottle's neck will adjust the pressure in the tank which will adjust the speed at which the sound waves travel, to a degree. I can also easily change the length and diameter of a baffle thanks to the threaded propane tank. If this still isn't enough I can start cutting and adding or subtracting cross sections of another propane tank.

As for locking the rear tire and going for a ride, this ain't my first rodeo. Stupid hurts, that's why I take all the plastics off when I'm screwing around.
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2005 ruckus 50cc custom
2009 ruckus 125cc 4speed
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Re: Sb50p sticker bomb build

Post by Chubbyfunkmonkey »

It may be worth noting that I live in an area with a lot of hills so top speed will be a luxury. I'm looking for low to mid range acceleration, which is close to where I'm getting the most torque now, fortunately.
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Re: Sb50p sticker bomb build

Post by eclark5483 »

So, let me say, I owe you an apology for my last statement. When I type on my phone .vs typing at my keyboard, I tend to be a little more impatient in my writing style and what I say tends to appear snide and condescending because I usually don't have time for explanations. (I PROBABLY SHOULD BE WORKING AND BEING PRODUCTIVE INSTEAD OF TYPING ON MY PHONE).

What I had meant to say was, if you take the time, and you really SHOULD, to look not only in the wiki, but search through years of back posts, you'll find that.. well.. it's all been done before. Maybe not the propane tank, but then you have issues with that which Wheelman has also explained to you. But if you look, you will find about a decades worth of people who have tried this that and everything else... famous last words are "BUT I KNOW HOW TO TUNE A CARB".. That's not to say that it won't work well for you even though you have an unknown, or even non existent sound wave going back into the cylinder, yes you CAN compensate with proper jetting. You simply replace what is getting shot back up on the pipe's side with a better flow into the carb.

As Wheelman pointed out, these PA carbs have issue if you don't feed them back pressure. I explained the cause on the previous page, Wheelman explained the effect. This is why I am going to say to you, that you are more then likely STILL running lean. Now don't take that as me saying you need to upjet the carb. And in this case, don't think the plug color or a plug chop will help much even though that would be the usual ideal method to figure out if you have jetted right. The reason this can be misleading is because you are lean on fuel, not on oil, so the piston can be well lubricated, the plug look good and you'll be scratching your head wondering what went wrong. Just ask many of these guys who tried doing BBK's, thought they had it all dialed in right, plug looks good, but then they soft seize or fry the piston completely. This could have been me had I not reached out to friends of mine with a dyno to get to the bottom of it all. My background is with Indian & Victory motorcycles at Polaris where I have put them together for years. I know engines (4 stroke anyway), inside and out. I don't do them anymore however since I took a nice cushy position in the paint department instead programming bots, but still... when I got my first Spree, my first thought was "OH, THIS LITTLE ENGINE.. PIECE OF CAKE, I'LL HAVE IT DONE BY THE WEEKEND". But, things did not go like I thought. A very simple engine turned out to be very complicated. So I searched... MAN did I search... many long night searching and reading and taking notes from tons of posts on this website from over the years. I was very determined because of who the bike was going to, so it had to run perfect. This is why I set out on my quest to find the right parts, reverse engineer the engine, try all those things that others have tried and said made things better. I wanted to see what the changes were doing to the bike itself inside the engine. Air/fuel stoich, efficiency, etc.

I wouldn't say I have perfected it, but I for sure collected enough data to leave open the possibility on improving what I was able to do. I honestly learned NOTHING new that hasn't already been covered in the wiki, or by one of the other members who have passed through the hallowed halls of the Spree forums. Trust me when I tell you Wheelman is the GO TO guy on the AF05, NOT ME. The vast majority of cues I have taken to get my bikes to run as well as they do, have come from his guidance. 2nd place goes to a grouchy guy that goes by the name Bear, but we don't talk about him much... you'll have to read old posts for a good time on that one. For what it's worth, he is a very smart individual.

But, I digress..

As wheelman was saying about the carb, and as I was also stating, you need that back pressure. You got your Jerry rig pipe, and for better or worse, maybe you found something that works well, time will tell, hopefully you won't learn by soft seize. But anyway, you should focus on that carb next. Back to what I was saying about you being lean still, combine that with what Wheelman is saying to you. If you want it to be where it needs to be, and back into rich territory giving you more power and more speed, you better believe that you need to find a back pressure that works well for it. Stock airbox really is the ideal solution here.

I told you before. You should be able to do 35 stock, even up to 40. I wanna help you get there. You are actually at a real advantage here since you have an Elite E and not a Spree. The Spree intake will wreck havok on you if you attempt a pod filter without restricting it big time. You have a somewhat better intake.. good enough to run a BBK even, but it still makes the PA carbs job a bit harder. This is by Honda design.

I know you said you read up and saw well this Elite only does 30, and this one does 35 and this is what Honda says too. And yes, that's ALMOST accurate, but consider this.

As I stated before, I got my stock Iowa Spree up to 35. Now what's an Iowa Spree? Well, it was the worst of the Spree's. Back in the 80's, Iowa let 14 and 15 year olds legally drive these with a moped permit. In order for a kid to drive one, the bike could not be capable of over 25mph, so Honda tamed down their weakest engine even more to market them in Iowa.. Thus, the "IOWA SPREE, IOWA EXPRESS, etc". They had a couple ways of taming them down. 84-85's you could find washers in the pipe, later years, jets lowered, mouth ends on pipes shrunk, etc.. Much like your own bikes. So when I say, it's been done before, there are very detailed images of the pipes inner workings, there are many posts with pipe hacks... the funny ones are the guys who think they can just run a straight pipe and it runs so great.. but anyways, what I would do next if I were you before playing with your pipe any more and tweaking it in any way, is get that back pressure on that filter set right. You might even find a #75 jet is too rich.

IMHO I would probably, at first, say that it is, and that you want more like a 72-74 on an SB50, but considering you may be losing the sonic pulse with your new fangled pipe, it would be OK to compensate part of that lost charge through the intake.. I agree.. GET A TEMP GAUGE SO YOU KNOW FOR SURE, THEY ARE CHEAP.
I bet once you get the back pressure on that pad filter set right, or go back to an original air box, that you pick up 2-3mph and it runs cooler.

And I'm sure you probably figured it out by now, the reason you lost bottom end, is because you no longer have a pipe that has a silly little restriction in it that creates that power. That's something you'll more then likely have to live with.
Last edited by eclark5483 on Wed Nov 22, 2017 10:03 pm, edited 1 time in total.
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Chubbyfunkmonkey
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Re: Sb50p sticker bomb build

Post by Chubbyfunkmonkey »

Well feel free to tell me what is on your mind regardless of how I proceed I am listening, I just can't help trying the wrong way first. The temp gauge will be the next step for safety and proper tuning. As far as the possibility of top speed is concerned I think you may be right after all, but it will take more than a good tuning to do so. My everything is better, low end, high end and everything in between, though I'm not sure that it's safe yet. After another hour jetting today and timing some runs I found that my crappy little free scooter now gets to 25 as fast if not faster than my ruckus. I bet I could hit 35-40 without adjusting anything but the gearing, though I would no longer be able to go up big hills.

As for the carb I adjusted the needle on the main jet way up when I first started tuning it because the idle system was so clogged up no fuel was getting through. When the electric choke would turn off the scooter would no longer idle and would die. I was able to get the needle positioned so that even at idle enough fuel was being pulled from the jet to keep the engine running (roughly though). When I cleaned out the idle system I repositioned the needle back where it had been. Should I back the needle off the main jet again? It may not help with full engine braking (closed throttle), but it would provide a richer mix throughout the throttle pull and I could try to ease off the throttle more instead of letting it snap shut.
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Re: Sb50p sticker bomb build

Post by eclark5483 »

At this point, it's all experimental on you. First find the suction you need, you'll know you are there when the off the line throttle feels best. When you reach that point, experiment with jets, the higher is always the better for max speed provided you don't start gurgling/4 stroking out. Reach that point, then ease back a hair, and you are golden. THEN work on that pipe, if you start getting rich in those pipe tune, then you are heading in the right direction. THEN read the plugs to know for sure.
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Re: Sb50p sticker bomb build

Post by Chubbyfunkmonkey »

it works? it doesn't work?... only time will tell, but it looks and sounds sexy as * :P

ImageIMG_1704 by chubbyfunkmonkey, on Flickr

as for the air filter i have a surprise for you a little later.
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Re: Sb50p sticker bomb build

Post by Meatball »

:popcorn:
I need to find some new haters...the ones I have are starting to like me.
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Re: Sb50p sticker bomb build

Post by eclark5483 »

Chubbyfunkmonkey wrote:it works? it doesn't work?... only time will tell, but it looks and sounds sexy as * :P

ImageIMG_1704 by chubbyfunkmonkey, on Flickr

as for the air filter i have a surprise for you a little later.
What tire is that?
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Re: Sb50p sticker bomb build

Post by Meatball »

eclark5483 wrote: What tire is that?
https://www.revzilla.com/product/irc-mb38-scooter-tires
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Re: Sb50p sticker bomb build

Post by Wheelman-111 »

Greetings:

Absolutely Love the look, CFM! You have to look twice (or more) to see what it is. Only problem I see is if you don't have baffles and get pulled over for noise, the Gendarme will see the threads and "know" you removed the "muffler" for the chamber.

From the dome-end look of the propane cylinder, I can see how a perfect parabolic pressure wave could come rushing back to the header to accomplish - for very little money and effort - what sophisticated chamber pipes try to do. Varying the distance to that reflective dish will set the RPM sweet spot for power.
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Most of my money is spent on scooterparts. The rest is just wasted.
"ISO": '03 Vespa ET4 Malossi187 74MPH
Flash 9: 2001 Elite SR Contesta 72 ZX Tran, 9:1 Gears, Stock Airbox/Carb/Pipe 58.8 MPH
Punkin: 2010 Vespa/Malossi S78, 61MPH
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Re: Sb50p sticker bomb build

Post by Chubbyfunkmonkey »

the tire is a jetty 10" x 2.75". it came with the scooter still wrapped in plastic, not sure where its from.

im not too worried about being pulled over for noise. I'v only been pulled over once on my ruckus (10X louder) and they only gave me a warning.

In regards to the potential vacuum problem with the air filter... problem solved

ImageFullSizeRender by chubbyfunkmonkey, on Flickr
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Re: Sb50p sticker bomb build

Post by Meatball »

Surprised you dont use a "Rainier" can.... :smile:

I can imagine you zipping by...RAAAA, NIEEEEER, BEEEEER....(old commercial) https://www.youtube.com/watch?v=AKFmc0oZXFI :bowrofl:
I need to find some new haters...the ones I have are starting to like me.
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Re: Sb50p sticker bomb build

Post by Chubbyfunkmonkey »

As with many problems beer seems to be the answer. I noticed that a beer can has the same diameter as the inner foam filter so i cut the can to the size of the filter so that it only allows about 15-20% of the surface area to take in air. The beauty is that i can slide the can on and off to expose more or less of the filter, controlling the characteristics of the intake system.

ImageIMG_1691 by chubbyfunkmonkey, on Flickr

ImageIMG_1692 by chubbyfunkmonkey, on Flickr

I knew two strokes were touchy but holy crap!

when the can is all the way on i get my best launch but i lose a lot off my top end. When the can is all the way off i have my highest top speed but it bogs a little off the line. Then the can is slid off about a third of the way my power really kicks in at about 15mph and i can climb hills better than i can on my ruckus.

ImageIMG_1693 by chubbyfunkmonkey, on Flickr
1989 sb50p
2005 ruckus 50cc custom
2009 ruckus 125cc 4speed
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