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Post by dmartin95 on Jul 26, 2014 14:27:52 GMT -5
Hi all, I'm new to the forum and was hoping I could find some advice about engine upgrades.
I recently purchased a Brand New Scooter for my wife that came with an upgrade from the dealership. I was told they had installed an 83cc upgrade kit. I was told the moped would be faster than a normal 49.5/50cc scooter, but it's not. It's not very fast at all. I am 160Lbs and this moped tops out at 32 MPH, level surface. Bogs down on hills to like 15~20MPH and has no more take off power than a low powered 50cc scooter.
When I purchased her scooter, I also purchased one for me. A Bintelli scorch 50cc. I can do 38MPH on level surface and run circles around her 83cc upgraded scooter.
So, I'm getting ready to contact the dealer, however I would like to be armed with a little bit of info.
I see these 83cc big bore kits on the net, but I also see upgraded heads, cams, carbs, exhaust, etc, etc,....
So, In short, here's my question. If you put an 83cc Big Bore kit on a stock 50cc moped, should you also change other parts such as the head, cam, carb and such?
I read a disclaimer on a scooter upgrade site that said to realize the upgrades, other components should be changed as well.
So what happens when you install a Big Bore kit on a 50cc without upgrading anything else? Should there be a gain or loss in performance?
(This moped is still under dealership warranty)
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Post by jjoshua20213 on Jul 26, 2014 14:47:01 GMT -5
They did it wrong, take it back
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Post by ramblinman on Jul 26, 2014 14:53:37 GMT -5
...So, In short, here's my question. If you put a an 83cc Big Bore kit on a stock 50cc moped, should you also change other parts such as the head, cam, carb and such?... they should have at least changed the jets and tuned the carb... sounds like they did neither or just did it wrong. |
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Post by JerryScript on Jul 26, 2014 22:14:23 GMT -5
You can run a stock head on an 83cc BBK, but as others have mentioned, you have to upjet the carb. For an 83cc to run without issues (bogging, backfiring, ect) at WOT, you pretty much need at least an  main jet, which would still most likely be lean (I use a  ). That's the easiest thing to check, pull your carb and see if it has been upjetted. If not, they may have lied about doing the upgrade at all. For final proof, you can pull the head and measure the piston face. I run an 83cc BBK with a stock head, stock exhaust, Keihin carb which is same size as stock, and a main jet. I can run steady 40mph at -  % throttle, top out a little over 45, and I have plenty of power to keep up with traffic taking off from lights. |
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Post by dmartin95 on Jul 26, 2014 22:19:05 GMT -5
I'm not entirely sure what the dealership has done. Monday I'm going to give them a call, I was just hoping to get some information about what all upgrading a 50cc engine entails. This Amore now has 260 miles on it. My wife is a first time rider and she has been taking it slow. However as she became more confident and got into the throttle, she noticed it wasn't even remotely keeping up with mine and she's supposed to have the upgraded moped. I rode it to try and figure out what was going on and it runs as if it's a 25cc moped  . I hope it's something as simple as adjusting the jets but I'm thinking more along the lines of other components needed to upgraded along with the piston and jug. I'm really hoping that someone who's done these upgrades can chime in. |
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Post by dmartin95 on Jul 26, 2014 22:22:30 GMT -5
Hi Jerry, you posted while I was I posting....
Could you explain a little further, in depth? What is up-jetting?
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Post by JerryScript on Jul 26, 2014 22:26:19 GMT -5
Inside your carb there are two jets you can change to different sizes. One is the pilot jet which supplies fuel during idle and throughout the throttle range. The other is the main jet which supplies the larger amounts of fuel when you open the throttle up. When you install a BBK, you are increasing the capacity of the engine, so you need larger jets to supply more fuel. Often the pilot jet does not need to be changed with a BBK install, but the main jet always has to be switched to a larger one, other wise the engine will not run properly.
I believe your engine does not have a BBK installed because you can get it up to 30mph without mentioning any running issues beyond a lack of power. However, there are other issues that could rob you of power, so you need to inspect the main jet, and for final proof the piston head before making any accusations.
You can find youtube videos that will show you how to change your jets so you can inspect them.
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Post by dmartin95 on Jul 27, 2014 1:50:05 GMT -5
Thanks for the response!
The retailer I purchased this moped from is a fairly reputable one (Jason from Grand Rapids Scooter) and didn't strike me as dishonest. I hope it's not the case that I was deceived. I believe it supposed to have the Hoca 50mm BBK (That's what is listed on their site) but I have no idea if he jetted the carb.
But I will take your advice and pop off the head and measure the piston to make sure it is in fact a 50mm piston. I would hate to level any accusation against this company because they seemed like a really good company that knew their stuff.
I logged onto youtube and watched a couple videos on how to rejet the carb and it looks like something that's withing my capability. I also found stores that sells kits with 10 jets ranging from #72 to #110 jets for #$39.99 (Is that a fair price?).
I will need to learn how to tell the difference between the jets.... How/what do I measure to determine what one I have?
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Post by ramblinman on Jul 27, 2014 4:01:25 GMT -5
I will need to learn how to tell the difference between the jets.... How/what do I measure to determine what one I have? they are engraved. i have to take a close up picture and blow it up on my PC to read them. my eyesight isn't perfect and the markings are tiny. |
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Post by dmartin95 on Jul 27, 2014 12:12:17 GMT -5
That's awesome! Just looking at online pictures it's hard to see any marks on the jets.
-----------------------
I was still curious about something.
If someone installs a 50mm Hoca BBK without doing any other mods, what kind of results should one expect?
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Post by triker on Jul 27, 2014 12:55:56 GMT -5
when I got my 50cc trike from ice bear it already had an 83cc bbk. stock head exhaust ect. the 19mm carb had a #28 pilot jet and a #80 main jet installed and it would run 40+mph on level but around 20ish up hills. I tried a # main jet and # 32 pilot and could not get it to run. I ended up with a #82 main and a#30 pilot. A # main was to big without an exhaust and intake upgrade. Now with a bbk you have more power which necessarily does not equate to more speed, you should be able to pull hills a little better and get up to speed faster. Say the belt in the cvt is running all the way to the top of the pulley in the variator and all the way down in the clutch pulley with engine turning 7500rpm@ 30mph with a 49.5cc engine and you install a 83cc bbk. At the same 7500rpm the belt can not move any more than it already was with the smaller engine, hence no more speed. The belt will move to the maximum at a slightly lower rpm because the larger engine develops more hp and torque at a lower rpm than the smaller engine. Roy |
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Post by alleyoop on Jul 27, 2014 13:19:02 GMT -5
Just keep this in mind the weights in the variator work with centrifugal force(how fast the crank is turning) so if putting in a BBK lowers your RPMS you will have to put in little heavier weights to get the belt up as high as before the change. Same applies to the Clutch springs the clutch pads get thrown out to grab the bell to turn the wheel by centrifugal force. If you want the scoot to start moving with higher rpms then you put in little stronger springs on the Clutch pads. Think of it as cars with a clutch, you put in the clutch to disengage it from the flywheel and then give it a little gas to get the rpms up then release the clutch and you may squeal the tires(HAHA).
It's a balance with the CVT tuning weights, clutch springs and pulley contra spring and all driven by centrifugal force, how fast the crank is turning.
Alleyoop
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main jet, which would still most likely be lean (I use a 
). That's the easiest thing to check, pull your carb and see if it has been upjetted. If not, they may have lied about doing the upgrade at all. For final proof, you can pull the head and measure the piston face.
% throttle, top out a little over 45, and I have plenty of power to keep up with traffic taking off from lights.
..BAD TO THE BONE..