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Post by quaddad573 on Oct 23, 2019 12:50:15 GMT -5
I'm curious to hear about some of your guys different 50cc builds and different mods that were the most bang for the buck. What are the advantages to an 85 mm rod crank does it help low end poewer top end power or all across the board? I haven't heard of this being do but can one run a longer stroke crankshaft with a 50cc jug with a spacer? Thanks in advance
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Post by dexameth on Oct 23, 2019 14:14:11 GMT -5
A lot of vintage Vespa builders will do a longer rod with a cylinder spacer to help with port timings. I think you're best bet is a derestricted exhaust if you wanna keep it 50cc. Then give it a better breathing carb and filter, and tune the rollers to grab the powerband of the exhaust pipe.
There's so many cylinder kits for the Minarelli that you can't begin to name them all. Some people, like @90gtvert, the mod of this forum, are HEAVY Minarelli builders and go as far as case cutting and trenching and port matching to get the most out of these engines.
Endless possibilities, just matters on what you are looking to get out of the engine.
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Post by aeroxbud on Oct 23, 2019 14:26:36 GMT -5
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Post by geoffh on Oct 23, 2019 15:02:22 GMT -5
I run a 50cc with a few mods cruise at 35 will go just over 40mph,it,s daily commute so I don't,t push for performance,it depends what you want to do on the scoot and how long for ,let us know.
Geoff
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Post by Zino on Oct 23, 2019 16:39:49 GMT -5
Pipe and BBk are the first 2 biggest mods and put me in the upper 40's
The Big 3 that do the most are BBk ,Pipe and Gears/Variator
Cast Iron Sport BBK (Power and extra rpms top to bottom) Malossi ,Polini,Stage6
Pipe (More RPMs and Power in a new PowerBand ) You can go with a street pipe like Malossi Wild Lion or a expansion pipe like the Yasuni R Add 3-6 mph The expansion pipe gives more Top end the street pipe has a better launch .
Gears/ Variator (Better Gear Ratio) Athena Polini Malossi Gears shoot for around a 11 to 1 final Ratio This added 8 mph top end to my Zuma You need to have the BBK to push the gears or you can increase your gear ratio with a variator change.
Variator acceleration shifting and a little more Top end sport variator malossi polini,stage 6 added 3 mph to the VINO
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Post by quaddad573 on Oct 23, 2019 17:37:20 GMT -5
I got to ask what is a bbk im new to all this sorry.
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Post by Zino on Oct 23, 2019 18:21:27 GMT -5
bbk is big block kit 70cc of extra power
2 kinds Cast Iron and Aluminum Cast iron is more forgiving to tuning mistakes ,Aluminum typically run higher RPM . .
In primarily 4 Classes Sport Class (Iron and Aluminum) Very reliable upgrade over stock similar Port Timing so power is in the same RPM ranges as stock. Aluminum Sport Kits may need a Carb Upgrade
Mid Race (Almost all choices are Aluminum) Port Timing raises the rpm's up a notch over Stock The stock cranks have a harder time with these.
Race (Aluminum) Extreme Rpm's Better Crank and other engine mods needed .
Hyper Race (Aluminum) Racing and Rebuilding regularily
Port Timing in a 2 stroke is similar to how a Cam shaft works in a 4 stroke .
When you Go above Sport Changing to a bigger Carb is also required for cooling and performance .
If you buy a pipe that complements your BBK you want to be within the same class . For example sport bbk could run stock exhaust or sport, mid race would be too extreme .
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Post by quaddad573 on Oct 23, 2019 20:06:18 GMT -5
Thanks This helps a lot i have to keep it a 50cc so i can't run a bbk but was thinking about changing to the 85mm rod crank doing some block porting with an upgraded ignition and exhaust carb it only has to run 15-20 min at a time so max compression on race fuel. Does the kx85 reed upgrade help much and whats a good performance intake? Not sure what jug kit im going to run next it will be a water cooled for sure
Another question i have is do the sell the Chinese block in a 50cc?
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Post by repherence2 on Oct 23, 2019 20:30:47 GMT -5
quaddad, you can also Google "tiba karotsu". he's a tuner in the Philippines. he does drag racing, and I think he may have done circuit racing. I have read some posts on other forums about his 50cc that is a race bike. you might want to check it out.
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Post by aeroxbud on Oct 24, 2019 2:07:16 GMT -5
You can get 50cc cylinders. You can even get 50cc sport and race cylinders. They are just not as popular as the 70cc kits. Polini, Malossi and stage 6 all do 50cc cylinders.
Just wondering why not more than 50cc? If you go for a longer stroke crank, it will be more than 50cc anyway!
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Post by Zino on Oct 24, 2019 8:18:25 GMT -5
You still have a lot of options .
stock bore you can open up the exhaust port to match your exhaust pipe size swap in a higher compression heads with a Squish band Raise the ports and widen the ports 1mm at a time . This is a very trial and error and if you go to far your cylinder is shot . There are Port maps on here .
Or Buy a 50cc kit and have all of this already pretty much done and done right
Pipes Depending on the race track if it is long and wide open Drag race track you would want a high rpm pipe . If you are on a shorter twisty track you would want a pipe that is torquier at low rpms.
On the race track a Overrange Variator would be priority over gears for take off and still give you top end .
You still probably want gears to push your top end .
You will want to upgrade the Carb to feed your beast MPH over MPG
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Post by quaddad573 on Oct 24, 2019 10:17:25 GMT -5
aeroxbud the class my son runs in is a 50cc quad class i try to stay honest about what he races to be fair to the other kids i enjoy trying to figure out how to get as much power out of the smaller cc engine .. the stroker crank question is just something that was on my mind because im an old v8 junkie and most engines i build are long stroke v8 but the other reason is you cant just look at a jug and tell the engine has a stroker if the jug still says 50cc on it most people wont think about it and go on there way and with a longer stroke it should hit harder out of the hole.
zino18 is there anyone around you can send a cylinder of to and have it ported? the cvt has been a big learing curve for me but i think im grasping it wit a lot of trial and error lol. im wanting to run a lower final drive gear will a overrange help keep mph up?
what style scooter engine can i look up to find minarelli parts the quad is a drr but most places dont have that unless its a quad shop
thanks everyone for input i really enjoy reading what you all have to say it really gets me thinking about my options
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Post by Lucass2T on Oct 24, 2019 17:19:30 GMT -5
Going from stock minarelli (minarelli horizontal i assume) to 'something' and keeping the stock jug...
Id say start with finding out where the restrictors are. Post pics, ask questions and post more pics, we can help.
second, a nice expansion chamber for more power. Stay away from ebay and china stuff, keep with brands like Tecno, Yasuni, Gianelli...the euro stuff.
Then do the cvt. Buy a sports variator and a bunch of different rollers for tuning.
Dont buy bigger carbs, bigger cranks, heads, air filters etc. Thats the next step and is kinda useless if you haven't tackled the exhaust and cvt first.
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Post by Zino on Oct 24, 2019 18:58:34 GMT -5
Try these guys for parts www.scootertuning.ca/en/10113-cylindersYou can find cylinder choices in the 50cc flavor on the zuma pages. Pretty high end pipes for those atvs . overanges think of it like this you have a extra high gear and a extra low gear it would add to top end and low end sport variator would give you a overdrive gear and give better shifting . How bad do you want to win it could cost thousands. I Chamfered and ported by hand with hobby files and emory cloth ,sandpaper it took along time over a hour. I focused on smoothing up the exhaust port to near mirror finish I ended up raising and widening with this clean up just under 1mm wider and higher for better flow of exhaust out . I left all the other ports rough for cooling purposes . The Chamfering was to knock the sharp edges off the ports to cut down on snagging a ring Some guys prefer to use a dremel instaed of files ,I am teaching my 11 year old son how to rebuild theses engines so going slow is better he has helped swap 3 cylinders so far.
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Post by christopher on Oct 25, 2019 10:15:36 GMT -5
Going from a stock exhaust to an aftermarket was my biggest 50cc bang for the buck. Opening up the air filter etc first didn't accomplish anything, except me buying jets to have around for tuning later. My jetting didn't even change nor did any of my 0-35mph times, I also struggled to get 35 mph. My exhaust was to restrictive with no factory restrictions in place. I put on a Tecnigas Next R, up jetted and saw 42 mph my first time out and my variator weight was to heavy, needed more rpm. Went to a lighter slider and my 0-35 times were cut by 50%' with that pipe. When I get another scooter, I will put on a new pipe, pull the air box snorkel, rejet and tune the variator first. Then see what I have.
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