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< Scooter Showroom ~ Overrev's Yamaha MHR 50 LC dragscooter |
| OveRReV |
 Posted: Fri Jan 18, 2008 2:11 am |
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Joined: 13 Oct 2007
Posts: 882
Location: Republic of the Philippines
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another project scooter for a customer of mine, this will be for 50cc class dragracing where the class is dominated by cast iron cylinder (stock) 50cc scooters bored to 55cc (max limit) & tuned ports.
a tuner here boasted that no niikasil plated aluminum 50cc kit will ever win against a 55cc cast iron cylinder equipped dragscooter, well this new engine's goal is to prove them wrong.
ENGINE
Malossi MHR 50cc LC kit
Malossi RHQ pin10 crank
Malossi MHR digital inner rotor ignition
Malossi MHR VL14 reedvalve
Polini 0.25mm reeds
Polini Evo crankshaft bearings
Yasuni C21 replica exhaust pipe (straight silencer)
KOSO black intake manifold
OKO PWK24 carb
Overrev hypertuned carters
the exhaust pipe is a cloned version of my old Yasuni C21 exhaust pipe but this is sized for 50cc, the lengths are the same as for the 70cc but the pipe sections have been sized smaller for 50cc.
the carter tuning work is so secret i can't show pics of it due to some of my rivals are surfing the net & may stumble upon this forum, i want this to be a surprise, shock & awe! 
i will post pics of the parts later after i finish working on the other bikes. |
Last edited by OveRReV on Fri Jan 18, 2008 9:12 am; edited 2 times in total
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| Areomyst |
| Posted: Fri Jan 18, 2008 3:05 am |
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Joined: 10 Jul 2007
Posts: 3085
Location: Haw River, NC United States of America!
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Sounds pretty good sir.  I'll look forward to the pics. For some reason I was expecting to see a smaller carburetor though. The 24mm will do well with this? Be sure to post photos of the races too when you get them, we love to see those as well! 
~Josh |
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| Vikter |
| Posted: Fri Jan 18, 2008 5:42 am |
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Joined: 02 Aug 2007
Posts: 1247
Location: South of Sanford, NC
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Hey OveRRev, is it the law to use a stock cylinder? What port work are you going to do to it? And, why a 24mm carb on a "55"cc?
Looking forward to pics!! |
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| OveRReV |
| Posted: Fri Jan 18, 2008 9:00 am |
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Joined: 13 Oct 2007
Posts: 882
Location: Republic of the Philippines
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Areomyst wrote:
Sounds pretty good sir. I'll look forward to the pics. For some reason I was expecting to see a smaller carburetor though. The 24mm will do well with this? Be sure to post photos of the races too when you get them, we love to see those as well!
~Josh
based on my calculations the suggested carb size fo my setup is a 23mm carb but there is no such carb size available so the only options are a Dellorto PHBL22 or an OKO PWK24 carb which i have a lot of stock in the shop.
i am after at least 15hp @ the rear wheel.
as far as my rivals are concerned this engine does not exist, until it is completed & has won the championship i will not post any info about this new project racer in other forums. |
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| OveRReV |
| Posted: Fri Jan 18, 2008 9:09 am |
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Joined: 13 Oct 2007
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Location: Republic of the Philippines
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60+zuma wrote: Hey OveRRev, is it the law to use a stock cylinder? What port work are you going to do to it? And, why a 24mm carb on a "55"cc?
Looking forward to pics!!
there is no limit as to what cylinder kit you allowed to use (aluminum or cast iron, AC or LC) as long as you don't exceed the max displacement limit of 55cc, you are also allowed any type of crankshaft stroke or bore size as long as you don't go overe the limit.
my reasons for using a 24mm carb are explained in my response to Areomyst.
here is what i plan to do with the timing;
194 exhaust
190 auxilliaries
132 primary transfer
128 secondary transfer
120 boost
the carters have been tuned to it's utmost, it is strictly for 50cc only, carter volume is lower than the usual which i think isn't enough for 50cc but it will do for now.
additional carter tuning will be done later after we switch to a VForce3 reedvalve but this will be far off into the future. |
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| D4o |
| Posted: Fri Jan 18, 2008 12:31 pm |
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Joined: 09 Jan 2008
Posts: 117
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Nice man.. I have the same crank and reed block  |
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| Big B NRG |
| Posted: Sun Jan 20, 2008 10:41 am |
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Joined: 21 Sep 2007
Posts: 1232
Location: The Netherlands
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OveRReV wrote: 60+zuma wrote: Hey OveRRev, is it the law to use a stock cylinder? What port work are you going to do to it? And, why a 24mm carb on a "55"cc?
Looking forward to pics!!
there is no limit as to what cylinder kit you allowed to use (aluminum or cast iron, AC or LC) as long as you don't exceed the max displacement limit of 55cc, you are also allowed any type of crankshaft stroke or bore size as long as you don't go overe the limit.
my reasons for using a 24mm carb are explained in my response to Areomyst.
here is what i plan to do with the timing;
194 exhaust
190 auxilliaries
132 primary transfer
128 secondary transfer
120 boost
the carters have been tuned to it's utmost, it is strictly for 50cc only, carter volume is lower than the usual which i think isn't enough for 50cc but it will do for now.
additional carter tuning will be done later after we switch to a VForce3 reedvalve but this will be far off into the future.
Those MHR Team 50cc cylinders are fast little cylinders! Dealer who raced with those cylinder in the Dutch championship pushed his 50cc cylinder to allmost 20 BHP!!
Allthough he did buy 10 of those cylinders and did every cylinder different, the result was
Why keeping the aux. exhaustports lower as main for sprint? |
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| OveRReV |
| Posted: Tue Jan 22, 2008 7:37 am |
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Joined: 13 Oct 2007
Posts: 882
Location: Republic of the Philippines
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Big B NRG wrote:
Those MHR Team 50cc cylinders are fast little cylinders! Dealer who raced with those cylinder in the Dutch championship pushed his 50cc cylinder to allmost 20 BHP!!
Allthough he did buy 10 of those cylinders and did every cylinder different, the result was
Why keeping the aux. exhaustports lower as main for sprint?
well i am going to do the conservative approach first & see if i can hit my target ET with those settings, i have concentrated more on improving the carters but the cylinder kit will also receive the same detailed treatment.
we don't have the luxury of buying a spare cylinder & much more 10 spare cylinders but i do appreciate his determination in tuning all those kits & finding one which works best.
it still makes me giggle to think you guys still refer to this kit as an MHR Team when it is clearly just an MHR with a 1pc head.  |
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| Big B NRG |
| Posted: Fri Jan 25, 2008 5:49 am |
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Joined: 21 Sep 2007
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Location: The Netherlands
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Hm..
On Piaggio you have 2 types. The MHR 50 and the MHR TEAM 50..
The MHR 50 uses a 80mm rod (different piston) and 1 piece head.
The MHR TEAM 50 uses a 85mm rod (pistonpen sits higher) and has a modulair head.
I thought it was the same on Mina, guess not...  |
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| OveRReV |
| Posted: Fri Jan 25, 2008 6:50 am |
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Joined: 13 Oct 2007
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Location: Republic of the Philippines
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Big B NRG wrote: Hm..
On Piaggio you have 2 types. The MHR 50 and the MHR TEAM 50..
The MHR 50 uses a 80mm rod (different piston) and 1 piece head.
The MHR TEAM 50 uses a 85mm rod (pistonpen sits higher) and has a modulair head.
I thought it was the same on Mina, guess not...
actually you're also correct, MHR 50 Mina uses 80mm rod with 10mm pin, MHR Team 50 Mina uses 85mm rod with 12mm pin. |
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| OveRReV |
| Posted: Fri Jan 25, 2008 9:50 pm |
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Joined: 13 Oct 2007
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Location: Republic of the Philippines
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here are new pics of the engine, the crankshaft, bearings, oil seal & the MHR inner rotor ignition is installed. the intake manifold has undergone some slight modifications, i will install it later after i cut a new set of reeds for the VL14, the 0.25mm reeds gave the best performance on the MHR 70cc Beta Ark i tuned fo a customer.
i also trial fitted the Malossi cylinder kit to see what it looks like with the kit on.
later i shall also do some minor modifications to the inside of the carb for better fuel delivery to the float bowl. |
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| Big B NRG |
| Posted: Sun Jan 27, 2008 3:54 pm |
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Joined: 21 Sep 2007
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So why didn't you go for the Team?
There weren't any difference in ports etc right? |
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| Areomyst |
| Posted: Sun Jan 27, 2008 5:32 pm |
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Location: Haw River, NC United States of America!
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The lower portion of the carters where the cylinder barrel fits... is that epoxy work I see here? Raising the primary compression, I take it? Or have you not yet worked your magic on this set of carters?
All the best,
~Josh |
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| OveRReV |
| Posted: Sun Jan 27, 2008 7:53 pm |
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Location: Republic of the Philippines
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Big B NRG wrote: So why didn't you go for the Team?
There weren't any difference in ports etc right?
well i saw a pic of the ports of the MHR Team 50cc mina & they were just the same as MHR 50cc plus the MHR is cheaper to buy & is locally available.
also it will be harder to find a piston for the 12mm pin 85mm conrod. |
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| OveRReV |
| Posted: Sun Jan 27, 2008 7:55 pm |
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Location: Republic of the Philippines
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Areomyst wrote: [
The lower portion of the carters where the cylinder barrel fits... is that epoxy work I see here? Raising the primary compression, I take it? Or have you not yet worked your magic on this set of carters?
All the best,
~Josh
hehehe, you have keen observation.
oh definitely i have worked my magic on this set of carters, what you see is just the tip of the iceberg.  |
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