tiba_karotsu
OVERREV TUNING
what's the best pipe for MHR50cc minarelli aircooled cilinder with hypertuned ports, it will be for dragracing only.
best pipe for MHR50cc AC Mina
- Thread starter tiba_karotsu
- Start date
I dont know how MHR 50cc is vs. Polini EVO 50cc, but on my race Rally i tried 50cc EVO (untuned) with C21, and it sucked. 6,76hp and 96km/t on dyna2000. Then i got the cilinder CNC modified so it would fit the C21 better. It went from this to this. I didn't get i tested after that, but i could feel it was faster, but still no more than 8-9hp i think. Then i made i big mistake and sold the Rally in parts, so i haven't found the solution for 50cc kits yet.
Btw. i still have the 50cc Evo cilinder for sale if you want to try it.
Btw. i still have the 50cc Evo cilinder for sale if you want to try it.
tiba_karotsu
OVERREV TUNING
good heavens! you're one screwed up dude & i mean that in a good way. 
i wouldn't possibly think of using a C21 with a tuned 50cc & more so with an untuned one but what the heck it's worth knowing if it will work.
if i can't find one commercially i might as well make it a project of mine to fabricate one based on the C21 (scaled down for 50cc), fabricating teh flange pipe & flange is no biggie but the cones & header will be a major undertaking, i will hire a welder for this one but cutting the cones from sheetmetal i can do myself.
i wouldn't possibly think of using a C21 with a tuned 50cc & more so with an untuned one but what the heck it's worth knowing if it will work. if i can't find one commercially i might as well make it a project of mine to fabricate one based on the C21 (scaled down for 50cc), fabricating teh flange pipe & flange is no biggie but the cones & header will be a major undertaking, i will hire a welder for this one but cutting the cones from sheetmetal i can do myself.
50cczip racer
Well-Known Member
i wouldnt possibly think of using anything but the c21 to test on a tuned 50cc
ive dyno tested over 9 pipes on my 50cc race set up and not one of the bespoke 50cc race pipes work better than the c20 does and slightly modified gives another half hp, i cant wait to test c21 when it arrives.
i,ve learnt that you,ve got to keep an open mind with engine development some of the strangest things work
evo and mhr 50 come with around 176/180 ex duration so will never work best with full race pipes
ive dyno tested over 9 pipes on my 50cc race set up and not one of the bespoke 50cc race pipes work better than the c20 does and slightly modified gives another half hp, i cant wait to test c21 when it arrives.
i,ve learnt that you,ve got to keep an open mind with engine development some of the strangest things work
evo and mhr 50 come with around 176/180 ex duration so will never work best with full race pipes
melf #50
Well-Known Member
i use evo50 and DPR exhausts , they perform very nice on evo50 and mhr50 , i now race with MHR50ac with DPR (and 14mm carb), this will give about 10/11 hp , my first year i had just over 10hp with evo50 and evo 50 exhaust wich i think is best for 50cc that you can buy , in the "topscooter" (Highest in dutch scooterracing in 50cc) they use different homemade or dpr made exhausts , with lc and 19mm they get 17 to 18hp!
I would try polini evo first anyway
I would try polini evo first anyway
tiba_karotsu
OVERREV TUNING
aha, so EVO50 pipe is the best commercial pipe available for the MHR50cc other than a custom made exhaust pipe, i can get a used EVO50 pipe here to test & thank you very much for your suggestions. we will be using a 24 to 26mm carb on this & the frame will be very light, i have yet to finish porting the auxilliray exhaust ports it's really cramped in there but it's doable only very difficult.
last question are the old MHR pipes (not MHR Team) any good compared to EVO50 pipe? they are abundant here as well.
last question are the old MHR pipes (not MHR Team) any good compared to EVO50 pipe? they are abundant here as well.
50cczip racer
Well-Known Member
another invisible post
from experience i dont think evo pipe is anywhere near the best
and certainly not on a mhr cylinder that youve started hypertuning
evo 50 pipes are designed for use with stock evo cilinders which have low port timings so work very well with small carbs so makes a good set up for example in a restricted carb class.
you can certainly test one and see what you think you never know what might happen
from experience i dont think evo pipe is anywhere near the best
and certainly not on a mhr cylinder that youve started hypertuning
evo 50 pipes are designed for use with stock evo cilinders which have low port timings so work very well with small carbs so makes a good set up for example in a restricted carb class.
you can certainly test one and see what you think you never know what might happen
melf #50
Well-Known Member
uhm , the evo exhaust is one of the best exhausts on een 50cc setup , I used it on many setups and conluded that they are best from 12.500 to at least 13.500..
off course one can make a better exaust but evo is one of the best pipes witch one can buy in a store..
thats all so what my story further above says
off course one can make a better exaust but evo is one of the best pipes witch one can buy in a store..
thats all so what my story further above says
tiba_karotsu
OVERREV TUNING
FreZh said:
the MHR50cc cilinder will have skyhigh port timings on the exhaust & transfers that's why i'm asking around for a good or best exhaust pipe.
btw i'm also known as OveRReV in the "other" forum.
tiba_karotsu said:the MHR50cc cilinder will have skyhigh port timings on the exhaust & transfers that's why i'm asking around for a good or best exhaust pipe.
btw i'm also known as OveRReV in the "other" forum.
Ahh yes
When you say skyhigh timings do you then mean short distance from the cylindertop or opposit?
I'm a bit lost in translation here
tiba_karotsu
OVERREV TUNING
FreZh said:Ahh yes
When you say skyhigh timings do you then mean short distance from the cylindertop or opposit?
I'm a bit lost in translation here
yup that's what i mean (short distance).
tiba_karotsu said:yup that's what i mean (short distance).
I made skyported 50cc 3Kj cylinder a few years ago (-> 207 degree exhaust port duration, transfers are secret), and it was amazing fast
A remvove the hal moon from the exhaust chanel and open it's diameter. Sure I converted the standard head to high compression ratio, low squish clearance and different shape combustion chamber! And the standard Asso /2 ring/ piston could rev up to the sky without any damege (the piston got a little tuning to)! Sure I rebore the standard piston pin to 12 mm and use an EVO crankshaft. The carb was 21 mm, and I used with a modified Giannelli Shot!I don't konw why I type this?
Your Alu cylinder will be very fast I think!
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tiba_karotsu said:yup that's what i mean (short distance).
Okay, how short?
When you do that i don't think the Evo 50cc exhaust would be a good choise. It is too thin to to preform well with a cylinder with skyhigh timings. At least in theorie it is, i haven't tried it. I would go for the C20 if i could try my 50cc Evo kit again after i have hypertuned the exhaust port even more. I think C21 stille is a bit too "thick" for a 50cc kit.
Else just try with any 70cc race/hyperrace exhaust you can get your hands on. When you modify a cylinder so much with hypertune both exhaust and transerferports, you can't be sure of anything no more.
tiba_karotsu
OVERREV TUNING
for starters i made it 200exhaust/***transfers/***boost, not exactly skyhigh but i'll test that for now.
Browni it's like old times again but only this time i get to port an MHR50 cilinder, the auxilliary exhaust port is a big challenge but i'm almost done.
Browni it's like old times again but only this time i get to port an MHR50 cilinder, the auxilliary exhaust port is a big challenge but i'm almost done.
