Port timings Metrakit pro race..MINA. 47.6

[DRXRACING]

Okay guys just left the degree wheel on a 39.2 stroke mina engine with a 47.6 metra kit pro race cylinder. The findings were pretty lame. IMO.
With a thin b gasket < 0.19mm

XO 85 atdc
TO 122.5 atdc
XD 188 degrees
TD 113 degrees
BD 37.5degrees

With 1.11 mm of base gasket


XO 83 atdc
TO 119 atdc
XD 193 degrees
TD 121 degrees.
BD 36 degrees

Of course I would have to machine the head/cylinder to tighten up the squish.
My question is this, Is this timing close to the pro race timings or is this a SP cylinder being passed off as a PRO RACE cylinder kit. Both are new and are from the US Metra kit distributer.
I'm thinking the cylinder should be timed at 195 exhaust and 129 to 132 transfer.

What do you think?
Since the main transfer is so close to the sub exhaust port I fear raising it to get the 129 to 132 timing. But raise the secondary and boost port.
Thanks in advance.

 

[Big B NRG]

That are not Pro Race timings.

I measured this; 194/186 (exhaust, Main/Aux) 125 transfers/boost.

With a ,5mm squish.

 

[tiba_karotsu]

i got different port timings on an MK PR2 kit here, if memory serves me right it was 198ex/128transfers with 0,50mm squish.

 

[DRXRACING]

Thanks guys, at BDC the transfers/exhaust weren't even uncovered. I will call the METRAKIT DISTRIBUTER and see whats up.

 

[DRXRACING]

Thanks guys, at BDC the transfers/exhaust weren't even uncovered. I will call the METRAKIT DISTRIBUTER and see whats up.

I was told the "ProRace " name can be put on anything they want . And the cylinder I recieved was the Prorace for the ATV. It differs drastically from the "Scooter" Version "ProRace" Series cylinder .
I was also advised nothing can be done to the port timings that will improve the performance when used with the ATV "ProRace" Metra kit pipe.
Also that a EXHAUSTED study had been done and the port timings as they are , are the best possible when combined with their pipe for the ATV.

They also say a aluminum watercooled cylinder kit for the 90cc jog engine will be out in February.
If my tone is a little harsh, I apoligize. I'm just a little pizzed off.

 

[50cczip racer]

is the cylinder kit a 1 or 2 piece head design 1 for sp 2 for pro
the port timings are similar to sp cylinders for derbi and minarelli 6speed
transfers are too low for good spread for quad but ex duration is fine
id just raise the transfers and run it as the sp and pro has huge sub ex port area

 

[DRXRACING]

is the cylinder kit a 1 or 2 piece head design 1 for sp 2 for pro
the port timings are similar to sp cylinders for derbi and minarelli 6speed
transfers are too low for good spread for quad but ex duration is fine
id just raise the transfers and run it as the sp and pro has huge sub ex port area

The head design is 2 piece. A combustion dome (Head) and a cover for the head.
What do you think about 124 or 128 on the transfers. Or what amount of blowdown timing?
Thanks for your information it helps me cool my Jets a little.

 

[Big B NRG]

I was told the "ProRace " name can be put on anything they want . And the cylinder I recieved was the Prorace for the ATV. It differs drastically from the "Scooter" Version "ProRace" Series cylinder .
I was also advised nothing can be done to the port timings that will improve the performance when used with the ATV "ProRace" Metra kit pipe.
Also that a EXHAUSTED study had been done and the port timings as they are , are the best possible when combined with their pipe for the ATV.

They also say a aluminum watercooled cylinder kit for the 90cc jog engine will be out in February.
If my tone is a little harsh, I apoligize. I'm just a little pizzed off.

I think you have been ripped off..

How can they sell anything as Pro Race?? Metrakit makes different cylinders for different engines (piaggio/mina) not for different purposes |(

I wouldn't go back to that dealer..

 

[DRXRACING]

That is my opinion too. Except this is the distributer. My question to the distributer was , Why are you selling me the lower performing cylinder kits and are you selling the higher performing ones to a select group?
I was told the Prorace for the scooter did not have enough torque to pull a atv on a mx track. At that point he offered to exchange.
I don't have the money these players have but I am well aware of the game. This year they will have the number one ranked rider sponsered by them. But the rider got there on my engines. So we will see if he stays number one.
It just makes me work harder and I enjoy it.

 

[StepVino]

Wierd response, if they can sell anything they like,
how can anyone ever know what they are buying.
At least they should inform the customer that there
is more than one version of what they are asking for,
and make sure they get the one they want.

Just for fun I tried playing with your numbers yesterday.
I could only get them to come out close to Big B's by
changing the crank to 40.5 or so, no change in barrel
height alone would do it.

 

[tiba_karotsu]

sell the prorace kit & get an Evo2 kit, much better quality & the ports has bigger time/area than Prorace.

 

[Big B NRG]

Even better, get a 7T Malossi Cylinder!

 

[50cczip racer]

LATERAL THINKING
use a stroker crank 42 43 44 45 47.5 durations will improve and capacity increase
thats providing its legal for class regs??
just built a stunning motor 82cc for quad racing and is showing 3bhp more than tuned 100 and + 2 on mhr team7t with superior torque also got 85cc option

 

[DRXRACING]

The metra kit is gone! Sold it this morning, along with a host of other things. I did deck it and raise the anemic compression.
I have the 7T 47.6 coming in with a engine waiting to be built with it. Also have the 44 x 50 7T Malossi coming in with no engine build waiting for it, And finally, have the 2fast4race stroker kit ordered by e-mail From Massimo.
50cc zip racer , you want to spill any clues on that 82cc build? And how are you set for race exhaust for the Quads?

 

[DRXRACING]

BUMPED for SP cylinder timing.

 

[darookie]

thank you drx racing, i read your post, what durations did you finally do on the MK you had? how did it perform? do you have any suggestions ?