Port Timing

[Mexicano]

Do some of you have a link to learn how to measure my port timings?

Thanks!

 

[narx]

Here you go, i hope this will help.

http://www.macdizzy.com/cylinder_map.htm

 

[Mexicano]

Thanks Narx!

 

[Mexicano]

well here is it..what do you think?

 

[Eoin70]

that exhaust duration seems a bit too big
what is the length of your conrod?

 

[Mexicano]

Thanks Pal!

My connecting rod is 83 m.m. from big bearing center to small bearing center.

The bore is 54 m.m. x 47 m.m. stroke.

 

[Eoin70]

usually the transfers and the bottom of the exhaust are @ BDC but with these numbers you gave i assumed a deck height of 0
so you have 189 on the exhaust and 125 on the transfers
this sounds like nice specifications, should make for some nice torque

 

[Mexicano]

Well I'm not sure about the "Deck" now, until I assembly the engine....
I will set a 9.5:1 C.R., but I need to raise the CR ( Now is 7.3.1) what is best: machine the top or the bottom of the cylinder?, which is the "effect" of each one? also I can machine the head to low the c.c.'s of it, I have 14 c.c. now.

Thanks!

P.D. How did you get those exhaust and transfer numbers?

 

[Mexicano]

This is the area of my ports:

 

[Mexicano]

Question for Big B and or Tiba!!!!

Hey Pals...can you give me your opinion on my port timings???

Thanks!

 

[Big B NRG]

Port timing is oke, I would change the shape of the exhaustport.

Making it more oval at the bottom will increase torque.

 

[DRXRACING]

For a little more rev try another 3 to 5 degrees of transfer timing. Could be as simple as doubling the base gasket.
More ovaled exhaust would perform better and watch out for getting too flat across the top of the port. Or ring problems may occur.
About 185psig or 165psig (Kicking pressure) will run good in this engine. that may well be around 11.5 to 12 cc.
How much distance between the exhaust and the transfer windows?
You should be able to build the head to suit the desired compression.

 

[Mexicano]

Port timing is oke, I would change the shape of the exhaustport.

Making it more oval at the bottom will increase torque.

Thanks Big B, I will work on that.

Regards,

 

[StepVino]

Here's another link for you again from McDizzy:
http://www.macdizzy.com/eltee.htm

You will get a better idea of where the timing is after you
test install it. You really need to know deck height...

You guys are bad . I have to get some work done, and you
start these interesting threads!

 

[Mexicano]

Thanks StepVino!

 

[Mexicano]

Port timing is oke, I would change the shape of the exhaustport.

Making it more oval at the bottom will increase torque.

Hey B!...I will buy a new cylinder and try to make a better one, can you help me???...I'm not a "expert" on this, so I would need you to tell me what to do to improve it, and some "drawings" showing where to port, can you help?


Thanks,

 

[Big B NRG]

Hey B!...I will buy a new cylinder and try to make a better one, can you help me???...I'm not a "expert" on this, so I would need you to tell me what to do to improve it, and some "drawings" showing where to port, can you help?


Thanks,

Sure I can help!

What cylinder are you buying, maybe you have a portmap for me that I can change?

Also I need info on stroke/bore/timing of all ports.
For shape:

 

[Mexicano]

Sure I can help!

What cylinder are you buying, maybe you have a portmap for me that I can change?

Also I need info on stroke/bore/timing of all ports.

Thanks Big B!!!

I will get the same cylinder..not to many options for my engine: AC, stroker 100 c.c., port map is the same and engine data is the same.

Bore: 54 m.m.
Stroke: 47 m.m.
Con Rod: 83 m.m.

This is the data I got last time for the cylinder map you can see now:

Exhaust Port STARTS opening at 80° (going form TDC)

Transfer Ports STARTS opening at 105°

Transfer Ports FINISH opening at 135°

Exhaust Port FINISH opening at 145°

Exhaust Port STARTS closing at 140°

Transfer Ports START closing at 135°

Transfer Ports FINISH closing at 100°

Exhaust Port FINISH closing at 75°

Is there something else you need to know??

Thanks again for your kind help!

 

[Big B NRG]

Ah oke, thx for the info. You prefere reliabilty over power I guess?
For the street use you want a torque scooter and not a screaming engine.

When I get home I will do some calculations

 

[Mexicano]

Ah oke, thx for the info. You prefere reliabilty over power I guess?
For the street use you want a torque scooter and not a screaming engine.

When I get home I will do some calculations

Big B:
jejejejeje...I know I can't have ALL..but I want the best of both worlds, I use my scooter at streets for 2 hour rides, but not every day, I want a "street Racer"..now I'm doing 10,000 r.p.m. with no problem, the scoot feels very fast with my 100 kgs. on it, but I'm sure this engine on expert hands like yours could do more... my set up is:

Big Bore 54 m.m. (tuned)
Full Circle Crankshaft, 47 m.m.
SKF Ceramic main bearings
KOSO 30 m.m. carburetor
Custom made manifold with inside ceramic coating
K&N air filter
Yasuni C21 exhaust system (modified for 110 c.c.)
Nology Hot wire
Nology Hot coil
HPI two curve ignition with light coils
Tassinari Vforce3 reed cage
Denso Iridium spark plug
Malossi boost bottle
Tecno-Moto varietor
Polini rollers
Malossi Delta clutch
Malossi clutch bell
Malossi yellow contrast spring
Polini16/49 Primary Gears (1:3.06)
Polini 14/41 Secondary Gears (1:2.93)
Bitubo Z01 rear shock absorber
Doppler race front suspension
Metrakit 220 m.m. front disc brake
Grimeca 2 pot caliper
Spiegler stainless steel braided brake hose
Custom made sub-frame
Koso digital meter