Bimotion porting program

[adet16v]

Anyone ever hear of this?

I aquired an MS DOS version of this program (freeware)

I haven't gotten into it much really as I have finals this week but Im going to try to put something together to experiment with a yami 650 motor I have...

It basically allows you to input all the specs of your motor and than set a hp target at a specific RPM and it calculates port areas and port timing etc. to make that power.

There is a much nicer/newer version available for purchase here (several hundred dollars)
http://www.bimotion.se/

If anyone wants to see the MS DOS version I have shoot me a pm and I will email you a zip file along with a PDF of the User Manual

If anyone has any experience with this program I would be interested to hear your thoughts. :biggthumpup:

EDIT: Here are 2 screenshots. I was just playing around, not sure how accurate some of the data I input was... but gives you an idea.

 

[Mouthfulloflake]

looks cool!

 

[RideItLikeYouStoleIt]

I definitely wouldnt trust that thing. MS DOS is like practically older than jetskis. :biggthumpup: Im going to be messing with a kawi 650 motor as well I think im just going to go with the flow and port where i think it would be without going crazy.

 

[Matt_E]

So you wouldn't trust it because it is DOS software?

Let us know how flow and port time area calculations have changed since DOS days.

 

[adet16v]

So you wouldn't trust it because it is DOS software?

Let us know how flow and port time area calculations have changed since DOS days.

x2

All the program is doing is saving you tedious calculations in a very messy excell spreadsheet.


To the guys that pm'ed, I will try to get an email out this evening. I have spent some time compiling some useful specifications of the 61x cylinder since thats probably what you all have!

 

[adet16v]

OK I have been messing with this some today.

I have come up with the following:

Stock 61x cylinder

Bore 81mm
Stroke 68 mm
Rod length 125 mm

Exhaust port opens at 91.5 ATDC, 39.6 mm from top of barrel Duration of 177 degrees
Exhaust port width 48 mm

Main transfer width 31.75 mm
5th transfer width 25.4 mm
Bust transfer width 21 mm

ALL transfer ports 55.4 mm from top of barrel (havent figured that out in degrees yet)
Combustion chamber volume 32 cc
Effective Cylinder volume 204.16 cc

I have verified some of these numbers from a 61x cyl I have sitting around, but not all. Feel free to correct if you see something wrong.

One problem I ran into, is that the exhaust port height displayed by the program is 28.4 mm but I measured my cyl and it is about 31 mm.... So I dunno if someone messed with my cyl or what, maybe someone could check out one of their x cylinders for me...

First pic This is a comparison of different exhaust port width with the associated Time Area for each width at the given RPM (6000). The target TA refers to the HP target that I set for this specific RPM (75 hp) This is currently very dumbed down... I have not accounted for the shape of the port yet.

Second pic This is a comparison of the TA that will be achieved with the exhaust port width that I chose in the previous step at various RPM

Third pic This is a summary of some of the specs associated with the exhaust port described above... again, very dumbed down. I have not done anything with the shape of the port. Notice my width of 57mm is 70% of the bore, which is generally considered the upper limit I believe.

I still cant figure out why its showing a 28.4 mm port height, when my port height on my x cyl is 31mm :banghead:

 

[Matt_E]

Why do you have a cylinder volume of 204.16cc?

Also, is the port height the actual open height of the port? Or the distance from deck to roof of port?

 

[#ZERO]

:thinking: Interesting

 

[adet16v]

Why do you have a cylinder volume of 204.16cc?

Also, is the port height the actual open height of the port? Or the distance from deck to roof of port?

That should be effective cylinder volume, sorry. That would be the volume of the cylinder when the piston closes the exhaust port and begins compression. (area of piston x depth of 39.6mm)

The port height is the height of the opening of the exhaust port which is about 31mm on my cylinder but shows up as 28.4 in the output.

The 39.6 mm is from the deck to the roof of the port, which I confirmed on my cylinder.

 

[Matt_E]

28.4mm may very well be the effective port height

Angles play into this, so it is likely the issue.

 

[adet16v]

28.4mm may very well be the effective port height

Angles play into this, so it is likely the issue.

Effective port height meaning the piston may not actually drop the full 31 mm of the port height... that could be it.

EDIT: anyone have a partially dissasembled motor that can verify this? this meaning at BDC the top of the piston is not completely flush with the bottom of the exhaust port.

EDIT: Guys that pm'ed me email addresses @gmail.com, the email I sent you bounced back. I think the zip file is an illegal attachment. Let me know if you can configure your accounts to allow it or another way to send it... sorry.

 

[Matt_E]

BDC is below the floor of the exhaust port, or even...Definitely not above.

 

[tom21]

MMMMMM maybe Matt. I just pulled the head off an 03 SJ tonite and I would have to go and look again to be sure but it did catch my eye cause it seemed like it didn't get low enough to get even.

 

[adet16v]

BDC is below the floor of the exhaust port, or even...Definitely not above.

thats what I remembered too... so the question is still unanswered

 

[tom21]

if you can stand to wait I will check tomorrow for ya.

 

[adet16v]

if you can stand to wait I will check tomorrow for ya.

That would be great.

 

[tom21]

2.683" from the top of the cylinder to the top of the piston measured in the center of the exhaust port. looking from the side the port is ramped upand the piston is right inline with that angle however the sleeve does not continue to ramp it levels out.

hope that makes sense.

 

[adet16v]

2.683" from the top of the cylinder to the top of the piston measured in the center of the exhaust port. looking from the side the port is ramped upand the piston is right inline with that angle however the sleeve does not continue to ramp it levels out.

hope that makes sense.

That does make sense, I think the measurement of the port height is taken from the top (crown) of the piston. Therefore, the outer edge of the piston sits perfectly flush with the floor of the port but the crown of the piston would be slightly higher in the middle accounting for the measurement of 28.4 mm as the port height in the program. Thanks :biggthumpup:

 

[tom21]

that is not exactly what I saw. what I saw and it may vary from motor to motor, was that the piston edge was up from the sleeve not even and the crown was obviously higher still. plus I measured it with a dial caliper so it may not be perfectly acurate

 

[adet16v]

The piston edge at dead bottom was not at or below the bottom of the exhaust port??

What about the transfers?

EDIT: With the piston at TDC, place a straightedge over the cylinder and tell me if the crown of the piston is touching the straight edge, and if not, how far below the straight edge it is.