Dear Diary: Fabrizi 50mm bore portmap/Port timings

[tuserv]

180 degrees? I don't understand. To me that's all the way down... Can you explain? Following with interest.

port duration of 180 degrees means exhaust opens at 90 deg before bottom dead center and closes 90 deg after bottom dead center, 90 + 90 = 180 deg.

[DirtyE]

Well said. And so when I move to 185 you can add 2.5 degrees to each? Right? Bells book was written so long ago his reference chart for port timing is way off when he compares it to rpm. Bigbnrg blog has a much better graph. Bell has port timings into the 200 degree range.

[DirtyE]

I should've just randomly thrown this together the first time, but by raising my exhaust 1mm my timing goes to 186 for the exhaust. Ill measure out 1mm and cut as straight as I can. Ill only cut maybe .8 of the mm and use the other .2 for chamfering. These are rough numbers cuz my hand isnt skilled enough to cut in tenths of millimeters, but just so you understand, im not cutting the full mm.
as you can see this will increase my blowdown, narrowing my powerband but increasing power output in the powerband.
now, bram chose my timings for me according to the c16 specifications. I will have to see rpm he is identifying with the c16. i think i can do that just by looking at these adjusted timings.

[DirtyE]

What a challenge. ~1mm raised. Mostly even. Measures 23mm to the top of the barrel so im in that 186 degree area. This is a pic of 1 side raised roughly 1mm..

[DirtyE]

I cut back the skirt of the cylinder on the intake as well. Just thought I'd share. My before picture sucks. But when I trimmed back the walls of the intake track there was cylinder skirt blocking flow in the front and rear. This area is the only place I skid my dremel across the nikasil. Hopefully a skid on the inside of the cylinder skirt isnt too big a deal.

[Wheelman-111]

Greetings:

Curse you DirtyE! Now I'll be up all night thinking I have to do the same thing...
Thanks for sharing.

[Pineapplegti]

Very nice

[DirtyE]

Greetings:

Curse you DirtyE! Now I'll be up all night thinking Ive to do the same thing...
Thanks for sharing.

Hey! I see your in texas. Id just keep your bike running well! up here in michigan we have these months of snow and ice. It leads to all kinds of problems.... OCD, ADHD, alcoholism. Cabin fever is a b****. I used to drink a lot but I quit that and its led to other issues where I must keep busy. I think I have become addicted to scooters again. Ive built motors before, but there aren't any previous motors where I've got the feeling that I understand what I am doing so well, especially in regards to the port timings and how exhaust, transfers and blowdown relate to the powerband. This is my third time flowing cases. Ive flowed mina and piaggio each once. Ive matched transfers and blueprint gasket matched cylinder to cases before as well with most every cylinder since the first couple maybe.

I am on a budget for this build so I want to do everything right. im really excited for it. Im excited to get one of graphite9's c16 pipes to put on it. I bought my elite for $100. If I can keep the total build cost under $1k I'd be really impressed, but that would leave out a few trick goodies like cdi and tranny updates. I dont want to sacrifice the performance of this scooter for budget hehe.

On a side note, hopefully were all learning something here! That blog I posted on page 2 is right on the spot.

[paulpauly7]

stock honda cdi is the best unless you buy the malossi .Dont buy any other "racing cdi's" from ebay they are crap .

[DirtyE]

More pics. Just need to bevel and polish. I give a lot of props to malossi. I was over at Whiteys house the other night, and the malossi casting is by far superior to that of fabrizi. This is my first real porting job where I am setting the timing. I'm glad my "advisor" suggested that I leave the transfers alone.

[DirtyE]

Clues at the scene of the crime. Now I must leave this behind for a week of sun bathing and swimming in the Carribean.

[DirtyE]

Ill come right and tell you its bigbnrg. I met him back in the day on scootertuning.net. when josh was starting up scooterinvasion I was thrilled to have such a collection of tuners there, I invited him to join the forum. For a while that forum had a bunch of top notch tuners from around the globe posting on it. Tiba or overrev put quite a bit of info up there too. Im 35, been screwing with scooters on and off for about 10 years now and always learn something new.

I have mixed feelings about fabrizi. They are known to be high end racing, but they leave something to be desired. When polini or malossi put out a racing cylinder like thr evo or 7T they just come looking nicer than the fabrizi. Its like top performances, great baseline, but you have to work a little to make it clean. Bottom line for me was the extra 10cc, the aluminum cylinder with bridged exhaust, and the single ring piston design.

[DirtyE]

Btw, I showed my wife these last two pics to let her know what I've been doing in the basement. She says, "oh you made it shiny?". No hunny, I changed the shape.

[kauaianman]

More pics. Just need to bevel and polish. I give a lot of props to malossi. I was over at Whiteys house the other night, and the malossi casting is by far superior to that of fabrizi. This is my first real porting job where I am setting the timing. I'm glad my "advisor" suggested that I leave the transfers alone.

did you remove 1mm from exhaust per the computer program or just advise?

wondering what that porting program says about making more power at the higher rev range. i'm assuming Fabrizi can make power at 11k right out of the box. interested to see what that programs says about making more power with that cylinder.

nice port job.

[DirtyE]

I did it per the spreadsheet and advice. I put numbers in the spreadsheet for squish, conrod, stroke...... and it tells me what the timing is. I consulted with bram about finding a good timing for exhaust to match the c16. Earlier in this thread I posted a link to his blog which provides information about exhaust port timing related to rpm, transfer port timing and the corresponding blowdown. It then explains about wide and narrow powerbands and how they relate to how your port timing is setup.