MOPED ARMY

I didn't widened any of my ports, I raised the exhaust by 3mm and lowered the intake port by 2.5mm. I was really conservative on it. I just wanted a safely ride able engine. well, my timing was off after installing the thin head gasket. ..about 0.5mm. just adjust it properly.... pix? I can scan pix of my portmaps? but that have to wait till tomorrow....I don't have them right here.

I don't want to sound like "Bob Bummer", but my Huret speedo is about 4-5mph off. Mine errs on the slower side (says 30 when I'm going 34-35). So maybe your going faster or slower than you think.

-Curly

Hey Bob Bummer, it doesnt matter, before Mike was getting 22-23 mph now he is getting 30-35mph range according to the same Hurret speedo, obvious a good improvement.

Mike we MUST compare notes some time soon!

Thanks for the kudos everyone....

Well...my Hurret is off too....about 2 mph on the fast side. But I have a performance gain of about 20- 25%, just by simple port work. Powerband is all around improved. But she still sucks at hills and against the wind...I guess it's time for a smaller front sprocket.

I use metric drill bits which are incremented in .5 mm as a go-nogo gauge, till I have the desired depth. It's really not hard to do, if you take your time and patience. Try to err of the side of caution. I am running the original stubby intake with a 13mm ID. Didn't use any sealant on my gaskets, just torque it to proper specs.

@warisesi....sounds good to me...aehm, I don't have any notes...lol. do you? :)

port work on my faster cylinder is on the way......I keep you posted

Mike

"my timing was off after installing the thin head gasket. ..about 0.5mm. just adjust it properly" are you saying it was the gasket change alone that messed the timing a bit? did the height changes of the ports not make a difference?

Wari,

I will get my degree wheel out and measure the angles on the "slow' cylinder, as soon as I have my 1970 50V faster one assembled and installed. Thanks for the info on the stock cylinder.

Steve

think about it for just a moment.................................................

you adjust the timing to about 1.5-2 mm BTDC. If you put in a thinner head gasket, that will effect your timing. you'll figure it out, if you ever practical set the timing before!!!!

.......in the meantime here are some port map sketches, for every bodies enjoyment......

Happy porting

Mike

Thanx Pylo, I need that in my life.....

crackstar

Awesome!

There's so much good information being exchanged here.

ok,

I did put the "faster" ported engine back on. I raised the exhaust port and lowered the intake port by 3mm. I had no difference performane wise. She exactly runs the same. Kind of dissapointed, but I want to keep you all updated, even if it didn't turn out as expected for me.

...and of course I deburred everything....nice tip on the riffler files, wari. They are on my shopping list on my next trip to Ottawa.

Back to the drawing board and doing some tinkering.......

Mike

What is the event timing now on the slow engine? Think you need to raise the transfers a bit, also back off the timing because stock is a bit too advanced on the Mobys.

ALSO sorry before i said duration of the event into intake 96 degrees, transfer 130 degrees, exhaust 134 degrees but it should be duration of the event into intake 96 degrees, transfer 100 degrees exhaust 134 degrees. I accidentally used the timing position of 130 as the duration - silly moi!

Get on the Princee mailing list so you can order by Canada Post, save the Ottawa trip fuel for a month of mopedding!

I like that Idea.

I'm going to start porting one of those 62cc malossi kits, and I'll also try that trick on the bottom end.

Nick was full of great ideas when I lived in Kalamazoo.

Nope I didn't do any matching on the crankcase just yet....but I think I have to go in the direction of a performance carb. Curious to know, how the 63cc Malossi kits are perfomance wise. Better pick up? higher top end speed? approx how much of a percentage gain compared to stock?

wari, I dunno where you came up with your numbers, but they look a bit off to me.....

math is fun, but doing it practical is better....didn't have time to check the timing events yet. I just discovered a have a serious issue on my faster engine (like a bent crankshaft on the variator side). Now how did you came up with these numbers. I usually use this procedure with a degreewheel

Exhaust port timing event

turn the flywheel, till the piston just opens the exhaust port on the descending stroke. Set you wheel to zero. Turn the flywheel in the direction of engine rotation till it just completly closes the exhaust port. Take the reading on the degreewheel.

Intake port timing event

turn the flywheel until the piston just about opens the intake port. Set your wheel to zero. Now turn the flywheel in the direction of engine rotation, passes TDC and just closes the intake with the skirt. Take the reading on the degreewheel.

Tranfer port timing event:

same as exhaust timing.....

puddles of gas.....hehe...I guess I have a rocket now and can travel to Mars on my next launch date.....

Say hi to fifty

Mike