Maybe I'm biased.....

[edfmaniac]

Maybe I'm biased, but after not riding my little custom Skorpion for a while, I broke it out to go to a little vintage bike gathering. I must say, this is the most fun I've ever had on two wheels. I could go on and on, trying to eloquently convey all the emotions that I felt today. But let's just say, the only thing that could have made the ride better would be to have my Marchesini wheels, Mikuni carbs and to have the visual aspects of the bike finished.

If you need more than 60hp on a 310lb motorcycle, you need to be on a track.

[Srinath]

Ok I've got the sneaking feeling I'll be following your footsteps ...

So you have a 1mm over bore ?
You have bigger valves etc etc I dont thing I'll do that, cos I'm inherently a guy that thinks that "I blew up this thing stock, god knows how I'll blow it if it was bumped and pumpped ..." so i'd save $$$

You running high compression ?
I may get high compression 1/2mm piston and call it a day.

Just have to run premium and make sure its rich as Warren Buffet on the jetting right ...

Mikuni ??? smooth bore ?

Cool.
Srinath.

[edfmaniac]

Mine is 102mm(686cc). You'd probably be better off just boring .020 over stock(100.5mm)
Install an 11:1 piston but you'll need to check the squish. My Weisco required an extra base gasket to prevent the piston from slapping the head.
Do a valve job. Mine has +1 stainless only because my valve seats were in bad shape. The machinist (http://www.kenzcycletech.com/) said there are OEM replacements that are good.
Matching/cleaning up the ports aren't that much extra labor if you already have it in the shop. Do it right the first time.
Choose which Megacycle cam you want. The X2 profile is supposed to be more than worthy, and it doesn't require a new HD spring set. The X4, which is in my bike, gives you more middle and top end but requires the upgraded valve springs and checking for valve clearances with clay. You'll have to degree the cam either way if you are building the engine.
Don't forget to address the decomp
New cam chain too
Stock carbs rejetted and have that Tunebike/Off The Road carb kit installed on the CV side. I'm really surprised at how much better these carbs feel after 40 hours of tuning(yes, I'm learning as I go) but I still lose ignition up above the 7500rpm area and am telling myself that these carbs just won't flow enough consistent fuel air/mixture above the 60hp barrier. I'm ordering Mikuni TM34 B-65 carbs soon.
I have Projection Components headers as well but I don't think you need them to get a good running engine.

[Srinath]

What is the original compression on it ?
Could I go to a 10.5 CR without needing that extra base gasket.

I am hoping I dont need to do any head work other than the 3 angle valve and heck I'll polish the ports etc ... The cams and so on I am hoping to avoid.

BTW in the old days we used to be able to do something called "back grinding the cam) - essentially they would take off a few 1000's off the non lobe side - back side of the cam. Maybe it needs longer valve lash screws but you'd effectively have a cam with higher lift for very little $$$ ...

Cool.
Srinath.

[Srinath]

CR = 9.2 courtesy google.
I think 10 - 10.5 will work excellently.

I live in nascar country, about 5 miles from Lowes motor speedway ... has to be some advantage of putting up with that left turn, left turn ... oh no what do I do now ... left turn ... BS.

My car mechanic has had a raptor in his past, and owns a 450 honda ATV and a 350 banshee right now ... I'm having him slice the cross brace out and make it un boltable first. I have a sneaking suspicion he's not gonna stop there and he's gonna yank the head. He's more curious than me how I managed to get no compression running 80 mph where it never let out a peep even seconds before. And how the thing has a nice looking piston top as viewed by the scope. He also builds race cars and what not for his kid to race and he inspects cars at races as a side job. Great engine mechanic no matter what you need to get done. I think polish, 3 angle and decking it will do on the head. 100.5 dia 10.5 compression and I can get by on 93 gas, should all work good.


Cool.
Srinath.

[edfmaniac]

You'll still need to check the squish unless measuring the distance from the pin to the top edge of the piston and comparing that to the stock piston will work.

I'd do the cam even if I had to put an OEM piston in the bike to save money. You'll get a lot more performance from the cam, even the X2.

Don't polish your ports, just match them and clean them up. Today's thinking is that the micro turbulence created by the ridges left behind from sanding, not polishing, makes it easier for the air to flow through and keeps the fuel in an atomized state instead of condensing on to the mirror smooth surface of the old school polished port.

[Srinath]

In a 4 stroke the head is far more important for performance.

What did the X2 cam cost ?

Cool.
Srinath.