100" alky Sportster

[55chevr]

Forward facing air intake scoops are tricky with carbureted motorcycles.   I tried a number of configurations and found that all produced a lean condition.  Bigger jets did not improve the condition.  It will take a lot of R & D to get that correct.

Joe

[RansomT]

I've tuned a many bike on my chassis dyno and the only twins I've seen in the 200 HP range has been the Ducatis.  And their peak HP is at or above 11,000 RPM.  Very recently, I tuned a extensively built S&S powered drag bike and it was in the 160 HP range. (can't remember the size, but IIRC is was bigger than 100" (1640 cc).  To get toward that 200 HP, you will have to add something to the ethanol. 

BTW, I'm a big fan of E98 ....

[delcrossv]

Forward facing air intake scoops are tricky with carbureted motorcycles.   I tried a number of configurations and found that all produced a lean condition.  Bigger jets did not improve the condition.  It will take a lot of R & D to get that correct.

Joe

That's what I figured. I have some thoughts on why that occurs but I'll need to test those.

[delcrossv]

....  Very recently, I tuned a extensively built S&S powered drag bike and it was in the 160 HP range. (can't remember the size, but IIRC is was bigger than 100" (1640 cc).  To get toward that 200 HP, you will have to add something to the ethanol. 

BTW, I'm a big fan of E98 ....

Was that gas? Because that's what a number of HD drag bikes make on gas. Well, we'll see what she does. I think those calculators make a whole bunch of assumptions anyway. 

[RansomT]

Yes that was gas ... C16 due to it's compression.

[delcrossv]

Did bore measurements and it just fits into the 1650cc class. 4.002 with the bore honed. 1649.03cc swept displacement. Phew!!

New pistons: (3.997" nominal)

[Seldom Seen Slim]

1649.03?  Yikes!!  Don't forget to have the engine measured when it's as cold as can be!

[delcrossv]

1649.03?  Yikes!!  Don't forget to have the engine measured when it's as cold as can be!

Amen to that! 

[delcrossv]

Had a nice phone conversation with Derek. We'll be running in A class. So 193 mph and change. 

[delcrossv]

Short update:
Custom bearing cage design is complete. Machinist should have those done by 2/15.

Still have to order magneto, wires, trans gears and primary drive parts.

Decided to go with piston coolers, not so much that the pistons will need cooling with E98, but I'm concerned the cylinders might get oil starved at the piston speeds we'll be operating at.

Also, the rollers tend to slide around the crankpin oil holes at high rpm as there's too much oil there. The sliding makes for flat spots on the rollers and premature failure. To alleviate that, I'm machining slots fore and aft of the oil holes- about 1/8 long and .010 deep to encourage the oil to spread out away from the feed holes. That's a FAFO experiment. Seems to make sense though. We'll see how that works out.

[delcrossv]

Short update:

Just got off the phone with Morris Magneto. Type F mag, custom advance cams, remote kill, and this will be the first one they've made with an electronic tachometer send. Should arrive in 4-6 weeks

Here's the partially machined cylinders. May drill the fins as they're pretty heavy at 18 lbs. Each. 

[Stainless1]

Weight is your friend at Bonneville....

[delcrossv]

Weight is your friend at Bonneville....

Even high up on the frame? Wouldn't that make it harder to get out of a wobble?

[delcrossv]

Magneto ordered. 26 degrees advance is what it'll provide, but I do have a choice as to where full advance kicks in.  Anyone have degrees of spark advance numbers for alcohol fuels? Just need something to start with.

[Stainless1]

Weight is your friend at Bonneville....

Even high up on the frame? Wouldn't that make it harder to get out of a wobble?

 Balance the weight on the wheels within 5%.  Most bikes that wobble have added a lot of weight to the rear wheel and end up with a light front.  This bike had about 100lbs on the swingarm, 40 in the middle and 30 in the front to make it balance with the rider on.  That silver on the top front is lead.  You are not cornering, you are going straight on a low traction surface. This bike was mid 180s and ran arrow straight...