100" alky Sportster

[mc2032]

This one tips the scales right at 800 lbs and a 50/50 weight split with the rider suited/saddled up.  Also full suspension front and rear (and used it all with past and current conditions).

[Speed Limit 1000]

Ross, nice shot of you sitting up to slow down after you 174mph run

[delcrossv]

Awesome! Thanks, gents. Undrilled it is then. ( don't think I'll need the ingot with this one)

[delcrossv]

Rods and cages are complete. pics forthcoming.

[tallguy]

Regarding 8,000 rpm . . .

Many years ago, in an article about H-D dragsters, I read that a big unblown v-twin could not breathe well enough to achieve that engine speed.  I wish you good luck with this project.

[mc2032]

Granted this is a small(er) Harley motor and is aided by a turbo, but it spins up pretty well (past 8000) in the lower gears.  We were geared a bit too tall and needed more room to stretch out (short course only qualified) and hopefully get back to the 8k range.  p.s. stock bottom end and rods, ebay pistons and borrowed heads.

[delcrossv]

Regarding 8,000 rpm . . .

Many years ago, in an article about H-D dragsters, I read that a big unblown v-twin could not breathe well enough to achieve that engine speed.  I wish you good luck with this project.

Thanks!

On nitromethane they can do 9k (for 10 seconds or so) but the stoich is like 1:1. That's one reason why we went with the M8 heads. Flow is like 375 CFM at 28", and that's more than I can stuff in the cylinders at 8k. The other is reduced valve inertia and corresponding spring pressure. The spring pressure on those drag engines is so high that with the plugs out you can't turn them over without a 4' breaker bar.   

[delcrossv]

Here they are, Rods and big end cages

[delcrossv]

Granted this is a small(er) Harley motor and is aided by a turbo, but it spins up pretty well (past 8000) in the lower gears.  We were geared a bit too tall and needed more room to stretch out (short course only qualified) and hopefully get back to the 8k range.  p.s. stock bottom end and rods, ebay pistons and borrowed heads.

Cool! Who's heads?

[delcrossv]

On another note, do you folks run an open velocity stack or is there enough stuff in the air that you'd recommend some kind of air filter?

[mc2032]

Coasted thru the timing traps after everything went quiet at 150 mph to find this (see attached).  Well, being on an every expense spared budget, I reached out and borrowed a set of heads, stockers, from a "no kill shelter" for used motorcycle parts. You can still smell the questionable/criminal past.  Nothing special, just cheap (free) and available.
Edit 1).  Cheap (free) and available sounds like one of my ex's.  She said she was "fast".  I thought "racer".  Nope, she just drank alot and put out on the first date.
Edit 2).  Trying to make old parts go fast is about as hard as making fast parts get old so I always opt for the least expensive parts.  YMMV.

[delcrossv]

Coasted thru the timing traps after everything went quiet at 150 mph to find this (see attached).  Well, being on an every expense spared budget, I reached out and borrowed a set of heads, stockers, from a "no kill shelter" for used motorcycle parts. You can still smell the questionable/criminal past.  Nothing special, just cheap (free) and available.

EEK! 

[delcrossv]

Trying to make old parts go fast is about as hard as making fast parts get old

LOL. That a great line!

[Rex Schimmer]

delcrossv,
Back in 2013 I was "smart" enough to buy a new copy of Kevin Cameron's book
"Classic Motorcycle Race Engines" fantastic book! and one that I find myself reading again and again which now is one of those occasions (I think it is the 4th or 5th time) and I came across some information of the causes of roller bearing "skidding" which may be of interest to you. According to Kevin the instantaneous rpm of a roller rod bearing changes by 25% twice each revolution of the crank revolution and it is the acceleration, +and-, of the bearing that causes the skidding. The major way of increasing the rpm that this occurs at is to minimize the inertia of the rollers and cage. I am sure that you have made every effort to minimize the weight of your bearings but 8000 rpm with a 4 inch stroke may be a challenge. Kevin also does an analysis of the Harley XR750 engine and that they were raced at 9000-9500 rpm but they had a 3 inch stroke also and they made 110+ HP also.
Keep up the great work and keep the updates coming.

Rex

[delcrossv]

delcrossv,
Back in 2013 I was "smart" enough to buy a new copy of Kevin Cameron's book
"Classic Motorcycle Race Engines" fantastic book! and one that I find myself reading again and again which now is one of those occasions (I think it is the 4th or 5th time) and I came across some information of the causes of roller bearing "skidding" which may be of interest to you. According to Kevin the instantaneous rpm of a roller rod bearing changes by 25% twice each revolution of the crank revolution and it is the acceleration, +and-, of the bearing that causes the skidding. The major way of increasing the rpm that this occurs at is to minimize the inertia of the rollers and cage. I am sure that you have made every effort to minimize the weight of your bearings but 8000 rpm with a 4 inch stroke may be a challenge. Kevin also does an analysis of the Harley XR750 engine and that they were raced at 9000-9500 rpm but they had a 3 inch stroke also and they made 110+ HP also.
Keep up the great work and keep the updates coming.

Rex

Thanks Rex, very interesting and does make sense. We went with Al cages, instead of bronze and a larger crankpin. Unless we tried something exotic, we're stuck with steel rollers. If it becomes an issue, I do recall Carrillo did make plain big end rods for someone, that may be something to try down the road.
Pretty bizarre: