A question for the hot rod gurus
Road Master
Joined: Feb 2014
Posts: 913
Likes: 5
From: indiana
when I started building my chopper I wanted the same thing fast revs. and your on the right track but you may have skipped a few things in the motor the biggest thing is the valve train you want everything to be as light as possible I used small stem valves and titanium collars cut the weight in half strong springs are a must and the cam needs very aggressive ramps you want those valves to open and close as fast as possible and you need lots of compression
you may have seen this it doesn't do it justice crappy video
you may have seen this it doesn't do it justice crappy video
Seasoned HDF Member
Joined: Nov 2006
Posts: 12,878
Likes: 5,449
From: la la land jerzey
my 89 has a sprocket and no compensator hanging on it - it is available in 24 tooth and 25 tooth - on choppy bumps my motor is and can be jerky But it is tweaked in a big way for power - yours could be different - every harley motor made before elect start 1965 Big Twins did not have a compensator
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Road Captain
Joined: Aug 2009
Posts: 691
Likes: 4
From: H-TOWN TEXAS
You are onto something, 1 HP gain for every 3 LB of rotating mass is the theory that was used in Unlimited Mudracing. My buddy runs the BDL belt system to remove rotating mass but affected his gear ratio so nothing gained and the cost of the belt drive is expensive.
The twinkies have the direct drive primary pulley but don't see them for a Evo. The best bang I did for accelleration with the smaller stroker was dropping the final gear ratio
The twinkies have the direct drive primary pulley but don't see them for a Evo. The best bang I did for accelleration with the smaller stroker was dropping the final gear ratio
I also started this thread to change the norm up a little. Not that I'm running a huge cubic inch set up, but most of the evo section performance topics are nothing more then a 80" with EV27. Not saying there isn't a wealth of knowledge here either because there is.
Outstanding HDF Member
Joined: Jul 2013
Posts: 2,874
Likes: 36
From: Houston, TX
I know the cost vs. gain isn't going to weigh out. As for the belt drive I'm not looking in that department I was more looking for chain drive options. When I still had an 80" in this bike I ran a direct drive motor sprocket, but didn't care for the added vibes. I already run a pretty tall ratio, but this motor is built to work within the 25-6500 so the taller ratio works really well for me.
I also started this thread to change the norm up a little. Not that I'm running a huge cubic inch set up, but most of the evo section performance topics are nothing more then a 80" with EV27. Not saying there isn't a wealth of knowledge here either because there is.
I also started this thread to change the norm up a little. Not that I'm running a huge cubic inch set up, but most of the evo section performance topics are nothing more then a 80" with EV27. Not saying there isn't a wealth of knowledge here either because there is.
Thread Starter
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Road Captain
Joined: Aug 2009
Posts: 691
Likes: 4
From: H-TOWN TEXAS
when I started building my chopper I wanted the same thing fast revs. and your on the right track but you may have skipped a few things in the motor the biggest thing is the valve train you want everything to be as light as possible I used small stem valves and titanium collars cut the weight in half strong springs are a must and the cam needs very aggressive ramps you want those valves to open and close as fast as possible and you need lots of compression
you may have seen this it doesn't do it justice crappy video
first fire 80" evo wood W9 10.97:1 compression - YouTube
you may have seen this it doesn't do it justice crappy video
first fire 80" evo wood W9 10.97:1 compression - YouTube
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Joe Kucinski
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,081
Likes: 2,159
From: Ohio
89" is a great engine, ran one for 6 years and so versitile, can flog it against the rev limiter or run long distance. The 89" loses piston weight because a flat top can hit 10-1 with a .030 head gasket with some head mods, flat tops have better flame travel and efficient, the extra stroke can pull down low which is another plus.
Wish I had more ideas on shaving weight but just not alot of options, higher horsepower HD engines always seem to draw to parts that are beefier and not break. A obvious boat anchor was the heavy 32 tooth trans pulley, I spent $180 on a chrome moly pulley just in thought of your rotating mass theory.
Dark Horse does the flywheel lightening, knife edging plus rod work just like hardcore automotive racing engines but another subject. Please keep us posted as this is pioneering on here
Wish I had more ideas on shaving weight but just not alot of options, higher horsepower HD engines always seem to draw to parts that are beefier and not break. A obvious boat anchor was the heavy 32 tooth trans pulley, I spent $180 on a chrome moly pulley just in thought of your rotating mass theory.
Dark Horse does the flywheel lightening, knife edging plus rod work just like hardcore automotive racing engines but another subject. Please keep us posted as this is pioneering on here
Seasoned HDF Member
Joined: Nov 2006
Posts: 12,878
Likes: 5,449
From: la la land jerzey
.190 wall tool steel wrist pins are 130 grams each you could install .087 wall casidiam coated titanium wrist pins ( BTW a dozen dont weigh what a tool steel one weighs ) -- use flat top w/ extra milled areas on cast pistons - casidiam coated titanium connecting rods leave out the brass bushing its heavy - carefull with the knife edge flywheels if you do that you need to oil spray the piston skirts - and use .043 stainless rings with Nikasil coated alloy cylinders, and windage scrape the wheels with a 4 stage oil pump - external oil lines no drainage to the block ( block oil is like running in water up to your knees - externals keep the oil at your ankles ) cam / pinion gear lightning holes - gun drilled cam core - titanium valves, retainers top and bottom - conical single flat wire valve springs - beryllium valve seats - this is a start if you really want it to challenge the dynos speed clock in making the speed of torque in one gear ( 4 th gear )