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Discussion Starter · #1 ·
Hey folks. New to the forum here (I do more reading than posting), but not new to riding. Lots of good discussion/info here....great resource. Now down to business.

I’m doing a new motor build and I’d love to get some feedback.

The bike “as-was” before the build:

2005 Thunder Mountain Custom (240 Blackhawk)
Came with 95 inch B motor with SE 203 cams (it’s essentially a 2004 Screamin’ Eagle Deuce motor from the number on the case)
1550 flattops and stock TC heads
Stock ignition module
SE air cleaner
40mm CV carb
Vance & Hines Big Radius pipes (with stock baffles removed and Big City Thunder Thunder Monster power baffles installed)

I rode it until the TMC warranty ran out (1 year)....put about 2,500 miles on it and then tore into it when winter kicked in here in Mile High country. I wanted to get more mid-high range grunt (I’m a fairly aggressive rider.....as uncle Totenkopf can attest) and I wanted to eliminate the 2 weak points in the motor (heads and chain-drive cams). I’m doing most of the basic wrenching myself (dis-assembly and re-assembly) while Otto in Illinois is doing the headwork, and machining ....plus providing some valuable advice that’s not in the service manual.

What’s changing:

Cams – pulled the SE 203s (anyone want them?.....let me know, I’ll make you a deal) and, after much discussion re: my riding style and desired outcome, ended up installing S&S 570g’s. Also installed the Baisley LMR-002 oil pressure spring. Will install SE adjustable pushrods when the top-end comes back from Otto.

Heads – Otto is doing his Pro-Street job on the heads (porting, bigger 1.900” intake/1.630” exhaust valves, guides, springs, polishing exhaust ports, etc....plus much more that I probably can’t do justice in this post).

Compression – Otto is a big fan of bumping up compression by decking the heads rather than using hi CR domed pistons (better A/F mix, squish, burn, etc), so he’s machining them to 10.3 to 1. We had much discussion about the right CR for riding up here at 5,200 feet of altitude.....and decided on 10.3 to 1 to put it on the edge at sea-level (where I rarely ride) but right on at mile high. I also shipped Otto my pistons & cylinders (just in case he needs to modify the valve pockets on the pistons for valve clearance issues....and just in case the jugs need to be honed). More for prevention on future shipments from CO to IL....

Other stuff: Installed Crane HI4-TC ignition module, and Otto’s re-working the CV carb and intake manifold to make it flow better....can’t do it justice on what mods he’s making.

I’ve probably left out some important details, but that’s the jist of it.

So.....I’m waiting on the heads, pistons, jugs, and carb to come back from Otto and I’ll finish re-assembly in the upcoming weeks. I’m pretty excited to see/feel the difference these mods will make. With me on the bike topping out at about 700 lbs, it should be a real stump-puller.

I’d love to hear feedback, suggestions, advice......

Thanks and keep the rubber side down-
 

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Sounds like a great build. Most definately will have to alter the valve pockets.
Just a fyi, S&S recommends a maximum of 10.0:1 cr for the .570's, but 10.3 should be fine.
 

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Discussion Starter · #3 ·
Compressor#v-

Yep.....we know about the CR advertised by S&S.....I brought that up to Otto when we started this whole thing.

He's confident that the added .3 will be fine up here at 5,200 ft of altitude in Denver. It might get a little detonation when I drive down to sea level, which is about 1 time every 2 years.
 

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Discussion Starter · #5 ·
Thanks for the advice wkohn, but it's a bit late for that. Already pulled the trigger on the build.

Maybe next time.
 

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Fire in the hole!

Well, Thunder90's new motor fired right up! I got to hear it over the phone and I must say, it sounded awesome with the compression and cams he's running! He and Otto did a great job!

Can't wait to see the numbers on this one! even though it will be tuned at 5200'+ elevation. It should be real healthy.
 

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Discussion Starter · #7 ·
Now that's what a motor is supposed to sound like!

Build is finally done, and she fired on the first try.

Now the break-in miles start (while trying with all my might not to jump on it). Otto's work is first class! Anyone looking to have quality headwork done, I'd highly recommend him.

As Totenkopf mentioned, the motor sounds real healthy and it's not even tuned properly yet. The ignition timing settings are real conservative and will be until I get some miles on it and get it to the dyno.

Aside from some fairly extensive grinding on the lower rocker covers to get clearance for the valve springs, this build went pretty much according to plan (except for a minor oil leak at the upper pushrod cover O-ring.....operator error).

Will post dyno sheet when done.
 

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Dyno sheet........

Thunder90,
When do you think you'll have enough miles to get over to the dyno at Ron's place? March sometime? I know it is somewhat weather dependent but I can't wait to see what the outcome is! I'm no dyno expert but I would think that once it's optimized at your elevation that the software could take your actual pulls and convert them to sea level as an estimate of what it would do as a flatlander motor. ;)

By the way, Rick is going to have to pedal REAL hard to keep up with you now!
 

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Discussion Starter · #9 ·
Weather isn't cooperating very well here in CO.....so I don't know. If I can get out on Sat & Sun for a few hours, I'll get a couple hundred on it.

I'm probably not going to take it back to Ron's place (for reasons you already know). I need to find another tuner in Denver.

Rick's Valkyrie will keep up with me on the top end, but has no chance from stoplight to stoplight. Forget about his Evo powered Heritage......that's an unfair fight!
 

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Discussion Starter · #10 ·
First Dyno Results - post build

Well, the weather finally cooperated and I got the break in miles on the motor and dropped it off to the dyno-tuner a few days ago. I ended up using Dave Beard at Rocky Mountain H-D due to some of the recommendations on this forum, as well as some local feedback.

The details of the build are in the first post in this thread, and in the Avatar below. Some details that aren’t in the build specs are:

Pro-street heads by Otto – bead blasted intake ports/polished exhaust ports/1.900” intake valves/1.630” exhaust valves/valve springs/etc....too much to list.

Crane HI-4TC ignition module set at 2 initial/6 advance
Carb – 52 slow speed jet/195 main

Dave called me this morning and gave me the highlights over the phone (I will pick up the dyno sheets later today and will post them here). I don’t yet know some of the details like AFR, torque/hp throughout the RPM range, etc.

The dyno run was pretty standard (4th gear, 5% load on the drum, etc)

Highlights:

Peak TQ: 100.1 ft-lbs
Peak HP: 95.7 hp

At first, I was a bit disappointed until Dave told me that these numbers are UNCORRECTED for altitude. Then I started to get a bit more excited. Keep in mind, I’m at 5,280 ft above sea level here in Denver......so if the theory of 3% loss for every 1,000 ft above sea level is true, then this is a 110+ torque motor down at sea level.

A few other limiting factors:

1) Pipes: I run V&H Big Radius pipes on this bike with BCT Thundermonster baffles installed. I knew before I did this build that I was leaving power on the table due to the pipes (Big Radius pipes are not known for power), but I hate the look and sound of most 2-1 pipes that are known to make big power. It’s a sacrifice I’m willing to make.

2) Carb – still running a 40mm CV, although Otto modified it a bit for me, and we added a 44mm intake manifold during the build.....so I can add a 44mm CV or a Mikuni 42mm at a later date if I want. That will probably be the next step.

All that said, I’d love some feedback on the numbers (given the altitude correction, pipes, and carb). There might be more left in the motor, but I’m pretty pleased with the first go on the dyno after the build was complete.

Will post dyno sheets tomorrow so you can see the both curves across the RPM range.

Feedback?
 

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Doofaluumpa
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Congrats on the build. Should be fun to ride.
 

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Pretty close to the build I just had done.
I have the cast SE 10.25 pistons,Baisley heads,S&S 570g cams and a Mikuni HSR42 with Rinehart true duals.
The first dyno pull with stock headers and my old tatered Hooker slip ons (105Kmiles) netted 105hp & 112 tq.
With the new Rineharts I actually lost a little tq but I'm still happy at 105/109.
 

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Discussion Starter · #15 ·
Dyno numbers - finally

Alright.....I can't find a scanner to save my life......so I had to convert the numbers into a spreadsheet and graph it myself.

Anyhow, here's the key info that wasn't on the printout:

Dyno altitude: 5,708 ft (Littleton, CO)
Temp at time of tune: approx 50*
Humidity: approx 20%
4th gear pull, 5% load on drum

Dyno was a Superflow dyno (not a DJ 250i)......

The torque numbers dip a little at 2,800 which I expected due to the Big Radius pipes, and he shut it off at 5,400 ("for safety reasons", he said) so I don't know if HP is topped out or not.

These are raw numbers at over a mile high.......can't help but wonder what it would do at sea level.
 
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