Dont worry about your parts getting lost at Darkhorse, he did my crank and no problems. All depends on riding style, but did my crank as the engine was apart and it was IMO, and "insurance policy" that was worth the money spent. Also dont worry about the stroker crank or going over square withthe engine, the HQ 120 runs smooth, and is reliable as all get out, and the 113 will perform the same when built correctly.

 

Hate to say it, but you dont know "smooth" until you have ridden a TC 107"(4.125" x 4" stroke) or 114" (4.250 x 4" stroke)or even a 121"(4.375" x 4") oversquare motor.

I'm sure the engines you mentioned do run really nice, but the setups I mentioned above if done correctly will run significantly smoother and inherently last alot longer as well.

I don't know anything about this "darkhorse" establishment, and that makes me a bit leery as I have done business with many reputable places across the US. One of the absolute BEST places to deal with is Eagle Motor company. http://www.emcv2.com Their case and crank work is known throughout the HP industry as the pinnacle.

 

Are you sure about that?

 

Darkhorse Crankworks is part of Hoban Bros, a top notch shop that does a lot of work for a lot of the major builders represented here on the forum. Can't believe you have never heard of them. Yes, an oversquare engine may be a bit smoother, but it is minimal. Nothing has the grunt down low of a stroker engine, it is inherent in the design.

 

Um, nope never have heard em. Just because its "known" on a forum doesnt mean its a really well known or respected company.

But regardless, let me teach you something(this coming from someone who builds and repairs engines himself).

Oversquare engines are ALOT smoother, as their inherant lack of piston to wall sideloading and RS geometry.

"Grunt" down low has nothing to do with how long a piston "stroke" is. Its all about the cubes in reality. If you really want to get into a debate on this, just be prepared to look foolish.

"Stroking" an engine has no advantage other than a "quick fix" to gain extra engine volume. But it is far from the best way to do it. Stroking should only be done when boring isnt an option anymore. Which is not the case with the TC engine.

 

Super is absolutely correct! If we are talking about a street motor (where drivability and longevity are very important), the big bore option will give more power on it's own compared to a stroke only option. The bore, when taken too far, will reach a point of no return and efficiency will suffer...but that won't happen within the confines of a TC motor. At 4.25", the chamber is very efficient.
A good example of this is the small block mopar. With a standard bore and stroke of 4.040" x 3.310", everything else being equal, the 340 Mopar will flat out spank a Chevy 350 using a bore and stroke of 4" x 3.48". The fact that the Mopar runs a substantially longer rod (6.123" vs 5.7") also helps because the rod ratio just gets better.
Keep in mind that the impact of the difference in the numbers is more than enough for the 340 to overcome the defecit of 10 CI's.

 

I just happen to have an original 70' 340 SIX PACK engine on a lift.

 

Awesome! kids today don't have a clue about those old push-rod v-8's. I ran my 340 with 10.5 - 1 compression (stock) lightened pistons, stock forged crank and rods with stock X heads and a Clay Smith solid (308/.525") with Crane Gold Race rockers. With the stock 3.91 gears it was more than a capable street fighter.

 

SuperAchmed: Are you in the HD engine building business? Have you built a "square" 104" or so v-twin, installed it in a bagger and used it for long distance trips? If so, what's been your experience?

Dalton didn't say Darkhorse was known on the forum. He said that well-regarded Harley performance parts designers/suppliers regularly use and/or recommend darkhorse for crank work, and those guys are well-known on the forum.

The performance marketplace is a pretty good economic model. If a guy could build equivalent or better power without spending the $1000 or so for a good stroker crank, they would be built and in wide use. The fact that they aren't suggests to me that while the square motor may make better hp for racing, it may not be the best choice for bagggers for "normal" use.

My buddy Kevin has been planning a square 104 or so HD using the 4.000" crank and 4.065 HD Bigger Bore cylinders for about a year. Who knows, maybe I'll give it a shot when I get around to doing my motor.

 

for sure, there's more than one way to skin a cat...I was too cheap to pay to darkhorse the crank on my '08 dyna...it's built to 115hp/115tq...I don't lug, holeshot, and always pull in the clutch going over railroad tracks and big bumps...if I had a 4" stroke motor I'd consider doing the 4.065" or 4.125" bore with stock stroke...I guess you mean kevin baxter of hq...they seem to be making several different pistons for that bore

superahcmed, you are taking an unusual approach with your motor, and that's ok...aren't you the guy that's building a 98" revolution nikasil build with 12 to 1 compression and wood #9 cams?...you'll find a lot of folks disagree with these choices, too...but if you like it, that's the important thing!