Oversquare builds : V-Twin Forum: Harley Davidson Forums

oldschool · 12-02-2004, 08:57 AM

Still tryin' to figure out which build to use for my TC88 (03 Wide Glide "bar hopper").

107" all bore, startin' to get my attention, only because all the sport bikes in my history were oversquare motors. Wouldn't mind splitin' the cases to put in better bearings anyway.

Any thoughts on the ups and downs of a 107" all bore motor? Zippers aint that far from me and they have a kit. Kinda expensive though.

Got any other good bar hopper recipies for 107"

Nightboy · 12-02-2004, 10:27 AM

Depends on the money you may want to spend. Overaquare motors tend to favor hp instead of torque though, dont they?Which for sportbikes is a good thing. I decided to go with a 98" build(4" stroke,3 15/16 bore) until S&S comes out with their new 88B cases. Close to square so less vibration while still favoring torque numbers.

**HDWRENCH** · 12-02-2004, 11:40 AM

The 107 kit is very popular and makes good numbers. both tq and hp. Adding the timken is a great idea at that time, plus the 107 use's you stock crank . I use the millenium kits to make the 107 with CP pistons they run great.

Lakes · 12-02-2004, 12:42 PM

oldschool, i like the 107" i think if i went bigger that is what i would use. i have had big inch in the past stokers and all that don't want to go back to a stroker.
the 107 will have more TQ its not the stroke gives you TQ its the size. just can't rev a Harley motor as high as those over square motors you had B4.
another good point on the big bore is your crank case pressure stays same as stock, with strokers it goes up.
good luck.
if you like revs Get a V-Rod and see Falicon

**HDWRENCH** · 12-02-2004, 01:13 PM

Yes your crank psi will go up but if you have a B motor and throw away the counter balancers as you are re-balancing anyways you get the increase case capacity so no problems. You have to realize that HD is ONLY balancing the B motors to 50% the A motors are 52% that is info from HD so where are they really???? I had my S&S 3.750 crank and pistons balanced to 62% dynamic. I am not a fan of Static balancing. If you are going to have the crank out cost of balancing is not that much as you are changing piston weight so balancing is a good idea,

GRock · 12-02-2004, 02:51 PM

107 is a favorite build for us here and you can really take the motor to a good TQ or HP level as with most HD. But they are strong and stay very smooth. The basic idea that nightboy approaches of the over square design being more toward hp is true to the extent that if you are building a high HP unit it is best to have short stroke and large bore. But the v twin doesn't LOSE it's TQ nor it's ability to might low end power. It simply allows you to develop more HP if that is the way you wish the build to go. My 107 has the TW6hg cam and develops 123 TQ and has over a 100 at about 2500 rpm. Fun to ride. We just did two, one with a TW8 and one with and Andrews 67. The tw8 just broke 120 hp and the 67 just missed, but both had TQ numbers that broke the 120 mark. Axtell makes a nice kit, and the Millenium is getting a great name because of nikasil bores.

JB socal · 12-02-2004, 05:58 PM

The 107 numbers look great, what kind of $$$ are we talking to take a stock 88b and make it a 107 fire-breather. Is a 107 still rideable as a daily commuter.

My neighbor has a worked EVO and it is has lost its daily rideability at the 115+ HP/Tq in my opinion.

GRock · 12-02-2004, 06:22 PM

Quote:

Originally Posted by JB socal

The 107 numbers look great, what kind of $$$ are we talking to take a stock 88b and make it a 107 fire-breather. Is a 107 still rideable as a daily commuter.

My neighbor has a worked EVO and it is has lost its daily rideability at the 115+ HP/Tq in my opinion.

Thats the beauty of the 107 all bore. You are not changing the piston speed because you are not stroking the motor. A lot of the extra pressures that go with strokers are eliminated by building with bore. Reliability stays high and, unless you work the hell out of the valve train by going monstrous lift cam, the engine can be as reliable as any other. Remember that the MOCO sells a stroked 103, (although it is a dog out of the box). I'll take the 107 with the 4" bore over the 103 any day. And not because of the extra 4 cubes either. You won't be sorry with this set up.

Stratplexi · 12-02-2004, 08:51 PM

Quote:

Originally Posted by HDWRENCH

Yes your crank psi will go up but if you have a B motor and throw away the counter balancers as you are re-balancing anyways you get the increase case capacity so no problems. You have to realize that HD is ONLY balancing the B motors to 50% the A motors are 52% that is info from HD so where are they really???? I had my S&S 3.750 crank and pistons balanced to 62% dynamic. I am not a fan of Static balancing. If you are going to have the crank out cost of balancing is not that much as you are changing piston weight so balancing is a good idea,

I really like this idea of balancing the crank & pistons and getting rid of the balancers. What kind of coin are we talking over and above the standard 95" kit? I assume you split the cases so one might as well go with a 103" and have it balanced, true?

Thanks

happyman · 12-02-2004, 08:56 PM

GRock,
what heads are you using on your motor?? also what was done to them your compression ratio and your ccp would be nice to know too. will axtell scale up a couple of pistons real close to the same weight? just for the sake of balance then i take it we need to have the assembly balanced or its a good idea at least .
thanks Happy

**HDWRENCH** · 12-02-2004, 09:03 PM

Axtell use JE pistons for the most part hard to get a piston that large to weigh what a 88 inch piston does. The weight on a flat top JE 4 .125 is 452 without pins or clips or rings. that piston builds 10.3 with a chamber volume of 85cc. Stock t/c is 89 so that leaves some room for milling, . That leave some good room for a vast selection of cams as well. Having the whole system balanced is a great idea as you are there any ways and it makes them even smoother .

happyman · 12-02-2004, 09:20 PM

would you know if axtell does balancing in there facility?? would have to find someone to do it. i think the woods 8 cam is not to bad a cam for a big bagger road glide to be exact. kinda like to hold the ccp down to no more than 190 if possible to keep things simple.
Thanks happy

SILVER BULLET · 12-02-2004, 09:47 PM

Stock twin cam head is 85 cc. They usually vary from 84 to 85 1/2 cc. Had a set the other day that cc'd at 82 and 85 1/2 but that is rare. This is a bare head with NO head gasket. Stock valves.

Road Bag · 12-02-2004, 10:12 PM

Does anyone know the difference in the case bore diameter, 4 1/8 Axtell steel sleeve VS 4 1/4 Millenium nikasil. Is the 4 1/4 taking the case too far? I've seen the head gasket, its pretty thin. I don't think it would live long with any detonation whatsoever. Hey Rock, why don't you build one of these 114s and wind it up for a while to see if the parts will stay inside it and let us know what you think.

oldschool · 12-02-2004, 11:35 PM

Thanks for all the help. 107" is very tempting. If I decide to up my budget, I think it'll be for a 107.

In order to get a better grasp on how a decision to go 107" affects component selection, I'm trying to confirm which motor parts are specific to a 4.125 bore. Are the pistons, rings, wrist pins, cylinders, base gaskets, head gaskets and case bores the only items that are dimensionally specific to a 4.125 bore build?

How 'bout the cylinder heads, must they be specific to a 4.125 bore?

Must any other parts of the motor be specific to the 4.125 bore?

I realize a lot of parts need to be upgraded for a lot more air flow and durability, but just wondering which are specific to the 4.125 bore.

Are Axtell, Millennium and Zippers the only choices for 4.125 bore cylinder, piston and gasket sets?

Thanks again!