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Has there been many problems with the all bore 114" RP cylinders such as the 98"?Also what type of power has fellow members with such a build achieved?Like the ideal of using your original crank but can it hold up to such an increase in inches?There are alot of 95" and 98" but you don't here much about the all bore 114?Which cam works best with this particular build?Hope I have not asked to many questions!!
 

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A guy I know has had his 114" Revperf for about 10k and no problems thus far. His makes around 125hp/129tq using heads done by a local guy and S&S .625 cams, TH pipe. Numbers will be influenced by heads, pipe, CR, and cams.
 

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I myself have there 98" cylinders with 15,000 miles and no problems yet.Not that I still don't worry!Winter is coming and just want to toss around some ideals.In direct contact with Steve "GMR" and might have a friend who wants to purchase the 37g,98" kit.Like the build but want quite a bit more torque.Would only want a case bore and crank installation.Have the tools from the last build to complete the rest.
 

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Big Bore

We have seen numbers on either side of 140 ft/lbs with a touring combo, that we have, with Axtell 4 1/8" cylinders that bring the configuration to 117" with a 4 3/8" wheel set.
 

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IronButt
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For the normal street 114 you should see upper 120's to low 130's. Of course you are always looking at avg numbers. As well we all know that you can spend a ton of money to get that last hp or tq number. The 117 is a tq build over the 114. It runs well but it still is a short stroke big bore engine, so it will rev fast but not produce tq curves like that of a longer stroke engine. I like the over square 107 kit myself, and then the stroker 117 kit is another great kit. We have built several 117's here in the last two months. They are alwyas fun to ride, power comes on low and hard pulling you well into the triple digits for speed in a no time flat
 

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Steve, so will the 117" stroker require a chain? In fact where is the torque cut off for a belt? Thanks.
 

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MaxHeadflow
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"but not produce tq curves like that of a longer stroke engine."

Don't tell me you think that longer stroke engines produce more torque because of the longer crank throw.

Bruce
 

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IronButt
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Read what I posted " tq curve " I did not say more tq just that the curve will be altered. And yes after building dozens & dozens of 114's with big bore short stroke, vs using a longer stroke smaller bore. You will see the curve with a longer stroke start to build faster in the lower rpm range. All things equal.
 

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Thread Ender
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Bruce Woltz said:
"but not produce tq curves like that of a longer stroke engine."

Don't tell me you think that longer stroke engines produce more torque because of the longer crank throw.

Bruce
Whoa, is this not true, generally speaking?
 

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IronButt
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I am basing what I posted on the amount of engines that i have built. As well the countless dyno sheets i have seen. And there is a common trend with a stroker building tq in a different manner than a short stroke enigne.
 

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could you post some dyno sheets of the all bore 114 and the the stroker 117 with simliar builds to illustrate your point. I have always thought that a 114 would be a lot of fun with a real nice torque curve, an even running smooth engine. That, to me, would be the ultimate bagger engine.


Could one of these be put together on a budget? If limited in rpm, could stock heads be machined to run this monster? could it be done with a chain cam? I am speaking about an engine for a trailer pulling bike or a side hack. What cam would you use? would you go to a longer duration because of the cubes?
 

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I agree with Steve, the 4-5/8" stroke is the prefered stroke by a lot of engine builders. That stroke matched with a great set of heads and cam will change the whole personality of the engine. The stock heads can be used in the 124 configuration but we recommend the stage 5 R&R castings for best torque results.
 

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<<Well explain to us why it is not true??>>

Bruce said that he AGREES with you that the longer stroke motor of equal displacement would have a different tq curve but not more peak tq, everything being optimized.

You clarified that you were not saying that a longer stroke engine will produce MORE peak tq....and he agrees.
 

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The more I think about this, I would venture to say that two identical motors, one with a longer stroke, the long stroke would make more peak torque.

Educate me, tell me why I'm wrong. Not trying to %[email protected] , just want to learn.
 

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MaxHeadflow
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Without getting to heavy into the math, if two motors that have the exact same displacement but one is a stoker and the other is oversquare and they generate the same cylinder pressure, have the same rod to stroke ratio, then they will generate the same torque at every positon on the crank. There is no machanical advantage. The reason is that the over square motor generates more pressure on the rod due to bigger piston to push the crank where the stoker generates less pressure but greater mechanical advantage. With the same rod to stoke ratio they balance out. If the rod to stroke ratio is increased then the motor will generate more torque. Not much but it can be a few fp. Some time ago I used that excel compression calculator to calcualte tq over the power stroke and some up the total torque. This is what I found. Later I read in the Desktop Dyna book the same thing. One thing to also bring up is that strokers loose more HP to friction than a short stroke motor.

So why does the stroker generate more "low end" TQ?

Well IMO, it's because when talking HD TCs the rod length is, for the most part, fixed, 7.667 inches. Strokers have a smaller R/S ratio. Less R/S decreases the dwell time at TDC (time the piston sits close to TDC), this helps keep the combustion controlled at lower engine speeds and staves off detonation. This allows the motor to be tuned to generate more TQ at lower engine speeds.


Bruce
 

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Now you got me thinking. Where did you get that spreadsheet?
 

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MaxHeadflow
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The original spreadsheet is the same as the one here used to calculate corrected CR. It was originally done by Moe Riggens. I just tweeked it a little to calculate torque based cylinder pressure and position of the crank.

Bruce
 
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