Big bore or top end power

[2003BDChopper]

Just bought my second 2003 chopper With the 107 SideWinder 4 inch bore and 600 cam.

First ride engine went poof. Some idiot assembled New pistons the wrong way that ofcourse resultet in skirt crash. Didnt help they set all piston rings upside Down.

Anway, i took it apart. Cleaned out the lower end, and ordered a 124 hot setup kit. The Company that ordered it didnt notice it was for a twincam.

So back to basics.

Now im trying to find parts for a decent setup that would produce some more Power.

I Guess in terms of cubic inch i cant get alot more then 1850-1900cc without stroking.

How can i get a decent result With at least 20 more horsepower and preferably alot more torque? Any thoughts?

PS: I Guess this should have gone in the performance sction. Oh well...

 

[john sachs]

If you feel you need the power of a big cube engine, cut to the chase, and buy a complete S&S 4 1/8" bore 124" engine for your Big Dog. When you get bored with it, you can always work it for more power.
John

 

[Sven]

My understanding:
Bore = Torque.
Cam = Top End.

Stock cam + Bore = Stumpullingrunt dependibility.
Cam + Bore = Strengthen Rods-port heads-up compression decking heads-lighten crank-stronger valve springs-larger carb-and/or-program software for map-exhaust system-lighten rockers and hope it doesn't have a short fuse.

Street = The reach around is affordable.
Performance = Wallet buster with a never ending reach around.

My understanding:
Piston pin is a mm or two of offset to the piston's centerline.
If no offset, piston would reach TDC and stop.
This makes the rod move past TDC with the offset so intake side skirt cocks the piston and is back to upright on the initial pass after TDC.
Reverse the offset, the exhaust side skirt scrapes the bore, no lube on the upright, meaning, stays cocked not upright for so many degrees = Loss of oil splash.
Would add valve pocket having intake touching closed pocket-adding to cock, and if not enough to bend valve for loss of compression, then back to oil lube loss, because if offset was reversed to normal, oil lube would be present.

How close am I?

 

[2003BDChopper]

John, The idea has been lurkin around my head ofcourse. But i still have much to learn about big twins, and really wanne know it all at some point. For that reason i wanne Upgrade what i have. And in the process, get some more knowledge.

Sven, Thanks.
Understandable all the way Down to: Valve pocket having intake touching closed pocket-adding to Cock.. By Cock u mean parts touching?

Guess i need to work on my English regarding technical terms..

Talking about power, i know whats needed roughly. But thought more in the lines of actual parts ppl have experience With. I'm not extremely familiar with all parts awailable.
I know there's only so much torque you can get without touching the lower end.. Thought id stick to top end for now, and see what i can get from that.

For instance how much lift can oem spring and retainer can take.

What*s a safe Max bore on a bored oem cylinder. And what*s is the biggest big bore kit awailable? Any brand superior to others?

Are there any big bore kits for the 107 at all? I cant find ANY..

The Super G should be sufficiant for quite abit of ekstra hp*s no? 130 ish?

Porting heads / Matching ports ofcourse is a must. Havent even looked at they're current state yet.

My understanding: Lightening the crank would decrease torque, but up top end. I love top end, but for me torque is superior to horsepower in an evo engine, unless u dont want your arms to fall off due to the vibrations at higher rpm*s

 

[Th3InfamousI]

John, The idea has been lurkin around my head ofcourse. But i still have much to learn about big twins, and really wanne know it all at some point. For that reason i wanne Upgrade what i have. And in the process, get some more knowledge.

Sven, Thanks.
Understandable all the way Down to: Valve pocket having intake touching closed pocket-adding to Cock.. By Cock u mean parts touching?

Guess i need to work on my English regarding technical terms..

Talking about power, i know whats needed roughly. But thought more in the lines of actual parts ppl have experience With. I'm not extremely familiar with all parts awailable.
I know there's only so much torque you can get without touching the lower end.. Thought id stick to top end for now, and see what i can get from that.

For instance how much lift can oem spring and retainer can take.

What*s a safe Max bore on a bored oem cylinder. And what*s is the biggest big bore kit awailable? Any brand superior to others?

Are there any big bore kits for the 107 at all? I cant find ANY..

The Super G should be sufficiant for quite abit of ekstra hp*s no? 130 ish?

Porting heads / Matching ports ofcourse is a must. Havent even looked at they're current state yet.

My understanding: Lightening the crank would decrease torque, but up top end. I love top end, but for me torque is superior to horsepower in an evo engine, unless u dont want your arms to fall off due to the vibrations at higher rpm*s

Understand the desire to build but in the end will cost you close to half of what it cost new to get the same to get everything machined correctly, never mind the time.


Sent from my 2PS64 using Tapatalk

 

[Mr. Wright]

Another thing you have to understand, is what the drivetrain will withstand. Bangs in 03 that transmissions a little tougher than the newer ones, but more horsepower means more maintenance on transmissions.if you're wanting more horsepower you might also think about a open primary with outer bearing supports to keep the bearings straight in the transmission

 

[Mr. Wright]

Hopefully you can figure out what I was trying to say. Drinking and posting is not my forte

 

[Sven]

Valve pocket having intake touching closed pocket-adding to Cock.. By Cock u mean parts touching?

Yes, parts touching. And no, meaning, the rod comes around and forces the skirt to cock as is. To confirm what I think is why the skirt burnt was forcing the piston's offset on the bore longer than needed. And if there is no valve touching the exhaust pocket side, to me it says the piston offset still caused it. Only the piston dome knows for sure. If there was no intake side scored, it means the rings should have scored that side of oil loss too. So I'm going to rule out the rings as a variable.

My experience is to set the pushrods adjustments first. If the tick remains, it's the piston skirt snowballing the aluminum away so the tolerance of the rocking widens. Thus the tick at TDC (top dead center), then when it comes around you hear the next tick ABDC (after bottom dead center). Make sense?

John might know how much bore is left on an already bored cylinder, as well as parts for said engine. But I sort of agree with John about plugging in a new engine. Here's how I look at the reach around. Say this took awhile to burn itself out. It still means micro snowballing the filter can't stop. So goes the crush at the oil pump blades and the galling at the sides of the pump's gear cover, so no longer a tight seal for pressure. Then the micros tumble inside the big end rod and scores that bearing system, meaning, the pin and what rolls over the pin. Now comes the splash where the micros are suspended in that splash, finds itself between skirt and cylinder wall, thus line scratching of the bore finish.

So how much are we looking at? New pump, rebuild the crank, replace all the bearings because those too were crushing micro if not chunks skidding the balls, not letting the balls spin 360 on their own until they [micros0] pop out of the cage. Say you're 2/3rd's the price of a 124", if not a few hundred away, because you skimped on the inserting of new brass sleeves for the cone, reused the cam and rockers and those score lines. Then the engine really didn't get super clean and the hidden micros dislodge eventually and score all the new parts.

Get it? For that 4 page parts page you could have bought the fresh plugin with all the torque ready to go, sell the scored engine to pay off some of the 124". Make sense here too?

 

[aspen874]

Sven, what planet do you live on

 

[2003BDChopper]

Sven, what planet do you live on

Thats alot of theory. Im not gonna og that deep into it all tho. Not enough experience on these engines yet..

I'll settle With boring .010 over / 10.5:1 with good clearances, port and deck the heads, match ports, s&s coil and ignition module. Not sure how wise a 640 cam would be. lower torque and even more rpm = vibration.. Might do oversized valves.

Understand the desire to build but in the end will cost you close to half of what it cost new to get the same to get everything machined correctly, never mind the time.


Sent from my 2PS64 using Tapatalk

Luckily i got a friend who has a machine shop. So no worries there. I dont mind spending a 3rd or even half of what a New engine cost. Thats the whole point for me really. I dont want a brand new engine.
I got tons of experience building car engines, supra engine etc. I want the same for Big Twins eventually

Another thing you have to understand, is what the drivetrain will withstand. Bangs in 03 that transmissions a little tougher than the newer ones, but more horsepower means more maintenance on transmissions.if you're wanting more horsepower you might also think about a open primary with outer bearing supports to keep the bearings straight in the transmission

I agree. Though i'll stick With closed for now. Got an open layin around, but thats for a new build im starting next year. Just missing a new frame from swedish fabricator.

Hopefully you can figure out what I was trying to say. Drinking and posting is not my forte

Your speaking plain English. Not so hard to understand . Now trying to get smart from Sven*s comments is a different matter and more of a headache
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[Mr. Wright]

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Your speaking plain English. Not so hard to understand . Now trying to get smart from Sven*s comments is a different matter and more of a headache

​

Don't feel bad, I have a 132 IQ, and can't keep up with Sven most of the time. He know his stuff, but it just gets lost in translation.