A question for those builders that approve building up on a stock bottom end???

Started by 838, September 28, 2020, 07:15:04 PM

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838

I've heard from those that disapprove of this many times. For those of you that feel that putting tq and hp to a stock bottom end is OK:

- Where is your sign off with crank runout?

- What HP and TQ would be your limit?

- What are your experiences with putting big(er) power to stock bottom ends that keeps you believing it's OK?

Thanks guys!

Ohio HD

It's not the power, it's how it's ridden.

I can break anyone's bike if I chose to, and you let me ride it.

I put a 107" on an '08 bottom end, 23k miles. six thousand miles later I beat the lower big end rod bearings and flywheel thrust washers to the point of knocking. A bit over 100 HP / torque with stock heads. The bike was never lugged, just run very hard. 

Darkhorse bottom end or stay home.

kd

It does appear that some are having decent luck with the SE 120R flywheels.  Again. you can break anything if you beat it hard and continually.  Hooking up hard will do it.
KD

rhuff

When I did my all bore 107 that was done by a very reputable builder and ended up around 120 HP and 130 TQ didn't suggest doing the lower end as the runout was nil on my 2003 even after 85K.  I did the lower end.  Best piece of mind ever.  I never dumped it or abused it, but I ran it hard for 25K before I sold it. 

jmorton10

I can tell anybody who asks what happened to me.

I bought a 2007 RK from a buddy who was hurting for $.  He had a very well known & respected shop (who will remain nameless) build him a 117" big bore motor (using Axtell barrels) reworked heads & then dyno tuned using the stock lower end.

When I bought it from him, it had 1700 miles on the motor & it ran great.  When it had 1900 miles on it, it scissored the flywheels which broke the oil pump impellor & trashed the motor.

Now I will be the first to admit I beat on my bikes LOL.  That is what high performance builds are for IMHO.  If I didn't ride that way, I would just ride a stock bike.

That 117" motor is sitting on a shelf in my shop & I now run a 124" motor that is entirely S&S parts & have proven to be basically bulletproof.

~John
HC 124", Dragula, Pingel air shift W/Dyna Shift Minder & onboard compressor, NOS

hbkeith

if its a TC and your going to RIDE the hell out of  it ( which a lot do not) , better do lower end , seen a lot of buddies with broken tywinkies  :potstir:

838

I have enough parts on the shelf to build this 96" into a little 120/120 103". Until I save up enough to do the bulletproof 117"-124"... I just don't want to break it's neck in the process.

shindig

My understanding is it mostly has to do with how the motor has been ridden.  Hard shock to the drivetrain is the issue.  Most people think about this as hard launches, or shifting.  But equally hard downshifts cause a problem as well.  Yes of course once you get into high hp and tq than that becomes a consideration.  Ride it nice and a stout 103 should be fine.

Hossamania

What's the point of a stout 103" if you're going to ride it nice? Might as well keep it stock and catch up when the fellows ahead decide to stop for a while...     :potstir:
If the government gives you everything you want,
it can take away everything you have.

harpwrench

The only crank problems I've had are with the rods, not runout, and from what I've gathered is that's a crapshoot whether it's stock or built, low or high miles.

jmorton10

Quote from: Hossamania on October 06, 2020, 12:14:42 PM
What's the point of a stout 103" if you're going to ride it nice? Might as well keep it stock and catch up when the fellows ahead decide to stop for a while...     :potstir:

LOL my feelings exactly ......

~John
HC 124", Dragula, Pingel air shift W/Dyna Shift Minder & onboard compressor, NOS

MikeL

I lost the crankpin/bearing on my 2000 RKC. It happened right after I went to 98 cid and 10.75 compression. That bike is now a 124. My 2002 fatboy is 98 cid at 10.1 compression. So far so good with the fat boy about 4k on the build. Both were upgraded with around 40k miles. Could higher compression cause a bottom end failure? The only thing different is the 2000 RKC back then I was using 15w50 mobile 1 non vee twin oil. All my bikes now use Amsoil 60 sae.


                                                                                                                                                                    MIKE


                                                                                                                                                                   

1workinman

Stock bottom end , ok I going to suggest this , you carry your bike to a builder to do a kit or what ever an it runs great and the bottom end gives it up. So what do you think the results are here its on you . I bought a used lol bad idea for me 103 in  12 street glide and it was tested ready to go checked out at the local Harley dealer . The crank was out in less than 1 k miles .  So I either stay stock or go SS or dark horse or who ever you  want . Do as you want but I never use a stock Harley crank  on a performance build . My money my bike

Deye76

"if its a TC and your going to RIDE the hell out of  it ( which a lot do not) , better do lower end"

Depends on what the definition of "ride the hell out it",  is . I usually spun mine to 6 grand, the guys that hammered 'em in 4th gear @ 2 grand can destroy a lower end in short order. My DarkHorse lower went north of 80K, still going strong when I sold it. Heavy guys who don't downshift are the stress testers.
East Tenn.<br /> 2020 Lowrider S Touring, 2014 CVO RK,  1992 FXRP

No Cents

   this is a pretty simple question to answer. If an engine build is going to exceed what stock is...you need to start building at the base and work up. Erasing the bottom end off the list of weak links.
   As mention...a Darkhorse bottom end, or a bottom end with a set of properly set up S&S wheels would "definitely" be my starting point if I was planning on adding more power. A solid bottom end set up is the "foundation" for adding more power. It would suck to put all your time/money and effort into an engine and the bottom end go south.
   Why chance it.   :nix:
08 FLHX my grocery getter, 124ci, wfolarry 110" heads, Burns pipe, 158/152 sae

Adam76

This is an interesting thread, I see tons of 95" - 98" build threads and dynos of guys doing these 100/90 builds and most of them don't mention any attention to the bottom end except checking crank run out.  :idunno:

Making me think twice about a 97" top end build I was planning on a Road King....

C-Cat

Didn't Stroker JK drag race a N2o 103 on a stock crank for a few seasons? Not advocating stock cranks for a build, although it seems some do hold up. Mine was at .0025 and I didn't hesitate to do a S&S 110 drop in. So far I'm really liking it.
124ci. 07 Streetbob 161/145
110ci. '11 Roadglide  129/127

kd

Quote from: C-Cat on October 12, 2020, 08:43:13 PM
Didn't Stroker JK drag race a N2o 103 on a stock crank for a few seasons? Not advocating stock cranks for a build, although it seems some do hold up. Mine was at .0025 and I didn't hesitate to do a S&S 110 drop in. So far I'm really liking it.

He also raced a built 120R with the OEM crank and did well. IIRC at one point he said he he had over 40,000 miles of touring and track time on that 120 and no plans to change anything.  This was before he went 103 (I thought turbo) E85 and continued to do well. I can't remember if the 103 had crank work or not but Jim didn't spend money if it wasn't broke.
KD

No Cents

  Jim's (strokerjlk)'s stock bottom end.
He told me afterwards he wished he had done the bottom end after this mess happened. 

[attach=0]
08 FLHX my grocery getter, 124ci, wfolarry 110" heads, Burns pipe, 158/152 sae

kd

Was that the 120 or the 103 Ray?  I certainly don't remember that coming up in conversation.  :scratch:
KD

No Cents

08 FLHX my grocery getter, 124ci, wfolarry 110" heads, Burns pipe, 158/152 sae

kd

Aha, .... damn Pro Charger.  :crook:  Nuff said.  It looks like it was a broken rod or piston started that.  Not that I am a proponent for always running the stock crank.  There is quite a difference between the 103 and the SE 4 5/8" crank though.
KD

Ohio HD

Let's build a big nice brick house on an old weathered wooden foundation. We'll come back later and fix the foundation.    :wink:

kd

Hey! Let's not get off topic by talking about building houses.    :unsure:
KD

Adam76

Quote from: harpwrench on October 06, 2020, 12:19:45 PM
The only crank problems I've had are with the rods, not runout, and from what I've gathered is that's a crapshoot whether it's stock or built, low or high miles.
Hi,  can you explain what you mean about the rods?  Thanks