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

[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.

[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

[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 

[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...     

[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]

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...     

LOL my feelings exactly ......

~John

[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.

[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.   

[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. 

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.

[kd]

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.

[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]

[kd]

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

[No Cents]

  the 103 with the Pro Charger on it.

[kd]

Aha, .... damn Pro Charger.    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.

[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.   

[kd]

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

[Adam76]

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

[838]

My decision in this situation was to stage 2 the 96" that's in there now. I installed a CR570II, 32t darkhorse and will be getting her tuned in the next few weeks.

I'm going to build a separate 124 on the bench (over the next year), install, and then sell the stage 2 motor. 

Right now the bike has a map from a SE204 on her with a few adjustments.. little engine likes the cr570II

[kd]

Are you actually riding it untuned?

[838]

No. Just not on dyno yet. Used PV data logs and mega log viewer to make a map based off an se204 calibration. Monitoring for  temps, knock retard and ve's on PV unit.

[Adam76]

My decision in this situation was to stage 2 the 96" that's in there now. I installed a CR570II, 32t darkhorse and will be getting her tuned in the next few weeks.

I'm going to build a separate 124 on the bench (over the next year), install, and then sell the stage 2 motor. 

Sounds like a good plan.

What compression will your CR570-2 build be? Any headwork at all?

Would you gain much by going from 96" to 103" at the same time with that build? Probably not that much I'm guessing, as that cam does so well as a bolt in anyways.
Thanks

[838]

The cr570-2 will stay a 96". Basically stock otherwise. Where it looks like there would be a benefit to going 103 would be in the lower rpm range and this is a light bike and I downshift so no real reason to go 103. I don't know if headwork would help this any and I'm saving money for a 124" so I'd rather put that money there vs. doing headwork for the 570-2.

[Adam76]

The cr570-2 will stay a 96". Basically stock otherwise. Where it looks like there would be a benefit to going 103 would be in the lower rpm range and this is a light bike and I downshift so no real reason to go 103. I don't know if headwork would help this any and I'm saving money for a 124" so I'd rather put that money there vs. doing headwork for the 570-2.

👍  Makes sense, good luck with it and let us know what you have with your final tune.

[shindig]

838 - you would for sure benefit from the 103.    You can up the compression to suit the 570-2 you want to use.  But I would just throw in a 107 kit for $600.  Headwork/tb leave alone.  Nice super cheap build.

[Bafflingbs]

After reading all of these types of threads, I admit it, I got worried about my FM 110" build. So, -$6,800 later, I now have a Darkhorse MOW crank, Timken conversion, high flow cam plate and oil pump, etc., etc. My build at the time, clocked in at 117/130. My primary started making a lot of noise, and was getting worse, so, I was afraid to ride it too far. At the time of the 110 install, the runout on my cam side, was .004. Not bad- not great. Worry, worry, worry..... I became obsessed with it, and began regretting the engine build. Am I concerned about my spending? Fk yes! Am I at piece with the outcome? Fk yeah!!! It runs soo damn good now! And runs as quiet as a church mouse. My only regret, not doing it all at once, in a shop that can machine the case themselves. I definitely would've gone bigger! 117-124" for sure. Instead, I did the upper first, lower second. Consequence: labor cost for complete tear down twice. [attach=0]

[Jaystn62]

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...     

I have to agree with Hoss. I built the 107" in my bike with a stock bottom end with intentions of some spirited riding. I have yet to do a "burnout". I don't dump the clutch in any gear. But I feel I push it. It feels, sounds and runs better than stock. Not saying I won't be putting a Dark Horse bottom end in it but if I do I'm going big after that.

[Adam76]

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...     

I have to agree with Hoss. I built the 107" in my bike with a stock bottom end with intentions of some spirited riding. I have yet to do a "burnout". I don't dump the clutch in any gear. But I feel I push it. It feels, sounds and runs better than stock. Not saying I won't be putting a Dark Horse bottom end in it but if I do I'm going big after that.

Hi Jaystn62, can I ask what the rest of the 107" top end build specs were and what tq/hp you got? Thanks 

[Die Hard]

I view a strong bottom end it as cheap insurance. You are gambling building for more power on a stock lower end in my opinion. The problem is, if you stay stock on the bottom and lose the gamble, you've not only lost the entire bottom end and possibly the case, you run a high risk of trashing the top end components in the process.