2nd thoughts How many agree

With $1.7 spent prior on my 95" motor upgrade & now looking at an additional 3K at least to repair & fix my crank that took a walk, I'm starting to wonder if you can really have both reliability & performance...or is the statement an oxymoron?

What's your thoughts?

TIA,
Cracker

If you only did a 95" upgrade, IMO, there shouldn't be any reliability issues. All you did was increase the bore and piston size. I wouldn't think THAT would have any impact on reliability. Now, if you ride it like you stole it BECAUSE of the 95" kit, then I would say that is an issue with your riding style which would have an impact on the reliability. Now, if you did cams, heads, etc, with that kit, then I would say this would cause a decrease in reliability because of high compression, etc, and lots of stress on the crank and bottom end. That high upgrade coupled with an aggressive riding style = low reliability. This is strictly my little opinion. I'm sure there will be others.

Now it's time to put in a stroker flywheel assembly.... use S&S.

Bill C.

You answered yourself correctly. The greater the performance, the lesser the reliability. Increases in heat, pressure, friction - basic physics at work. Of course, there is a level were poor performance means less reliability, but that is when you're ride is detuned and mismatched beyond reason. Doubt you meant that..ya know, like running an engine with no oil - it will not perform well and will not be relaible. Same with not matching your air/fuel to your exhaust, whether EFI mapping or carb tuning.

I totally disagree. The engine in its stock state is no more reliable than after the stated 'hop-up'. The fact that the engine has the capability to accept the 'hop-up' sustains this as well. All that was done to the engine was an eight percent increase in functionality and if the reliability has decreased, then Harley Davidson Motor Company has totally destroyed the 2007 models with their nine percent increase with their "basic physics". "The greater the performance, the lessor the reliability" is total bunk! Don't talk that talk around a race track or drag strip!

There are two different aspects to the initial situation and question preying for input. Who did these upgrades to the engine and in what condition was the engine in the first place? There are many so call 'expert' engine builders out there that have been destroying HD engines from the time of the Flat Head. Most of these 'engine builders' would screw up a ball bearing. There is no reason for the 88ci TC to become less reliable increased to 103 ci much less 95 ci. If heat, pressure and all that bunk will decrease the reliability of an engine, then Arizona or Colorado must have piles of autos at their borders from those increases and the resulting destruction of engines....

Clem - feel free to disagree, but "Ya cannot change the laws of physics, Captain". More power through means more heat bulid up, more friction, higher wear rate = less reliability. That's why perfectly engineered drag racing engines are only good for a few runs before needing a rebuild. Even if you baby the hopped-up engines you lose because then they aren't operating in their prime range and they'll have other engine issues. Any engine has its peak efficiency range, and if you run an engine that has a higher than stock peak efficiency range then it will build more heat and wear out quicker. Not to mention the drivetrain issues, all the way to tires and brakes. Just the way it is.

I don't think the 95 should be less reliable than the 88..at least I'm hoping so cause that's what I did... but I didn't change the cams or bump the compression up. Just an air cleaner, new jugs, new cast pistons and had the stage one download done. I use synthetic oil. I let the top of the rocker boxes get warm before I ride off and I don't load the motor up untill it's warm. I keep the tach between 2700-4000 RPMs. I don't baby the bike, pull a trailer with it. So far so good. I had an 89 inch EVO stroker a while back. It was a fun bike but I had some issues with it. To be honst I'm a little nervous about bumping up the compression on this one.

Do you mean 'longevity'? The longevity of an 88ci verses a 95 or 96ci? I could agree that the life expectancy of an engine that has been 'up-graded' may be shortened to some extent - but not its 'reliability'. Fuel injection, high tech carburetors, electronic ignition, oil cooling, roller bearings and etc make the Harley Davidson engine quite advanced in performance in its stock configuration to sustain appreciable upgrade without changing the physical properties that you claim decrease with performance. It is infinitesimal at the eight percent that has been done in this instance. Take the engine up to a super output - 100+ percent increase in horsepower and I'll agree with you, but not a measly eight percent - the engine is downgraded from the dealer that much! Besides, I believe you confuse reliability with longevity in this case. Either way, you don't think much of the Harley engine do you! Go buy yourself a Honda - they last 'forever' and the Japanese have far more Physicists than the USA - you'd love the company.

Thanks for allowing me to disagree! Big of you!

:bicker:
You can't do the "apples & oranges" thing. If you just want a flawed argument to sound like it makes sense, go ahead - I give you my permission! :roflmao:

My argument remains based on the question originally posed by Cracker, with the framing of the question being the upgrade of the 88 to a 95, with the usual accompanying mods assumed (exhaust, air cleaner, cam). I had to assume that he wanted performance upgrades for MORE POWER so that he could actually use that power, rather than just brag in the parking lot about his cubic inches. Within that framework, I am not so much expressing opinion as scientific fact. Will an upgraded to 95 88 be as reliable as a stock 88? And what about the rest of the bike afterwards - the drivetrain most specifically? Generally, no.

Now, if he meant as a friggin lawn ornament, dang - I have to concede there will be no difference. So those that disagree can be right, as long as the bike won't be ridden. :roflmao::roflmao: :roflmao:

I'll try to answer some questions & clerify some things...

The bike was 05EG carb model at 10K I installed a build called from HTT site the "Hippo 95" with SE FT pistons valve pockets relived by SBC, SE heads that were locally CnC ported with a multi angle valve job guides cut accept up to 600 lift cams, new double 170 springs & CC'd to 78. Also added a MIK42 with stock intake matched CnC job to the heads. S&S 570G cams, SE adjustable push rods, VPC clutch & Baisley LMR-2 oil spring & DTT custom map ingnition & V&H Pro Pipe & later to come was a 3.37 final drive ratio.

The motor ran like a raped ape, 1 base run dyno made about 100/100 before I installed the 3.37 final & quiet for the 1st 5K...then the wheels must have walked a bit cause best I can piece it together my pinion shaft runout was
.02 when I did the gear drives but after 5K on the motor the gear drive started to get noisey more so after the oil temp would hit 200+.

At 10K on the upgrade I could not take anymore of the noise & went to have the GD cams pulled to install the new roller chain conversion TW44N cams & that was when the TIR was found to be .055.

So now its getting a 106 S&S crank with Timken conversion installed by a reputable shop.

The motor upgrade was pushing my limits the crank job is way over my head!

One has to know his limits...well there is a bit of the history behind my post.

Thanks for your replies & sharing your thoughts, just hopng that this bike is not going to turn into a $$$ pit! I've got a brother I ride with that loves to tell me I told you to leave it stock!!!:soapbox:

Cracker

Ha ha, you got your 'scientific facts' from that decision you made first thing in the morning. Don't strain too much there. You might make a good call....The HD engine, you do not know! I know it's tough for you to understand the Twin Cam and its capabilities so you're forgiven....

I'm so glad I read this thread. I now realize the error of my ways. I'm just so glad that my 2007 Road King Police bike with the 103 CI and a 6 spd (comes that way from the factory, with and oil cooler) has a 2 year warranty on it. Whatever was Harley thinking, putting such an unreliable engine in bikes designed for the police department? I bet I'll take a beating on the bike when I sell it, as I'm certain others will know how much problems and cost will come with the bike. I'll be lucky to find a buyer at any price.

Just a little sarcasm there. Bottom line, if you take a bike out that's stock, and do holeshot after holeshot with it, lift the front wheel by popping the clutch and straining every part in the drivetrain.... it will likely find a weak link. The more you use (or abuse) the power a machine has, the more likely you are to break something. Heat is an enemy of an engine, but only after a certain point. GM has the capability of operating at 180 degs, or even less. Many models for years ran 200-210, just to try to get cleaner burning engines..... all without sacrificing reliability in the least.

My 103 CI pulls like no Harley I've owned in the past, and all of them prior were modified. It pulls as hard at 2500 RPM (102 foot pounds of torque at that RPM) than any of them did at any RPM. As for reliability or longevity, there is no proof either way on how it will do if ridden the same as a 88 CI in comparable conditions. Show me a test on it, proving the point, and I'll stand corrected. All I've ever heard are opinions. As for those, I've heard that the oil cooler on my bike will pretty much compensate for the additional CI heat, and that this engine will not be working as hard as it's 88 CI counterpart, and the longevity could well be increased.

That being said, and getting back to the original thread.... Yes I'm sure you can have both reliability and performance. I'm also sure that the more you twist the wick on any machine, the sooner you will find the weak link. Think of it like a tach, at 2k your reliability is higher, and performance is lower. At 6k, your performance is higher and reliability is lower. Your riding habits will determine which side of the spectrum you lean towards the most......

To "generalize" performance mods in relation to reliability is where the problem is. For instance, properly porting the heads (not over kill) for better flow will increase the performance, not affect reliability and in the case of a TC, will open up that choked exhaust port letting it run cooler and increase the reliability.
A mild cam change keeping the same base circle and not exceeding the stock spring pressure will again improve performance with little affect on reliability. Now put in a monster cam that requires bigger valve springs for a greater seat pressure and you have just added a lot of stress and load to the cams, cam bearings, lifters, rockers and rocker assembly which will have an affect on durability/life of engine. Stock or near stock compression ratio bigger pistons, again not really adding much load, but pop in some high dome 10 to 1 or more and now you are slaming the pistons, crank, and crank bearings so my 2cents is it all really depends on exactly what you are doing to improve performance to know how it will affect reliability.

Hey GH, how you been?

I agree with Reese. Radical upgrades produce radical results power wise and also usually catastrophe wise. Minor mods, such as mild port work to free up the choked up exhaust may actually extend the life of the engine.

Been well Reese my friend. I've been on the road a lot recently. Out of the past 3 weeks (one was vacation on the bike) I've put 3500 miles on the two bikes I have..... love this time of year! Yeah, I know, you live in the sunny warm south...... I have to enjoy it while I have it!