Board index Flathead Power-Technical Questions, Answers, and Suggestions Big Twin Flatties Still trying to figure out what is happening in the UL motor

Still trying to figure out what is happening in the UL motor

Post Thu Jun 15, 2006 8:01 am

Posts: 604
Location: Largo, Fl

I don't care WHO you are or how much you have written about a subject, whatever it may be, anyone who considers himself the Ultimate Last Word, un-contradictable, still has A LOT to learn. If your replies just automatically Trump anyone elses, because "the correct answer is yours" then maybe instead of trying to "Enlighten" us with Knowledge, you must think that you wrote the book on that also!

Post Thu Jun 15, 2006 8:48 am

Posts: 228
Location: Burlington Iowa USA
Maybe if you built as much as you wrote you would have more merit. I've yet to see atcual stuuf you have built and applied your thoughts to. Most of your information (which has a direct link for sales) are at the exspense of other peoples hard labor in the past. That your takeing credit for. Dreams are Dreams and actually building are 2 different things. Personally I think your about the most arrogant person I've ever heard and are disruptive to everything positive about this board and have never gave much merit to your stuff. If you'd like to race sometime just let me know. Come on down.
Chopper Larry

Post Thu Jun 15, 2006 8:55 am

Posts: 228
Location: Burlington Iowa USA
And here's the post for when it's deleted.


Joined: 01 Oct 1999
Posts: 2637
Location: Hempstead NY USA
Posted: Thu Jun 15, 2006 1:36 pm Post subject:


When a question is asked, I'm quite pleased to find that an answer has already been posted. I have no interest whatever in demonstrating my own ability, or arguing whether the earth is flat. There are 2 excellent reasons why you will not see a response from me:
1. the question has already been answered.
2. I don't know the answer.
Perhaps some of you would be well advised to follow that rule?
However, when the same tired subject is raised, repeatedly, and where the answer is well known, and still misunderstood, misconstrued, misinterpreted, despite the author of the post in question purportedly have already read my very accurate, complete and intensive explanation, I have no patience for either re-inventing the wheel or permitting the correct answer (mine) from remaining in the thread as is it were merely one of the many possible answers.
Why do you insist on discussing these matters when you ignore the answer?
To some of you the questions are not matters of physics or logic but of taste where everyone's answer has equal value. Let me illustrate:
Q: how many quarters do I get for a dollar?
I then see the answer posted as follows:
1. 2
2. 5
3. 11.58
4. 15%
5. only on Tuesday
I then post the only possible answer, and either get back such gems as "I was told that...", "in the real world...", and "the famous old-time mechanic always did this...", or I can just watch helplessly as people see not only my answer but the previous answers and continue to post nonsense.
By suggesting that my purpose here is to amuse you, and that my control of my own posts is "childish" (whereas criticizing me is not), you convince me that this is a waste of my time.
Please: which of you here has spent as much of their own time and money making this information available at no cost? I have over 100 separate web pages devoted entirely to enlightening the public on these matters, and you're proving to me that this time has been wasted.

Post Thu Jun 15, 2006 10:05 am
Pa Site Admin

Posts: 5843
Location: Ohio USA

Whew !!!!!!!!!!!! Man it's getting a bit hot around here !! Must be the tempers flying, or is it the global warming ! :) Ease up fella's. If Panic wants to pull his posts, so be it. Get back on the topic track. I am sure there are many who know as much about this topic as Panic does and will chime in on it.

I to enjoy your knowledge base Panic but I also wish you wouldn't dump it. Thanks, Pa

Post Thu Jun 15, 2006 11:01 am

What a useful and informative remark. Let's all follow your example, shall we?
Rather than answer questions and post accurate information, let's, instead, make rude personal remarks.
Rather than address the subject, let's attack the identity if the speaker.
Rather than bother with those annoying facts, let's make semi-literate and completely unfounded assertions ("Most of your information...are at the exspense of other peoples hard labor in the past. That your takeing credit for"). Since you haven't actually said something useful, that makes you immune to criticism, doesn't it? Please, point out the contributions you've made here? I'll wait...
When someone attempts to correct or add to a prior post, rather than actually read the new material and agree or disagree based on content, let's just make the same remark again, continuously. The person who speaks longest is right, isn't that the premise?
Now be a good little boy and quickly duplicate this so that I can't delete it. I can't win, you're too smart for me.

In future, I will simply find fault with other people's statements without offering assistance - as you do. Rather than analyze the content, I'll just insult the speaker - as you do.

Yes, that's much better.

Post Thu Jun 15, 2006 11:19 am

Posts: 325
Location: Viola, WI

i agree with Pa, ya,ll need to play good fella's. keep it up and i'll yank the edit priveledges and then once something is said, it's said. there won't be any going back to change what came out of your mouth whether you want to or not.

Post Thu Jun 15, 2006 12:40 pm

Posts: 591
Location: Crewe, Great Britain

Hi all... Hum... this is not politics, let's keep our cool!!!

I personnally feels a lot of misunderstandings here come from the fact we don't always know how people actually use their bikes... I know from experience what seem to work for me, had the same flatty for 20 years, learned the hard way and found ways to cope with it...

Basically, I ride "flat out" whatever I'm riding or driving, hence my motors go through different problems than others here could experience.

The only time I can remember experiencing the piston burn problems that started this thread was when I first ran that KHK: idiotically swapped oil inlet for oil return, hence one very badly 1/2 melted rear piston (t'was probably also running lean as well...)...

Maybe some of you are not driving them flatties hard enough... they're tough beasts and were made to cope with a lot, although modern gas might not be one of them.

It must be obvious to most of us here that flatties like to run on the rich side, it helps internal cooling BUT the manufacturers probably never intended them to be ran ONLY at 1/2 throttle, where one can't really set the jetting right, so running either more rich or more lean. That's probably when you run in problems that are quite hard to comprehend???

To come back to a querry from WZ 407 about CR's and plug locations, here're a few more contentious issues:

Jerry Branch KR article with 6.13 to 1 CR: must be a printing error or the writer thought it was wrong when Jerry might have said, more likely, 5.13 to 1, as, as far as I know, he was the ONLY one to also trim the side of the pistons facing the channels....

I've got a french article, done when this french m/c magazine owner came to the factory just after the 68' Daytona win when O Brien says to him "Yeah, 5.5 to 1 ratio", the french guy does not agree but then looks at the sprawling heads, the relief work on the cylinders, agrees and concludes "Well, 60 bhp with that ratio is as good a work as 60 bhp on a 6 cylinder 250cc works Honda of the same period" and HE'S RIGHT.

One will definitively hit a brick wall in power delivery with anything flatty with "normal" bore/stroke ratio past 7 to 1 in my eyes. From the late 40's till 1970, all American m/c racing proves that their's no other way to tune flatty but to treat it like a 2 stroke and relieve as much as you can get away with. THIS will give you power, while the CR keeps going down... Can't believe the Dutch guy with 8 to 1 CR, he's telling porkies as we say here (or he's not running a flatty)!!!

Damn, dinner's ready again!!! I'lll follow up later...

Last edited by thefrenchowl on Thu Jun 15, 2006 1:35 pm, edited 1 time in total.

Post Thu Jun 15, 2006 1:27 pm

Posts: 591
Location: Crewe, Great Britain

Follow up... Spark plug recess...

Well, if you can only run your flatty on the rich side, it follows you'll run the risk of fouling/wetting your plugs. That's why it was found quite early in flatty history that protecting your plugs was essential (especially with period plugs...), hence various "shields", as in extraneous casting bits sticking in the heads, appeared...

But it was found, in America, probably just after WW2 that they were hampering the flows in racing engines. I'm not up to much on the WR evolution but their late heads show recesses rather than shields, which were carried on on the K and the KR.

It has also been shown that the recess will work on any type of distribution, acting as a "funnel" that helps to spread the flame front quicker, hence you could then shorten the advance by a few degrees, it all helps in the power quest... I know of a french OHC M/C 500cc racer that had them from its inception in 1932.

Now, to come back to these melted pistons... It's for sure there wasn't enough oil there for whatever reason... So that plus any amount of dilution from the gas used...

There's quite a few iron head Sportsters in our club over here and most of them complain about the gas and related pinking problems, some run with an extra head gasket, some went to 7.5 or 8 to 1 pistons, endless problems... Well guess what, the way I drive my 58', NEVER had any pinking, more revs means more turbulence, more mixing and a better burn. And I'm not saying it's better tuned than the others, std Linkert, std Fairbanks... I just like the sound of an iron Sporty at 6500rpm!!!... It goes back to my previous note, USE ALL THE RANGE OF GEARS AND REVS available...


Post Thu Jun 15, 2006 2:22 pm

Posts: 801
Location: Planet Earth
OK enough of the crap.

I started this thread because I had something happen that I could not figure out. Most times I can discover what had happened but this one stumped me and though maybe someone had run across it. I will continue until I figure it out be it with the posts that are put here or not. By the numbers the motor should not have had the problem. Everyone has their opinion and or ways of doing things. If it works for you then that is a good thing. Piston clearance, oil, fuel, compression and probably other things (I am not going to go back and look at it all right now) have been suggested as the cause. I may or may not agree with some of the thoughts of what happened that have been put here but I will keep it to myself. This is not the first motor I have ever built and not the first flathead either using the same or similar specs. And they are still out there running. This does not mean I could not have screwed something up and missed it. If you never made a mistake then you aren't doing anything. If you can not or will not stick to the subject then don't bother. If someone wants to delete their post so be it although I did want to get some of the info posted before it was pulled. But so be it.

So either stick to the subject or forget it. If you have a problem with someone email them directly. Trying to antagonize someone or thinking you are going to make them look like an idiot usually backfires on ya.

As I stated, I may have found something that might be the culpret. I have not pulled the motor out of the frame yet to take a look besides it's Laconia bike week.

Pa or Admin,
If it doesn't stop then pull the thread, it isn't worth reading.


Post Thu Jun 15, 2006 5:30 pm

Posts: 332
Location: north central Ma.

have you considered the lack of a good additive package in the oil you use? For the past three or 4 years the EPA has been making over the road oils decrease this additive package that is needed in older motor and race engines.

Use the "valavoline racing oil" look for mpz additive on the back regular oil has all most none now.

Best oil i've ever used is BRAD PENN oil it's at the old Kendell plant that made the good oil now Kendell was bought out and sells pour quality oil. But the workers at the Bradford plant re-opened the plant and make the old formula as "racing oil" so it has the additives needed.

Torco MPz is a good one too.

Molybdenum phosphate zinc

I've been trying to get Brad penn to let me distribute there oil hear in MA but have not had any luck.

"Smok'in the competition NOT Tobacco"
"Transplant organs, Don't bury them!"
Why dwarf? 5/8 scale race cars!

Post Fri Jun 16, 2006 1:11 am

Posts: 2399
Location: atascadero cal usa
although it appears greybeard and i were throwing stones at eachother
we were only messing around
sorry to have screwed with the post jim

Post Sat Jun 17, 2006 6:09 pm

Posts: 3160
Location: Central Illinois, USA
While Jim does his forensics, and the rest cool their pride, I have re-read this thread repeatedly,... before it was truncated.

I am alarmed that appearances might place me on the same side of the fence as my dearest detractors. We do not share the same agenda, although we all serve the same end. (Vintage Motorcycling)

To my best interpretation, Panic has been irritated by requests for clarification, including my own.
I learned from my experiences on both sides of the podium that professing information to a student is not enough: Questioning is a vital part of the learning process, as the teacher learns far more from the student than he can ever teach himself.

Questions are what a tech forum are all about.
Stoopid newbie questions are not stupid.
Dumb questions never are.
Specific questions deserve specific answers. (When an honest opinion can be given!)
Rebukes and derision ruin credibility: Instantly.

Meanwhile, still wondering how you get eight volumes into six,.. with your foot,...

Patrick: Can you make it clearer to me?


Post Sun Jun 18, 2006 3:43 am

Posts: 591
Location: Crewe, Great Britain

Hi All,

I agree with Cotten, when a problem is not obvious, the one with the problem MUST be willing to have open ears as there's no way you gonna get a straight answer to an unseen before querry, the discussion will meander a bit to the benefit of all participants and the meandering will make some other guy's brain kick in with another possible hypothesis... As long as the sweet meandering does not involve too much hair raising white water rafting and personnal attacks, fair enough, we should all learn something in the end...

Jim's problem can only be broken to only 3 things: bad piston or clearences, oil or gas and/or a combination of these 3.

When I HAD to refill straight oil from a rally site, away from home and my "proper" supply of straight 30 or 40, the only place was usually a farm supply place where they usually stock straight 30 for lawnmowers and the like... Well, I don't do it anymore cause I know it costed me a few ring sets and scored pistons as these cheap straigh oils are not suited to high reving engines...

To come back to the 6 into 1 = 8, I'm not saying it will BE equal to 8, I'm just saying that compression, never mind how slow a rise it is, will generate heat and alter, on the up, the final figure.

Remember from your youth your hand pump for your bicycle tyres? It does get hot when you uses it. When it's done, let's say it's 7, let it cool down and then only will it go back to 6...


Post Sun Jun 18, 2006 9:44 am

Posts: 1676
Location: Interlaken, NY USA

Cotten, et al, Here's the appropriate section from Panic's paper that explains why the compression gauge reads higher than the straight math computation of compression ratio times atmospheric pressure, 14.7 lb/
(hope you don't mind the intrusion Panic)

From Panic's Paper:

"At cranking speed, the absolute cranking pressure ("CP") is a function of the 1.25 power of the effective compression ratio (i.e., for 8-1 compression ratio, use 8^1.25) times atmospheric pressure (14.7 psi @ sea level, etc.). This adjustment (1.25 power) is a polytropic value used in preference to the traditional adiabatic value (1.4) for the ratio of variable heats for air and similar gases at the temperatures present. This compensates for the temperature rise caused by compression, as well as heat lost to the cylinder. 1.25 is not accurate in all cases, since the amount of heat lost will vary among engines based on design, size and materials used, but provides useful results for purposes of comparison.
To predict a pressure gauge reading subtract 14.7 (or the correct atmospheric pressure at test elevation) to compensate for the fact that a gauge in free air reads "0", not 14.7 psi, even though atmospheric pressure is always present. "

As Patrick said, it's all due to the heating of the compressed gasses during the compression stroke. Here's the important point from Panic's treatse:

"(1.25) for the ratio of variable heats for air and similar gases at the temperatures present".

(i.e., for 8-1 compression ratio, use 8^1.25) times atmospheric pressure (14.7 psi @ sea level, etc.).
So it's not straight multiplication, thus the higher than expected psi readings.

You all already know this 'cause you've all seen Diesel engines run.
You comress gas, it heats, further raising its pressure. And this happens even at cranking speed or else a Diesel engine would never start, right? And some Diesels have compression ratios as low as 15:1, so you know there's some high temps in there.
Hope this helps.
And Jim, if you can wait a year, or so, this discussion has pushed me to the decision to finally do the sporty pump on by BT flatty over the winter next year. I'll do the external oil feed this time rather than drilled passages. It's just too easy not to try.

Dr. Dick

Post Mon Jun 19, 2006 6:40 am

Posts: 3160
Location: Central Illinois, USA
I share Panic's frustration.
Let me attempt to make this very short, with no intent for disrespect to anyone:

Once again, Panic's treatis (which has not been contested so far in any way) only reaffirms that when the rpm approaches zero, then the dynamic variables drop out, and simple PV=C prevails.

That's why a gauge test remains a useful diagnostic.
A lup-de-lup with the foot, even three in succession, dismisses dynamic conditions. No doubt a Mopar with an electric starter would venture into the realm of "effective" ratios, so Panic's treatis is quite explicit that the full potential is reached well beyond the undefined "cranking speed": "The point in the engine's RPM range where this reversion stops and full-stroke capture (or more!) occurs is frequently the torque peak."

Beyond that, ...
I am sincerely disheartened that Patrick in his youth didn't lube his airpump seals, but I fully agree that compression makes heat, as it is the crux of my contention that Jim's is quite elevated.
On a kicked compression test on a cold motor, the mass of the castings quickly reduces a minimal temperature change to nil.
Think how long and fast you would have to kick to even feel a temperature change on the exhaust header. A kicked compression test is of such slow rpm that it approaches static conditions.

Once again, my simple contention is that a 120psi gauge reading on a foot-stomped Flatty V-twin indicates radical compression. Great for competition, but short-lived.


Post Mon Jun 19, 2006 9:32 am

Posts: 801
Location: Planet Earth
Well I just got back from Laconia and have been doing some reading on this post. Got a lot to do in work so this will be short I think.

No biggie just thought it was all getting out of hand. My comments were not directed at you just at what was going on.

I am thinking about a Sportster pump or looking into possibly modifying a UL pump in some way.

As far as what has been posted as Cotten said I have a lot to look at but at this time other things have to take priority.

With regards to the cranking compression, the gauge reading was taken with the motor at running temp., throttle wide open and both plugs out. Also this is an electric start motor not a kick start.

One other quick question.

People have mentioned that Ethanol and oil don't play well together. I am not blaming the Ethanol. Just wondering if it might effect MMO when mixed with the gas?


Post Mon Jun 19, 2006 10:33 am

Posts: 332
Location: north central Ma.
Oil and Alky can gell the oil BUTonly in high % over 90% After all there are E85 cars comeing from the factorys now and thats 85% ethonal. I think it's more the close tollerances and the lack of a good MPZ addditive package.
Now 2 stokes run alot on alky and yes you must use specail oil or it will seperate out i had my RD350 set up for alky at one point 48hp in a bike that came as 19hp fun!!!!

"Smok'in the competition NOT Tobacco"
"Transplant organs, Don't bury them!"
Why dwarf? 5/8 scale race cars!

Post Sat Sep 09, 2006 12:14 pm

Posts: 530
Location: Ogden, Utah, USA
Jim: Did you ever get a look inside to find the real problem? I am still curios at what is gone wrong in there.
Steve H

Post Sat Sep 09, 2006 8:11 pm

Posts: 801
Location: Planet Earth

Nothing is jumping out as the actual cause. Piston clearence OK, rods are straight and square to the case deck, bore is square to the base flange, oil pressure and volume OK (working on a pump modification), head and cylinder deck square to the bore and flat, manifold tight (no leaks), head gasket seal was tight, pinion shaft and bushing OK. The list goes on and on as far as what I have checked. So I am going to chalk it up and rebuild and modify a few things.


Post Sun Sep 10, 2006 11:47 am

Posts: 530
Location: Ogden, Utah, USA
Jim: Just for my self, and I will miss stuff that has been posted before. The damage was not on a thrust face. That would be front to back.The damage is just where Panic and others have suggested that tempreture distortion will have the greatest effect on the bore dimension. It may be possible that what you have is crud from the wrist pin installation and the circlip retainer. If the wrist pin was installed from the cam chest side and any junk was suspended on that neat little shelf on the piston where the pin goes in you may have held it in place for later distribution during service.If the pins were installed the same way fornt and rear you may just see what is common from an assembly mistake.We are all creatures of habit and pattern. I have seen the same disaster when racing 2 strokes and it NOT a criticisum. Any time a process gives bad results you can learn from it. This may not be from bad habits just something overlooked. A small bit of any material can cause this kind of damage and the design feature of the parts may contribute to the overall effect. Look very close at the piston and wrist pin for any signs of any shit trapped in that area. It may be just a bit of crud that was working around in the clearence area caused by the thermal distortion and not a design flaw.Look at the ring grooves for any material that may have been caught and held in this area. A small chip is all it would take. A freind put in new rings with one small score mark from the ring tail on the piston. Sure this was a 2 stroke but the fail was very simaler. The 2 stroke cyl suffers from the same kind of distorton problems and has huge holes cut in it to add to the effect. One of the reasons the rings are pinned so the end wont go out the ex port. That will cause a dramatic fail for sure. Hard bits from break in may get trapped in this area as well and it my be time to look for a source. Not the best of news but if the piston and pin are not the cause you will want to find what is the source of the contamination or the fail will repeat it's self. Good luck and good hunting. Keep us posted on what if anything you do find. I can learn from your expensive fix without my dollars at risk. Sound cold but it is one of the reasons we do this kind of idea exchange isn't it? :)
Steve H


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