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Re: mail-order LSR [Re: kevin roberts] #788846 11/02/19 1:03 am
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Kevin why change the bearings so often?


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Re: mail-order LSR [Re: kevin roberts] #788953 11/02/19 9:26 pm
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i think they take a beating, mark. my compression ratio is pretty high, and i spin the motor up higher than i really should as well..

the first set i installed had bits of mung embedded in them when i took them out to look. my own incompetence at fully-flushing a used oil tank. i replaced those and ran them a season and a half, and then threw a rod.

so that meant a re-grind and undersize shells.

i think these are only the third shells i've had in the bike. but since i'm already that far into the motor to inspect it, the shells are relatively cheap.

should have done it with rod bolts too. those get only a single torque now, run or not.

.


every day you do not take a chance is a day of your life that you will never get back.
Re: mail-order LSR [Re: kevin roberts] #789009 11/03/19 10:17 am
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ARP will love you Kev, might get a best customer award wink only teasing it’s worth changing those bolts. If you haven’t done it’s worth getting the crank nitrited.


beerchug
Re: mail-order LSR [Re: kevin roberts] #789047 11/03/19 6:37 pm
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these were torqued during setup. turned out journals were ground but not polished enough, so they went back to the grinder and he took them down. but i i won't re-use the bolts.

[Linked Image from i.imgur.com]

these were torqued to stretch and in thier respective holes at the moment.

[Linked Image from i.imgur.com]

everything is color coded to avoid missing anythin

[Linked Image from i.imgur.com]

[Linked Image from i.imgur.com]


every day you do not take a chance is a day of your life that you will never get back.
Re: mail-order LSR [Re: kevin roberts] #789048 11/03/19 6:41 pm
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these were torqued during setup. turned out journals were ground but not polished enough, so they went back to the grinder and he took them down. but i i won't re-use the bolts.

[Linked Image from i.imgur.com]

these were torqued to stretch and in thier respective holes at the moment.

[Linked Image from i.imgur.com]

everything is color coded to avoid missing anythin

[Linked Image from i.imgur.com]

[Linked Image from i.imgur.com]


every day you do not take a chance is a day of your life that you will never get back.
Re: mail-order LSR [Re: kevin roberts] #789214 11/05/19 3:12 am
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I cannot see how rpm would worry rod bearings. I used to think lack of rpm was worse till I started driving my daughters old tip truck. Having the crank radius s rolled can strengthen against breaking.

Looking forward to seeing it racing again.


mark
Re: mail-order LSR [Re: Mark Parker] #789215 11/05/19 3:21 am
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Originally Posted by Mark Parker
I cannot see how rpm would worry rod bearings.



just inertial forces putting pressure on the big ends, even if the oil wedge stays coherent.

i think maximum piston speed on the long rod triumphs is something like 3000 feet per second at 6800, if my memory is right.

that's getting pretty vigorous, according to old gordon jennings.

Last edited by kevin roberts; 11/05/19 3:23 am.

every day you do not take a chance is a day of your life that you will never get back.
Re: mail-order LSR [Re: kevin roberts] #789234 11/05/19 8:43 am
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Originally Posted by kevin roberts
Originally Posted by Mark Parker
I cannot see how rpm would worry rod bearings.



just inertial forces putting pressure on the big ends, even if the oil wedge stays coherent.

i think maximum piston speed on the long rod triumphs is something like 3000 feet per second at 6800, if my memory is right.

that's getting pretty vigorous, according to old gordon jennings.

Triumph is about 3800 fps at 7000 rpm according to online calculators. Production cars like the Honda Civic R have somewhat long stroke of 86mm and can rev over 8000 rpm with piston speeds of 4500 fps...Production American V-8's can exceed 4000 fps, Drag race Pro Stock 500 cubic inch V8 pushrod engines are close to 7000 FPS..I beieve in Gordon's day 4200 fps was considered the maximun for racing engines..Your engine with MAP rods, forged pistons and a billet crank should be safe for 8000 rpm for limited durations..Nevermind the rod issue that was a freak problem..It's a question of engine design and money...


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: mail-order LSR [Re: kevin roberts] #789247 11/05/19 3:04 pm
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old gordon jennings agrees with you on it. this book was my introduction to motor theory way back when

Two Stroke TUNER’S HANDBOOK

A quick and easy method of establishing a limit for crankshaft speed is by
working with piston speed. Actually, with "mean" piston speed: pistons do not travel at
uniform velocity; they move from a dead stop at each end of their stroke, accelerate up to
a maximum speed that often is in excess of 120 mph, and then brake to another complete
stop. For convenience, we use just the mean piston speed and the safe limit for that, for
engines having bore-stroke dimensions within the range considered normal for
motorcycles, is about 4000 feet per minute. And mean piston speed may be calculated
very easily by applying the following formula:


Cm = 0.166 x L x N


Where: Cm is mean piston speed, in feet per minute
L is stroke, in inches
N is crankshaft speed, in revolutions per minute


Thus, using again the Kawasaki F-5 engine as an example, with L being 2.68-inches and
N given as 9000, we find that

Cm = 0.166 x 2.68 x 9000
Cm = 4000 ft/min

Here we have a theoretically-predicted limit that seems to agree quite closely with
observable reality in the field: Reports from those actually racing modified F-5
Kawasaki’s indicate that the engine does in fact retain acceptable (within the framework
of that word's meaning in racing) reliability when red-lined at 9000 rpm, and ravels with
horrifying abruptness if pressed further. Of course, it must be stressed here that few
engines, the F-5 not excepted, retain more than marginal reliability at mean piston speeds
of 4000 ft/min, and even this presupposes frequent replacement of the piston and the
crank/rod bearings.

You will be on far more solid ground if your engine is not asked to endure mean
piston speeds above 3500 ft/min. Anything above that takes an engine into the twilight
zone of reliability, and the ground between 3500 ft/min and the near absolute limit of
4000 ft/min is covered with unpleasant possibilities, but these often may be minimized
with the proper selection of materials and lubrication. I should note here that there are
exceptions to this rule among some of the old-fashioned, long-stroke engines, which tend
to have very light (and strong) reciprocating parts relative to their absolute stroke. An
example that comes to mind is the Bultaco 125cc TSS, which had a stroke of no less
2.36-inches (decidedly long for a 125) but which would, in “factory” road racing trim run
up to 11,500 rpm, just like the Yamaha TD-2 (with a much shorter, 1.97-inch stroke), and
that represents a mean piston speed of 4500 rpm. Obviously, Bultaco held the opinion
that the resulting thin-ish margin of reliability was acceptable, but their TSS never was as
predictably trouble-free as Yamaha's TD-2, which at the same crankshaft speed (11,500)
has a mean piston speed of only 3775 ft/min.


it was a sad day for motorcycling when he kicked the bucket. his writing style made motor engineering accessible to me for the first time. plugging numbers into his formula gives me 3900 feet per second at 7275 rpm

this book is online too, courtesy of somebody

http://www.amrca.com/tech/tuners.pdf

Last edited by kevin roberts; 11/05/19 3:11 pm.

every day you do not take a chance is a day of your life that you will never get back.
Re: mail-order LSR [Re: kevin roberts] #789251 11/05/19 3:34 pm
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Yes, learned it from reading Gordon and others...,, Modern example is a 5700cc Nascar V-8 with a 4.25 bore and 3.25 stroke. They run for 500 miles flat out at beween 7000 -9000 rpm with the piston speed at 9000 being 4800 fps...After 500 miles the engnes are still good for another race but the well funded teams do replace the rotating parts or the whole engine just to be sure...The Honda cars I mentioned will run what seems like forever at very high piston speeds...


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: mail-order LSR [Re: kevin roberts] #789263 11/05/19 4:59 pm
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I have just done the calculation for my Greeves with a 200cc Villiers engine.
The stroke is 72mm = 2.8346" and I rev it to 11,500 RPM so the mean piston speed works out at 5411 ft/min


BSA B31 500 "Stargazer"
Greeves 200 "Blue Meanie"
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GM500 sprint/LSR bike "Deofol"
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Re: mail-order LSR [Re: kevin roberts] #789294 11/05/19 11:50 pm
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that machine of yours is an exception everywhere. i don't know how it holds together anyway.


every day you do not take a chance is a day of your life that you will never get back.
Re: mail-order LSR [Re: kevin roberts] #789298 11/05/19 11:56 pm
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clayed the pistons and it ain't right.

i like to run 0.060 piston to valve clearance on the intake, and then 0.080 on the exhaust. the intake on this setup was fine, somewhere around 0.070:

[Linked Image from i.imgur.com]

but the exhaust is way way too close, around 0.010 only:

[Linked Image from i.imgur.com]

never had this issue before, so i'll look at possibilities tomorrow. could be i have the exhaust cam timing messed up, which is most likely. or the valve pockets in my pistons weren;t cut deep enough, but the pockets look just like the others i use.

need to check.


every day you do not take a chance is a day of your life that you will never get back.
Re: mail-order LSR [Re: kevin roberts] #789359 11/06/19 8:26 pm
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totally odd. i put the degree wheel on the exhaust and rechecked it, and i was a tooth and a keyway out, with the cam running around 88 BTDC, way, way retarded. obviously this was why the exhaust valve clearance was so little. with the tappets screwed down the motor couldn't even turn over. dunno ho i did that, but that's why checking things works.

anyway, went to the other keyway and swapped a tooth on the exhaust, rechecked the intake (it was fine), and the timing is where it should be, 104/108.

[Linked Image from i.imgur.com]
[Linked Image from i.imgur.com]


every day you do not take a chance is a day of your life that you will never get back.
Re: mail-order LSR [Re: kevin roberts] #789365 11/06/19 9:41 pm
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Well, you caught the mistake...


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: mail-order LSR [Re: kevin roberts] #789370 11/06/19 10:32 pm
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huge amounts of exhaust valve clearance now

[Linked Image from i.imgur.com][Linked Image from i.imgur.com]

intakes are okay too, but as usual the valve pocket is too small. i checked with ed valiket about making them larger, bu he said it would just delay them.

[Linked Image from i.imgur.com][Linked Image from i.imgur.com]

i just dremel them until they're large enough.might see about leaving the base gasket out this time around


every day you do not take a chance is a day of your life that you will never get back.
Re: mail-order LSR [Re: kevin roberts] #789374 11/06/19 11:36 pm
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Do you have an old valve that is a bit larger? I haven't done it, but they say if you cut some radial "teeth" into the top of an old valve, install it in the head without springs, install the head and bring your piston up to TDC, you can turn the old cut valve in a drill and use it to enlarge the pocket in the top of the piston ensuring that you have sufficient clearance all around.

If you leave the base gasket out, it's the same as milling the barrels or head. You will of course change the rocker angle slightly and you may have to shorten the pushrods and tubes. In any case, do it if you have sufficient clearance.

Tom

Last edited by koncretekid; 11/06/19 11:39 pm.

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Re: mail-order LSR [Re: kevin roberts] #789433 11/07/19 4:45 pm
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its not hard to widen the pocket around the bottom. i have to have the pistonz in my hands anyway to smooth and polish them. theyre juzt sitting in the jugz right now with no rings or circlipz while i check clearancez.

ill see about vertical clearances. while i had tbe head up to my nose i noticed that the left side combustion chamber took a smack around the rim that moved some metal. i didnt notice that before because i was concerned about the valvez, which appear okay. so i have to do some grinding there too. once i do that ill see what i can get away with.

rocker arm movement is pretty interesting az another tuning parameter. my exhauzt cam only has .373 and .374 inches lift, compared to the nominal .375, and mezsing with the centering of the rocker arms iz a variable i haven't studied much.

Last edited by kevin roberts; 11/08/19 11:31 pm.

every day you do not take a chance is a day of your life that you will never get back.
Re: mail-order LSR [Re: kevin roberts] #789462 11/07/19 11:17 pm
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got some more options on timing to look at as well. these are pretty unusual these days:

[Linked Image from i.imgur.com][Linked Image from i.imgur.com]


every day you do not take a chance is a day of your life that you will never get back.
Re: mail-order LSR [Re: koncretekid] #789490 11/08/19 12:45 pm
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Originally Posted by koncretekid


If you leave the base gasket out, it's the same as milling the barrels or head. You will of course change the rocker angle slightly and you may have to shorten the pushrods and tubes. In any case, do it if you have sufficient clearance.

Tom


Leaving out the base gasket on a Triumph has no effect on the tubes..The gasket is about .018 thick it's removal will have a slight effect on rocker geometry but from my expereince not a real issue...And aftermarket cams often don't have the same cam lobe heel height so the tappets might be slightly lower of higher than stock..But it's best to check all this stuff anyways..


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
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