S.S.Bearing- What to Do about it??

[VicenteRC]

I bought the SS bearings at Boca Raton.  They told me to remove the 
seals.  I follow the instructions when fixed the OS 140 RX.  I will fix 
the Mintor and I won't remove the seals to check.  Looks like we have 
to experiment and find the best solution.  The problem is that will 
take a long time to report the results.

Vicente



----- Original Message -----
From: Ed Miller <edbon85 at optonline.net>
Date: Tuesday, August 5, 2003 8:33 pm
Subject: Re: S.S.Bearing- What to Do about it??

> I agree. Both left and right side main bearings on 2003 Harley 
> Twin Cam 88
> inch engines are roller bearings. Up to 2002 the left side ( 
> primary drive
> side ) was a Timken tapered roller. Harley found the larger non-
> taperedroller bearing eased assembly AND was able to handle much 
> greater loads. So
> much more the 2003 Harley Road King SVO bike has an 103 inch 
> version of the
> Twin Cam engine. Seems to me the way the crankshaft is made and 
> the way the
> front bearing is installed that most if not all the thrust load in 
> an OS 140
> RX is handled by the front bearing. Another fact supporting the roller
> bearing theory is the '99 and half the year '00 Harley Twin Cam 
> engines used
> a ball bearing on the outer side of the rear ( cylinder 2 ) 
> camshaft. This
> ball bearing failed on some bikes. The way it was installed it 
> handled only
> axial load, no thrust load. In December '99 Harley replaced it 
> with a roller
> bearing and the rear camshaft bearing failures stopped. These camshaft
> bearings are oiled solely by splash, not pressure. We might need 
> to make
> some thin shims the ID of the crank OD and OD just slightly less 
> in diameter
> than the inside edge of the roller bearing outer race for spacing. 
> Or we
> need a roller bearing with an inner race that has a small lip ( 
> flange ) on
> both sides.
> All this is based on the assumption the rear bearing is undersized 
> which I'm
> not thoroughly convinced of. I'm beginning to believe not only are we
> running the wrong percentage of oil in the big 2 strokes but we 
> should also
> be looking to use more Castor oil and less Synthetic oil in the 
> blend. The
> rear bearing in an OS 140 RX is larger in OD and width than those 
> found in
> all YS120-140's. The firing pulse on a YS 4 stroke is especially 
> violent and
> really tough on the con rod, wrist pin and rear bearing, not to 
> mention the
> detonation that is common on YS 4 strokes. Bearing failure on a YS 
> usuallyis the destruction of the cage whereas the bearing 
> "failures" on the RX seem
> to be roughness which indicates pits on the balls and/or the 
> races. Rust or
> dirt is usually the culprit for pits in the races and balls. Years 
> ago I had
> a YS61 rear exhaust and experienced short bearing life. I replaced 
> thatengine with a YS61 AR which had a SEALED stainless steel rear 
> bearing and I
> never had to replace the rear bearing in that AR. I was using a 
> 13x10 APC
> and 20 to 30% nitro in that AR so it was seeing a pretty good 
> load. Boca
> sells a packed with grease, sealed, stainless steel rear bearing 
> for the OS
> 140 RX, I intend to install it in my OS with the seals left intact.
> Ed M.
> ----- Original Message -----
> From: <patterndude at comcast.net>
> To: <discussion at nsrca.org>
> Sent: Tuesday, August 05, 2003 6:15 PM
> Subject: Re: S.S.Bearing- What to Do about it??
> 
> 
> >
> > You found roller bearings that fit an OS140RX???  Please provide a
> reference.
> > THis would be an amazing find.  I disagree with you that these 
> wouldn'thandle
> > the thrust load.  On the contrary, our bearings carry almost no 
> thrustload.
> > They handle radial load almost entirely.  I would think a roller 
> bearingwould
> > be a great solutions.  As evidence to this conclusion, look at what
> Zenoah,
> > Desert Aircraft, and other gas engine mfg do - they use roller 
> bearings.These
> > engines are designed for far more life than modelers put on them 
> and the
> > bearings are never changed.
> > --Lance
> >
> > --
> > District 6 AVP
> > www.aeroslave.com
> > > In a message dated 8/5/03 4:18:50 AM Pacific Daylight Time,
> rcaerobob at cox.net
> > > writes:
> > >
> > > >
> > > > Assuming that OS doesn't offer a solution to lubrication of 
> the rear
> bearing
> > > > on the 1.40, what other options are available?
> > > >     What mods could be made to the crankcase to permit more 
> oil flow
> back
> > > > there?
> > > >     Would increasing oil content of fuel make any difference?
> > > >
> > > > If the real core problem is undersizing of the bearing for 
> the load
> > > > application the motor endures, then a real fix would be a 
> redesign of
> the
> > > crankcase
> > > > to use a larger and wider bearing.  Pretty unlikely that 
> would happen,
> I would
> > > > guess.
> > > >     So what's the solution besides keeping the bearing suppliers
> > > > well-funded??
> > > >
> > > > Bob Pastorello, Oklahoma
> > > > NSRCA 199, AMA 46373
> > > > rcaerobob at cox.net">rcaerobob at cox.net
> > > > http://www.rcaerobats.net/">www.rcaerobats.net
> > > >
> > > >
> > >
> > > Continued - A larger bearing is a double edged sword, larger 
> bearingmeans
> > > larger balls and larger diameter races and thus higher surface 
> speed,between
> > > the balls and races at a given RPM.  I'm not enough of a 
> mechanicalengineer to
> > > say where the trade off is, but I know in other engines larger 
> bearingshave
> > > not solved the problem (OS .61).  The solution is a 
> tapered/timpkinbearing,
> > > I've tried to find a match, but no success, the problem is 
> that we are
> using a
> > > ball bearing in the wrong application, auto manufactures tried 
> this for
> years
> > > on wheel bearings, tapered bearings solved the problem.  I can get
> roller
> > > bearings that fit, but they will not stand the thrust load.  
> Again,stainless
> > > has
> > > worked for me, several different engines and I have a lot of
> data/experience,
> > > many thousands of flights on mine and others engines, most 
> recently the
> OS 140
> > > and believe me I've tried all the "fixes"  Interestingly I 
> just changed
> the
> > > bearing in a new OS 140 RX, just because it had 140 flights 
> and I was
> planning
> > > to go to a contest this weekend, bearing seemed fine.  Turns 
> out that it
> is a
> > > stainless bearing, with the seals removed (I've never found a 
> stainlesswithout
> > > seals).  The bearing was fine, no corrosion, I jumped the gun. 
> No for
> the
> > > rest of the story I had this engine apart for other reasons 
> and it was a
> year or
> > > so back so it's possible that I just changed the bearing 
> because I was
> in
> > > there, but I think I would remember and I keep pretty good 
> records so
> that is a
> > > doubtful answer.  It will be interesting to see it the new 
> engines start
> > > showing up with stainless bearings or if this was a fluke, 
> maybe they
> were out
> > > of
> > > bearings at the factory and used the bearing from the EFI or...
> > >
> > > Bob
> > >
> > > Bob
> > =====================================
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> >
> >
> 
> 
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