Changing crank seals on an RD-400
Lee K. Gleason
its procedures assume a complete teardown is required, and goes into the
detail necessary to completely dissasemble engine & trans.
I'm wondering if I can get by with substantially less dissasembly. Anyone
done one of these lately? Can I split the cases just by removing the bolts
in the bottom of the lower case? Any other advice for this project?
--
Lee K. Gleason N5ZMR
Control-G Consultants
lee.g...@comcast.net
Nagarjuna's Catuskoti clawed me!
> � I'm wondering if I can get by with substantially less dissasembly. Anyone
> done one of these lately? Can I split the cases just by removing the bolts
> in the bottom of the lower case? Any other advice for this project?
It sounds like you're the guy with a manual and some tools that TOG
keeps warning us about...
Do actually think that you can pull the crankshaft and pistons out
through the bottom?
If you could, how would you ever get the piston rings back into the
cylinder bores without breaking them?
S'mee
> My 77 RD-400 needs new crank seals. I have the factory service manual, but
> its procedures assume a complete teardown is required, and goes into the
> detail necessary to completely dissasemble engine & trans.
>
> I'm wondering if I can get by with substantially less dissasembly. Anyone
> done one of these lately? Can I split the cases just by removing the bolts
> in the bottom of the lower case? Any other advice for this project?
Follow the manual...duh. BUT if there is no need to disassemble the
transmission don't. Oh and ignor NCCM aka Krusty, Gael etc...he's an
all around idiot and pervert.
The Older Gentleman
> My 77 RD-400 needs new crank seals. I have the factory service manual, but
> its procedures assume a complete teardown is required, and goes into the
> detail necessary to completely dissasemble engine & trans.
>
> I'm wondering if I can get by with substantially less dissasembly.
No
>Anyone
> done one of these lately?
No
> Can I split the cases just by removing the bolts
> in the bottom of the lower case?
Yes, but it won't help.
> Any other advice for this project?
Hand it over to someone who knows what they're doing, or have them
standing by.
--
BMW K1100LT Ducati 750SS Honda CB400F Triumph Street Triple
Suzuki TS250ER GN250 Damn, back to six bikes!
Try Googling before asking a damn silly question.
chateau dot murray at idnet dot com
S'mee
Gentleman) wrote:
> Lee K. Gleason <lee.glea...@comcast.net> wrote:
>
> > My 77 RD-400 needs new crank seals. I have the factory service manual, but
> > its procedures assume a complete teardown is required, and goes into the
> > detail necessary to completely dissasemble engine & trans.
>
> > I'm wondering if I can get by with substantially less dissasembly.
>
> No
>
> >Anyone
> > done one of these lately?
>
> No
>
> > Can I split the cases just by removing the bolts
> > in the bottom of the lower case?
>
> Yes, but it won't help.
>
> > Any other advice for this project?
>
> Hand it over to someone who knows what they're doing, or have them
> standing by.
>
Having NOT torn down an RD I'll take for granted your advice is
better. 8^)
Bill Smith
<lee.g...@comcast.net> wrote:
> My 77 RD-400 needs new crank seals. I have the factory service manual, but
>its procedures assume a complete teardown is required, and goes into the
>detail necessary to completely dissasemble engine & trans.
>
> I'm wondering if I can get by with substantially less dissasembly. Anyone
>done one of these lately? Can I split the cases just by removing the bolts
>in the bottom of the lower case? Any other advice for this project?
Take the clutch cover off and remove the clutch. Behind it you will
find a flat ring that's attached to both the upper and lower cases
with three screws (this helps axially locate the transmission main
shaft bearing), once you remove it (and the alternator along with it's
cover, of course) you can split the cases. With both pistons at mid
stroke you can lift the crank enough to replace the seals. When you
drop the crank back in, make sure that the little locating bumps on
the bearings are in the recesses machined for them in the cases along
the parting line.
This a quick and dirty (literally) way to do it, but I wouldn't
recommend it. You must clean all the adhesive off the mating surfaces
to insure a leak free assembly, if you don't you could have a lean
condition and a piston seizure as a result. This is difficult to do
with the transmission and crankshaft in place with a big possibility
of crud in both of them after you're finished with the assembly.
It doesn't take that long to do it right, these are hammer simple
engines to work on. Disassemble it completely, inspect everything as
long as you are in there and reassemble it clean, you'll be happier.
Doing it right once is much quicker than having to do it twice.
Bill Smith
Nagarjuna's Cataskoti clawed me!
> Take the clutch cover off and remove the clutch. Behind it you will
> find a flat ring that's attached to both the upper and lower cases
> with three screws (this helps axially locate the transmission main
> shaft bearing), once you remove it (and the alternator along with it's
> cover, of course) you can split the cases. With both pistons at mid
> stroke you can lift the crank enough to replace the seals. When you
> drop the crank back in, make sure that the little locating �bumps on
> the bearings are in the recesses machined for them in the cases along
> the parting line.
What about the labyrinth seal between the two crankshaft halves?
Does it ever wear out and leak air back and forth between the two
crankcase sides?
Vito
| Take the clutch cover off and remove the clutch. Behind it you will
| find a flat ring that's attached to both the upper and lower cases
| with three screws (this helps axially locate the transmission main
| shaft bearing), once you remove it (and the alternator along with it's
| cover, of course) you can split the cases. With both pistons at mid
| stroke you can lift the crank enough to replace the seals. When you
| drop the crank back in, make sure that the little locating bumps on
| the bearings are in the recesses machined for them in the cases along
| the parting line.
|
| This a quick and dirty (literally) way to do it, but I wouldn't
| recommend it. You must clean all the adhesive off the mating surfaces
| to insure a leak free assembly, if you don't you could have a lean
| condition and a piston seizure as a result. This is difficult to do
| with the transmission and crankshaft in place with a big possibility
| of crud in both of them after you're finished with the assembly.
|
| It doesn't take that long to do it right, these are hammer simple
| engines to work on. Disassemble it completely, inspect everything as
| long as you are in there and reassemble it clean, you'll be happier.
| Doing it right once is much quicker than having to do it twice.
|
This fits my recollections.
The man who tuned our TZ engines believed that at least some seal problems
were caused by worn main bearings that let the crank move up, down &
sideways in the seals so he recommended replacing the bearings and both the
end and mid seals whenever changing any of them. They used to be cheap from
a bearing supply house if not from Yamaha.
Pender
"Vito" <vi...@cfl.rr.com> wrote in message
news:4b008070$0$4953$9a6e...@unlimited.newshosting.com...
bottle during a hurricaine and it didn't even hurt the turkey.
Bill Smith
clawed me!" <macm...@gmail.com> wrote:
>On Nov 15, 10:57?am, Bill Smith <squand...@comcast.net> wrote:
>
>> Take the clutch cover off and remove the clutch. Behind it you will
>> find a flat ring that's attached to both the upper and lower cases
>> with three screws (this helps axially locate the transmission main
>> shaft bearing), once you remove it (and the alternator along with it's
>> cover, of course) you can split the cases. With both pistons at mid
>> stroke you can lift the crank enough to replace the seals. When you
>> drop the crank back in, make sure that the little locating ?bumps on
>> the bearings are in the recesses machined for them in the cases along
>> the parting line.
>
>What about the labyrinth seal between the two crankshaft halves?
>
>Does it ever wear out and leak air back and forth between the two
>crankcase sides?
It leaks all the time, even when new, but not enough to cause a
problem since fuel air and oil are being exchanged between the two
crank cases. All the seal has to do is slow the exchange down a lot. I
always replaced them whenever I rebuilt the crank assembly.
Bill Smith
Lee K. Gleason
Hmmm...given that, I might not want to do it myself. Anyone know a shop
in Houston that can be trusted to work on a vintage two stroke? I have
motorcycle T-shirts older than the mechanics in most of the places round
here, and I doubt most of them have ever heard of a two stroke...
Robert Bolton
<lee.g...@comcast.net> wrote:
> My 77 RD-400 needs new crank seals. I have the factory service manual, but
>its procedures assume a complete teardown is required, and goes into the
>detail necessary to completely dissasemble engine & trans.
>
> I'm wondering if I can get by with substantially less dissasembly. Anyone
>done one of these lately? Can I split the cases just by removing the bolts
>in the bottom of the lower case? Any other advice for this project?
The RD-400 looks like a 2-stroke (I googled a few pics). If so, it
shouldn't be very hard to pull the engine out of the bike and take the
top half off. Not having a valve train to mess with makes pulling
thing apart a snap. With my Suzuki 200, I was able to slip the
cylinders back over the pistons without using any tools.
Robert
The Older Gentleman
> The RD-400 looks like a 2-stroke
Well, no shit, Sherlock ;-)
> (I googled a few pics). If so, it
> shouldn't be very hard to pull the engine out of the bike and take the
> top half off.
Ye-ess...
> Not having a valve train to mess with makes pulling
> thing apart a snap.
Yeeee-essss...
>With my Suzuki 200, I was able to slip the
> cylinders back over the pistons without using any tools.
And how do you access the crankshaft from the top end? Youy've still got
the split the cases.
You don't really have a clue how to help here, I'm afraid.
je...@somewhereinharris.com
S'mee
Gentleman) wrote:
> Robert Bolton <robertboltond...@gci.net> wrote:
> > The RD-400 looks like a 2-stroke
>
> Well, no shit, Sherlock ;-)
>
> > (I googled a few pics). If so, it
> > shouldn't be very hard to pull the engine out of the bike and take the
> > top half off.
>
> Ye-ess...
>
> > Not having a valve train to mess with makes pulling
> > thing apart a snap.
>
> Yeeee-essss...
>
> >With my Suzuki 200, I was able to slip the
> > cylinders back over the pistons without using any tools.
>
> And how do you access the crankshaft from the top end? Youy've still got
> the split the cases.
>
> You don't really have a clue how to help here, I'm afraid.
shame it wasn't a Titan eh?
Nagarjuna's Cataskoti clawed me!
> shame it wasn't a Titan eh?
You'll never fix that Titan by pounding your keyboard...
S'mee
says the bum Grumman fired becuase he wouldn't vacume out the LEM
"that's womens work" LOL what you don't know about me won't give you a
stroke you incompetant failure.
JohnAinLA
When the trannie seals went out on my RZ-500 we did all the seals and
the
bearings too. Figured while it was open take care of it all. And
really not
that much more work after taking the motor out and splitting the
cases.
Hey, it's a 2-smoke! How much is there inside andyway!
HTH,
JohnA in LA, CA USA
The Older Gentleman
> Hey, it's a 2-smoke! How much is there inside andyway!
Helluva lot on an RD500 ;-)