Lower crank pressure question...

[skiracer]

Thanks Mike.  Timing is at 2.5 BTC.  "X" measurement is well within the specs. Pipe is clean.  A couple others have mentioned using Loctite to me also.  Actually, the flat side of the seal with the metal band is remaining in place.  The actual sealing portion along with the small spring is what is coming apart and sitting on the crank shaft when I take it apart... Thanks for the input.

quote:Originally posted by 454MRW

I don't have access to a 76 MC5 250 timing information, but the 74 manual shows 2.55mm BTC, and the 79 shows 2.0-2.1mm BTC. If you're within those specs I would look for a restriction in the pipe possibly from carbon build up or debris from mice moving around while running. If you're not experiencing any spark knocks I would assume your deck height is okay. You might try using red Loctite threadlocker if the seals seem a little loose. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978-1979 MX-6 175 & 250 KTM's
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

1976 MC 5 Original Owner
1982 Suzuki PE 175
1976 Penton 175 XC
1985 20' Hi Point trailer

[454MRW]

I think I would try slightly less advance on the timing then, maybe 2.1-2.2 and see how it runs. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978-1979 MX-6 175 & 250 KTM's
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

[Daniel P. McEntee]

Originally posted by skiracer

Thanks Mike.  Timing is at 2.5 BTC.  "X" measurement is well within the specs. Pipe is clean.  A couple others have mentioned using Loctite to me also.  Actually, the flat side of the seal with the metal band is remaining in place.  The actual sealing portion along with the small spring is what is coming apart and sitting on the crank shaft when I take it apart... Thanks for the input.

   
   That is the part that freaks me out, you are tearing the rubber apart. that may be harder to do than to just unseat the seal. The thing that keeps coming to mind is a detonation of some sort, but you say it doesn't run like that. Another thought is defective seals, especially if both sets came from the same source. If you can't find out anything specific, I would try another source for the seals to try it again.
  Is it tearing the clutch side seal, or just the ignition side? Maybe that should be telling us something.??
   Type at you later,
   Dan McEntee

[skiracer]

Dan, I have ordered a couple seals from another source.  I don't think the clutch side is leaking, otherwise the oil from the tranny would be getting into the cylinder making the bike run rich. Mike, I will check the timing and try a lower number.  thanks!

1976 MC 5 Original Owner
1982 Suzuki PE 175
1976 Penton 175 XC
1985 20' Hi Point trailer

[454MRW]

How much side to side play is there on the crank? Just another thing to check. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978-1979 MX-6 175 & 250 KTM's
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

[skiracer]

None.....

quote]Originally posted by 454MRW

How much side to side play is there on the crank? Just another thing to check. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978-1979 MX-6 175 & 250 KTM's
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

[/quote]

1976 MC 5 Original Owner
1982 Suzuki PE 175
1976 Penton 175 XC
1985 20' Hi Point trailer

[Oldebonz]

Is the shaft where the seal rides perfectly smooth?I put a little anti seize on that area for initial lubrication .Seals are life and death important for me.I road race a large displacement Bultaco single,last thing I want is an air leak and seizure over 100mph! Or lower! I change my crank seals every 4-6 races,but the Bultaco has 2,back to back seals on each crank side in  easily removable seal holders.

[Richard Colahan]

I'm far from the most experienced mechanic on this site...but I'll say that this is the first time I've heard of the inner portion of a crank seal "seizing" on the crank end and tearing away from the outer portion.

My thoughts mirror others:
> correct dimension seal? Too small ID may be binding on crank end and causing problem.
> The wrong type of seal? I may be wrong here...but perhaps not all seals are designed to to the same thing...even though dimensions are the same. For example, a fork seal and a crank seal have 2 different requirements to meet.
> A rough surface on the running area where the seal lips meet the crank end??? As mentioned...it has to be smooth...
> I agree that a bit of lube on the lips is a good way to start out a new seal.

I don't think it's timing or back-firing...which would tend to blow the whole seal out of it's retainer.



Richard Colahan
1969 V1225
Upper Black Eddy PA

[Oldebonz]

Any chance the seal is in too far and rubbing on main bearing? Just thinking...  Some engines don't have a positive stop for the seal,can be cocked slightly?? One of the bearing companies I deal with now states that they won't sell seals that are for automotive or motorcycle use where the seal has to hold pressure and oil,had to sign a disclaimer that I guess they need for liability protection. Anybody know anything about this??

[skiracer]

Thanks Richard. Correct seal type and size. Crank is smooth, didn't put any lube on this latest installation.  I have concerns that the lube will works it's way onto the ignition.

quote:Originally posted by Richard Colahan

I'm far from the most experienced mechanic on this site...but I'll say that this is the first time I've heard of the inner portion of a crank seal "seizing" on the crank end and tearing away from the outer portion.

My thoughts mirror others:
> correct dimension seal? Too small ID may be binding on crank end and causing problem.
> The wrong type of seal? I may be wrong here...but perhaps not all seals are designed to to the same thing...even though dimensions are the same. For example, a fork seal and a crank seal have 2 different requirements to meet.
> A rough surface on the running area where the seal lips meet the crank end??? As mentioned...it has to be smooth...
> I agree that a bit of lube on the lips is a good way to start out a new seal.

I don't think it's timing or back-firing...which would tend to blow the whole seal out of it's retainer.



Richard Colahan
1969 V1225
Upper Black Eddy PA

1976 MC 5 Original Owner
1982 Suzuki PE 175
1976 Penton 175 XC
1985 20' Hi Point trailer

[skiracer]

No, seal is in the correct location.  KTM motors have a housing that the seal sits in, and it is then bolted to the center cases.

quote:Originally posted by Oldebonz

Any chance the seal is in too far and rubbing on main bearing? Just thinking...  Some engines don't have a positive stop for the seal,can be cocked slightly?? One of the bearing companies I deal with now states that they won't sell seals that are for automotive or motorcycle use where the seal has to hold pressure and oil,had to sign a disclaimer that I guess they need for liability protection. Anybody know anything about this??

1976 MC 5 Original Owner
1982 Suzuki PE 175
1976 Penton 175 XC
1985 20' Hi Point trailer

[454MRW]

Without initial lubrication upon startup the seal will experience accelerated wear and possibly fail. I always wipe a little premix lube on them when installing. Always. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978-1979 MX-6 175 & 250 KTM's
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

[skiracer]

Thanks Mike..

quote:Originally posted by 454MRW

Without initial lubrication upon startup the seal will experience accelerated wear and possibly fail. I always wipe a little premix lube on them when installing. Always. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978-1979 MX-6 175 & 250 KTM's
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

1976 MC 5 Original Owner
1982 Suzuki PE 175
1976 Penton 175 XC
1985 20' Hi Point trailer

[G Ellis]

Backwards....[][8D]

[skiracer]

Well, sometimes it is hard being of Polish decent.......  Turns out that I was installing the seal in backwards.........  Go figure.  I have only installed about 10 of these in my life time, must be old age setting in.  A big thanks to everyone that took the time to share their ideas on my seal issue.

1976 MC 5 Original Owner
1982 Suzuki PE 175
1976 Penton 175 XC
1985 20' Hi Point trailer