Okay, I need a lesson in motor theory 101.... What causes excessive lower crank pressure; enough to push out the crank seal on the mag side. The motor on my 250 has now done it twice. This last time I ran the bike less than 6 hours. The bike ran great, never missing a beat. Any thought?
1976 MC 5 Original Owner
1982 Suzuki PE 175
1976 Penton 175 XC
1985 20' Hi Point trailer
Usually a good thing for starting...warpage on case where seal seats??Lubing seal outer surface when installing? Freeze seal,use hot air gun on case where seal fits ,press in place with fingers.No lube on seating surface.
James,
Pull the pipe off the bike and burn it out with an acetylene torch. I am guessing you have some kind of guests that moved into the pipe or some other exhaust obstruction. I did the same on Husky WR430 last spring and the problem was rodents in the pipe!
Thanks,
Kevin
Oldebonz has great points and just to be sure measure you new seal (OD) and measure the crankcase(ID). Had this happen three times by a competent Tech back in the 1970s and it turned out to be the wrong seal.
Ron Carbaugh
As a rule, I use steel cased CR seals in the crank area not rubber. My reasoning is the above problem plus rubber does not press straight. I go old fashioned CR brand and arbor press them with a little Gasgacinch as lube/glue.
Where do you get them?
Quotequote:Originally posted by kip kern
As a rule, I use steel cased CR seals in the crank area not rubber. My reasoning is the above problem plus rubber does not press straight. I go old fashioned CR brand and arbor press them with a little Gasgacinch as lube/glue.
1976 MC 5 Original Owner
1982 Suzuki PE 175
1976 Penton 175 XC
1985 20' Hi Point trailer
I too have had this happen to me with a 175 Husky pipe. I know this pipe is clear, thanks for the input Kevin.
Quotequote:Originally posted by KJDonovan
James,
Pull the pipe off the bike and burn it out with an acetylene torch. I am guessing you have some kind of guests that moved into the pipe or some other exhaust obstruction. I did the same on Husky WR430 last spring and the problem was rodents in the pipe!
Thanks,
Kevin
1976 MC 5 Original Owner
1982 Suzuki PE 175
1976 Penton 175 XC
1985 20' Hi Point trailer
Thanks! Very good points...
Quotequote:Originally posted by Oldebonz
Usually a good thing for starting...warpage on case where seal seats??Lubing seal outer surface when installing? Freeze seal,use hot air gun on case where seal fits ,press in place with fingers.No lube on seating surface.
1976 MC 5 Original Owner
1982 Suzuki PE 175
1976 Penton 175 XC
1985 20' Hi Point trailer
Okay, some more details to what happened.... Upon removing the backing plate for the mag, pieces of the seal were hanging on the crank shaft. When I removed the plate that holds the seal, the back half of the seal was still set in place within the plate. So basically the front half the seal tore away from the back half. Or, to put it another way, the rubber seal portion ripped away from the steel casing of the seal......
1976 MC 5 Original Owner
1982 Suzuki PE 175
1976 Penton 175 XC
1985 20' Hi Point trailer
I posted a photo on the POG Facebook page for you to see.
1976 MC 5 Original Owner
1982 Suzuki PE 175
1976 Penton 175 XC
1985 20' Hi Point trailer
I get mine from Applied Industrial, (CR Seals)
Thanks Kip!
quote]Originally posted by kip kern
I get mine from Applied Industrial, (CR Seals)
[/quote]
1976 MC 5 Original Owner
1982 Suzuki PE 175
1976 Penton 175 XC
1985 20' Hi Point trailer
I have been reading this thread with an interest in learning something out of it. In thinking about what you are experiencing, I thought about something a friend of mine told me years ago. He cautioned against using any kind of starting fluid to start a balky engine with, because it is much more explosive than a gas/oil mixture and you could literally blow out the main seals. This leads me to ask if you have had any problems starting the bike and done this, or have any problems with it backfiring really bad? Using really high octane fuel or some kind of exotic race gas? If the pipe is nice and tight, and you have a big backfire, the resulting pressure has to go somewhere and maybe the seals are a week point, especially when you think about the condition you found them in. Maybe some sort of timing issue? Just my uneducated wild a$$$@# guess.
Type at you later,
Dan McEntee
Dan, thanks for your interest and input. You have given great questions and observations. Okay, no back firing, no special gas just non ethonal. Bike starts on the second or third kick so no additives there. I checked to see if there was play in the crank bearing; none felt. If a crank bearing starts to go bad wouldn't I feel a lot of vibration from it? As far as the timing and compression I take a concerative stance.
1976 MC 5 Original Owner
1982 Suzuki PE 175
1976 Penton 175 XC
1985 20' Hi Point trailer
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
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.
Quotequote: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
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
QuoteOriginally 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
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
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
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
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.
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
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??
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.
Quotequote: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
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.
Quotequote: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
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
Thanks Mike..
Quotequote: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
Backwards....:D[:p]:)[8D]
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
No shame whatsoever! We have all done similar or worse brain farts!! It's just nice to figure out the problem and understand why!
Hundreds of views on this topic...my guess is more then one of us will make a mental...or written...note to ourselves to double-check direction of seal installations...just to be sure! [8D]
Richard Colahan
1969 V1225
Upper Black Eddy PA
I have always gotten seals in the right way but I once holeshotted a National and ran the bike out of gas shortly after the first corner because I forgot to turn the gas on. None of us are immune from brain farts.
Larry P
Along this same topic but on a Puch does anyone have opinion on seal direction? Puchs are DIFFERENT from most 2 strokes. The crank bearings are not lubed by 2 stroke mix. Both crankshaft seals are directly against the flywheels and then the bearings. Unfortunately shop manual says to place seal lips one way and parts says the other. Have seen them both ways. Ideas?
Get a hold of Matt at Motor West in Milwaukee.He is THE Puch guru.
Most older Huskys have the clutch side seal inboard of the lh main bearing...that bearing is lubed by the clutch/trans fluid...so that's not unusual. On the mag side the rh bearing is inboard from the seal...lubed by the pre-mix "mist".
However, on the PUCH, how would the magneto (dry) side bearing with an inboard seal get any lubrication?
Just wondering...[?]
Quotequote:Originally posted by t20sl
Along this same topic but on a Puch does anyone have opinion on seal direction? Puchs are DIFFERENT from most 2 strokes. The crank bearings are not lubed by 2 stroke mix. Both crankshaft seals are directly against the flywheels and then the bearings. Unfortunately shop manual says to place seal lips one way and parts says the other. Have seen them both ways. Ideas?
Richard Colahan
1969 V1225
Upper Black Eddy PA
Puch has a slot with a slinger that lubes mag side with tranny oil. I spoke with Matt some time ago and he didn't remember. I have several Puchs and haven't had mine apart in years so can't remember either.
thanks!
Quotequote:Originally posted by Larry Perkins
I have always gotten seals in the right way but I once holeshotted a National and ran the bike out of gas shortly after the first corner because I forgot to turn the gas on. None of us are immune from brain farts.
Larry P
1976 MC 5 Original Owner
1982 Suzuki PE 175
1976 Penton 175 XC
1985 20' Hi Point trailer