Can't get it running

[Andreas Piepke]

Hi Penton enthusiasts,

After some time away from this I finally rigged up a pressure test for my 1973 KTM engine. Getting parts that work and are gas tight was an ordeal in itself. I tried 5(!) different pressure hoses before finally arriving at the on shown in the image below. I am using a valve opener hose which has a female NPT thread on one end and an appropriate spark plug connector with rubber o-ring on the other.



After pressurizing the engine to 5 psig I see the pressure dropping (exponential in time as expected) at a rate of about 0.0044 psi/s. This means that the pressure halfs in about 2 minutes. I sprayed the engine with soap water but can't find a leak. I guess at this point I have to conclude that (a) the engine is not gas tight, and (b) I have to take it out of the frame for closer inspection. I hope I don't need to dismantle it altogether! Any more ideas for what to do short of taking the engine out?

Cheers

Andreas

[brian kirby]

Definitely a leak somewhere, it should hold pressure longer than that.

Brian

[Dale Sonnenschein]

Pull the mag case off and the flywheel and ignition and spray the crank seal and the flange it's in with soapy water and see if maybe the leak is there. after that it may be the crank seal on the clutch side. Also spray the bottom of the engine and check the center case gasket.  Good luck. It's a pain to go through this after all your great work. The bike looks awesome.

73 Jackpiner
73 Husky 360 WR/RT
76 Husky WR360
78 husky cr250
10 ktm 250xc
02 bmw r1150r

[Andreas Piepke]

Hi All,

So Brian and Dale I've done what you said. After taking the magnet, ignition, and ignition holder off this is what I found:



There is oil on the seal holder. There was also a little oil on the back of the ignition holder. I pressurized the engine to 5 psi and found a tiny leak at the crank seal:



These are tiny bubbles, the leak is probably quite small. This side is easy to fix so I'll go and replace the seal and the gasket under the seal retaining plate. I hope that'll cure my problems! Is there any way to get to the gasket on the left side without taking the engine apart? I don't even know how to test the left side seal. I drained the transmission fluid, it doesn't smell like gasoline but not like ATF either. I cringe when thinking that I have to take the engine apart just to get to the seal.

Thanks for your input, keep sending ideas!

Andreas

[Dale Sonnenschein]

Andreas,
That may be the problem. I think if it were the trans side, it will suck trans oil in. It would show in the exhaust by showing more smoke than normal. I know the 250 I had was hard to start. Sometimes it's the routine as much as the bike. I kicked it slow thru 2 or 3 kicks and then kicked it to start. It's all a learning process.

73 Jackpiner
73 Husky 360 WR/RT
76 Husky WR360
78 husky cr250
10 ktm 250xc
02 bmw r1150r

[brian kirby]

I think you found your problem.

Brian

[Gordon Brennan]

I think I'd lead it out behind your house, and when it's not looking, hit it with a shovel.

[454MRW]

To check the other side seal, stick the crankcase filler vent hose in a container of fluid then pressurize the engine. If you see any bubbles, there is a leak.
Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978 KTM 250'S
1975 Can Am 175 TNT 250 conversion
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

[454MRW]

Gordon, does that scenario usually follow with a story to the kids that their favorite pet must have ran away?

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978 KTM 250'S
1975 Can Am 175 TNT 250 conversion
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

[Andreas Piepke]

Thanks for the tips! I think I will pass on the one requiring the shovel. The test with the bubbles is a great idea. I'll try this should the engine not be leak tight after replacing the right side seal.

Andreas

[Andreas Piepke]

Hi All,

So I took the seal holder off today and inspecting the seal showing the leak. The seal seems to be in good order, I cannot see an obvious problem with it. I took photos of both sides of the seal and seal holder:





The manual gives no value for how far to press the seal in. I choose a location relatively far out so the lubrication channel stays open. Have a look at the crank, the seal seems to sit at the far end of the sealing surface.



I am wondering whether I should simply press the seal a little further in and see whether or not this fixes the problem. I would appreciate any guidance you guys can give me on the proper position of the seal. I don't want to ruin the crank bearing by obstructing too much of the lubricating channel.

Thanks!

Andreas

P.S.: This is irrelevant for this string and the POG but for your enjoyment a picture of the other project I am working on, a 1973 Norton Commando with an electrical issue.

[454MRW]

Beware of old NOS seals found on eBay, sometimes they are not worth buying due to age and stiffness. NOS in this case means Not Often Sealing, lol. Get a new one from Al Buehner or match it up at a local parts store or bearing supply house with a fresh new one. Not sure on the positioning, but the as installed pics look like it should go in a little farther and polish up the crank surface and inspect for tiny slight rust pitting. Always apply a little sealant around the outside of the seal where it presses into the retaining plate. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1978 KTM 250'S
1975 Can Am 175 TNT 250 conversion
1976-78 125-400 RM's & 79 PE250 Suzuki & 2012 DR650
2007 CR125R Honda
1977 MC250 Maico

[Andreas Piepke]

Thanks Mike, I'll do that. The seal in the pictures was actually purchased new from Al. I see no problem with the seal itself.

Cheers

Andreas

[Daniel P. McEntee]

Again, the photos are outstanding! Almost like being there! As it sits now, it's not too difficult to do as you are thinking, push the seal a little further into the holder and re-pressure test it. The lip on the seal may not be seating correctly when it is. Might be possible to measure where the "sweat spot" on the crank shaft is by measuring off machines surfaces on the case and seal holder. Try and mate up the lip of the seal with the wear surface better. If the outside edge of the seal blocks the lubricating channel at all, perhaps it can be snipped a bit at that point and opened up?
  Like others have said, I think you found you problem.
   Good luck and keep us informed. Too bad you have had to do all this extra work, but this thread has been very informative and instructional.
   Thanks a lot,
  Dan McEntee

[slvrbrdfxr]

Andreas,
If it were me, I'd remove the seal to make sure the seal plate surface doesn't have any corrosion pits. I had that happen to me on an engine with a brand new seal which looked fine until I removed it. The corrosion pits were so deep that the air was actually escaping around the outside of the seal and not between the lip and crank journal. Can't hurt to look.
Dave McCullough