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boxershorts
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Albany, NY
Joined: 07/20/2011
Posts: 15

Well, in the process of restoring the /5 got most of the headlamp and electrics wired up but I noticed when I went to kick it was stuck. Rolls in neutral but when the clutch is popped it skids. I should have seen this way before but didn't. Anyone have ideas as to see what is frozen? I feel that it is not too serious because the bike was well cared for and garaged. Maybe just some light rust?
Any ideas as to what to do next would be appreciated.
Thanks, John

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6596
So, it should likes the

So, it should likes the tranny might be OK, at least in neutral...probably means the driveshaft and final drive are OK since they also turn in neutral. I'd probably be spraying a good penetrant into the spark plug holes, something like Aerokroil. I understand that a 50-50 mix of kerosene and ATF is an even better penetrant. Let it sit continue to spray...and wait. Time is what helps in this situation.

At what position are the pistons stuck? If they're all the way down, then there's a better chance that rust may have attacked the cylinder walls. If the pistons are up, that can help protect the walls from direct moisture.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

boxershorts
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Albany, NY
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Hi Kurt, Thanks for the

Hi Kurt,
Thanks for the reply. You certainly are an an asset to the posters here seeing all the responses by you I have seen including my post a few weeks ago, thank you. I will try the penetrant in the spark plug holes. I assume by ATF you mean transmission fluid. The last post I read on this subject said Acetone and ATF?
Assuming this frees things up, do I need to remove the cylinder heads and cylinders to remove the excess penetrant and polish the walls with something like #0000 steel wool? In other words, what are the steps after the penetrant and if this doesn't work can I remove the cylinder heads and tap the pistons with a wood block? How about piston rings?
Thanks, John

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6596
Thanks, and ooops..right,

Thanks, and ooops..right, acetone and ATF or automatic transmission fluid. But PB Blaster or Aero Kroil should do a good job too.

If the pistons are stuck and you end up getting them freed, I would certainly thing you're in for a complete teardown. I would imagine that crank bearings, etc., will need some attention. After the top end is off, you should examine the cylinder walls for possible damage. Clean them up with soapy water and get some light on them. They might be good with just a honing. But you'll also need to measure the bore dimension as well as the ovality to see what you have to do on the rebuild, either go with stock, first over, etc.

If the pistons are stuck, then I think things begin to approach the destructive stage. If the pistons are near bottom dead center, you could remove each cylinder and with help, rotate the crank so that each cylinder/head moves away from the case, exposing a small portion of the connecting rod. As a last resort, you may be forced to cut the connecting rod so that you can remove the cylinder/head and really begin to work on the stuck piston. The cylinder/head is more valuable than the connection rod. Once free you can being working on the stuck piston from the back side.

Have you tried removing the head? If you can get the head off, then you can more effectively work on the top of the piston. You could try some heat or maybe even some dry ice in the top of the piston to shrink it and get it to free up.

I would continue with the penetrant and wait this out...only go to the last resort when that's the final straw. Work at this from the least destructive techniques to the most destructive...hopefully somewhere along the way, it will let go.

Maybe some others have some ideas you could try.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

TrophyMoto
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upstate s.c.
Joined: 03/29/2009
Posts: 78
I made this to get stuck

I made this to get stuck pistons out. It has a nut welded to the other side.

  • img_1905.jpg
boxershorts
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Albany, NY
Joined: 07/20/2011
Posts: 15
Piston loosening device

So how does this work? I guess you bolt on to the cylinder bolts and that center bolt is like a ram rod where you hit this end with a mallet? Or do you screw it in slowly to press on the piston?

Thanks

TrophyMoto
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upstate s.c.
Joined: 03/29/2009
Posts: 78
Screw it (with heat!!) to

Screw it (with heat!!) to press out the piston! First time I tried it I could not believe how well it worked! It was one of those "DOH why did I not think of this before" moments!
I should also add I have fitted it with a "foot" on the piston end, so as to not tear up the piston too bad.

Dave Reina
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Brooklyn, NY
Joined: 11/21/2010
Posts: 91
Frozen Pistons

Hi John,
I would get some penetrant into the cylinders, Put an air hose nozzle in the spark plug hole with a rag around the nozzle and blow lots of penetrant around so that it gets pushed all around the joint where the cylinder and top ring meets. Maybe do this several times over a day. Then I would put the bike in 2nd or 3rd gear and gently rock it back and forth. This usually works if things are not totally nasty.
Once free you can decide if you want to try it without removing the cylinders.
Dave Reina

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Dave Reina
Brooklyn, NY

boxershorts
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Albany, NY
Joined: 07/20/2011
Posts: 15
Unstuck!

Thanks everyone for the input. I guess I am lucky because after spraying PB Blaster and letting it sit for a few days I rocked it in 1st gear and it broke loose. Now on to getting it started.

JT

wa1nca
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VBMWMO #8374
Ashfield Ma.
Joined: 09/27/2012
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I also made a similar puller

I also made a similar puller and it works great
I tried soaking the jug and heating it several times with no luck
The best thing about this is that you can't damage the rod bearings or crankshaft by pulling the jug from the piston
I have also heard that if you make a adaptor to fit into the spark plug and that is fitted with a standard grease fitting ( valve must be closed )
You then can fill the jug up with grease and it will come off again without any damage to the rod bearing or crankshaft
I don't like of putting the bike in gear and rocking it because it could damage the rod bearing or crankshaft

Tommy

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Tommy Byrnes
54 R51/3 55 R50 64 R27 68 R69US 68 Sears Allstate 250 (Puch)

Littlemicrocars
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VBMWMO #9343
Joined: 11/11/2017
Posts: 21
siezed pistons

for seized pistons I remove the push rods and fill the chambers with brake fluid, right up to the spark plug hole. let it sit overnight and then check to see if the brake fluid level as gone down. this means that its seeping past the rings and will eat the rust away.far stronger than penetrating oils. you can also attach a spark plug adapter that accepts an air line or grease fitting... if you use a grease fitting gun you can build up hydraulic pressure to push the brake fluid past the rings and never damage anything... if you use air pressure I hook up a gate valve in line to the spark plug fitting Do the barrel that has the piston closest to tdc first then rotate to the other side. each time backing off the gate valve then do the other side with pressure .. Back and forth .. rocking the rear tire is useless and hard on the trans, and drive shaft ,etc. Often the bmw ISETTA dyno has to be dealt with the grease gun hydraulic pressure method. you must have something to catch the dyno when it comes off, sometimes airborn for several feet---fun part Leo

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