Freeing a Siezed Motor

[troyhamilton]

ive often thought if you added air pressure thru a air hose at lo presure it would push the acetone/trans fluid down faster to break the cyl loose

[canuck750]

That would be simple, my snap-on knock off compression gauge kit has hoses with air connections, it would be simple to throttle back my air pressure to say 5 psi and attach the air to the compression gauge hose threaded into a spark plug hole. But it will depend on the valves being closed and the chances of that for both cylinders is slim. Still neat idea.

[troyhamilton]

yeah right on about the valves must be closed

[Rough Edge racing]

Now there's a testament to the ruggedness of a flat head Ford!

  Nearly 100 percent of Ford flatty V8's have cracked blocks...There's even a list of good and bad cracks....Excessive force leads to more problems....

 I used to into vintage trucks and freeing up rust seized pistons was common...A lot of pounding and beating got things freed up and also bent connecting rods...You would be surprised how easily rods bend..You would be surprised that a low speed engine will run ok with bent rods...I wouldn't force something like a performance  bike engine.If it doesn't free up easily with the usual oil in the cylinders..Pull the head(s) and rig a auto damper puller across the bore and use the screw thread to push down on the piston...Just break it loose don't try to move it....

[pete roper]

You're all still assuming it has a cylinder locked in the bore. What if it isn't? One of the things these bikes were famous for is buggering their starters, can't remember the exact details but it locked them solid! If it's an electric start model the pistons and barrels may be fine but it may have a locked starter clutch, or sprag, or whatever bit of shit they have? Could also be a locked main or big end! Why assume it's a piston in a bore?

Pete

[Rough Edge racing]

You're all still assuming it has a cylinder locked in the bore. What if it isn't? One of the things these bikes were famous for is buggering their starters, can't remember the exact details but it locked them solid! If it's an electric start model the pistons and barrels may be fine but it may have a locked starter clutch, or sprag, or whatever bit of shit they have? Could also be a locked main or big end! Why assume it's a piston in a bore?

Pete

  Exactly, I asked early on that the cause needs to be determined ....But the flow when with a corrosion seizure...

[Antietam Classic Cycle]

You're all still assuming it has a cylinder locked in the bore. What if it isn't? One of the things these bikes were famous for is buggering their starters, can't remember the exact details but it locked them solid! If it's an electric start model the pistons and barrels may be fine but it may have a locked starter clutch, or sprag, or whatever bit of shit they have? Could also be a locked main or big end! Why assume it's a piston in a bore?

Pete

Mine "buggered" it's sprag, but that didn't lock anything up, I just had to kick start from then on. Bottom-end is a possibility - it's ball and roller bearing mains and roller bearings for the rods. Think they supported the crank well enough? 

[dguzzi]

Wonder if Evapo-rust might help (if its rings) I've seen that stuff work magic on rust.

[canuck750]

You're all still assuming it has a cylinder locked in the bore. What if it isn't? One of the things these bikes were famous for is buggering their starters, can't remember the exact details but it locked them solid! If it's an electric start model the pistons and barrels may be fine but it may have a locked starter clutch, or sprag, or whatever bit of shit they have? Could also be a locked main or big end! Why assume it's a piston in a bore?

Pete

I may get lucky and find its not piston or crank! that would be a nice surprise, sounds like I need to do some examination / disassembly before I start with filling the lump with release agents.

Thanks Pete, I remain hopeful.

[Antietam Classic Cycle]

Wonder if Evapo-rust might help (if its rings) I've seen that stuff work magic on rust.

Now there's a thought!  The Morini engine I'm rebuilding had been disassembled and the internals left to rust in a damp basement. I soaked all of it in EvapoRust and the better part of it came loose, some of it was even reusable...

[SmokinJoe]

My two cents: After you make sure best you can that it's really the pistons that are stuck, take the head off so you can see any apparent damage. I use penetrating oil and a hair dryer or heat gun set on low. I oil it up, heat the cylinders from the outside at the ring level and try rocking the rear wheel in gear every few days till I either give up or it does. I don't give up easily. I use similar tactics of oil and mild heat on recovered antique firearms. An 1866 found underground after the plains Indian wars took me a year to properly disassemble.

[Muzz]

Depending on the machine, it's construction and where in the bore the pistons are, you can sometimes free the barrel and lift. If there is movement up you could assume that it is the piston rather than the crank. No movement, well, it could still be either.

[canuck750]

This is the bike I purchased, it has been listed on the Canadian Classic Bike Exchange for a long time and before that I saw it a shop in Calgary years ago, it just kept poping up and as much as I tried I just couldn't pass on it.



"1974 Benelli Tornado. 650cc . Motor is stuck, In need of a full restoration. "

I have ordered a full set of gaskets, cables, rubber pieces and seals from a Benelli parts supplier in Germany. http://www.benelliparts.de/. link courtesy of "Guzzista". Looks like most of the parts are available.

I think it will fit nicely between a Moto Guzzi V7 Sport and a Laverda SF1.

This Benelli also shares the Delorto VHB29 carbs, CEV and Bosch electrical, and Borrani rims common to Guzzi. Front forks are Marazochi and the rear shocks are the same Ceriani as on my Laverda 750 SF. Wolfgang stocks parts for both. Instruments are 80mm Veglia, and headlight is the similar to the CEV on the V7 Sport. I found a used set of side covers on Ebay.

[Mark Dasher]

Jim,

I recently have been dealing with reviving a 1928 Triumph Model NSD (550cc).  It probably has been sitting for 50+ years.  I soaked it in Kroil and gave the heat/cool cycles for a month or so, then adapted a zerk fitting to the spark plug hole and pushed the piston out with a pneumatic grease gun.  Took maybe five minutes!  This is a blind head engine (single casting head and cylinder) which actually made it simpler.  Valves both closed of course...

One other break I had was that the piston was about 1/3 way down stroke, so I was able to lift cylinder up and clean up rust on cylinder walls under the piston skirt.  If your pistons are stuck in that Benelli, I doubt they will be as bad as they were in this relic!  :)  Pics below:

View under piston.  NOT pretty!

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Hydraulic pressure doing it's magic!

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Voila!

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This is "before" the revival.  I'm not restoring this bike.  Just bringing it back to life and keeping all that wonderful patina!
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Acetylene tail light

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[Aaron D.]

The Tornado is interesting, super short stroke and all. Quite revvy. I seem to have heard it was one of the competitors for the police project that originated the V7, that would be cool if it's true.

So Jim are you planning on recreating the Italian '70s bike scene? My friend did a " 4 horseman" collection from the decade, a LeMans, Laverda, Ducati, MV. The Benelli makes a fascinating addition.

Mark, I love that Triumph. And I do enjoy sidevalve engines-don't know iI could handle the fixed head design!

[pressureangle]

By far the best penetrant in the U.S. is Kroil.

http://www.kanolabs.com/

Kroil, time, and heat if possible will get you there. The most important ingredient is patience.
Another useful tool is Evap-O-Rust (harbor freight) but it needs to be used first as its water based and won't displace oils.
I've never used the grease fitting method but that's going into the memory banks for the future.

[Mark Dasher]

The Tornado is interesting, super short stroke and all. Quite revvy. I seem to have heard it was one of the competitors for the police project that originated the V7, that would be cool if it's true.

So Jim are you planning on recreating the Italian '70s bike scene? My friend did a " 4 horseman" collection from the decade, a LeMans, Laverda, Ducati, MV. The Benelli makes a fascinating addition.

Mark, I love that Triumph. And I do enjoy sidevalve engines-don't know iI could handle the fixed head design!

I understand the Tornado's were quite quick and more powerful than their contemporaries - maybe approaching 100hp per litre?

Yes, Aaron it's been a challenge so far!  It took me some time to find someone to bore and sleeve the cylinder.  It was too rusted to bore oversize.  The crank has a loose crankpin and the mains are shot of course, but it's all fixable and I've found a couple of good sources in the UK for parts.

[Mark Dasher]

By far the best penetrant in the U.S. is Kroil.

http://www.kanolabs.com/

Kroil, time, and heat if possible will get you there. The most important ingredient is patience.
Another useful tool is Evap-O-Rust (harbor freight) but it needs to be used first as its water based and won't displace oils.
I've never used the grease fitting method but that's going into the memory banks for the future.

Kroil is absolutely the best stuff and yes, patience is the key!  :)  I let this thing soak in Kroil for at least a month before using the grease gun method.

[Antietam Classic Cycle]

The worst thing about the Benelli 650 Tornado S is vibration - the higher you rev it the worse it gets. That's why they have the "porcupine" footpeg rubbers and nearly everything (except the engine!) is rubber mounted. 

[TBShorty]

My son bought a 76 T140 from a guy in Maine.  He said it was stuck in gear when he parked it in a crawl space/basement with a sand floor.  It was there for 23 yrs. and the only salvageable sheet metal was the gas tank and headlight bucket.  He took the engine to a Brit Bike repair shop in Phoenix where the tried for several weeks to free the pistons.  Finally had to hole saw through the piston crowns and pry the rest out.  The pistons were junk anyway from corrosion.  Interesting that the bottom end was in great condition.  They cleaned out the sludge trap stuck in new bearings, freed up the clutch and fitted new pistons with over bored cylinder block.  Silly thing runs great.

[canuck750]

Nice work Mark! and thanks for the tips. I am going to find some of that Kroil stuff.

I would like to get one of each of the Italian manufacturers early 1970's models, I doubt it would include a MV and even a Ducati is looking like a hard pill to swallow. But the Laverda, Benelli and maybe a Morini would be a nice to go with the Moto Guzzi. I have really fallen for the Laverda 750 and I think the Benelli will be just as interesting.