So I picked up an 1991 evo police bike with a seized engine. No idea why it seized. Maybe from sitting over 10 years or maybe overheated. Or other reason. The front cylinder came off easily but the rear piston is stuck in the cylinder and won't let go. I tried soaking with acetone and ATF for a week and hitting it with a hammer and block of wood. No luck. I am now soaking it in kerosene but not very hopeful. I will do a rebore with new pistons anyway so I don't mind if piston breaks.
Does anyone have any ideas on a better way to remove the piston. The engine is still in the bike so I cant get a clean angle on it with a hammer and 2x2. And the piston is about 3/4 way down. Thanks
my idea would require the engine out. take the base nuts off turn the motor over so the piston and barrell comes up and take the piston off at the conrod
Odds are your going to be going though the whole thing anyways, so a little persuasion isn't going to affect the end game. What I do when I'm going though old Honda 90 engines that've been froze up for yrs., is to use an Air hammer gun with a broad hammer head on it, and just rattle the piston down & the flywheels will roll over, make sure the other rod isn't just dangling & flopping around. Your going to get new pistons anyways, and the wrist pin bushing is probably shot too already.
P.S. Its a '91, there's a good chance the case are garbage, so don't discount the idea of a create engine.
So the front cyl is off. If you pull up on the front c-rod does the rear cyl (assume the head is off) come up off the case? That is, is the main crank free and loose? Is there scoring on the rear cyl? Wrist pin keepers do do a number on the cyl / bottom end once they pop out of the piston pin slot.
Place a thick piece of metal on piston ,then bolt a piece of metal accross bore that is tapped for a fine thread with bolt to push on piston.
Rusted piston rings are really hard to get loose. Heating the cylinder short of warping it "may" allow you to press the piston free.
Quote from: tomfiii on September 25, 2019, 02:03:50 PM
Place a thick piece of metal on piston ,then bolt a piece of metal accross bore that is tapped for a fine thread with bolt to push on piston.
All good ideas but I may try this one first.
Quote from: Toomuchstuff on September 25, 2019, 05:29:35 PM
Quote from: tomfiii on September 25, 2019, 02:03:50 PM
Place a thick piece of metal on piston ,then bolt a piece of metal accross bore that is tapped for a fine thread with bolt to push on piston.
All good ideas but I may try this one first.
Be careful not to pull the studs from the case. The early studs seemed to be prone to that just on their own without the added stress of what you propose.
:agree:
I would soak it for a couple days with Kroil or any other penetrating oil, then use an H-beam puller held across the bore with two of the cyl studs, and try to push it loose. Something like this:
[attach=0]
Hopefully the studs don't come loose before the piston does!
-JW
I am a little concerned about the studs in an old case so I think I will bolt a steel plate with a hole in the middle to the 4 studs and bolt my h beam puller to that. That way 4 studs are taking the load instead of 2.
Thanks for all the ideas. I will update once I attempt it.
Put your torch on the piston, get it bad hot. When it cools the piston should come free with a few taps from a dead blow.
If you put a puller on the head studs, do not exceed about 45 pounds foot when you tighten it down against the piston. Leaving some pressure on it over night might help, but there is a lot of risk to the case involved.
This engine will have be completely gone through. Might as well pull the engine now. If that cylinder can be raised off the case, you could rig up a contraption to grap the base of the cylinder instead of using the cylinder studs. If you aren't already aware, EVO engines were notorious for weak engine cases, especially around the cylinder studs.
Quote from: turboprop on September 26, 2019, 08:17:48 AM
This engine will have be completely gone through. Might as well pull the engine now. If that cylinder can be raised off the case, you could rig up a contraption to grap the base of the cylinder instead of using the cylinder studs. If you aren't already aware, EVO engines were notorious for weak engine cases, especially around the cylinder studs.
that makes sense too. but maybe he dosent want to remove the engine. i would also try heat from a oxy torch
So after work I went into the garage to try the torch method because I was concerned about damaging the cases with the puller.
I lifted up the cylinder and it lifted right off leaving the piston and rod exposed. Soaking it in kerosene for a week actually worked very well.
Thanks for all your help again.
K I S S method! :up: :wink:
Quote from: koko3052 on September 26, 2019, 07:55:28 PM
K I S S method! :up: :wink:
Keep it Soaking Stupid? :teeth:
Quote from: Toomuchstuff on September 26, 2019, 05:01:48 PM
So after work I went into the garage to try the torch method because I was concerned about damaging the cases with the puller.
I lifted up the cylinder and it lifted right off leaving the piston and rod exposed. Soaking it in kerosene for a week actually worked very well.
Thanks for all your help again.
a great result.patience.whats the next step.a previous post said the whole engine needs going thru. why ?
If it sat long enough for the rings to rust & stick, what kind of shape do you think the crank & main bearings are in?
Quote from: rigidthumper on September 27, 2019, 05:41:30 AM
If it sat long enough for the rings to rust & stick, what kind of shape do you think the crank & main bearings are in?
The piston wasn't rusted. It seems like they were all gummed up with a varnish like substance. I think the previous owner may have put some oil or something else into the spark plug hole and then let it set for years.
I am not sure what the next step is but it will definitely need a rebore. I may pull the motor just to clean the cases and have a look inside.
Better check it for tight rods! I bought a engine out of a wrecked bike, little to no wear in the top end, thinking I could do a top end, cam and lifters . The rear rod had a tight spot when pushing it through by hand, not real tight but you could slightly feel it at one point. I wound up putting a new crank and rebuilding the whole motor....
Quote from: tomfiii on September 25, 2019, 02:03:50 PM
Place a thick piece of metal on piston ,then bolt a piece of metal accross bore that is tapped for a fine thread with bolt to push on piston.
A long time ago I had a customer bring me a an old 80 UL. Same thing you got going on. I tried alot of different things but in the end made a puller similar to this and it that worked. I Used A short piece of Oakwood though and a piece of angle iron drilled to go into the head bolt holes.
I realize he got'r done, but slap the head back on, and get a spark plug adapter and push 150 PSI air pressure into it. If it don't move then, it is stuck!!