94 RM250 Piston hitting cylinder head.

Ryan_Glatz
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Ryan_Glatz
Edited Date/Time 12/18/2018 11:51am
Picked up a 94 rm250 used. Had no piston. Bought new wiseco kit (67mm stock. 89-95 rm250 piston kit) for it. I I noticed a new hot rod crank rod in it as I installed the piston. Anyway I get it back together and the piston is about an eighth inch(1/8)high out of my cylinder. Now I checked the vin# it's a 94 frame and I know my engine is between 90and95. I also took a piston out of a 1990 rm250 thinking maybe I got the wrong piston but the piston I pulled from a running 1990 rm250 was also coming up about an eighth of an inch out of my cylinder. I have to use like 5 base gaskets to make the cylinder flush with the top of piston edge. Anyone ever get this before?
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Hcallz5
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Hcallz5 12/12/2018 4:10pm
12/12/2018 4:10pm
Call up hot rods and ask them if they make a long rod for that engine. Does your head look like it has been machined or is the still the factory casting?
Ryan_Glatz
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Ryan_Glatz 12/13/2018 7:03am
12/13/2018 7:03am
It looks all stock. I'm prety sure the rod is the same size on 89-95 rm250. Maybe the head was shortened (squish)? Is that a possibility? I just want to know if I can put a base riser on there. It takes like 5 base gaskets to get the cylinder flush with the piston edge.
Ryan_Glatz
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Ryan_Glatz 12/13/2018 7:06am
12/13/2018 7:06am
I would just use the multiple gaskets but it leaks air and runs lean. Also coolant leaks if I stack all those gaskets together. I was thinking of making a plastic or rubber gasket about 1/8 inch thick. Maybe that will work?
Ryan_Glatz
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Ryan_Glatz 12/13/2018 7:09am
12/13/2018 7:09am
I'm trying to remember.... Is the piston flush with head gasket o rings at tdc or flush with the aluminum?

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c0ncEpT
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c0ncEpT 12/13/2018 7:59am
12/13/2018 7:59am
It either has a stroker crank in it or a long rod.
Ryan_Glatz
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Ryan_Glatz 12/13/2018 12:25pm
12/13/2018 12:25pm
Ryan_Glatz wrote:
I'm trying to remember.... Is the piston flush with head gasket o rings at tdc or flush with the aluminum?
Anyone know On a stock rm250 with piston at tdc where does the piston sit?
FahQ
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FahQ 12/13/2018 12:27pm
12/13/2018 12:27pm
You do have a cylinder head gasket right?
Stroker crank, long rod, or cylinder was machined down. The hot rods crank could be the wrong year.
You can call cometic they can make an aluminum spacer to get you straight.
I would aim for 1.1 -1.2 mm squish.
Measure your base gaskets, use one on top and one under the spacer.
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Ryan_Glatz
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Ryan_Glatz 12/14/2018 12:15am
12/14/2018 12:15am
Not an actual gasket. It's the 2 o rings but yeah I got em both on. The cylinder head is not bolted on and I turn the engine by hand the piston is pushing the cylinder head up about an eighth inch. Is the squish band on both top and bottom of cylinder? I never had to measure squish. I know the cylinder head is squished out lol. There ain't a ridge inside where the dome starts to go up to the plug anymore from being sanded or serviced so many times or it was really warped and it took that much to get a level surface......
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Paul_Pitzonka 12/14/2018 1:32am
12/14/2018 1:32am Edited Date/Time 12/14/2018 1:40am
Ryan_Glatz wrote:
Not an actual gasket. It's the 2 o rings but yeah I got em both on. The cylinder head is not bolted on and I turn...
Not an actual gasket. It's the 2 o rings but yeah I got em both on. The cylinder head is not bolted on and I turn the engine by hand the piston is pushing the cylinder head up about an eighth inch. Is the squish band on both top and bottom of cylinder? I never had to measure squish. I know the cylinder head is squished out lol. There ain't a ridge inside where the dome starts to go up to the plug anymore from being sanded or serviced so many times or it was really warped and it took that much to get a level surface......
it definitely sounds like is very possible it has a long rod/stroker kit in it as has been implied...The cylinder head issue sounds like someone milled the cylinder head and didn’t set squish, or had enough squish with a cylinder spacer installed and was milled as a way to return the compression to stock or higher... it is possible the person re-assembling it prior to you didn’t realize what he was doing and installed a long rod, or it is possible he lost the spacer for the cylinder during re- assembly (reason for not installing piston?) ... Also to check squish you measure distance between the cylinder head (the flat area outside the dome) and the top of the piston... solder or clay (what I’ve used) work great as ways to obtain this measurement... using the above method requires the head to be installed though which sounds like it’s impossible in your situation...
Ryan_Glatz
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Ryan_Glatz 12/14/2018 3:27am
12/14/2018 3:27am
Ryan_Glatz wrote:
Not an actual gasket. It's the 2 o rings but yeah I got em both on. The cylinder head is not bolted on and I turn...
Not an actual gasket. It's the 2 o rings but yeah I got em both on. The cylinder head is not bolted on and I turn the engine by hand the piston is pushing the cylinder head up about an eighth inch. Is the squish band on both top and bottom of cylinder? I never had to measure squish. I know the cylinder head is squished out lol. There ain't a ridge inside where the dome starts to go up to the plug anymore from being sanded or serviced so many times or it was really warped and it took that much to get a level surface......
Paul_Pitzonka wrote:
it definitely sounds like is very possible it has a long rod/stroker kit in it as has been implied...The cylinder head issue sounds like someone milled...
it definitely sounds like is very possible it has a long rod/stroker kit in it as has been implied...The cylinder head issue sounds like someone milled the cylinder head and didn’t set squish, or had enough squish with a cylinder spacer installed and was milled as a way to return the compression to stock or higher... it is possible the person re-assembling it prior to you didn’t realize what he was doing and installed a long rod, or it is possible he lost the spacer for the cylinder during re- assembly (reason for not installing piston?) ... Also to check squish you measure distance between the cylinder head (the flat area outside the dome) and the top of the piston... solder or clay (what I’ve used) work great as ways to obtain this measurement... using the above method requires the head to be installed though which sounds like it’s impossible in your situation...
That makes sense the cylinder wasn't on it when I got it. Actually the whole bike was apart. Maybe the spacer got lost along with the carb seat and Airbox.... Lol
kxman
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kxman 12/15/2018 11:54am
12/15/2018 11:54am
Head machined and was set up for a flat top piston is my guess
Ryan_Glatz
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Ryan_Glatz 12/15/2018 2:29pm
12/15/2018 2:29pm
You can see the head gives no clearance at all. It's been shaved one too many times
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Paul_Pitzonka 12/15/2018 2:50pm
12/15/2018 2:50pm Edited Date/Time 12/15/2018 2:51pm
Ryan_Glatz wrote:
You can see the head gives no clearance at all. It's been shaved one too many times
I’m definitely going with it’s stroked... that piston is way above deck height... do you happen to remember what rod is in it?
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dkurtd 12/15/2018 3:03pm
12/15/2018 3:03pm
Ryan_Glatz wrote:
You can see the head gives no clearance at all. It's been shaved one too many times
Paul_Pitzonka wrote:
I’m definitely going with it’s stroked... that piston is way above deck height... do you happen to remember what rod is in it?
I'm with Paul, there is no way that piston should be above the deck like that. Something is wrong, either the rod or the piston.
Ryan_Glatz
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Ryan_Glatz 12/15/2018 3:15pm
12/15/2018 3:15pm
Ryan_Glatz wrote:
You can see the head gives no clearance at all. It's been shaved one too many times
Paul_Pitzonka wrote:
I’m definitely going with it’s stroked... that piston is way above deck height... do you happen to remember what rod is in it?
Just know it's hot rods I'll go pull cylinder off and see if I can find some numbers or something else on it.

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Ryan_Glatz
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Ryan_Glatz 12/15/2018 3:43pm
12/15/2018 3:43pm
Hot rods ck105 it fits my bike. My piston is right. Could this bike be a rmx.... But even if it is..... isnt 94 rmx 100% innerchangeable with 94 rm250??
Ryan_Glatz
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Ryan_Glatz 12/15/2018 4:13pm
12/15/2018 4:13pm
Ryan_Glatz wrote:
Hot rods ck105 it fits my bike. My piston is right. Could this bike be a rmx.... But even if it is..... isnt 94 rmx 100%...
Hot rods ck105 it fits my bike. My piston is right. Could this bike be a rmx.... But even if it is..... isnt 94 rmx 100% innerchangeable with 94 rm250??
1994 rm250 says suzuki vin decode. The rod is right the piston is right.......
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Paul_Pitzonka 12/15/2018 5:06pm
12/15/2018 5:06pm
Ryan_Glatz wrote:
[img]https://p.vitalmx.com/photos/forums/2018/12/15/310401/s1200_20181215_182614.jpg[/img]

Base of the cylinder has been milled off... that cylinder has been worked on before notice the 75 ground into the side... also look at the height between the engine displacement tag and the base compared to a stock cylinder..
4
Ryan_Glatz
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Ryan_Glatz 12/15/2018 5:18pm
12/15/2018 5:18pm
Ryan_Glatz wrote:
[img]https://p.vitalmx.com/photos/forums/2018/12/15/310401/s1200_20181215_182614.jpg[/img]

Paul_Pitzonka wrote:
Base of the cylinder has been milled off... that cylinder has been worked on before notice the 75 ground into the side... also look at the...
Base of the cylinder has been milled off... that cylinder has been worked on before notice the 75 ground into the side... also look at the height between the engine displacement tag and the base compared to a stock cylinder..
I see. That's my problem. Thanks for pointing that out. It may have taken another week before I noticed that.
Ryan_Glatz
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Ryan_Glatz 12/16/2018 7:14am
12/16/2018 7:14am
Ryan_Glatz wrote:
[img]https://p.vitalmx.com/photos/forums/2018/12/16/310518/s1200_1544972858256344690092699374784.jpg[/img]

Cometic never answered back on my enquiring about making a base riser and I want to ride....... This should work but what you guys think. Jigsaw? I got cork gasket for bottom and top of it...or just paper gasket if my thickness target requires it....... Any opinions?
Ryan_Glatz
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Ryan_Glatz 12/16/2018 7:19am
12/16/2018 7:19am
Ryan_Glatz wrote:
[img]https://p.vitalmx.com/photos/forums/2018/12/16/310518/s1200_1544972858256344690092699374784.jpg[/img]

Ryan_Glatz wrote:
Cometic never answered back on my enquiring about making a base riser and I want to ride....... This should work but what you guys think. Jigsaw...
Cometic never answered back on my enquiring about making a base riser and I want to ride....... This should work but what you guys think. Jigsaw? I got cork gasket for bottom and top of it...or just paper gasket if my thickness target requires it....... Any opinions?
It's aluminum sheet about the thickness I need. But it's an aluminum baking sheet.... To hard you think? Or is it's ability to endure intense heat a plus in my alication

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