WISECO piston/cylinder clearance

jaguar

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#1
I just received my 67mm dia WISECO prolite piston and the information with it says .05mm is the normal clearance for it but that with modified engines more clearance may be desirable.
So my bike has a ProCircuit pipe which boosts performance but it still has the limiting 28mm carburetor. And the cylinder is steel sleeved.
So what would you recommend for clearance?
Kawasaki recommends .07-.09mm and I once cold seized a piston on my KDX that had .08mm clearance so going less than .07 spooks me although I learned my lesson and don't ever gas it hard when the engine is cold.
 
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#2
My guess is that the steel sleeve liner will not expand as much as will an aluminum bore so more clearance is possibly needed. Ask this Q on Eric Gorr's forum. Also, e-mail LA Sleeve and ask them --they make & install cast iron - steel liners.
 

jdbrusch

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#3
Are you going with a big bore kit or something? the stock piston on the 200kdx is only 66mm.The instuctions that came with my kit stated a clearance for 60mm to 73mm pistons of .0025" or .064mm.
The best thing to do to prevent cold siezing the motor is to let the bike warm up untill the rads are hot.Hope this helps.
 

jaguar

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#4
Yeah I know stock is only 66mm. My steel sleeve is damaged and so I needed to go much larger in diameter, otherwise I'd have to have it sleeved again.
I was hoping that someone with a Wiseco piston would comment on how things went after installing it with .05mm (.002") clearance. (such as did it seize easily, etc)
 

BRush

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#5
All Eric Gorr’s kits use Wiseco pistons. You could try calling him and asking what clearance he uses. He’s pretty good about quick phone questions. Since the Kawi pistons are cast and Wiseco are forged, you cannot use the Kawi clearance recommendations. I think you have to go with the Wiseco recommendation. My bigbore kit came with the Wiseco, but I did not bother to check clearances since a) I did not have a bore gauge or inside mike with the required level of accuracy and b) I trusted EG to get it right. No seizing problems.
 
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jdbrusch

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#8
I am running a wiseco piston(also sleeved) right now in my bike and the instuctions that came with the kit indicated a clearance of .0025"(.064mm) for cylinder sizes of 60mm to 73mm,I am not sure why they would recommend a tighter fit with a oversized piston in a steel sleeve,maybe because the sleeve has been taken down it will not expand as much???
If possible ask the shop that is doing the boring what they recommend or usually set the clearances at at final honing,its possible the wiseco pistons expand less then the oem kawasaki one which would need less clearance once everything is brought to temp.
The main reason for a cold sieze is running the crap out of a cold engine,the piston expands faster than the cylinder and thus you lose the clearance that would have been ok if the engine was allowed to warm up properly.
 
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jdbrusch

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#10
It is the Pro-lite version in the standard size-66mm,I installed the sleeve myself at work and had it honed to the clearance(.0025") that they gave in the instructions that came with the piston kit, has been working good for almost 8 years,like I say I am not really sure why there would be a difference in the clearance between the two kits,might be a good idea to email(if possible) or get in touch with wiseco for the proper specs.Do they give any other clearances in the instructions? My instuctions were not model specific and gave clearances for different bore sizes.
I also run a 01 wr 250f and just out of curiosity checked what the clearance for that is and they have a clearance of only .040-.065mm(.0016-.0026")so its even tighter that whats recommended for you, but this being a four stroke might be different,not sure.
I will try to give a shop here that does sleeving and cylinder plating a call tomorrow and see if they can give me some info on this.I will get back to you asap tomorrow after work.
James..
 

shr

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#11
"jaguar"

You ask me why....., well 30 years of experience in installing sleeves in two stroke cylinders is why.
 

Braahp

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#15
The Wiseco will expand more than a cast oem. I would never use Wiseco or Seizco as many call them. Sure they are great but you just have to set them up much looser than a cast piston. A longer warm up period is needed also to get the Wiseco to expand. Why folks recommend them I don't know.