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Author Topic: Wiseco piston to Cylinder Clearance Question  (Read 2880 times)

Offline Chuck D

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Wiseco piston to Cylinder Clearance Question
« on: March 26, 2013, 08:29:43 pm »
So manual says servic limit is .0047 and spec is .003". So according to the manual .005" is wore out. Wiseco says .0037" piston to cylinder clearance. Iv herd from a couple people .0055" is what you want to set it up with. If I hadn't herd any different I would set it up at .004". So I kinda wanna here from some people that have actually set there clearance and have time on the setup. I'm boring my cylinder in a couple days.
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Offline Iceracer

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Re: Wisco piston to cylinder clearance
« Reply #1 on: March 27, 2013, 06:35:28 am »
Don't trust the Wiseco box I think they let there kids do the labels. But this time they are close. Clearance is directly related to type of piston. OEM were cast pistons, cast pistons due to there ratio of silica/ aluminum don't expand as much as forged pistons like Wiseco. So the manual is only relevant to cast type pistons from Suzuki or art etc...
The new generation of Wiseco are much better than the old pistons from 10-15 years back. I used to set up with .005 " clearance to be safe. But it was hell on piston life and boring cylinders. I now set up at .0035"  and spend more time on break in.  During break in you actually size the piston to the bore. What happens is you go through a progression of heat cycles continually hotter. In doing this the piston expands during operation and obviously cools when you shut it down. These Cycles actually end up shrinking the piston slightly also the skirt of the piston collapses. Of the two the places where the piston shrinks the crown is the one that losses less size  it has the most mass but also the most support so it hold s it size better than the skirt.
The skirt on the pistons are the weak point due to lack of material and poor rod angle. So on a new engine once the skirt  collapses and you have sized yourself on the high side of tolerance. You can end up with excessive clearance. .002" can be the difference between a long service life and one that's noisy and will need to be bore every year after only a few trips. In the end you need to maintain the piston properly. Good quality oil and more is better. Its the only  cushion between the piston and the cylinder if its not there it can't work.

Moral of the story proper break in is critical. And proper warm up is crucial.But don't go less than .0035" on a 500 or you run the risk of seizure.

Offline Yoyodyne1

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Re: Wisco piston to cylinder clearance
« Reply #2 on: March 27, 2013, 06:39:58 am »
Stock piston clearance is for a factory cast piston.  Wiseco are forged and need a bit more clearance.  Set it at .0037 only IF you can give it a nice slow break in period, which is preferred.  On the other hand if your the type that says "screw break in, ride it like you stole it" .005 is what you want.

Offline Chuck D

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Re: Wisco piston to cylinder clearance
« Reply #3 on: March 27, 2013, 09:47:25 am »
I realize the difference in cast and forged pistons. I have personally stayed away from wiesco pistons with all my rebuilds in the past. I am just trying to get some feed back from people with experience with there different clearances. Why does Dr. Q recommend .0055". I'm just worried if I set it up at .0055" it's gonna slap.
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Offline MotorGeek - Jerry Hall

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Re: Wisco piston to cylinder clearance
« Reply #4 on: March 27, 2013, 10:01:00 am »
The power output also has an influence on piston clearance. As the power goes up the piston clearance has to increase.   

Like Carl said.........the skirts collapse but the area above the skirts do not collapse and will need more clearance to keep the upper portion of the piston smaller than the bore when the engine is under a heavy load. 

Offline Kyle T

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Re: Wiseco piston to Cylinder Clearance Question
« Reply #5 on: March 27, 2013, 03:09:50 pm »
What about machining the ring area of the piston down a little? Tighter skirts and looser ring areas?

Offline MotorGeek - Jerry Hall

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Re: Wiseco piston to Cylinder Clearance Question
« Reply #6 on: March 28, 2013, 07:47:26 am »
What about machining the ring area of the piston down a little? Tighter skirts and looser ring areas?

Pistons are not round and are tapered.  It takes a special piston turning machine to machine the profile on the OD of the piston.  It takes a lot of trial and error testing of different piston shapes to arrive at the optimum profile.  The OEMs sometimes go through 20 or more profiles before they find the one that works with a stock engine at stock power levels.  It is obvious Wiseco does not do this much testing on their profiles base upon the ware paterns I see on the OD of the piston.  When the power level is increased significantly, the profile needs to be changed. 

I think that design of the Wiseco piston needs to be changed for the LT500.  Wiseco want about 8000.00 to make a forging die to my specifications. There is additional cost for programming and machining different skirt profiles from the handful of what they call there standard profiles.  I would probably need to charge 300.00 or more for a piston to help recover special programming and tooling cost due to the small number of pistons produced. 

Offline Maxxh2o

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Re: Wiseco piston to Cylinder Clearance Question
« Reply #7 on: March 28, 2013, 10:47:33 am »
Good info here.  A question for the builders would also be what kind of prep is needed for a prolite out of the box.  Is chamfering needed on edges, and is the oil hole on exhaust skirt necessary.  thx

Offline Glamisrider

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Re: Wiseco piston to Cylinder Clearance Question
« Reply #8 on: March 28, 2013, 11:18:08 am »
I think that design of the Wiseco piston needs to be changed for the LT500.  Wiseco want about 8000.00 to make a forging die to my specifications. There is additional cost for programming and machining different skirt profiles from the handful of what they call there standard profiles.  I would probably need to charge 300.00 or more for a piston to help recover special programming and tooling cost due to the small number of pistons produced. 

Have you contacted JE pistons here in Huntington Beach they do a lot of aluminum pistons ( I can buy there screw ups from the local metal recycler around the corner)?




Offline Mercenary223

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Re: Wiseco piston to Cylinder Clearance Question
« Reply #9 on: March 28, 2013, 11:23:32 am »
Have you contacted JE pistons here in Huntington Beach they do a lot of aluminum pistons ( I can buy there screw ups from the local metal recycler around the corner)?

What do you do with the pistons that were out of spec?





Offline MotorGeek - Jerry Hall

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Re: Wiseco piston to Cylinder Clearance Question
« Reply #10 on: March 28, 2013, 01:51:16 pm »
I think that design of the Wiseco piston needs to be changed for the LT500.  Wiseco want about 8000.00 to make a forging die to my specifications. There is additional cost for programming and machining different skirt profiles from the handful of what they call there standard profiles.  I would probably need to charge 300.00 or more for a piston to help recover special programming and tooling cost due to the small number of pistons produced. 

Have you contacted JE pistons here in Huntington Beach they do a lot of aluminum pistons ( I can buy there screw ups from the local metal recycler around the corner)?


No I have not talked to JE.

Wiseco and JE are both owned by Dover Dirversified Corp.  the last time I checked. 

10 years or so ago, Dover bought Wiseco, Carrillo Rods, JE, Vertex, and a hand full of other companies.  I heard the smart guys at JE quit and started CP pistons not long after Dover bought JE.

My design would require new dies an would not be able to use any of their existing dies.  I have not seen any companies making any two-stroke pistons like my proposed design.

Offline Q2W

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Re: Wiseco piston to Cylinder Clearance Question
« Reply #11 on: March 28, 2013, 02:51:56 pm »
CP claims they will make any custom piston you want.

    CP Pistons CP Pistons is a state of the art piston manufacturing company. CP utilizes current state of the art CNC machinery to produce their forged pistons. CP has a vast line of High Performance Auto, MX & ATV, PWC, and Street pistons, included 2-Stroke pistons. Each piston is machined to exacting tolerances and matched to rings, clips, and pin. CP offers X forgings where available to reduce weight and gain strength. CP is also able to make any custom piston you could dream of. CP offers skirt coatings and DLC coated pins to performance minded customer.

http://www.cp-carrillo.com/Segments/CustomProducts/tabid/68/Default.aspx

What do you think, Jerry?

Offline Rider414

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Re: Wiseco piston to Cylinder Clearance Question
« Reply #12 on: March 28, 2013, 02:57:40 pm »
Give them a shout Jerry! Could be the next big thing -
Ain't ever seen it......but I have heard it.

Offline Mitch Keller

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Re: Wiseco piston to Cylinder Clearance Question
« Reply #13 on: March 28, 2013, 03:31:37 pm »
Watch this video, then you will understand why the tooling is so high.
http://www.youtube.com/watch?v=oJX_vGJnxi0
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Offline Glamisrider

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Re: Wiseco piston to Cylinder Clearance Question
« Reply #14 on: March 28, 2013, 06:04:35 pm »
What do you do with the pistons that were out of spec?

Nothing I said I could buy them not that I do, seen them there before when I was picking up other stuff.


No I have not talked to JE.

Wiseco and JE are both owned by Dover Dirversified Corp.  the last time I checked. 

I was not aware of this maybe CP is the place to be calling?

If you did this new piston design how much modification would be required to the cylinders we are running now?


Offline Mitch Keller

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Offline Glamisrider

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Re: Wiseco piston to Cylinder Clearance Question
« Reply #16 on: March 29, 2013, 10:40:33 am »
Well it looks like Cp bought Carillo Rods so that's not owned by Dover anymore.

It also looks like they are putting some coating on the Moose 2 stroke piston skirts?

Maybe Cp is the place

Offline ShankJr

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Re: Wiseco piston to Cylinder Clearance Question
« Reply #17 on: July 21, 2014, 02:50:46 pm »
I think jerry would have to call and give them his design changes for this to be a viable option

 

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