Cylinder decking, how much is too much?
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Cylinder decking, how much is too much?
Hey guys. I have my cylinder being replated and freshened up at powerseal. The cylinder mating surface for the head gasket had lots of little dings in it. They told me they are going to deck the head. I just want to make sure this won’t affect the squish too much. I understand that there is no way of telling exactly how much material will need to be taken off. I told them that my RB head was set up for 93 octane pump gas. Do you think I should be ok and that these guys would consider these things when doing the work. Thanks
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2005 KDX220r 1991 KDX200 2022 KTM 500excf
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Re: Cylinder decking, how much is too much?
Lowering the cylinder height would in effect lower the head closer to the piston. This would increase compression and reduce the squish to possibly unsafe levels if the head isn't reworked to account for it.
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AZ State Parks & Trails OHV Ambassador - Trail Riders of Southern AZ
Current KDX: '98 KDX220
Old KDX: '90 KDX200 -White/Blue
'11 GasGas EC250R
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Re: Cylinder decking, how much is too much?
I guess what I’ll do is measure from bottom of cylinder to top on my current cylinder and compare it to the new cylinder. Thanks
2005 KDX220r 1991 KDX200 2022 KTM 500excf
- Chuck78
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Re: Cylinder decking, how much is too much?
You can custom cut your own base gasket out of a bulk sheet of uncut thicker gasket material, or have Cometic make you a custom thickness base gasket to correct your deck height, but this will also ever so slightly alter your port timing.
I'd ask if they can possibly make a custom MLS (Multi-Layer Steel) head gasket slightly thicker for you. Tooling up for MLS gaskets is more involved than paper gaskets or fiber type head gaskets though, so they may not do a 1-off. Since it's stock bore though and not a completely custom big bore size, maybe they can do this.
Also, with an MLS gasket, you could possibly stack a few layers from a second gasket over the dowels?
I'd ask if they can possibly make a custom MLS (Multi-Layer Steel) head gasket slightly thicker for you. Tooling up for MLS gaskets is more involved than paper gaskets or fiber type head gaskets though, so they may not do a 1-off. Since it's stock bore though and not a completely custom big bore size, maybe they can do this.
Also, with an MLS gasket, you could possibly stack a few layers from a second gasket over the dowels?
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Re: Cylinder decking, how much is too much?
I wonder if they can Nikasil plate the head gasket surface after decking????
Perhaps it wouldn't do as good in the long term under compression though? Not a malleable finish? Doesn't hurt to ask.
Thicker head gasket is the best solution if possible. If not, a thicker base gasket is the easiest solution (but with altered port timing).
Perhaps it wouldn't do as good in the long term under compression though? Not a malleable finish? Doesn't hurt to ask.
Thicker head gasket is the best solution if possible. If not, a thicker base gasket is the easiest solution (but with altered port timing).
'97 KDX220R - purple/green! - KLX forks, Lectron, FMF, Tubliss
'99 KDX220R project - '98/'01 RM125 suspension, Titanium hardware, Lectron Billetron Pro, Tubliss
'77 Suzuki PE250 & '83 Suzuki PE175 Full Floater - restomod projects
'77 Suzuki GS750-844cc, '77 GS400/489cc & '77 GS550/740cc projects
'62 GMC 1000 Panel Truck
'88 Suzuki Samurai TDI/Toyota swaps
'88 Toyota 4x4 pickup
'99 KDX220R project - '98/'01 RM125 suspension, Titanium hardware, Lectron Billetron Pro, Tubliss
'77 Suzuki PE250 & '83 Suzuki PE175 Full Floater - restomod projects
'77 Suzuki GS750-844cc, '77 GS400/489cc & '77 GS550/740cc projects
'62 GMC 1000 Panel Truck
'88 Suzuki Samurai TDI/Toyota swaps
'88 Toyota 4x4 pickup
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Re: Cylinder decking, how much is too much?
Thanks I asked about that. Not sure what the deal will be until at least next week. I’d shoot for a thicker head gasket if it’s an issue.Chuck78 wrote: ↑04:48 pm Jul 01 2023 I wonder if they can Nikasil plate the head gasket surface after decking????
Perhaps it wouldn't do as good in the long term under compression though? Not a malleable finish? Doesn't hurt to ask.
Thicker head gasket is the best solution if possible. If not, a thicker base gasket is the easiest solution (but with altered port timing).
2005 KDX220r 1991 KDX200 2022 KTM 500excf
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Re: Cylinder decking, how much is too much?
They are going weld and machine the cylinder head surface so I should be good to go.
2005 KDX220r 1991 KDX200 2022 KTM 500excf