SuzukiSavage.com - Cheap Compression Upgrade

DragBikeMike

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Cheap Compression Upgrade
01/10/20 at 13:13:57

Want a little kick for a bargain basement price? Got the top end torn down for a winter project? Why not add a little more squeeze with some copper gaskets?

You can reduce your deck height from .190” (negative) to .176” (negative) by installing copper base and head gaskets. That’s good for about a 0.2 bump in compression ratio. The copper gaskets cost about the same as OEM gaskets. No machining, no changing the piston, strictly plug & play.

The stock head gasket is .028” thick, and the stock cylinder base gasket is .018” thick. If you replace the stock gaskets with .016” thick copper gaskets you will reduce the deck height by .014”. That will reduce combustion chamber volume by about 2.5cc.

The gaskets are available from Copper Gaskets Unlimited (CGU) in Phoenix, AZ. They can be ordered in various thicknesses (.016”, .021”, .026”, .032”…..). The head gasket is $28 bucks and the base gasket is $15 bucks. I’ve been running one of their base gaskets for quite a while and it’s absolutely oil tight. I think the quality of their product is excellent, perfect fit.

For those who are running a 97mm piston, CGU makes a special head gasket. The stock OEM gasket overhangs the bore. The CGU special 97mm gasket is just right, no more overhang.

To order, contact Lani at CGU. Website www.coppergaskets.us. Email is coppergasketsunlimited@yahoo.com. Lani already has CAD drawings for the LS650, he said just ask for “Suzuki LS650 head and base gaskets”, and of course provide the desired thickness.

Here’s a shot of the copper base gasket next to the OEM composite gasket.

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Cylinder_Base_Gasket_CGU_2.jpg

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verslagen1

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Re: Cheap Compression Upgrade
Reply #1 - 01/10/20 at 14:09:08

verslagen1 wrote on 12/06/18 at 13:00:09:

verslagen1 wrote on 03/17/07 at 23:35:13:

.07" stretch will retard the cam timing by 7°.

Or 1° for every .010" chain stretch.

I would be interesting to know what the cam timing is with a new chain.
And how much tolerances affect cam timing.

Armen wrote on 12/07/18 at 03:07:36:

By moving the crank sprocket on the crank one spline, and the chain on the sprocket one tooth in the other direction, minor changes in timing are possible. Looking at how stretched some of the cam chains are (pics posted on the forum), people using the modified tensioner are getting away with some really stretched out chains and really extended tensioners. Maybe the extended tensioner and a new chain would be enough to make up for the additional slack created by cutting the cylinder down?

Or using thinner gaskets.

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Mavigogun

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Re: Cheap Compression Upgrade
Reply #2 - 01/27/20 at 19:09:32

DragBikeMike wrote on 01/10/20 at 13:13:57:

Want a little kick for a bargain basement price? Got the top end torn down for a winter project? Why not add a little more squeeze with some copper gaskets?

You can reduce your deck height from .190” (negative) to .176” (negative) by installing copper base and head gaskets. That’s good for about a 0.2 bump in compression ratio.

Help alleviate my ignorance- increase power by reboring to accommodate a larger piston - OK, check, that makes sense to my American-bigger-better understanding - but increase power by reducing volume with a thinner gasket - wha.... huh?

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IslandRoad

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Re: Cheap Compression Upgrade
Reply #3 - 01/27/20 at 19:19:21

@Mavigogun, reducing the hight of the combustion chamber (with all else unchanged) = higher compression ratio which translates to higher power output. It's the same principal as installing a high compression piston, which is slightly taller than stock but has the same diameter. You just squash the fuel and air a bit tighter before combustion to get a bit more bang for buck.

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« Last Edit: 01/27/20 at 20:31:28 by IslandRoad »

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batman

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Re: Cheap Compression Upgrade
Reply #4 - 01/28/20 at 19:28:30

Islandroad ,why not just send the head out and have it shaved .014 ? same gain ! you could most likely reuse your stock head gasket. I believe that's why DBM said only if you're going there. I don't really favor copper gasket use ,except for when needed for very high compression ,as they need special handling and preparation , to avoid compression and oil leaks.

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zevenenergie

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Re: Cheap Compression Upgrade
Reply #5 - 01/31/20 at 02:06:25

Wow Dave, thank you for this tip.

I was tinking:

If you replace the cylinder gasket with a liquid gasket.
Then you save 15 dollars, and you will reduce the deck height by 0.018"

That will reduce the combustion chamber volume by about 3,1cc.
And you can use the stock head gasket.

Will that work?

And if the cylinder is a bit worn, can it hurt that the top piston ring bumps against the not worn part of the cylinder?

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Armen Serious Thumper Offline Half-Witted Wrench-Jockey from Jersey Posts: 1431	Re: Cheap Compression Upgrade Reply #6 - 01/31/20 at 05:10:17 The advantage of thinner gaskets as opposed to shaving the head is that the squish band will be tightened a bit if you lose gaskets or shave the cylinder.
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DragBikeMike

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Re: Cheap Compression Upgrade
Reply #7 - 01/31/20 at 11:28:46

This nugget of gold isn't a magic bullet. It will bump up the compression ratio (CR) just a bit. It's a nice option if you have the engine torn down for some other reason. I wouldn't tear the engine down just to bump up the CR 0.2 points. But if you already have it torn down, these copper gaskets are a nice option to consider.

Regarding shaving the head vs installing copper gaskets, the decision is simple. Shaving the head involves removing metal. That metal can't be replaced once its removed. I always go for the option that can be easily reversed if I don't like the results.

Another benefit to the copper gaskets is they can be reused by simply annealing the gasket. CGU supplies good instructions for annealing, all you need is a propane torch and a pan of water. I'm not a fan of reusing the OEM multi layer steel (MLS) gasket. It has a special coating (the black stuff) that always peels off when you disassemble the engine. Also, the fire ring most certainly deforms when the gasket is compressed. That will never return once the gasket is removed.

Copper gaskets do tend to weep a bit, but I haven't developed any weeps or seeps on my base gasket yet. Got a little over 1000 miles on it now and it's still 100% oil tight.

Good point about the cylinder ridge. I currently have three cylinders. The original 2016 cylinder (about 3500 miles), and two eBay cylinders. One of the eBay cylinders is obviously very old and beat up real bad. None of these cylinders has any discernable ridge. I generally run a rigid hone through a barrel before I use it. If there's any hint of a ridge, that hone will wipe it out. Unless you are dealing with a high mileage jug that has a ridge, I don't think installing a thinner base gasket, or using a sealant in lieu of a gasket, will cause any problems with rings.

If you used the sealant in lieu of a base gasket, and also installed the thinner head gasket, you would double the reduction in volume, and end up with a 0.4 point bump in CR. If you don't like the results, you haven't done anything permanent.

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