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Discussion Starter · #1 ·
I need to have the cylinder head removed on my '03 to replace a head gasket. I don't especially want to sink a lot of additional money into it, but since it has to come out anyway, I thought I should at least consider some performance mods while I'm at it. Any idea how much benefit and incremental cost would come w/ any of the following:

* Port and polish
* Mill down head to increase compression (ran fine on mid-grade, don't mind having to use premium)
* Daytona cams (Is that the only difference between the S3 and the 955 Daytona engines or would I need different valves to work w/ the cams?)
*Other?

My bike is stock except for a TORS and a Tuneboy.
 

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A mild clean-up of the ports (no polishing - a waste of time), cut down the valve stems and a full valve job should be relatively mild on the wallet. If you want to use the Daytona cams (higher lift and more duration) I wouldn't cut the head much.
 

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Discussion Starter · #4 ·
What do you mean by cutting down the valve stems? I'm not familiar w/ that one.

I definitely won't be doing every possible upgrade, but I'm trying to figure out which combo would strike the best balance of power, economy, and reliability. It sounds like some mild porting and then cutting the valves should be at the top of my list. I assume new Daytona cams would probably be the most expensive, so unless they provide a very large increase in power all by themselves w/o necessitating the other upgrades, I guess they'd be at the bottom of the list. Would a mild increase in the compression ratio (assuming I stick w/ stock cams) be a good second step? I don't have a feel for whether or not that might be worth the additional expense.

Thx.
 

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He may mean cutting down the valve guides. Smaller valve stems mean new valves, not cutting. I think the valve guides do protrude into the runner a little more than needed.
 

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No.
I mean reducing the stem diameter .030 to .040 inch to increase area through the seat. The diameter in the guide remains stock.

The valve guide needs to be reshaped, not removed. Some bowl clean up and shaping, a bit of work on the long turn radius, a little clean up on the short turn radius, and a bit of work to bias the flow into the cylinder makes the biggest gains without screwing with the port velocity.

A few well placed dimples will also reduce the fuel wet out issues in the port, and add throttle response.


 
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