SuzukiSavage.com - Shaving down the head

Rockin_John

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Re: Shaving down the head
Reply #15 - 01/13/07 at 22:47:37

I didn't mean to have split the thread from the "head shaving" discussion, but there are some interesting ideas floating on both branches of the thread...

I know that shaving the head is a very old and time honored way to low bucks compression boost with pushrod engines, but as is being discussed, it brings with it possible chain length and cam timing issues. Though it still may be the easiest/best way.

It's been so long since I worked on V-Dubs that I'd forgotten about the 94mm piston possibility there. I haven't looked, but it would surprise me to find an existing piston with the right deck height (wrist pin to deck) and enough material on top to maybe mill some off for the 4-valve head. Unless as someone suggested, maybe a car like the Camery. Doesn't it alread have a 4-valve/cyliinder design? Bet the angle of the valves wouldn't be right though.

I don't know enough about metallurgy, but might it be possible to TIG weld some material on top of a Savage piston and then machine it back down? Or would it not survive the conditions inside the cylinder?

As Realthng said, if we could get enough people to commit to buying some, and get Wiseco to do a run of 50-100 pistons I'd be willing to up for at least one, maybe two depending on the price. Especially if they would make them available in a "one over" size.

Pardon me folk, but sometimes I just "think out loud."

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Reelthing Serious Thumper Alliance Member Offline Fish or ride that is the question Posts: 5397 Houston,Tx Gender:	Re: Shaving down the head Reply #16 - 01/14/07 at 01:19:09 in reading back on that other post - looked like the piston minimum order was 24 @ $112 (included rings and wrist pin) - 1 over size wasn't a problem according to the last info we had.
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Yonuh Adisi FSO Serious Thumper Offline Savage Jedi (Knight) Posts: 3622 Pilot Valley NV, aka Tatooine Gender:	Re: Shaving down the head Reply #17 - 01/14/07 at 02:47:50 Is that $112 each?
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Reelthing Serious Thumper Alliance Member Offline Fish or ride that is the question Posts: 5397 Houston,Tx Gender:	Re: Shaving down the head Reply #18 - 01/14/07 at 07:43:15 That was the price per each when the fellow called wiseco in 2005 - w/rings and pin - but the minimum order was for 24 - if the info was correct * sorry went back and read the post - price was $122 *
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Rockin_John

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Re: Shaving down the head
Reply #19 - 01/14/07 at 11:16:26

Reelthing wrote on 12/31/69 at 16:00:01:

That was the price per each when the fellow called wiseco in 2005 - w/rings and pin - but the minimum order was for 24 - if the info was correct

* sorry went back and read the post - price was $122 *

Sounds pretty reasonalbe to me.

The Wisco piston changes I've done in a couple of dirt bikes, the performace can change incredibly!

In fact, I'm kind of surprsed that the price is that low, and It may not be now. Looking at their web site, many of the pistons for muli-cylinder bikes cost $130+ each.

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wvhunter62 YaBB Newbies Offline Posts: 35 Gender:	Re: Shaving down the head Reply #20 - 01/14/07 at 20:55:56 If you deside to do a group buy, I am in for at least 1 maybe 2. Twenty-four is a low minimum should be easy to achieve.
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justin_o_guy Ex Member	Re: Shaving down the head Reply #21 - 01/15/07 at 00:48:59 I wonder how many hard miles I need to get on it in order to justify a new piston?
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azjay Serious Thumper Offline aridzona... its a dry heat Posts: 816 Gender:	Re: Shaving down the head Reply #22 - 01/15/07 at 06:30:04 justin_o_guy wrote on 12/31/69 at 16:00:01: I wonder how many hard miles I need to get on it in order to justify a new piston? only a few,,,without oil
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Savage_Rob Serious Thumper Alliance Member Offline Mechanically Inclined Amateur Posts: 6972 Texas (Dallas area) Gender:	Re: Shaving down the head Reply #23 - 01/15/07 at 07:42:58 azjay wrote on 12/31/69 at 16:00:01: only a few,,,without oil Voice of experience.
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LANCER Serious Thumper Alliance Member Offline Savage Beast Performance Parts Posts: 10661 Oklahoma Gender:	Re: Shaving down the head Reply #24 - 01/15/07 at 07:51:04 Amen.
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barry68v10 Serious Thumper Offline Posts: 955 Maryland Gender:	Re: Shaving down the head Reply #25 - 01/15/07 at 19:21:56 Quote: I wonder how many hard miles I need to get on it in order to justify a new piston? 30-50k? My guess anyway, provided you keep the oil on the INSIDE of the bike
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Savage_Greg

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Re: Shaving down the head
Reply #26 - 01/15/07 at 21:53:30

vroom1776 wrote on 12/31/69 at 16:00:01:

hey all,

If you shave a little bit of metal off of the head where it seals to the cylinder, you can raise the compression ratio.

I remember doing some calculations on HC pistons and cylinder volumes, but I couldn't find that post. Anyway, if one were to shave 0.1" off of the head (not necessarily a good idea, but maybe 1/2 as much?) the compression ratio would increase to about 10.2:1 (compared to stock ~8.5).

To do this... take off the head. get some grinding compound (e.g. alumina dust), and some oil, as well as a large piece of flat glass. Run the head around on there in figure 8s until you have removed as much material as you want.

All that being said (typed), I have not done this. It was suggested to me by a gear head friend of mine. keep in mind he wants to split the case and balance my flywheel, too...

This is all just for grins, right?

If you're gonna shave anything you gonna take it to a shop to have it done, and you're certainly not taking off .100"...by hand on a piece of glass or any other surface.

A light polish like that might be okay on the head cover if you were using a compound or something, but a 1/10" is a bit much...or a 1/20" too.

Then you gotta worry about how much extra slack you're putting in the cam chain, and the change in the cam timing (as someone said).

You gotta remember the squish area, which is really small on the Savage engine. Plus ya gotta have clearance for those pesky old valves too...wouldn't want the old piston to smack 'em now

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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28884 L.A. California Gender:	Re: Shaving down the head Reply #27 - 04/04/07 at 21:55:58 For every .07" of chain stretch, you get 7° cam lag. So unless you shave the cylinder by one chain pitch (.257") you're going to have to deal with it. Or a little less would give cam advance... hmmm. Food for thought
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mpescatori

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Re: Shaving down the head
Reply #28 - 04/05/07 at 04:24:48

vroom1776 wrote on 12/31/69 at 16:00:01:

yeah, I've been thinking about other things that could go wrong...

At any rate, I'm just trying to figure out CHEAP performance mods....

If a cheap performance mod is what you're after, consider forced air intake.
Fit a highly flexible 40/50mm hose to the intake (like a vacuum cleaner hose) and guide it to the front of the bike, under the headlight; then attach a large funnel to it, anything between 4 - 6 " diameter. From a distance it'll look like a second headlight. Then take a test drive on the open highway and WOT.

In theory, the air funneled in should marginally supercharge the Savage; in practice, if done properly you should improve intake air pressure from an average 0.8 bar to around 0.9 to 1.0, thereby effectively supercharging the engine with a 0.1 - 0.15 bar increase in pressure.

At low speeds there would be no effect at all, at high speeds (beyond 60/70mph) ... you may need a 160 main jet, if there is such a thing...
...so you'd be running rich at low speeds, and better and better as speed increases...
...maybe lean beyond 110mph...

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justin_o_guy

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Re: Shaving down the head
Reply #29 - 04/05/07 at 14:57:21

I've been thinking about the cxam chain length being affected by head/deck shaving. IF there was no chain tensioner then the slack would be on the back side & the chain would actually appear shorter, since the cam & crank are closer. The tensioner only pulls the slack out & I am starting to think the whole"Makes the chain appear l;onger & retards the cam" idea may be bass akkerds. Anyone clear me up on this? OHHH Wait a MINute,, wait a MINute! I got it. It just came thru in a picture. As the head is lowered, the cam axis is closer to the crank, & the crank has to rotate far enough to remove that slack before the cam will turn, so it is retarded that far. SO, (using large numbers for illustration, not even close to acceptable mods) If ( really BIG if) we cut 1/2 inch off the head, the circumference of the crank gear would have to move 1/2 inch before the cam would start to turn. The tensioner woiuld have to soak up a whole 1" of slack. IF ( another Big If) the circumference of the crank gear was 6" then the 1/2 inch slack would translate to 1/12th of the O.D. & be 30 degrees retarded. So, all we need to do is use correct numbers & the amount it is retarded is there. Is this correct? Note, since I am just starting to get my head around this, I am not gonna be surprised if I am wr,, wr,, wr,, incorrect..

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