Decked my head

[Benjamoid]

Well during my port and polish I managed to nick the edge of my combustion chamber a few times so I had to take my head over the tha machine shop and have it shaved...

Guy said he took about .012 off. Will this affect my timing enough to worry about it? I read somewhere that when you lower the compression by stacking head gaskets that you advance the timing, so lowering the head will retard it. Also read that these bikes are already pretty advanced, so im assuming a bit of retard will not hurt anything. Am I right?

I already know that these engines vibrate, and that rasing the compression will make it worse... I dont really care.

Thanks

 

[XSLeo]

You can get copper gaskets made in any thickness. You can get one .012 thicker and put things back where they should be. Now if I only new the place to get them.

 

[Benjamoid]

I could, but I kinda wanted to bump the compression up a bit anyhow, just to see how it runs.... Im just wondering if making just a bit retarded is gonna hurt? Judging by what xsjohn says about how these are pretty advanced from the factory im thinkin I should be fine.

 

[CDNTX650]

i always retard mine slightly with stock CR anyways. XS johns reccomendation.

 

[Benjamoid]

Ok, well I guess we will see how things turn out... Thanks guys

 

[JasperLP]

Have you considered the possibility of a piston hitting a valve? Just asking.

I got a solid copper gasket for my XS-1B, don't know what all thicknesses he makes.

Copper Gaskets Unltd. www.coppergaskets.us

 

[Benjamoid]

It is not something im worried about, I wouldnt think that the engine was built with only .010 inch clearance... As with any engine rebuild I planned on turning the engine over by hand a few times before any attempt at starting to make sure everything is good to go.

I have yet to find any info on higher compression with mostly stock motor so im interested to see what it will do...

 

[CDNTX650]

Shop to phone might be 650 central or Heiden tuning and ask.

 

[Punkskalar]

Just redegree the cam and you will be fine. I have taken out .020 before and it works well, just have to press off the gear on the cam and set it back...

 

[grizld1]

Ben, lowering the deck over a stock bore by .012" will not cause trouble with valve-piston, piston-dome, or squish (piston edge-combustion cap edge) clearances, although when bore is increased past .060" over it's best to check squish clearance. Whether the .012" you took off is significant to valve timing or not is hard to say. Replacement head gaskets for these machines are made in both 1 mm. (.040") and 1.5 mm. thicknesses, so where actual deck height ends up is going to depend on what gasket you took off and what gasket you install.

There's really no substitute for finding actual valve timing, but if you install a gasket of the same thickness and wind up with a .012" drop, you won't be advancing the timing a great deal. At most you'll notice that the engine's a little livelier at higher rpm's. As far as compression goes, any increase will be extremely small.

 

[Benjamoid]

Well im going to try it w/o degreeing the cam. I think that .012 is so small that it wont make a huge difference, if anything like griz said it may help it a bit... Motor should be done this week, but bike wont be done till spring, so we will find out then how everything works out.

Btw, I am using Mikes complete gasket kit, so whatever head gasket thickness came with that is what im using...

 

[grizld1]

I don't know what that kit has in it. If it's a Vesrah kit the head gasket will be around .048" uncompressed, if it's Athena it'll be .060". Depending on what you took out of there, your final deck height could actually be increased.

 

[Benjamoid]

My new one is athena. Bike only has 12k on it, so im assuming it was a stock gasket that I took out.

 

[grizld1]

Right. OEM thickness is about .043" compressed, the Athena gasket is .060" uncompressed, and gasket compression will cut a couple or three thou' off that. With .012" milled off the head you'll wind up real close to where you were.

 

[Benjamoid]

Well thats kinda dissapointing, I was curious to see how the slightly higher compression would work...

Mabey I will just really crank the head bolts down, squish the head gasket more...