anybody seen an xs combustion chamber like this

[jay760]

Bought this over the weekend, there are a few threads on porting but has anybody seen this done before? I know it needs cleaning!!!

http://i1009.photobucket.com/albums/af219/jasonwinterson/head002.jpg

http://i1009.photobucket.com/albums/af219/jasonwinterson/head001.jpg

 

[scabber]

I can't say from the pictures but it looks like the sharp edges in the valve pockrt area have been blended. Haven't seen it done on a 650 head but if your running high compression pistons it might heip lower compression. Doesn't look factory. Got me thinking. Sharp edges can cause detination.

 

[jay760]

I think they've done this

 

[scabber]

I think your right. I've got a head I'am working on now. Can you get some pictures looking into the ports. I'am interested to see what they did in the guide boss area.

 

[jay760]

I'll have to clean it up a bit first! I've got a couple but they aren't very clear, not much has been taken out especially the exhaust

 

[gggGary]

I think they've done this

So where is that pdf of the head work from, and where can I get a copy?

NO cliff hangers guys!

 

[jay760]

I got it in a box of spares at a swap meet, the only place I know of that's capable of work like this is here http://cylinderheadshop.com/ but they are in the UK, in the middle of cleaning it up I'll get some pictures of the ports later in the week, this is how they look now

http://i1009.photobucket.com/albums/af219/jasonwinterson/head008.jpg

http://i1009.photobucket.com/albums/af219/jasonwinterson/head003.jpg

 

[scabber]

I think that head will perform real well once you get it cleaned up. It was a good casting to start with, some lack material in the turns area those ports look real good. Nice find.

 

[jayel]

from the looks of the corrsion it was used on one of the rare Unterseeboot XS's, I've seen them look somewhat like that but never that bad looks like it was in a flood

 

[scabber]

I would get it bead blasted probably sat in the rain with the carbs off. The one picture that has been removed did look pitted real bad.

 

[scabber]

I see the picture has been restored it should clean up nicely just clean up the high spots the pits will fill themselves with carbon.

 

[jay760]

Isn't the extra layer of rust to raise compression? been cleaning it up tonight, coming up quite good, probably leave the layer of crud on the outside, don't want it to look out of place when it's fitted

 

[jay760]

just cleaned it up a bit

http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead020.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead019.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead018.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead017.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead016.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead015.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead014.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead013.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead012.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead011.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead010.jpg

 

[scabber]

That looks good cleaned up nice you be happy with that head once you get it on your bike. thanks for posting

 

[Jack]

just cleaned it up a bit

http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead020.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead019.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead018.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead017.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead016.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead015.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead014.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead013.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead012.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead011.jpg
http://i1009.photobucket.com/albums/af219/jasonwinterson/ebayandhead010.jpg

There's room for improvement in both ports and those valve seat angles(you only have one) are in desire need of a full preparation too. You want to reduce the most resistance possible in the exhaust port without diminishing port velocity and still maintain a flow ratio near 70 to 75%.

 

[jay760]

Judging by the parts that came with it I think it was done in the 70's I don't know if they had different valve angles then

 

[Highside]

I can't say from the pictures but it looks like the sharp edges in the valve pockrt area have been blended. Haven't seen it done on a 650 head but if your running high compression pistons it might heip lower compression. Doesn't look factory. Got me thinking. Sharp edges can cause detination.

Actually, it's done for flow reasons. You're removing so little material that I doubt it has much effect on CR. It would only help reduce detonation if you were running a high CR in the first place.

 

[Jack]

Judging by the parts that came with it I think it was done in the 70's I don't know if they had different valve angles then

Most likely to induce low lift flow#s or seat longevity.

 

[scabber]

Well Highside since you Quoted me The got me thinking part was related to better flow. Not cc the head no one knows for shure at this point how mutch compression would be lost. I didn't have the benefit of head cut away at the time was just making some quick observation. Although I haven't worked for a professional race team I have worked on a NDRA record holding car many years ago and modifing a combustion chamber is not new to me. I do agree with jack the ports could use some more work not knowing you porting skills I wasn't going to advise you on that they would work better than stock and three angle valve job would make flow better. Jay you have been here longer than I have you probably seen his pictures,

 

[jay760]

Yes I've seen his pictures, I also know how difficult it is to get right and how easy to get wrong!! and once wrong it's knackered so will be just polishing up the exhaust a bit more, I know the head could do with a bit of updating with the valves but I run to a very tight budget, it was more a thing of not many people do this to the chamber