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head work

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andy230:
Hi guys,

Sorry to labour the point!

I'm sorting the SRX head (finally!) this weekend.  Waited a while on parts.

Should I clean off the old carbon from the racer's head while I'm in there??  Will it actually make it flow any better?  Will it make any more power at all?

I'll lightly grind the old valves, and grind in the new one proper...

Just wondering if I should de-coke before bolting it all back together.  And is it theoretically better to polish (ie with brasso) the combustion chamber??

Have to say tho, the Slipsteam head work on the ports and round the tracts is lovely.  Quite a lot of metal has been taken off round the guides...

Cheers

a

themoudie:
Aye Andy,

Personally wouldn't bother with the 'bull', just clean carbon off with a lollipop stick and cocktail sticks. If there is more effort required than these will take to remove the carbon, are you revving it hard enough? ;-)

Opinion varies between polished mirror finish and clean unpolished surface. First assumes greater flow hence total volume of charge to burn. Second assumes 'golf ball' effect which provides lots of minor eddies in the charge giving better atomisation and mixing of the charge, hence a more complete burn of the charge. The shape of the ports has more effect than either finish on potential charge volume.

You also mention that a lot of alloy has been removed from around the valve guides. Whilst Slipstream know their stuff, I just wonder if too much has been removed, reducing support for the guides and allowing them to flex at high rpm. Common problem with over enthusiastic removal of alloy on Duke single heads in the inlet port, when trying to get them to breath properly. I don't think I need to elaborate on the consequences of flexing, loosening, valve guides at high rpm!!! :-O

Finally, after grinding in your valves, finish off with Brasso or Solvol to get really smooth seats. Wash away ALL traces of grinding/polishing compound. Smear seats with a touch of light machine oil before assembly and some graphite and engine oil on the stems to ensure they don't 'pick up' when first starting.

All the best, Bill

andy230:
Cheers!

wont bother with polishing the chamber then.

Gave the old valves a quick grind, and the new one a wee bit more.

Noticed some pretty mild pitting on the exhaust valve and seats.  Didnt want to give it too much, but there are still marks.  Acceptible?? Am not getting seats and valves anyway!  But can these be removed??

Seemed to be going ok before...

And whats the opinion of after solvet cleaning to stick it in a dishwasher afterwards?  Or is that just daft?!

a

peterj:
I always end up doing a kero leak test. If it doesn't leak, I don't worry about pitting, if it does the grind some more.

The dishwasher ounds like a reasonable idea, but I'd be giving it a very good hand wash first to get at the bits the spray wont reach and probably more importantly minimise the risk of the missus finding out why the best china smells of 20/50............

themoudie:
Aye Andy,

As peterj says "I always end up doing a kero leak test. If it doesn't leak, I don't worry about pitting, if it does the grind some more."

It's in the grinding man!

By the way have you noticed how PC this forum is? I referred to a Cocktail stick in my previous message and it inserts asterisks. Non emasculated male bird next! ;-)

Cheers, Bill

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