4k 3k Big Port

[shauns ke30]

Hay lads just want to no a couple of qustions I have looked every where but I can't find the questions that I'm looking for..

I'm going to put a 4k in to my ke30 soon and I want to put the old 3k head on it do I have to big port the 3k head???

And how much of a differance does it make by puting the 3k head on the 4k apart from more compresen???

And is it as esy as just slapping the 3k head on? Or do I have to do some engen work??

Sorry for the spelling.

Cheers shaun

[DearmanKE]

you do not need a 3k BP head, they will both raise the compression the same amount,

id say it wont make any difference at all except for raiseing the compression(unless its a BP one,)

 

and I'm fairly sure you can just slap it on, wait for an answer to that one from someone who has done it before tho

[Taz_Rx]

and I'm fairly sure you can just slap it on, wait for an answer to that one from someone who has done it before tho

 

:)

 

as both have the same size bore it doesn't really matter if you use a 3k or 4k HG.

 

You'll also need to use the 4k pushrods or the 3k ones will pull up about 10mm or so too short.

 

 

To make the most of the raised compression you really want to do the usual mild mods too: Carby, cam, exhaust etc.

[towe001]

And don't forget the valve gear (rocker posts, etc) are a better quality on the 4k. So swap them over as well.

 

With the 3k big port, from memory the oil thingys around the valves are different so if you use the 4k gear you'll have to swap that stuff over as well. Which would be a trip to a engineering shop.

[Taz_Rx]

And don't forget the valve gear (rocker posts, etc) are a better quality on the 4k. So swap them over as well.

 

With the 3k big port, from memory the oil thingys around the valves are different so if you use the 4k gear you'll have to swap that stuff over as well. Which would be a trip to a engineering shop.

 

INCORRECT.

 

The old head (3kbp included) had the old valve stem seals that were just an o-ring around the very top of the valve. later 3k and 4k ones had the stem seal on top of the stem.

 

You can swap the rocker gear between the 2 different type of stem seal heads without having to also swap the stems/seals them selves. :)

[towe001]

Cool.

Going to have to look into that on my big port in the morning. I was told the seals,etc had to be changed over.