Katit's 1978 KZ650 project

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Yes! once the guides are fitted the clearance will reduce.
The new valve 'may' still slide in the guide but the clearance will be too small.
Measure the valve stem, add the clearance required and that will tell you the bore size of the guide that is needed.
As mentioned, the valve stem is usually undersized by the amount of clearance required ( but this must be checked as some aftermarket valves aren't ) so a true 7mm guide bore should result in the correct clearance.
 

I don't know... To me correct clearance achieved if valve will be moving freely with no sticking. When engine warms up - guide will be expanded more than valve anyways.
So, if there is hone(oil) and it moves freely - it should be just fine. Give it some break-in time and there should be no problem.

This is what I am going to stick with anyways I feel like in this particular case too much is worse than maybe little too tight. Why am I changing those in a first place?

wrote:

wrote:

Yes! once the guides are fitted the clearance will reduce.
The new valve 'may' still slide in the guide but the clearance will be too small.
Measure the valve stem, add the clearance required and that will tell you the bore size of the guide that is needed.
As mentioned, the valve stem is usually undersized by the amount of clearance required ( but this must be checked as some aftermarket valves aren't ) so a true 7mm guide bore should result in the correct clearance.


 

I don't know... To me correct clearance achieved if valve will be moving freely with no sticking. When engine warms up - guide will be expanded more than valve anyways.
So, if there is hone(oil) and it moves freely - it should be just fine. Give it some break-in time and there should be no problem.



 

No!. When the engine gets hot the valve to guide clearance REDUCES not expands.
This is why you need the correct clearance cold to provide close running but not zero clearance when hot.
You must measure and set the cold clearance to the correct specs otherwise you risk the valves jamming in the guides when hot which will lead to piston to valve contact.




 

wrote:

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wrote:

Yes! once the guides are fitted the clearance will reduce.
The new valve 'may' still slide in the guide but the clearance will be too small.
Measure the valve stem, add the clearance required and that will tell you the bore size of the guide that is needed.
As mentioned, the valve stem is usually undersized by the amount of clearance required ( but this must be checked as some aftermarket valves aren't ) so a true 7mm guide bore should result in the correct clearance.



 

I don't know... To me correct clearance achieved if valve will be moving freely with no sticking. When engine warms up - guide will be expanded more than valve anyways.
So, if there is hone(oil) and it moves freely - it should be just fine. Give it some break-in time and there should be no problem.




 

No!. When the engine gets hot the valve to guide clearance REDUCES not expands.
This is why you need the correct clearance cold to provide close running but not zero clearance when hot.
You must measure and set the cold clearance to the correct specs otherwise you risk the valves jamming in the guides when hot which will lead to piston to valve contact.

 

Ok, then I am going to put head with valves (just drop valves in) in a oven, get it to 150C or so and check if valves move freely. That should do it

wrote:

wrote:

wrote:

wrote:

Yes! once the guides are fitted the clearance will reduce.
The new valve 'may' still slide in the guide but the clearance will be too small.
Measure the valve stem, add the clearance required and that will tell you the bore size of the guide that is needed.
As mentioned, the valve stem is usually undersized by the amount of clearance required ( but this must be checked as some aftermarket valves aren't ) so a true 7mm guide bore should result in the correct clearance.




 

I don't know... To me correct clearance achieved if valve will be moving freely with no sticking. When engine warms up - guide will be expanded more than valve anyways.
So, if there is hone(oil) and it moves freely - it should be just fine. Give it some break-in time and there should be no problem.





 

No!. When the engine gets hot the valve to guide clearance REDUCES not expands.
This is why you need the correct clearance cold to provide close running but not zero clearance when hot.
You must measure and set the cold clearance to the correct specs otherwise you risk the valves jamming in the guides when hot which will lead to piston to valve contact.


 

Ok, then I am going to put head with valves (just drop valves in) in a oven, get it to 150C or so and check if valves move freely. That should do it

No! the valves and guides get hotter than that during operation.
Just make sure you have the correct cold clearance to begin with, it's not complicated.

wrote:

No! the valves and guides get hotter than that during operation.
Just make sure you have the correct cold clearance to begin with, it's not complicated.

It's not. But where do I get "exact" correct 7mm gauge?

wrote:

wrote:

No! the valves and guides get hotter than that during operation.
Just make sure you have the correct cold clearance to begin with, it's not complicated.

It's not. But where do I get "exact" correct 7mm gauge?

You need to measure the valve stem = micrometer.
Then measure the new installed guide with a small hole gauge and micrometer etc then calculate the current clearance.
Only then will you know what size the guide bore needs to be.
If all the clearance is already on the new valve stem you don't need the tools to measure the bore just an accurate 7mm pin etc as a go/no go gauge and then hone until it slips through the guide.

MauiZ1 just posted he purchased a gauge to check his guides. Ask nice he might tell you where he got it. 

No eBay APP ID and/or Cert ID defined in Kunena configuration

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MauiZ1 just posted he purchased a gauge to check his guides. Ask nice he might tell you where he got it. 

I already got set of micrometer gauges, so I just went and ordered basic/cheap set of bore gauges. Should do it.
Right now my main goal is to get them (guides) installed. I can work on getting seats cut right away, while waiting on those




 

More progress. Liked idea of using cap hole as a guide. Machined aluminum bushing and press adapter to fit tight and stop when correct press depth achieved. ID of bushing is just right to fit new valve guide.

All guides went in easy and quick. Proper tool makes a difference! Pressed back some old guides into other head (original) which going to be my test bed for cutting valve seats!

Now, zed1015 were absolutely right. Right now I can't insert valves into guides. Micrometer gauges and hone is on a way but meanwhile I can work on valve seats...

 

Question about valve seat cutting. I tried on scrap head and this is result. There is some deep pitting, hopefully you can see it on a picture, so main surface (45 degree) need to be cut pretty deep to get to clean metal. At least on this head. Is this expected? Or leaving some of this pitting is OK?

BTW, per manual only intake needs 3 angles. Exhaust needs just 45 and external angle

 

The seat should be a uniform 1mm wide.  Use the top and bottom cuts to center the contact patch on the valve face.  When cutting the valves on my 750 the seat widths were pretty uneven but I was able to clean them up nicely using Suzuki type cutters with a 75 degree throat cut and 30 degree top cut.  Kawasaki references the top and throat angles opposite of normal convention; the throat cut they call a 30 but most people refer to it as a 60.

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The seat should be a uniform 1mm wide.  Use the top and bottom cuts to center the contact patch on the valve face.  When cutting the valves on my 750 the seat widths were pretty uneven but I was able to clean them up nicely using Suzuki type cutters with a 75 degree throat cut and 30 degree top cut.  Kawasaki references the top and throat angles opposite of normal convention; the throat cut they call a 30 but most people refer to it as a 60.

Ok. I am all in For now I can only do 45 degree (because I can't fit valves to check where the spot is). Once I get tools (hone) - I will get other angles finished.

I also think I know how I am going to grind valve tips myself. Not a rocket science afterall...