Valve Clearances

[MPittma100]

Do It The Right Way The First Time

I will add that grinding valve tips has to be done within reason. Normally you are only talking off a few thousandths. Much more than that and you will need new seats as has been suggested. The shop that I use has done this for many years - no failures.

MP

[TomB]

What Steve is saying is that the spring cap is nearly level with the valve stem top so you can't remove much from the stem otherwise your bucket will be sat on the spring cap, not good.

I've ground valve stem tops before, and made shorter pushrods, but as Steve says it may not be possible on these heads.

Any machinist will only do what you ask him to do, (speaking as a machinist) but a good one will point out problems occurring as a result the owner may encounter from what he's being ask to do.

[xssidecar]

Wow!!;so much information and advice for me to sift through.I can't reply to all of you individually so a big group thankyou to you all.I will slowly digest all you have said and then decide what to do.The problem with getting a new head is that these bikes hardly exist in NZ certainly not as bits for sale so a head would have to come from overseas with all the cost which that would entail,but hopefully that scenario won't arise.I will let you know what solution I eventually come up with.
Oh and by the way ,the valves I got off mpitma which as you will see were the wrong head size (reasons can be seen in my earlier posts) are for sale now as I can't use them.I would sell them for what I paid for them so if anyone needs 4 inlet valves just drop me a line.
Thanks again guys for everything and fingers crossed I haven't got a disaster on my hands.
Cheers xssidecar (Gerry)

[ViperRon]

I am offering this as something you can try. I know the cylinders will slide right out of the jug assembly if you put it in a stove and heat it makes it easy to replace 1 bad cylinder rather then boring all 4. So if you can find a new seat on Ebay and I have seen them offered (different sizes for the 79's and latter models) then you might try heating the head in a stove oven and gently tap the seat. I bet it will come out.

If your wife catches you and it does smell of buring oil you might be out quicker than the seat's.

[xssidecar]

Thanks ViperRon,
That's something to think about.I didn't know they were available.I will keep a look out and if this all goes pear shaped then I may have another option.
The difficulty of getting anything here in NZ can be very frustrating.Isn't the Internet great--- mostly!!
Cheers xssidecar

[Orange4]

When you find out what size shims you need, let us know. I have some extras here from 260-290.

[IanDMacDonald]

What should have happened is that your machinist, that reworked the head, should have already adjusted the valve lash prior to giving it back to you.

He should have asked you for the camshafts, followers, and shims along with the head. He then would have ground the tips of each valve to correct all of the valve lashes. Tips can be ground to correct the lash without causing failure as long as it is done within reason. The shop I use shop does it every day. This procedure would have completely eliminated any need to adjust lash when the head was installed. I am very surprised that he did not do this.

MP

This is exactly what I was thinking, as this was the advice given to me by others on here when I had the valves installed in my cylinder head . I asked them to set the lash for me, which involved me giving him cams, caps, oil seals, etc. He did install the caps in opposite order (I asked him not to torque caps, as I had to remove cams to get chain around them), which has made me question if the lash is set correctly. I know I should check his work, but I was too excited to get that head on and see the bike run.

[Orange4]

If I had a dollar for every time I let enthusiasm run the show...

When working with subcontractors you really have to be a snoopervisor. You have to be their boss and make sure they know their s**t. Write down what you want them to do in detail. You may feel bossy or demanding but that will be nothing compared with the frustration of paying for something done wrong. Remember, you are protecting them as well.

If they get dismissive with your concerns take your business elsewhere or talk to a supervisor. From my experience, no one knows less than a know-it-all.

Then when it all goes well, be a good boss and thank everyone.

[MPittma100]

Good Machine Shop

I have a machine shop kinda not near me. It is in Gainesville, GA. He is very good. Anything from a race engine to a motorcycle to a stock engine - he does it all very precisely. Installed last head from him and all lashes were dead on. He had replaced all valves, ground seats, glass beaded head, assembled, and adjusted lash.

MP

[MPittma100]

Wow!!;so much information and advice for me to sift through.I can't reply to all of you individually so a big group thankyou to you all.I will slowly digest all you have said and then decide what to do.The problem with getting a new head is that these bikes hardly exist in NZ certainly not as bits for sale so a head would have to come from overseas with all the cost which that would entail,but hopefully that scenario won't arise.I will let you know what solution I eventually come up with.
Oh and by the way ,the valves I got off mpitma which as you will see were the wrong head size (reasons can be seen in my earlier posts) are for sale now as I can't use them.I would sell them for what I paid for them so if anyone needs 4 inlet valves just drop me a line.
Thanks again guys for everything and fingers crossed I haven't got a disaster on my hands.
Cheers xssidecar (Gerry)

The valves were the correct part number. Wonder why they did not work?

MP

[xssidecar]

Hi MP,
I thought I had explained in an earlier post:So sorry if I did not make myself clear.The valves you sent should have been the correct ones according to my Model and Year.But it turned out that my head has the smaller headed valves from the earlier bikes.Mine is what they marketed as I think what they called an Australasian market bike and maybe being such a small market they used up earlier parts on ours;Please don't think I intimated that you sent the wrong ones.You did right and anyway it was me that said they were right.Not being used to working on these Jap engines (British and European are my usual) I didn't think to check as I figured Engine and Frame numbers would have sufficed.I will double check everything for now on.I'm learning a lot and you all have been a great help and given some very useful ideas to explore.
Thanks again
xssidecar

[TomB]

A new slant on the problem....

On the UK XS forum there's a discussion going on about a bloke who needs valves, he got a set but they were too short, another bloke has answered that XJ's-3H5's and 4R1 are some of the engines that use the shorter Exhaust valve. 93.5 mm compared to 95mm. If they're the same size valve diameter it may help with shims on a seat re-cut head.

Just a thought, I didn't know there was different length valves, one of you knowledgeable fellas will know.


.

[crazy steve]

...I didn't know there was different length valves, one of you knowledgeable fellas will know..

The '80-up bikes have the shorter valve stems, but the valve diameters are larger. Yamaha had to 'sink' the valves deeper into the chamber to get enough clearance between them. I suppose it may be possible to cut the late valves down to the early diameter, but that would only work for the 78-79 head, no help for the later one....