Valve Guides

How can you tell whether you need to replace your valve guides? Also, how big of a job is it to do and how do you know what size you need?

Let'roll, very briefly, in case you want to get started.
The first sign of the need for this job to be done is the blowing of blue smoke. (black is usually fuel, or is it vice-versa?) However, this could be the valve seals. If you aren't blowing smoke you usually don't have to worry.

Assuming the head has been removed from the engine. You would usually check the guides when you are doing something else like rings or a valve-grind, seal replacement or blown head gasket. This check, is for side-play and fit tolerance between guide and valve stem. DO *NOT* press/ drift or hammer the existing guides without, firstly, heating the head. It tends to take metal with them and your new guides will be loose.

I was always reluctant to do this job, mainly because the guides looked too tight and I thought I would "butcher" them if I tried to get them out. However, with my wife's oven a whole new methodogy arose.

Simply, heat to 200 degrees Centigrade for 30 mins and handle with care, having all guide punches ready, it is a simple job. There is is usually a small circlip that allows you to hit the new guide into the correct depth. When you hit the new guide in, there is a definite change in sound when the circlip bottoms. Only some of the new guides may have to be ream and this would only be if new valves were fitted. For a full 8 guide job re-heating would be required many times. Be careful head dowels don't fall out and become lost!

You would do your valve-grind after the new guide has been fitted.

RegardZ

Wow Garn, you are amazing if you did guides yourself! Personally I would leave this to a experienced shop, but hey if you think you can tackle it yourself, more power to ya.

And you could also get the blue smoke syndrome from bad valve seals and not necessarily worn guides.

I've heard it's better to replace all 8 guides at once even if only one or two are bad since you don't want to keep reheating the head over and over.

We do a bunch of these, so here goes...
If you can rock the valve in the guide, it needs to be changed.
The 900s were brass, the 1000s are cast iron. Not sure about the 650/750 at the moment. Any of these motors that have the original guides, they will be worn out.

To start, the nose of the guide that protrudes into the port must be completely decarboned. We do this with a media blaster. If there is carbon on the guide and you attempt to knock it out, the carbon will broach the hole in the head out oversize.

After you have done this, figure out if your guides are brass or iron. Check them with a magnet. If they are brass, do not heat the head. The brass expands at nearly the same rate as the aluminum, so you are not accomplishing anything. If they are iron, heat the head. If you heat it for an hour at 300/350 degrees, you can knock all of the guides out at once. Don't need to use the wife's stove for this. Get a two burner electric hot plate from Rite Aid, and cover it and the head with a large metal bucket. This way the smell stays out in the garage

We manufacture bronze guides for these heads kzzone.com/valves.html We install them cold, in a press with a special fixture that holds the head in exactly the right position.

PLEASE DO NOT POUND NEW GUIDES INTO THE HEAD, regardless of what the manual says. You can damage the guide and/or get the guide in crooked.

After the guides are in, we size them if necessary with a precision Sunnen valve guide hone, to accommodate the correct Serdi pilot.

Then the head is pit into the Serdi cylinder head machine, and the seats are machined exactly concentric to the new valve guide. www.aperaceparts.com/headwork.html

I believe it can be too much of a job for someone not set up to do it.

As a footnote, we also manufacture a variety of oversize guides for the people who have screwed up these heads trying to do this.

Jay
kzzone.com/

Post edited by: APE Jay, at: 2005/12/08 23:52

I've done a fair bit of engine work on My bike(personally),but I would NOT try to install valve guides Myself.That's a job for the Pros...too many if's,and Who wants to have to pull the head again?(and again).
Pay the money,and get them installed(and checked) by a Professional...You'll be glad that You did.

Jay, agree with you in-part. Two items; only the early Z's had phosphor bronze guides the later had steel. Secondly is that 330 degrees C or F.

Could not agree with you more, regarding the decarbonising of the nose of existing guide to allow smooth extraction (I did say I would be brief).

For Savedrider: You have to be pretty skilful to do all eight at one heating session. I would never attempt it! I think there is a strange relationship in the wear pattern of the inlet and and the exhaust valves (and I could be "ass about front" here!). The exhaust valve-stem seldom wears, whereas, the inlet valve-stem does wear. Meaning it is more likely the inlet-guide wears less than the exhaust-guide. Resulting in one or other guide usually needing to be replaced. Hence, it is usually only 4 guides needing replacement. These can be removed at one heating session.

For Sandy, as I said, I was reluctant to tackle the task. Now, I would not hesitate!

Regardz

My bike does not smoke and it has plenty of compression, it is just that I will be replacing the valve seals this winter and figured I would ask about the guides. Thanks to all that responded!

LTGTR - First, you can use a Tee bore gauge to measure the inside diameter of a guide but I have done this and don't find it very useful... maybe my technique is bad or my tiny bore gauge isn't particularly accurate but the guides just don't seem to wear perfectly round and measuring is an exercise in frustration. Jay hit the nail on the head with the wobble test... if the guide wobbles excessively, replace the guide. You judge if you are able to do it but the instructions given in this thread are pretty sound. I will give you one bit of advice... IF YOU ARE MARRIED AND WANT TO CONTINUE BEING MARRIED!!! DO NOT LISTEN TO GARN'S ADVICE ABOUT USING YOUR WIVE'S OVEN!!! I strongly suggest you will stink up your house. This is a NON STARTER in any house where the wife has access to blunt objects. Also, in the good ol' days before o-ring chains, we used to put our drive chain in a coffee can with oil and boil the oil on the stove. DO NOT DO THIS EITHER... LARGE KNOTS ON YOUR HEAD WILL RESULT.... (don't ask how I know these things for sure...).

ANYWAY... one last bit of guide advice... the new guide hole will not be exactly the same as the old one. This will mean that the valve seat will be NO GOOD... this phenomenom is called valve concentricity. Anyplace that installs new guides and doesn't want to touch up the seats doesn't know its business I think. Valve jobs on a Kaw involve three cutters with different angles. A bike machine shop will know how little is needed to dress a seat where a car machine shop may be heavy handed and chop your seats to smithereens. I suggest if you want to get your head done, to do a valve job at the same time as well as replace the valve stem oil seals at a minimum. Also on the 900s you can measure the spring length to ensure they are in spec. On the 1000s you have to have a caliper capable of compressing the springs. But... measure the springs as well to ensure they are in spec. I lap the valves/seats after every valve train related job... very lightly just to clean up the seating surface. Call the bike shops in your area to find a bike specific machine shop and if you don't find a shop that caters to and understands bikes, you might want to farm the work out to a place like APE where they know what they are doing. Be VERY careful about using an automotive machine shop for head work... you ain't got a small block Ford engine in that bike!

pound em out grease em and pound em back in. Hve the seats cut and go. No big deal. And grease that hole too mind u er youll be sorry. Ive done this so many times and screwed up enough guides and holes that i got the record hands down. I called ape and they said off the shelf the guide would slide onto a stock kz valve. Not! They wouldnt even start. Well course then i had to hone them. Then install them then hone again. This is a bitch with homade tools but you get good. And you get smart about whats said to you. And you think of things like dry ice to cool the guide before removal or that spray called cold power for Estes land rockets. You can drive out guides with the back end of a drill bit. But dont do it! The lips not wide enough. Or is it? My advice? Its all in the words. This has been the about all the makings of success. Dont let em scare ya, dont let em fool ya, and heed all warnings or else. Never mentioned the fact that i ruined all 8 guides and got more from another company. Whoa be! the same guides. Huh, they fit the valve nice, say ape on them hmm. Oh well gotta wreck these now so grrrrr zzzzzz chp chp chp, slide a valve in and ahh. Think back to all the learning, driving one out backwards etc. The good old days. School. Honing class, driving class, APE saying WELL WYD YA HONEM! Well whyd ya tell me........ Guess we all make mistakes. If your installing your guides and one or more does not hammer in tightly to the seat take it out and go with a .002 over to make sure it wont work out when your running hot. Like when your hammering one in and the other one pops out, lol. Its easy so relax and just do it. I do car heads and everything and they all drive out and all drive in. A big hammer helps alot and wear glasses always.

Post edited by: nads.com, at: 2005/12/11 00:41

Post edited by: nads.com, at: 2005/12/11 00:45

Post edited by: nads.com, at: 2005/12/11 00:45

APE Jay wrote:

If they are brass, do not heat the head. The brass expands at nearly the same rate as the aluminum, so you are not accomplishing anything.

Jay, with bronze guides I've always heated the head, but blown compressed air down the guide to cool it before pushing it out - they seem to come out very easy this way

Jeff.Saunders wrote:

APE Jay wrote:

If they are brass, do not heat the head. The brass expands at nearly the same rate as the aluminum, so you are not accomplishing anything.

Jay, with bronze guides I've always heated the head, but blown compressed air down the guide to cool it before pushing it out - they seem to come out very easy this way

Jeff;
They come out just fine cold. I can have the old guides out and the new ones in in the time it takes you to heat the head to 350

I might add, we use an air hammer and a 7 mm guide driver ( from Goodson www.goodson.com/store/template/product_d...b000f4ad683782b2c0ba to remove the guides. However, sometimes if I am in a hurry, I just use the guide driver and a big hammer and have them knocked out before I could have found the air hammer and gotten it hooked up.

Jay

Post edited by: APE Jay, at: 2005/12/12 20:54