Top end rebuild

[doctorgonzo]

Sorry...grumpy, middle-aged engineer here...but I still think you should measure everything before going off and dumping a bunch of money into parts you may not need.

Shim and bucket valve actuation is very durable from the standpoint that there is no side load on the valve stems and guides. This leads to excellent durability. If you have a micrometer, measure the valves from your old engine and the valves from the new/used head, and find the best ones. As long as the valves measure within the service spec, you will not gain anything by changing them. Use the best valves of the lot and then check the side clearance between the valve and guide - you will need a dial indicator. Chances are pretty good that the guides will be good as well but measure to make sure.

The Suzuki parts are very high quality and I seriously doubt you can get better parts from the aftermarket. Hot rod V8 guys like stainless valves but stainless steel is softer than the hardened carbon steel used in the stock valves. To improve durability, the better stainless valves have hard chrome plated stems - good luck finding something like this for your GS engine.

Measure the pistons and cylinder bores as well.

Replace stuff that's worn. To measure is to know (sorry, had to throw that in there again.)

.

I understand Mr "old engineer" and I respect your opinion, don't EVER think I don't or that I don't appreciate your help.

The heads on the valves from my "new" head are carboned like the bike ran very rich for a very long time. Will a lengthy soak in berrymans take that off? I couldn't even get an accurate measurement on them as they are now. The ones in my current head may be better, but I was wishing, hoping to take the route of keeping the bike rideable while a new head was made ready than only be down a day or so while I install it, check the pistons and the bores, etc...

As far as the guides, it just makes me nervous, the service manual says not to reuse, and and I fear damage to them when they are takenout.

[Nessism]

As far as the guides, it just makes me nervous, the service manual says not to reuse, and and I fear damage to them when they are takenout.

Simple, don't take the guides out unless they are worn - you can check with a hole gauge. If you take the guides out the the valve seats will need to be cut because the guide will index slightly differently.

As for the valves, soak for a while and take a scraper of some sort to them - just don't scrape on the valve stem or valve seating surface. Didn't realize you were planning on a quick switch over so that complicates matters in terms of judging which valves are best. Strangely, the intake valves in my 3500 mile 850 also have crud on them; that stuff builds up real fast and doesn't really hurt anything - also highlights how silly undercut valves are for a street engine.

Good luck.

[doctorgonzo]

Thanks Ed. You don't think the chemical dip and other work at the machine shop will hurt the guides if I were to leave them in? I'll throw the valves in the dip tonight and see what I can do to get them clean enough for a good meaurement.

[doctorgonzo]

Looks like dip 8 hours, wipe off the carbon it loosened, dip 8 hours.... is going to get the valves clean. The heads look a bit pitted. The shafts are smooth and straight. This is the valves from the salvage head. I have not examined my current ones. I haven't measured yet for spec. Is light pitting acceptable, or should I consider that a "do not re-use" on a valve?

[Nessism]

It’s normal for there to be a little texture on the head of the valve, it won’t hurt anything. Important thing is the stem and the face that contacts the seat; no imperfections allowed. If the valve stems measure out okay, you can check the contact patch where the valve touches the seat by using some fine lapping paste. If you have a good machine shop in the area, someone that knows their way around a motorcycle head, you can have them ever so lightly kiss the valve face and seat with a cutter. The idea is to only take enough material to clean up the seating surface. Many shops take off too much material which is what you don’t want.

Hope this helps and good luck.

[psyguy]

like ed said, just measure everything - as per the instructions in the manual - if you dont have all the right measuring tools get a shop measure it for you (and best - in front of you, so you can note down the measurements and decide what you want to do)

valve guides are not expensive so lightly cutting the valve seats and putting the new guides should give excelent results without having to buy all new valves - which ARE expensive

carbon can be taken off the valves mechanically as well - a BRASS wire wheel on a drill works well (but stay away from the very edges of the valves)

finally, have the head mating surface re-surfaced (planed)

[doctorgonzo]

like ed said, just measure everything - as per the instructions in the manual - if you dont have all the right measuring tools get a shop measure it for you (and best - in front of you, so you can note down the measurements and decide what you want to do)

valve guides are not expensive so lightly cutting the valve seats and putting the new guides should give excelent results without having to buy all new valves - which ARE expensive

carbon can be taken off the valves mechanically as well - a BRASS wire wheel on a drill works well (but stay away from the very edges of the valves)

finally, have the head mating surface re-surfaced (planed)

Some updates.

Took the head to the shop yesterday, not extra confidence inspiring. Old school auto (though recommended by the local suzuki dealer) shop. They said they didn't have anything that would take the carbon off, but they would "give it a good wash", and they are going to verify it's not warped and mill if necessary. I took it in with the valve guides still in place, and actually even the old oil seals on it. I tried to remove one oil seal and it just crumbled to bits. That's going to wind up being a tedious job with a pick set I'm afraid, getting those old seals off. The lower retainer on the guide is also still in place as I couldn't figure from the manual how to get it out without driving out the whole guide. They show some type of what looks like a bladed tool, being used, but not much detail.

I checked the intake valves from the "new" head after a "good enough" cleaning, and they are all just out of spec, but within service limit, so they get tossed in a box I'm afraid. The head must have come off a fairly high mileage engine it appears. No luck on locating stainless steel valves, nobody seems to carry them, and Dynoman or APE can make them from blanks, but that's for $45.00 each. So, it's final decision time on whether to go ahead and tear down my current head to see if mine are in better shape (I am assuming they probably are with 30K miles), or order new OEM ones. I did find that Babbits has oem valves for $22.00 for intake and $38.00 for exhaust, so $200.00 for all new, gonna have to decide in the next day or so.

I'm leaning towards not taking out the guides now, but might still change my mind.

Edit:
The machine shop just called. The head was "not bad" in their opinion, but was slightly warped. They had to take a few thousandsth off it.

[psyguy]

I checked the intake valves from the "new" head after a "good enough" cleaning, and they are all just out of spec, but within service limit, so they get tossed in a box I'm afraid.

to ME, this would suggest that you need NOT throw money at the new valves

[doctorgonzo]

to ME, this would suggest that you need NOT throw money at the new valves

Like so many "spend the money, don't spend the money" decisions on this it's "well, I could put new valves in now, and probably never have to worry about them again" or "Put in the ones that are worn, but within service limit and 20K or 30K from now (3 or 4 years), be doing this job again"... as usual, I'm torn.

By the way Psyguy, I have become mildly obsessed with New Zealand after becoming a huge Flight of the Conchords fan.

[Suzuki mad]

If you can afford to replace the valves then do so. If you can't then go with what you have.

In your post your said this was a 'high mileage head.' If thats true you'll get more than 3-4 years out of the valves.

Suzuki mad

[Nessism]

If the old crusty-head valves are just slightly out of OE spec, the good head currently installed most likely has valves that are IN spec so just wait. The 8 valve GS valves and guides are extremely durable so I wouldn't be in a big hurry to replace them unless you plan on keeping the bike for another 100k miles.

[doctorgonzo]

If the old crusty heads valves are just slightly out of OE spec, the good head currently installed most likely has valves that are IN spec so just wait. The 8 valve GS valves and guides are extremely durable so I wouldn't be in a big hurry to replace them unless you plan on keeping the bike for another 100k miles.

Gotcha, that pretty much is the plan at this stage. I am replacing the springs as that's cheap.

[psyguy]

By the way Psyguy, I have become mildly obsessed with New Zealand after becoming a huge Flight of the Conchords fan.

if you ever plan to visit, make sure to get in touch

and if you need some further encouragement, then movies like:
the fastest indian
the lord of the rings
the piano
should help your decision

[doctorgonzo]

Back to the valve question, I've decided the exhaust are probably going to have to be replaced. The intakes off the salvage head cleaned up ok, but the exhaust are a lump of carbon. Assuming the exhaust on my current 30K mile head are going to be much rougher than the intake as well. I actually found an incredible price on both intake and exhaust valves from Vesrah, like $17.00 for intake and $18.00 for exhaust from Sudco. I have an email in the them to see if I can order direct as long as I meet minimum or if they can direct me to a dealer. Anybody already have a dealer account with Sudco?

EDIT:

Never mind, Intake discontinued and Exhaust out of stock from Sudco.

[doctorgonzo]

Bumping this thread as the rebuild is now in full swing. I have a thread on the UJM site, but gonna keep this one updated as well. I'll ad pics tonight. Today's good news is that after resigning myself to cleaning up the exhaust valves and hoping they were in spec I got an email back that one set of stock size Vesrah valves does indeed exist somewhere in the world and can be had for $21.95 each IN and $24.95 EX, but they'll only sell the full set. Probably gonna go ahead and take them. The old ones are probably useable, but as much work/money as I'm throwing at this thing another $200.00 to have brand new high quality valves throughout is hard to pass up. This bike is for life now.