1982 gs450 valve guide replacements --- machinist, cylinder head suggestions

[prichmon]

I have an 82 gs450T which I found had 2 bad valve guides and 1 exhaust with some play.

I ordered all 4 NOS units from ebay. I bought new circlips, 7mm driver and had a Machine shop ream the guides.

The intakes I used an air hammer with a 7mm driver to remove the guides. 1 cracked some pieces of the boss on the way out.
I used the air hammer to drive in the 2 new guides. The guides went is easy with some oil.
The valve guides ended up tight in the middle like the circlip is pinching. I wonder if I drove them in too hard?

The exhaust would not come out at all. I heated the head to 300*f in the wife's oven, let it soak for 15 minutes and the guides came out fairly easy.
U used a ball pein hammer to drive exhaust in an attempt to limit the load I put on the guides. The exhaust went in great.

I took the head to the local machine shop to get the valve seats and valves matched.
The MS called to tell me all 4 guide bosses are cracked. The exhaust have reamed fine. The intakes won't make proper clearance.
The MS suggests I get another head.

My iniital thought is to replace the intake guides and mill down the boss area to remove the cracks. Or should I just try to find a replacement engine or head?

Could someone give me a suggestion for repair?

Thanks guys!!!

Rich

[Nessism]

I would try to find a low mileage used head. eBay has a bunch of used heads. When faced with similar issues, I would hunt one with a mileage discloser. Hopefully, you can find one. Or better yet, post a WTB ad here.

[zed1015]

If the guides are cast iron in an alloy head you must heat the head to remove and replace them.

[chuck hahn]

Heat the head at 375 to 400 for a good while then drive the vguides outfrom the combustion chamber side. If you didnt order the retainer clips reuse them on the new ones. I personally dont ream the holes. I just turn the new ones in the lathe and done. Screw that 12 MM bullscrap.

[GregT]

As Nessism says, find another head. It is easy to crack the area around the guide holes putting them in cold. Far easier to find another head than go to the trouble of machining and making new guides.
If it was an uncommon or rare model it'd be a different story.

[Suzukian]

I would press something out, but never use an air hammer. The vibration will break the brittle components. A hydraulic press, with a guide pin inserted all the way through (even if you have to make it), and a jig to mount the head perpendicular with the press will save you lots of trouble.

[prichmon]

Thanks guys. I'm in the process looking around for something reasonable. I appreciate the thoughts!!!!

RR