Rebuilding Head 78 GS1000

[Anonymous]

I was replacing the intake boot O rings like Keith said and I broke off one foe the bolts. I tried an easy out and broke that off too. Now it's a cluster...I have an extra head and I was thinking I should get it rebuilt. The bike has 30k on it. Should I get the cams reground? Is that really neccessary? Also I read other posts about degreeing the cams at 106. How do you do that. I don't want to spend a bunch of money, I figure having the head rebuilt is going to be $300 to $400. With the extra head I can just have that one rebuilt before having to tear the old one off. Any suggestions before I start?

[SqDancerLynn1]

Is the head the same year?? 30K the cams should NOT need any work.

[Anonymous]

I'm assuming its the same year, I got it as extra parts with the bike. It is an 8 valve. I don't know of any way of verifying the year without just looking closely to see that they are the same. I don't know how many miles the extra head has, I was just going to rebuild it to be on the safe side. Do you think I should just clean it up and maybe replace the seals and call it good? Who can tell me about degreeing the cams at 106 deg.?

[SqDancerLynn1]

The intake mounting and opening are a different size on the later heads

[saaz]

If you want to limit expenditure, just put in new valve stem seals and give it a clean up. The cams and everything else should be fine. Unless you modify things the valves should not need lapping in. I still have the same valve guides and valves in mine at 155,000kms. I had the cam redone, but only to go to a more performance spec. The top ends ogf the GS are nearly bullet proof. Valve guide seals go with age, but I am talking about 20 plus years here!

[KGB]

I agree with Saaz,
Check the valves and seats.
New guides are cheap and good insurance.

You can get carried away......I started out with a top end rebuild and ended up with a $2500 complete rebuild. No regrets.
If you don't do it, ask around and find someone who knows these motors and has a good reputation.

If you want to limit expenditure, just put in new valve stem seals and give it a clean up. The cams and everything else should be fine. Unless you modify things the valves should not need lapping in. I still have the same valve guides and valves in mine at 155,000kms. I had the cam redone, but only to go to a more performance spec. The top ends ogf the GS are nearly bullet proof. Valve guide seals go with age, but I am talking about 20 plus years here!

[Anonymous]

Thanks for the input. It is easy to get carried away. I'll see if I can borrow a spring compressor and replace the seals. I have a dynojet kit and air filter on the way and am hoping to get this thing going over the Christmans Holiday. Tis the season to be jolly! (When you're fixin up your GS)

[terry]

Hey mate, if you're gonna replace the head go get a "Big Port" head offa 80-82 model engine. (even the "G" models had big port heads)You'll get about a 10 BHP increase right away, and you can still use your cams, pipes etc, but you'll need some bigger carbs (34 or 36mm CV's are very good) and the appropriate airbox.

Of course, your old head is infinately repairable, just get a 3/8" electric drill with a 1/4" round nose burr and some cutting fluid to remove the remains of the ruined "eay-out" (Hah!) and 6mm screw, then clean out the crud with some thinners, fill the crater with JB weld or Devcon, and when it's hard insert a 6mm "helicoil" and bolt your carbs back on, easy.

I've done it on two of my GS engines now, and it works fine. I'd be happy to do it for you, but the shipping to and from Oz would be a killer, and anyway, the big port heads are bolt on horsepower! Cheers, Terry. :twisted:

[Hoomgar]

Want to jump in and second what Terry just said. We are rebuilding my 78 GS1000 and we went with a 1980 GS1000G head and cylinders for the larger intake ports. We are also using the 34mmcv carbs off it. You have to swap both cylinder and head as the two are not compatible due to bolt pattern diiferances. You can see the added bolt on the larger ported head and cylinder combo in this pick here:



Rock on buddy.

[Anonymous]

I've never used a Heli coil before. Are you saying I should completely fill in the hole with JB weld? How do you then put in the heli coil?

[RacingJake]

I'd first take it to a machine shop and see what they say. They can do it quicker and who knows maybe they can save the threads.

At least they can give you a price for the job. Call around.

[katman]

coils are stronger than original. My head has all the cam caps replaced with coils. Many road racers did the same thing but I would get a shop to do it. You sound unsure so get a pro to do it.

[Anonymous]

I think I'll just swap the head since I already have an extra one. besides that the screw for the tach drive at the front of the head has had the threads messed up, and it leaks. I didn't do that one! Thanks for the info though.

[massakins]

Jkev, I'm located in the Everett area and am very familiar with the GS1000 heads. Contact me at massakins@aol.com and lets see what I can do to assist you to rework your head. For what its worth, I have all of the tools and spare parts on hand plus 20+ years of doing it. Degree cams almost as long as well. Contact me if you're interested in learning how and we can probably make it happen. BTW, I'd have the broken bolt extractor removed with a laser, i.e. burnt out, to minimize damage to the base metal. I always used helicoils as a last resort because even though they are stronger than aluminum, they have proven to be not very durable if bolts are removed and replaced frequently. In your case, its probably not a problem.

[katman]

I always used helicoils as a last resort because even though they are stronger than aluminum, they have proven to be not very durable if bolts are removed and replaced frequently. In your case, its probably not a problem.

Repeated removal of bolts is exactly why racers use the helicoils. In my experience if they are installed correctly you can't even get them out if you want to.