1978 GS1000 Complete Engine Overhaul With Mods

[Hoomgar]

Well I saw katman do this so I thought I would as well since it is so much fun to jaw with everyone about.

My 1978 GS1000C as I have told many of you is getting some serious attention this winter. I am having to engine overhauled both top and bottom. The crank has been trued and welded as well as having the one end replaced with a new part. Falicon went $650.00 to do the work and from what I hear that is good. The transmission looks clean but the clutch basket was worn as well as the clutch so it is getting both new clutch basket and clutch. I good bead blasting and the bottom is done. Currently we are waiting for the crank to arrive to begin reassembly of the bottom.

The top end is being borred to 1098cc? I think that is right. Anyway it will be an 1100 now and we are porting and polishing the head as well as building up an exhaust dam before putting that back on. I never knew about the exhaust thing but my mechanic showed me how it will reduce turbulance in the exhaust ports of the head. Joe Paparo is the mechanic doing my engine work for me. He is the best when it comes to working on vintage motorcycles and any others for that matter. He really knows his stuff and I am very lucky to have him here for me.

The frame is painted now as well as all the frame parts and I have aquired new side covers for it. I also got a pair of used rear shocks in great shape coming. Things I need to do yet are the tank. It needs a dent fixed and repainted if touching up is too far gone. The seat is good, I just recovered it this year. I also want to find a Wes Cooley Replica race faring for it. No luck so far on that.

I bought a new pair of factory replacement engine gaurds for it but I also bought a used Wes Cooley engine gaurd with foot pegs on it. Not sure which one I want to go with yet but I am leaning towards the factory parts for look and size.

Please check it out at my new home page I am building and feel free to bombard me with all your great feedback and opinions. I want this baby to come out as sweet as I can You can check it out here:

http://home.ptd.net/~megabyte/projects.html

 

[Guest]

Hey hoomee,

web page looks great... so does the frame and forks. She is going to look brand new when you are done.

isn't winter great?

katman

 

[KEITH KRAUSE]

Hi Hoomgar. I did a complete restoration on my '79 GS1000EN about 3 1/2 years ago. It was quite a learning experience. My only engine performance related mod's were, welded/trued crank, welded clutch basket, 1085 Wiseco pistons, V&H 4-1 pipe, K&N ovals, Dynojet kit in the stock carbs, Dyna "S" ignition/coils. It runs great, much stronger than stock. If you want the widest powerband, I would suggest timing your cam's at 106 degrees each.
I did a lot of other things to my bike. Check out my website below if you want some idea's. Let me know if I can help you with your project.
Good luck!

 

[Hoomgar]

Thanks guys. I am really pumped about it. My mechanic has me all fired up about it. He has a lot of ideas as well. He told me that if I want to do anything to the cams at all I should consider getting bigger carbs since these stock ones are borderline already for the work we have done so far. The stock ones are 26mm but he told me to find 29mm at least or bigger. He said I should look for a pair of 33mm smooth bore round body carbs if I can find them and then he would do some cam magic for me.

If i get more than 100hp out of it I will be happy. She only dyno'd @ 63 when we tore it down and it really wasn't running that bad then.

 

[Paul]

Re: 1978 GS1000 Winter Rebuild

Re: 1978 GS1000 Winter Rebuild

Falicon went $650.00 to do the work and from what I hear that is good.

I was told last week that Falicon don't want to know about 20 year old GS1000 cranks

.....as well as building up an exhaust dam before putting that back on. I never knew about the exhaust thing but my mechanic showed me how it will reduce turbulance in the exhaust ports of the head.

What is an exhaust dam?

I also want to find a Wes Cooley Replica race faring for it. No luck so far on that.

Airtech make a replica. I have a spare but shipping costs from here to USA would make the cost prohibitive!

I bought a new pair of factory replacement engine gaurds for it but I also bought a used Wes Cooley engine gaurd with foot pegs on it. Not sure which one I want to go with yet but I am leaning towards the factory parts for look and size.

What is the difference? do you have any pics?

 

[Hoomgar]

Re: 1978 GS1000 Winter Rebuild

Re: 1978 GS1000 Winter Rebuild

Falicon went $650.00 to do the work and from what I hear that is good.

I was told last week that Falicon don't want to know about 20 year old GS1000 cranks

Well that must not be trus because I just had it done

.....as well as building up an exhaust dam before putting that back on. I never knew about the exhaust thing but my mechanic showed me how it will reduce turbulance in the exhaust ports of the head.

What is an exhaust dam?

This was news to me too Paul. On the exhaust port of the head the gasses are forced to the top of the port on their way out and the bottom of that opening is actually not needed so it allows the exhaust to create turbulance in that area which in turn creates drag or back pressure that you don't want there. He is going to build the dams out of an epoxy that takes the heat and fixes this issue. On later models you can see the dam there from the factory. It is something they were not aware of when they made these engines in the 70's. Very interesting, I never knew about this.

I also want to find a Wes Cooley Replica race faring for it. No luck so far on that.

Airtech make a replica. I have a spare but shipping costs from here to USA would make the cost prohibitive!

I have looked at Airtech but now their web site has gone offline. I keep checking back on them.

I bought a new pair of factory replacement engine gaurds for it but I also bought a used Wes Cooley engine gaurd with foot pegs on it. Not sure which one I want to go with yet but I am leaning towards the factory parts for look and size.

What is the difference? do you have any pics?

I do have pics. But the ebay pics will work.
The factory replacement engine gaurds are here:
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2443022188&category=34284

The Wes Cooley engine gaurd with foot pegs is here:
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2443606554&category=35588

 

[robinjo]

Definately go for the factory guards! LOL

 

[saaz]

Factory definitely. I have some of those so called wes cooley guards..I doubt they were ever used on his race bike! From what I hear they are more likely to bend you frame or break your leg in a crash. I would prefer some sort of crash knobs....

 

[Hoomgar]

2 votes for factory so far plus mine

The thing I like about the Wes Cooley gaurd that is making me wonder back and forth is the fact that it has the foot pegs on it. I really like having them for some of the long rides we take. I have long legs and my knee's get cramped and I need to stretch out my legs at times. The front highway pegs are nice for that. But other than that the Wes Cooley gaurd has everything going against it. It is heavy compared to factory gaurds, it doesn't mount on as gracfully as the factory gaurds and therefor scratches your frame paint and leaves marks (I just painted my frame), and I also agree it doesn't look as good for a bike that I am trying to make look sporty.

So I am still leaning towards the factory gaurds, but have not made a final decision yet. More opinions are welcomed

 

[Paul]

If you are going to use crash bars, go with the factory type.
The "Wes Cooley" bars look like they are out of the arc! The sort of thing the GPO (UK postal delivery service) used to use on their 125cc BSA Bantams in the '60s! They used to use them so they could lean bike on them while making deliveries!

 

[RacingJake]

Re: 1978 GS1000 Winter Rebuild

Re: 1978 GS1000 Winter Rebuild

.....as well as building up an exhaust dam before putting that back on. I never knew about the exhaust thing but my mechanic showed me how it will reduce turbulance in the exhaust ports of the head.

What is an exhaust dam?

This was news to me too Paul. On the exhaust port of the head the gasses are forced to the top of the port on their way out and the bottom of that opening is actually not needed so it allows the exhaust to create turbulance in that area which in turn creates drag or back pressure that you don't want there. He is going to build the dams out of an epoxy that takes the heat and fixes this issue. On later models you can see the dam there from the factory. It is something they were not aware of when they made these engines in the 70's. Very interesting, I never knew about this.

Jake says,
Is the dam the same thing as in my picture of a 82 GS1100E Head. Just click on my WWW button below to see my exhaust port with a floor. I'm thinking this thing cause to much back pressure and should be removed along with opening up the port to match the exhaust gasket thats still in there.

Jake

 

[Hoomgar]

Re: 1978 GS1000 Winter Rebuild

Re: 1978 GS1000 Winter Rebuild

Jake says,
Is the dam the same thing as in my picture of a 82 GS1100E Head. Just click on my WWW button below to see my exhaust port with a floor. I'm thinking this thing cause to much back pressure and should be removed along with opening up the port to match the exhaust gasket thats still in there.

Jake

Jake the floor you refer to is it yes. And it does exactally the oposite of what you are thinking. If you remove it you will create the back presuure your thinking you are removing. It is actually there to aleave the back presure. I too was taken by this. But talk to the pro's Jake and they can explain it better to you. That was put there by the factory because they learned about it by trial and error. Removing it would be folly and would actually create the problem that it is there to remove. Seems wrong but it isn't. Having a professional motorcycle engine mechanic explain it to you would be better since they know what the heck they are talking about like I don't You don't want to hone that out of there for sure without putting it back.

 

[Hoomgar]

My crank came in from Falicon today. I am planning on going out tomorrow and getting pictures of the engine all torn down and prettied up. And the crank. Hopefully there will be some progress on the porting and polishing of the head so I can show that as well.

 

[Anonymous]

welded crank?

welded crank?

hello, im new to this...what do you mean when you weld the crank?...i am currently rebuilding a 82 gs650, and have questions about cam timing. would retarding the exhaust cam a tooth create a crossflow action?, or am i just being foolish. also, are the engines interference fit?

thanks, Ian

 

[Billy Ricks]

People that build race motors also epoxy the bottom of the curve on the intake port to create more velocity.

This is from Bob Bertaut's website. http://www.bertaut.com/gsengine.html

 

[SqDancerLynn1]

hello, im new to this...what do you mean when you weld the crank?...i am currently rebuilding a 82 gs650, and have questions about cam timing. would retarding the exhaust cam a tooth create a crossflow action?, or am i just being foolish. also, are the engines interference fit?

Changing the cam timing by a tooth is asking for trouble, it will never run right if it even runs at all or it may self distruct. if you want to change it you need to get slotted cam gears or very carefully slot your original gears so that the cam can be degreed

 

[Hap Call]

Re: welded crank?

Re: welded crank?

hello, im new to this...what do you mean when you weld the crank?...i am currently rebuilding a 82 gs650, and have questions about cam timing. would retarding the exhaust cam a tooth create a crossflow action?, or am i just being foolish. also, are the engines interference fit?

thanks, Ian

Welding the crank refers to ball bearing (as opposed to plain or babbit bearing cranks) that are welded at certain places to insure that the crank does not twist under load...this is something done on the 1000 and 1100 engines because they can produce the power to do this. I doubt that your 650 would ever need this. I'm not sure if the 650 has roller bearings.

Don't mess with your cam timing. The 650 engine has a well deserved rep as a rock solid reliable engine and changing the cam timing could cause problems you don't want to deal with.

If you're looking for more power, it is best to go up in displacement.

Hap

 

[KEITH KRAUSE]

Amen. Simple, honest advice.

 

[Hoomgar]

I have the pictures guys and even a little video footage but need some more time to go through it all and sort out what to post on my web site. I may omit the video clips just due to the size. I will post in here again when I get them up there

 

[KEITH KRAUSE]

Cool! Can't wait to check it out!