1978 GS1000 bored out to 1173 by RC Engineering

[jskellington]

Yeah, Keith, those oil lines definitely need to be rerouted. I like the way Reno Bruce has sent his over the top of the motor, then down between the carbs and into the return adapter. That's another winter project. I'm gonna switch to stainless lines and look for a bigger, more efficient oil cooler than the old Lockhart. It's immediately apparent how much more heat comes off this motor than my stock bike.

Speaking of heat, I finally got the header to mate with the pipe using three or four windings of muffler bandage on the header pipe to snug things up. Then I aired the tires, checked all the bolts and headed in a gargling slow way for Interstate 580, which is about a mile from my house. My friends, you should have heard the lovely howl as the engine went to work. Third gear took me past the speed limit before I'd gotten to the top of the ramp so I nicked it into fourth and eased my way onto the highway. Fine tuning is definitely in order, but like I said before, this bike wants to go.

Hey Bad Billy B, thanks for your advice on the spark plugs. The previous owner told me to gap the plugs at .065 in., which is nearly double the distance of the factory specifications. Does that sound right to you?

[KEITH KRAUSE]

Hey Bad Billy B, thanks for your advice on the spark plugs. The previous owner told me to gap the plugs at .065 in., which is nearly double the distance of the factory specifications. Does that sound right to you?

That's quite a gap. I forgot what ignition and coils you're running.
The Dyna people suggest increasing the gap (forgot the amount) when running their S ignition but it wasn't nearly that much gap.
I run the Dyna S and their green 3.3 coils but I stayed closer to the wide end of the factory gap, about .030". I recently changed my plugs "just because" and after nearly 30,000 miles on the rebuilt motor, the plugs were in very good condition with only the slightest rounding of the ground electrode tip. I could have re-used them easily but the bike needed a birthday gift. My bike shows no sparking/heat related problems at all. I only have 1085 pistons/V&H/K&N's so I'm not sure how your additional mods factor into the need for a larger gap. I'm not into serious racing either or the knowledge gained there. Perhaps someone will educate us as to what the benefits are to such a large gap?

[BadBillyB]

Hey Bad Billy B, thanks for your advice on the spark plugs. The previous owner told me to gap the plugs at .065 in., which is nearly double the distance of the factory specifications. Does that sound right to you?

I would recommend gapping them to .028"......I always indexed mine when I installed them. A properly indexed plug will have the ground electrode facing the intake valve.

As far as the VHR megaphone goes, mine was purchased last December and right out of the box the 2 pieces would not go together. Careful examination showed that the very end (and only the very end) of the megaphone was slightly curved inward. All it needed was a light tap with a muffler cone and it slid right on. No cutting or expanding was needed.......Nice pipe......BadBillyB

[jskellington]

BadBillyB, your mention of indexing spark plugs, a new term to me, sent me straight to Google. Believe it or not, Wikipedia had the best explanation of the process.

Indexing spark plugs

"A matter of some debate is the "indexing" of plugs upon installation, usually only for high performance or racing applications; this involves installing them so that the open area of the spark gap, not shrouded by the ground electrode, faces the center of the combustion chamber, towards the intake valve, rather than the wall. Many experts believe that this will maximize the exposure of the fuel-air mixture to the spark, and therefore result in better ignition; others, however, believe that this is useful only to keep the ground electrode out of the way of the piston in ultra-high-compression engines if clearance is insufficient. In any event, this is accomplished by marking the location of the gap on the outside of the plug, installing it, and noting the direction in which the mark faces; then the plug is removed and additional washers are added so as to change the orientation of the tightened plug. This must be done individually for each plug, as the orientation of the gap with respect to the threads of the shell is random."

Is this consistent with your understanding of the process?

On a related note, I'm beginning to realize that the previous owner's arsenal of B9 and B10 spark plugs and instructions to widen the plug gap were symptoms of a weak spark problem that wasn't being addressed at the source. I didn't test the old Gerex ignition system and coils before replacing them with the Dyna S and green coils, but my strong hunch is that the entire system, from stator to spark, was weak from age and inattention.

And to Keith's earlier point, the two vent tubes from the carburetors had hoses on them, which coupled with the velocity stacks was probably leading to intermittent fuel starvation and plug fouling.

As time and weather permits (I don't have a garage), I'm going to check the valve clearances and identify what sort of cams Russ Collins dropped in there. After I vacuum synch the carburetors, I can start reading the plugs.

Thanks again for the help.

Jack

[renobruce]

What a sweet toy you have there, Jack. I'd love to see it run in person. I hope you plan on coming up next summer for the 2nd Western States get-together! Sounds like you will have the bike all worked out and running the way you want by then.

[BadBillyB]

BadBillyB, your mention of indexing spark plugs, a new term to me, sent me straight to Google. Believe it or not, Wikipedia had the best explanation of the process.

Indexing spark plugs

"A matter of some debate is the "indexing" of plugs upon installation, usually only for high performance or racing applications; this involves installing them so that the open area of the spark gap, not shrouded by the ground electrode, faces the center of the combustion chamber, towards the intake valve, rather than the wall. Many experts believe that this will maximize the exposure of the fuel-air mixture to the spark, and therefore result in better ignition; others, however, believe that this is useful only to keep the ground electrode out of the way of the piston in ultra-high-compression engines if clearance is insufficient. In any event, this is accomplished by marking the location of the gap on the outside of the plug, installing it, and noting the direction in which the mark faces; then the plug is removed and additional washers are added so as to change the orientation of the tightened plug. This must be done individually for each plug, as the orientation of the gap with respect to the threads of the shell is random."

Is this consistent with your understanding of the process?



Jack

Yes, that about sums it up. What I usually did was buy 8 plugs and minimize the thickness of the shim by trying them in different cylinders hoping they would line right up w/o any shims. Moroso used to sell shim kits for doing just this.....It's fun to be anal.....BadBillyB

[terry]

I didn't test the old Gerex ignition system and coils before replacing them with the Dyna S and green coils, but my strong hunch is that the entire system, from stator to spark, was weak from age and inattention.
Jack

Have you still got the Gerex ignition Jack? I've got a motley collection of old electronic ignitions (Martek 440, 880, Dyna 3, Dyna S, Prestolite, ARD etc,) but I've never seen a Gerex? I might be able to help you out with a bigger cooler as a trade? Cheers, Terry.

[jskellington]

Yeah, I've still got it. Lemme paw through my boxes of spares and make sure I've got all the bits. I'd be delighted to trade it for a bigger oil cooler.

Jack

[terry]

Yeah, I've still got it. Lemme paw through my boxes of spares and make sure I've got all the bits. I'd be delighted to trade it for a bigger oil cooler.

Jack

Thanks Jack! Cheers, Terry.

[jskellington]

We'll call this photo Dr. Jeckyl and Mr. Hyde:

http://s88.photobucket.com/albums/k175/jpmason_2006/GS1000e/

Not the greatest photo but you can see I'm keeping busy with these two 1978s.

The one on the left, obviously, would be the Russ Collins 1173. It's got heavy clutch action that launches the bike like a slingshot and the howl from the megaphone is dangerously intoxicating. It'll get you over the speed limit absurdly fast, but the front end gets the shakes between 75 and 80. Could be the steering head bearings or the front wheel bearings (though neither seems loose when I give the front end a shake) or something else, but it definitely gets your attention if you get too enthusiastic on the freeway.

[terry]

G'Day Jack, that bike looks brilliant mate! The gerex ignition arrived yesterday, thanks for that mate, your bigger cooler must be very close to arriving in CA, so I hope you like it! (Does anyone here know how to fit and time one of these ignitions?)

I think you've inspired me to rebuild the remains of my 1979 GS1000SN, I've got enough bits to build it now, I bought a NOS Wiseco 1170 kit for it recently, have a pair of "Ivan Tighe" race cams, a later "big port" head, some 34mm Mikuni flat slide carbs, (I'd prefer 36's, but these supposedly flow better than 33mm smooth-bores, so should be up to the task) etc etc.

I do, however, need a pipe for it, do you still have the old one off your bike, and if so, would you like to sell it? I'm getting an old CB750 Supertrapp pipe ceramic coated by HPC Coatings in the "brushed alloy" color, and they'll give me a discount if I get them to do another pipe at the same time, so I thought, why not? Let me know mate?

Also, did all the 1978 bikes run alloy rims like yours? I'd love a pair of them too, I'm not keen on the current 17 inch rim fashion, I understand the technical advantages re: fitting modern tires etc, but don't much like the look? Have a good one Jack, Cheers, Terry.

[dsw1953]

Sounds very nice

[KEITH KRAUSE]

The 75/80 steering wobble is most commonly caused by loose steering bearings. Shaking the front end doesn't always expose it. After my restoration, I thought I had the bearings torqued pretty good. First time over 80 the bars wobbled without warning and scared heck out of me.
Loosen the center bolt, center bolt pinch bolt on the side and the upper fork pinch bolts. Make a mark with a marker to record where the steering stem nut is now set. Try 1/8 turn tighter on the nut, tighten everything and test. Repeat if necessary. I tighten the center bolt and side bolt first, then the fork pinch bolts. Top center bolt torque is 36 ft/lb I believe.
With the bike on the centerstand and wheel off the ground, the bars should turn side to side with just a little drag.
If you do find that tightening doesn't help (I doubt it) then you can return the steering nut to where it was (the marks) and search elsewhere for the reason.
There is a factory steering stem torquing procedure but it seems incorrect to me and I can't follow it (tried back in '80 and gave up ever since making sense of it). It's based on the steering nut being tightened within a certain range and then backing off the center bolt(?) but it's too vague to bother with. The method I use above results in the same adjustment anyway. Works for me.

[terry]

G'Day Keith, is there a possibility that the steering head bearings are worn out?

I'm just thinking that even though they're ultra-tough tapered rollers, like most things that don't cause us trouble, they probably get very little in the way of maintenance?

I don't want to admit it, but my steering head bearings are probably still circulating in the OEM grease from 1981?

I'm just thinking that if there is some wear in them, adjusting them may not make any difference? I'd hate Jack to assume that his steering head bearings aren't the culprit, and start looking elsewhere, when it's possible that they're cactus? Cheers, Terry.

[KEITH KRAUSE]

Yes, the bearings could be bad as you say.
I have a feeling they're good and tightening them down will get rid of his wobble. Tapered bearings are very tough as you mentioned.
When I said if tightening doesn't help to "look elsewhere", I could have used better words. Bearing wear could be still be possible, along with many other things that cause wobble.
I suppose I'm just basing my advice on past experience and the likeliness of what may be wrong. Loose bearings first, worn bearings somewhere down the list with a lot of other possibilities.