1978 GS1000E mild performance build (thanks rapidray)

[philosopheriam]

Folks,

I spoke to rapidray on the phone, and he gave me some helpful pointers with respect to a mild performance build on my 1978 GS1000E engine. For the record, he is a helpful guy and super easy to talk to!

Here are my current build specs:
Wiseco 1100 kit
APE bronze guides
APE stainless 1-pc valves, 2mm+ intake, 1mm+ exhaust
APE head studs + nuts
Stock springs/retainers/keepers
APE manual CCT
Victor reinz (Wiseco) fiber/steel head gasket
OE base gasket

In any case, here are a few remaining questions I have for the GS audience (I didn't want to chat Ray's ear off as he seemed a bit busy when I called).

1. Although I don't want to spend the money, he "strongly" recommended a set of 34mm flat slide carbs - I keep waffling as I just spent some $$$ and time rebuilding my VM26's (cleaned, polished tops + bowls, new pilot jets and needle valves, etc), however, I need new carb boots and it seems like a waste of more $$$ buying new boots for a set of carbs that I may ditch in the future. So, I may be money ahead just selling my VM26's now and putting the cash towards a new set of flat slides, I think...

2. He recommended a set of hotter cams w/adjustable timing gears, timed to 105 on the intake and 107 on the exhaust - more specifically, he mentioned that WEB makes two grinds of street cams and that I should go with the second option:

WEB Camshaft Profiles:

OPTION 1:
VALVE LIFT.365/.365
DURATION 286°/286°
DURATION @ 0.050" 245°/245°
GRIND NUMBER 118
High performance street profile for stock engines. Very broad power range. Stock base circle.

OPTION 2:
VALVE LIFT .395/.395
DURATION 284°/284°
DURATION @ 0.050" 256°/256°
GRIND NUMBER 110
Good mid and upper end performance for hot street. Requires Exhaust System, High Compression Piston / Big Bore, and Performance Valve Spring Kit.

Here is my question - the guys at APE suggested keeping the OE valve springs for a street motor to reduce valve seat wear - the second cam requires performance valve springs. Would the first cam grind listed be a good compromise instead?

3. He recommended a radius valve job - pardon my ignorance, but what are the advantages/differences of a radius valve job vs. a 3-angle valve job?

4. He recommended porting work to the head (using a 1980 head as a template), as the 1978 head is a small-port design. Would it be cheaper to fit a 1980 head to my motor or should I just port my existing head?

5. What type of sealers (if any) should be used with the gaskets I listed above?

Sorry to ramble, thanks for the input everyone!

[ozman]

1 yes you need better carbs if you want the benefit of the other mods

2 adjustable cam sprockets so you can degree the cams

option 1 looks good for a nice plenty of low down street motor plus would work with stock springs

be careful with option 2 unless your prepared to change retainers and use under bucket style shims
its not pretty when they try spitting a shim out because of high lift cams

3 both styles of valve job work no huge advange in 1 or the other

4 port your existing head, you already have it ! some of the porting guru's of road racing prefer the small port head as a starting point because it gives them more meat to work with in shaping the ports


ozman

[philosopheriam]

1 yes you need better carbs if you want the benefit of the other mods
Right now, APE seems to have the best deal on the carbs, pod filters, and intake boots. When it comes time, I will probably buy from them. IT breaks my heart to sell the original carbs, especially after the work I put into them, but I didn't plan on my project going in the direction it has...

2 adjustable cam sprockets so you can degree the cams
Understood

option 1 looks good for a nice plenty of low down street motor plus would work with stock springs
That's what I was thinking - I want more power but I want this to be a good streetable bike, as well...

be careful with option 2 unless your prepared to change retainers and use under bucket style shims
its not pretty when they try spitting a shim out because of high lift cams
Understood

3 both styles of valve job work no huge advange in 1 or the other
From some brief research, it seems that the radius seat is cut with a single carbide cutter, providing for a more uniform seating area that flows better. How much better is the real question, I suppose...

4 port your existing head, you already have it ! some of the porting guru's of road racing prefer the small port head as a starting point because it gives them more meat to work with in shaping the ports
I will talk to my engine builder to see if he has any experience in porting GS heads - if not, then I will need to find someone to do this as I have never ported a head myself and I don't feel like experimenting on the one I have.

ozman

Thanks for the input!

[Ecklund]

1 yes you need better carbs if you want the benefit of the other mods

2 adjustable cam sprockets so you can degree the cams

option 1 looks good for a nice plenty of low down street motor plus would work with stock springs

be careful with option 2 unless your prepared to change retainers and use under bucket style shims
its not pretty when they try spitting a shim out because of high lift cams

3 both styles of valve job work no huge advange in 1 or the other

4 port your existing head, you already have it ! some of the porting guru's of road racing prefer the small port head as a starting point because it gives them more meat to work with in shaping the ports


ozman

This may be old hat for many members but is interesting stuff to me.

I thought I was good to go with the carbs as I bought the bike with 29s. Now I might be in the same problem as the OP in that I'd like to keep the current carbs but it appears that the mods would demand more carb.

Not that I'm against adjustable sprockets or degreeing the cam, but does it make some sense to buy the advance or retard you want/need in the cam and install it straight up? Other advantages?

Using stock 25 y/o springs? Hmm, if money is the issue, and when isn't it, maybe leave off the adjustable sprockets and buy new springs. Especially with a new cam. I may have misunderstood.

Are shims that unreliable with high performance cams? At what level cam is the switch necessary?

Would do valve job just because I'm in there and again, its over 30 years old.

Will need to find someone to do the porting. Hard to believe back in the day when the magazines did this basic upgrade they left out the head porting.

Thanks for the info

[philosopheriam]

I bought new OEM springs - I wasn't planning on reusing the old ones.

[ozman]

This may be old hat for many members but is interesting stuff to me.

I thought I was good to go with the carbs as I bought the bike with 29s. Now I might be in the same problem as the OP in that I'd like to keep the current carbs but it appears that the mods would demand more carb.

Not that I'm against adjustable sprockets or degreeing the cam, but does it make some sense to buy the advance or retard you want/need in the cam and install it straight up? Other advantages?

Using stock 25 y/o springs? Hmm, if money is the issue, and when isn't it, maybe leave off the adjustable sprockets and buy new springs. Especially with a new cam. I may have misunderstood.

Are shims that unreliable with high performance cams? At what level cam is the switch necessary?

Would do valve job just because I'm in there and again, its over 30 years old.

Will need to find someone to do the porting. Hard to believe back in the day when the magazines did this basic upgrade they left out the head porting.

Thanks for the info

covering your points
1 29mm smoothbores are a upgrade and suit 1100/mild cam setups nicely

2 adjustable sprockets are cheap why do any of the work if your not prepared to cheaply make sure cams are exactly where they should be cams are somewhat mass produced and there is slight variations between them, degreeing gets them spot on the cam timing you want

3 i was not say use 25 year old springs i said use standard rate springs on mild cams prolongs seat life again new springs are cheap

4 have you seen a picture of a head with shim poking out of it ... not nice
just my opinion but anything over 365 lift we use under bucket shims

5 again i did not say dont do a valve job i said either valve job works ok and its not a motor where you need extract the last .1 of a hp
if you have someone who can cut only 3 angle its ok if they cut radius then use that

ozman

[GregT]

All good advice - my input is stay with the small port head...You don't need the max flow for a street motor, midrange is most useful - and that's what you'll get with the small port head.

Ozman, you're pretty conservative with cam lift vs shim under...I've always worked on .415inch lift as the max for shim over - and never spat one out.

[ozman]

All good advice - my input is stay with the small port head...You don't need the max flow for a street motor, midrange is most useful - and that's what you'll get with the small port head.

Ozman, you're pretty conservative with cam lift vs shim under...I've always worked on .415inch lift as the max for shim over - and never spat one out.

yes i tend to err on the better safe than sorry side of things
cheaper to build things to last rather than rebuilding because they didnt last

ozman

[GSX1000E]

I have those cams in two bikes currently (.395/.395) and have never spit a shim even at 10,500 rpm. Both engines are a tad over 1100cc's. One has Yoshi springs and 36mm CV carbs.
The other has S & W springs and 29mm smooth bores. Both are at 10.5:1 compression ratio with 4-into-1 pipes. Both are a lot of fun to ride.

[philosopheriam]

All good advice - my input is stay with the small port head...You don't need the max flow for a street motor, midrange is most useful - and that's what you'll get with the small port head.

Ozman, you're pretty conservative with cam lift vs shim under...I've always worked on .415inch lift as the max for shim over - and never spat one out.

The real challenge is finding someone competent enough to port it properly, otherwise, it IS staying stock...

[stetracer]

You don't need the same size exhaust cam as intake cam. If you use a smaller exhaust cam than your intake you will get more bottom end pull without any loss of power. If it were me I would use the .395 lift intake cam and the .365 exhaust cam and set them at 106i/108e with a good set of springs set at 50 lbs. of seat pressure with a set of titanium retainers to lighten the valve train up. No need for under buckets on cams under .400 lift it is the shorter duration higher lift cams you got to watch out for
A 3 angle valve job is a stock valve seat cut where a radius cut valve is just what it implies it is a radius so you end up with a smoother flow over the seat and a nice narrow seat (much better). If you can't get a radius cut most machine shops that do any speed work will do a 5 angle seat cut that will be a little better than the stock 3 angle cut.



.

[Ecklund]

covering your points
1 29mm smoothbores are a upgrade and suit 1100/mild cam setups nicely

2 adjustable sprockets are cheap why do any of the work if your not prepared to cheaply make sure cams are exactly where they should be cams are somewhat mass produced and there is slight variations between them, degreeing gets them spot on the cam timing you want

3 i was not say use 25 year old springs i said use standard rate springs on mild cams prolongs seat life again new springs are cheap

4 have you seen a picture of a head with shim poking out of it ... not nice
just my opinion but anything over 365 lift we use under bucket shims

5 again i did not say dont do a valve job i said either valve job works ok and its not a motor where you need extract the last .1 of a hp
if you have someone who can cut only 3 angle its ok if they cut radius then use that

ozman

Again good topic and thanks fir the post.

Also thanks for the clarifications.

Your comment on why one woukd degree a cam makes sense to me. May I ask how one would know to advance or retard the cam beyond confirming cam spec sheet.

[stetracer]

When you degree the cams in the #'s or lobe centers you chose depend on where you want the power to come in at low #'s will yield you low rpm power and higher #'s will bring the power to the upper rpm. It won't change the amount of power the motor makes just where it makes it. But if the Cam lobe centers are to far off then you will lose power. I would not go below 102 for the intake cam for road racing or 114 for the exhaust for drag racing. With no more than a 3 degree spread

The cams in my sig. on my 85 GS1150 are in at 110 intake and 113 exhaust and it stills has plenty of power down in the low rpms.

[Nessism]

When restoring my 1000S I bought a set of Neeway cutters so the seats could be dressed proper like. Not exactly a "5 angle valve job", but it was a fun project. While working on the head the one thing that caught my attention is a sharp machined edge right on the short side radius of the ports. I know better than to get into the ports too much and start grinding away metal, but I found that a file fit perfectly into the port so the sharp edge could be smoothed down. Interestingly, I'm working on a Kawasaki KZ750/4 right now and the ports have an almost identical sharp corner on the short side radius. Going to try the file trick on that head too. Lacking a flow bench, and the knowledge on how to use it, I'll limit my port work to flash removal and smoothing things like these sharp edges. Not sure this is pertinent to this discussion, but you guys might want to check out the ports while the head is off if you get a chance.

[Ecklund]

When you degree the cams in the #'s or lobe centers you chose depend on where you want the power to come in at low #'s will yield you low rpm power and higher #'s will bring the power to the upper rpm. It won't change the amount of power the motor makes just where it makes it. But if the Cam lobe centers are to far off then you will lose power. I would not go below 102 for the intake cam for road racing or 114 for the exhaust for drag racing. With no more than a 3 degree spread

The cams in my sig. on my 85 GS1150 are in at 110 intake and 113 exhaust and it stills has plenty of power down in the low rpms.

It sounds like a trial and error process. Then again after all these decades I suspect most combos have been tried.

Its clear you have gained your info throughg hard won experience - the best kind.