G4 Cams/Rocker Arm Issues

[RJ]

Hey guys,
I'm looking at doing a G4 cam swap into my '82 1100E. APE claims that in order to run the heavier springs required to control the valves with the higher lift cams, the rocker arms need to be reworked with a harder surface for increased wear resistance. Man, that's $65 per arm for a grand total of $520 just for rocker arms alone. My question is how necessary is this mod?
Thanks, RJ

 

[rosco15]

You need to check the valve springs at the installed height. At about 40-42 pounds its not a problem. If you set them up over 50 you will wear into the rocker arm.

 

[jgordon]

Re: G4 Cams/Rocker Arm Issues

Hey guys,
I'm looking at doing a G4 cam swap into my '82 1100E. APE claims that in order to run the heavier springs required to control the valves with the higher lift cams, the rocker arms need to be reworked with a harder surface for increased wear resistance. Man, that's $65 per arm for a grand total of $520 just for rocker arms alone. My question is how necessary is this mod?
Thanks, RJ

It needs to be done (-:

 

[RacingJake]

I was running G4 cams in my 1100 head with just stock valve springs and had no wear problems for the past 2 years. Then I installed G4 cams in my 1150 head with HD springs and oem rockers and no wear in the last year. Maybe I'm just lucky.

Welded rockers is the way to go and when I step up to the G13/G7 combo they will be going in.

Ryan's right, installed height will have a great effect on wear.

 

[ronin1166]

rosco15 wrote:

You need to check the valve springs at the installed height. At about 40-42 pounds its not a problem. If you set them up over 50 you will wear into the rocker arm.

RacingJake wrote:

I was running G4 cams in my 1100 head with just stock valve springs and had no wear problems for the past 2 years. Then I installed G4 cams in my 1150 head with HD springs and oem rockers and no wear in the last year. Maybe I'm just lucky.

Ryan, Jake (et al),

In my GS1100-based 1166, I'll be running Web Cam 168's (.348" L / 257 D @ .050") which are similar to the G4's (.355" L / 256 D @ .050").
APE HD springs and APE Ti retainers. APE slotted sprockets.
The bike will be street-driven 90% of the time...probably 2,000 mi./year...I want it to last.

I have some questions:

** How do you determine installed spring pressure?
40#-ish - I assume on the seat, not at the nose, correct?

** I don't have access to a spring-checker, but I do have dial indicators, etc. If you know the spring rates (from APE), is it accurate enough to measure installed height, then do the math to determine seat pressure?

**Also, how close do the pressures need to be from to the next? (Obviously, you want a 'cylinder pair' to be very close).
If adjustment is needed, who sells spring-seat shims?

**My 168's are used, but in excellent shape, no visible wear. Rocker-arm selection has me in agony.
At this point, I've narrowed it down to new OEM rockers ($35/each from cycle-parts.com), or hardwelds ($60-ish from APE, Megacycle, etc.).
Will the stockers hold up? Or do I REALLY need to buck-up for hardwelds?

** While I'm here, how about cam timing?
Mild port cleanup, I favor the "small-port / hi-velocity" school.
I want this thing to pull hard in the 'real-world'...i.e. 4,500 - 7,000+ or so.
Wht would be a good starting point for lobe centers? 108 / 108?

Comments welcome...preferably supported by facts and/or experience.

Thanks In Advance,
Ted

 

[Billy Ricks]

Vance & Hines recommends either welded rockers or new rockers with their cams.

 

[Billy Ricks]

The Web Cam 168's have the same specs as the V&H modified grind I have, I suspect Web Cam makes the V&H cams. As I already said V&H recommends either welded or new rockers. I got lucky and got a complete set with an NOS head I picked up off Ebay for less than $50.

 

[rosco15]

** How do you determine installed spring pressure?
40#-ish - I assume on the seat, not at the nose, correct?

The way i do it is to put the valve in the head. Put your TI retainer on the valve with your keepers. Measure from where the bottom of your retainer sits to the top of your TI retainer. This is the installed height of your spring and retainers. Check both intake and exhaust. They might be slightly different. Then get a spring checker. stack the bottom retainer, spring, and Ti retainer together and compress to your installed height. WIthout shimming, on a couple sets of APE springs, I get between 38-42 lbs. I think stock springs are only like 20lbs when I checked.


**My 168's are used, but in excellent shape, no visible wear. Rocker-arm selection has me in agony.
At this point, I've narrowed it down to new OEM rockers ($35/each from cycle-parts.com), or hardwelds ($60-ish from APE, Megacycle, etc.).
Will the stockers hold up? Or do I REALLY need to buck-up for hardwelds?

I would just run what you have. Why buy new ones unless yours are really bad. If they did start to wear into the rocker arm you would notice it when your valve adjustement starts to get out or wack. There is a guy at the track ran those 348 lift web cams on his 9.20 dragbike for 6 years on stock rockers. Heck there is a guy running some big 420 lift cams, 1428 high compression motor, running 8's on stock rockers. jake and I both do it. Just don't set them up over 40 pounds. And a top end oiler would probably be a good idea.

** While I'm here, how about cam timing?
Mild port cleanup, I favor the "small-port / hi-velocity" school.
I want this thing to pull hard in the 'real-world'...i.e. 4,500 - 7,000+ or so.
Wht would be a good starting point for lobe centers? 108 / 108?

I would use what web recomends. I wouldn't go real high. I ran 110/110 and found the bike would actually launch better lower with the numbers staggered a bit. 108/109. You might want to try something like 107/108.

 

[ronin1166]

WIthout shimming, on a couple sets of APE springs, I get between 38-42 lbs.

OK - 40lbs.

Is that on the seat (valve closed), or on the nose (valve open at max lift)?

Ted

 

[rosco15]

That would be valve closed

 

[oldschoolGS]

I ran the G2's (.330 lift) and Megacycle springs for about 20,000 miles in my 16v 750 on stock rockers without any problems. I ran full synthetic oil for the duration and experienced minimal wear and no loss of reliability.

When I switched to the G15's (.350 lift), I went with the hardfaced rockers.

It is a big cost, but if you are sinking thousands into the motor already, what is another $500. :lol:

Personally, unless you are building a rip snorting, weekend ridden hot rod, I'd stick with the more moderate .325-.330 lift cams for long term reliability. I am going back this route on my 750/816cc rebuild.

Good Luck, Ed.
1983 GS750ED
2005 GSF1200SZ