Rocker Arm Interchange

[gs11ezrydr]

I was wondering if any one has tried running the 88-89 GSXR 750 rocker arms in any of the GS1100's or GS1150's I have been told that they are a different ratio and will increase the actual valve lift. Or have I been misinformed. Thanks

[rapidray]

I use them on my race motors. Same ratio but stronger, lighter rockers. The pads are narrowrr so less drag also. Ray.

[stetracer]

I was wondering if any one has tried running the 88-89 GSXR 750 rocker arms in any of the GS1100's or GS1150's I have been told that they are a different ratio and will increase the actual valve lift. Or have I been misinformed. Thanks

Yes you are correct on them being a different ratio but it will decrease you cam actual valve lift. The GSXR/ Bandit rockers are 1.54 and the GS 1100/1150 are 1.64 This will translate to about 0.010 of cam lift loss.

[rapidray]

Sorry but you are wrong about the ratios. They are both very close to 1.52. If you don't believe me, call Web Cam & ask them. They make most of the welded rocker arms & KNOW the ratios. Ray.

[stetracer]

Sorry but you are wrong about the ratios. They are both very close to 1.52. If you don't believe me, call Web Cam & ask them. They make most of the welded rocker arms & KNOW the ratios. Ray.

Your are right the GSXR rockers are 1.52 but the GS rocker are closer to 1.60 and I am about 99% sure I am right about this.

And I am positive if you put a Cam Motion G21 .380 advertised lift cam in gsxr it has .368 of actual lift put that same cam in a GS1150 and you get you get .383 of actual lift. How does this happen if they are the same ratio can you please explain this? Is it in the head itself so when you switch the rockers it doesn't change the ratio. Maybe the rockers are the same and the heads are different. I smell an experiment When I build my next 1150 head which is soon I will put some gixxer rockers in it and see what happens.

[gearhead13]

I checked the valve lift on a spare head with a dial indicator with both gsxr and 1100 rockers and there was always less lift with the gsxr rockers. Also, after running gsxr rockers for a while I had a good look at the valve tip and you could see where the rocker arm screw was wiping across the valve tip, causing the stem/guide to wear faster. The geometry of the two is not the same as well as different ratio rocker.

[gearhead13]

I thought about this some more. Ray said they make more lift on his race motors. With race cams with over .400" lift with reduced base circles, the smaller base circle changes the ratio and geometry.
I checked the lift on a set of stock cams and I am positive that the gsxr rockers produced less lift.

[gs11ezrydr]

Thanks alot for the replys.From what I gather here I believe I am going to stay with the stock GS rockers. Since I have heard of the adjusters swiping across the valve tips from some other forums also.Can't be good.And backing up on the ratio again going the wrong way.Ok now I have another question.Do any of you all know the stock base circle for the 82 GS1100E and possibly know what the base circles are for the Web Cam grind #168 which is the .348 lift 282 duration and the Cam Motion .355 lift 256 duration and poss.the Megacycle .355 lift 250 duration and if any of these would require the longer adjuster screws.Thanks again guys I am a newby here and I am gratefull for all of your vast knowledge so far it has been very helpfull

[gearhead13]

I am running .340" lift cams with stock length adjusters. You wouldnt need the longer ones until .370" or .400" and up.

[gs11ezrydr]

Ok Thanks again.I am trying to gather as much info I can before I get my head back from Star Racing where I am having there so called stage II porting done to it.I am still on the fence with going to the 1150 intake valves.I am a service manager for a Suzuki dealership here in Ky.So I can get the valves at dealer cost wich is $17.49 each and it doesn't increase the cost of the porting job but a few bucks per valve seat to cut them to fit.From some of the other forums on here it seems to be the thing to do to the 1100 heads.Any input is appreciated.

[blowerbike]

you can get stainless 28.5 intakes for similar money.
or you can grab some used 1150 intakes for kinda cheap.
i have had stock valves pinch the stem off in the keeper groove.
never had that happen on stainless valves.

[gs11ezrydr]

Thanks I am kinda wanting to stay with the stock valve sizes just to see how I can get them to run then maybe later go up on the size and note the differances.Speaking of pinching off the valves at the keeper groove.While I was inspecting my valves,keepers,retainers etc.I noticed on all of the intakes that the keepers showed some signs of galling on the backsides that contact the retainer right at that groove.Therefore I have replaced all 32 of them.Have you ever seen this happen before or has the valves been possibly floating and jogging the keepers around inside the retainers.Or is something else happening that I need to know.I am installing some heavier valve springs just in case.

[blowerbike]

i have never been big on spending money over and over and over again.
we are only talking .5mm bigger verses the 1150's 28mm..verses 28.5 stainless.
the largest valve an 1100 will accept on a stock seat is 28.5mm.
IMO valve float causes the valves to pinch in the keeper groove(stock valves).
HD springs are a must but if memory serves me the seat pressure needs to stay in the low 40's so as not to destroy rockers and cams plus a street bike gets a lot more use then a drag only that can get away with a little more seat pressure with the same cam and valves sizes.

[madjack57754]

Don't forget that the oil bump can also hit the lobe on higher lift cams. That is why it is recomended by aftermarket cam mfg.s to take it off the follower

[gs11ezrydr]

Thanks to all.I believe that I am convinced that it would be the right thing to do and go with the 28.5 stainless valve option.Also on some other threads I have seen where the 28.5,s flow alot better at lower lifts.Like you said pouring good money after bad.I will order up some tomorrow.One last question Ferrera or Kibblewhite Black Diamond Hum!