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Discussion Starter #1
Anybody have experience with converting a 91/92 1100 shim head to the "forked rocker type" ?
I compared the heads and it does not seem a big deal to me. If I use the 90 valves, springs, rockers and cams, I guess I only have to make spacers to get the rockers in the right position ?
The question left is that the 90 camshaft in the 91/92 head has about 1mm play sideways. Would it be needed to weld and machine this, or can it run with a little play ?
 

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The conversion is not worth the money it would cost to do it right, you are much better off pursuing an actual rocker head as opposed to trying to convert the head...
-Karl
 

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I don't know about the conversion...but 1 mm of end play is too much for a cam. You could shim it or weld/modify the head.
 

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Frankie,

You may want to check with Dwayne at Cycle Concepts on that. They have done a great deal of 7/11 swaps and motor builds and would be able to help you completely.....

He can be reached at:

Cycle Concepts
1638 Lynwood Dr
Lancaster, SC 29720
803.285.8093

JDB1371
 

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i didn't change my shim head over to rocker, i just bought a rocker head! you can find them stock fairly easy. i have seen them for $300 to $500 (a lot more if they are massaged-lazer, bellucci, carpenter, ape, etc.)!
 

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Discussion Starter #6
Just happen to have a 91 head with nice portjob, and rockers + valves + stage 1 cam for a rocker head. Damn.
 

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don't know if you would want to send it to us since you are in another part of the world, but all you need is the rocker arms and the springs out of a early 1100...when we convert them we install nice billet spacers that replace the springs...as for the free play in the cam, there will be alittle until the cam is tightened down...put all the cam caps on and see if the cam wants to walk when you turn the cam...

dwayne
 

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Bringing this back to the top.
I have a few questions, yeah yeah yeah, everyone says it cheaper just to buy a rocker head but thats not an option for me since i have all the parts laying here. Heres what i have, a '92 ported shim head, 2 bent valves. Heres what i want, that '92 ported head with a rocker arm conversion, I have one rocker head with a mess of destroyed valves and no cam caps that i can take all the rockers and rocker shafts reatiners and springs ETC from so i have all those parts for free. I also have a complete set of 16 mint rocker head valves and springs from one of my other heads when i went to oversized valves on both sides and had it ported. So i have tons of good valves, and all the rockers and shaft i need to stick in this shim head for free. I need to know what these spacers are that are needed, and if the rocker cams do infact need to be modified so that the proper end play is achieved (since i do not have any shim head cams). I have a bunch of rocker head cams also to stick in this motor so I'm set there. If anyone knows of a source that sells these spacers let me know, i just need to figure out these few missing pieces of info before i get all the seats re-cut in this shim head
Thanks!
 

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gsxr12161216, you won't need any spacers if you have a complete rocker head there for parts...the spacers i was refering to are used in place of the springs that are used to keep the rockers aligned with the valve...if you guys have any questions about this conversion just give us a call...thanks!!!

dwayne
 

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So what I'm hearing here is pull the valves, and shafts and rockers and rocker springs (basically all the guts) from the rocker head and stick it in the the shim head and it will all work? No problem with cam side to side clearance? This almost sounds too easy!

Thanks!


Anyone need some shim head parts, cause i will have a bunch of guts on the bench soon!
 

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gsxr12161216 said:

So what I'm hearing here is pull the valves, and shafts and rockers and rocker springs (basically all the guts) from the rocker head and stick it in the the shim head and it will all work? No problem with cam side to side clearance? This almost sounds too easy!

Thanks!


Anyone need some shim head parts, cause i will have a bunch of guts on the bench soon!
I think Simon is going to need the spring-retainers to go with his new Yosh cams [/envy]
 

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Discussion Starter #13
I just finished converting my head. I used the 91 shim head, 90 valves, rockers and camshafts.
I made thin spacers out of steel plate to center the 90 cams. I glued them with a 2 component metal in place, but they basicly can't go anywhere since they are kept in place by the camshafts and cam bearings.
I had 8 bushings made (16mm outside, 12mm inside, 8mm thick) to space out the rocker arms.
Also had to use the rocker arm shafts from the 90 head, to get proper alignment between the oil holes in that shaft and the rocker arms. With that 90 rocker arm shaft I needed to redrill the other holes, the 3mm ones that supply oil to the cam bearings. To do this I turned the shaft 90 degrees to close of the existing holes. I then drilled new holes at the places where they should be. (Also the hole for the 6 mm bolt that keeps the shaft in place).
It has run about 1500 kilometres now, and she runs sweet and silent. Just recently removed the valve cover for inspection and everything looked fine.
 

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Why do you need the spacers for the rockers? can't you just use the spirngs over the shaft like the rocker head originally had? Also can you not use the shim rocker shaft instead so you do not need to re-drill oil hoels or are they different sizes?

Thanks!
 

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OK i just pulled both heads apart to se what you are talking about. The rocker shafts are different lengths from both my heads, and you are right the holes do not line up for the rockers, or the cam journal. Did you weld up or block the extra hole in your shafts??T Also the rocker head shaft does not look like its captured at the left end since its shorter than the shim shaft? To me it looks like it will be easier just to weld closed the holes for the old shimmed rockers since they are recessed already it wil be easy to weld and not blow the OD of the shaft (4 holes per shaft), then all i that needs to be done is drill new holes for the rocker oil holes (2 holes per shaft). I do see why you needed the spacers, as mine do not line up right with the valves either once i dropped the rockers in the shim head and used the stock shaft springs. I think i will make a spacer for one side and use the spring on the other??
 

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Discussion Starter #16
Yes, I had a total of 8 spacers made and used the stock spring on the other side of the rocker.
Everything you wrote about the rocker arm shaft differences is exactly what I ran into. I agree that welding the existing holes and drill new ones would probably be the best solution, but I'm not a great welder. I found that if I put a 90 shaft in the 91 head and turned it 90 degrees, the oil holes for the cam lobes were all blocked, while the small holes for the rocker arms lined up. Then I drilled new holes for the cam lobes and for the bolt at the end of the shaft. I would have preferred another solution and might still do that, but for now it's working ok.
 

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I got a guy who is a good welder, I'm not good enough for that myself! Thanks for the info ,we both seem to be on the same page, just different ways to get there! I've herd these shafts are VERY hard to drill due to thier hardness, how hard were they for you ?
 

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Discussion Starter #18
Like a hot knife through butter. They are not hard at all.
Let me know how it works out for you with the shafts, I might eventually go that way too.
 

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Were you using carbide?? Mike at lazer porting told me they were hard as a rock! I thought i would have to do them at work with carbide. please advise me as to what you used!

THanks!
 

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Discussion Starter #20
I used the cheapest quality drills I could find at the local DIY store.
Since I did not want to hammer them to make a center (I did not want to risk unroundness) I grinded a little flat spot, and then simply drilled them with a hand drill and no-quality drills. No problem what-so-ever.
I occasionally drilled some other shafts (gear box), so I know what hardened means, but this is defenitelly not it !
These were '90 shafts, posibly Suzuki has changed the hardness from '91 ?
 
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