Difference in Heads - Suzuki GSX-R Motorcycle Forums Gixxer.com
 
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post #1 of 20 (permalink) Old 12-09-2018, 06:30 PM Thread Starter
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Difference in Heads

After endless searches, I still find myself confused about some of the key difference.
What I'm fairly sure of:
1st gens are pretty much the same for 70mm long stroke.
2nd gen 88-89 DOT, 73mm bore, Larger valves yet smaller combustion chamber? What I am unsure of is if the DOT was used on other bikes such as Katanas. IF so, How do I distinguish the origin of a head and or Cams?

90-92 is where I am not so clear other than it is again for a long stroke. Apparently the 90 does not use Shims which some claim is an advantage. Are there other differences in the 90, 91, 92 heads and how do I distinguish those?
Some claim (including Kelly Roberts) the 92 best suited for builds? What is different on the 92 from the 91?
Some claim the DOT is Head of choice while others say 90?

I understand some of this is subjective and it has ALL likely been hashed and re-hashed over the years. But as I mentioned, searched till I'm blue. Perhaps there is a definitive "Head Guide" I haven't found?
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post #2 of 20 (permalink) Old 12-10-2018, 01:21 PM
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Re: Difference in Heads

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Originally Posted by Metlhd View Post
After endless searches, I still find myself confused about some of the key difference.
What I'm fairly sure of:
1st gens are pretty much the same for 70mm long stroke.
2nd gen 88-89 DOT, 73mm bore, Larger valves yet smaller combustion chamber? What I am unsure of is if the DOT was used on other bikes such as Katanas. IF so, How do I distinguish the origin of a head and or Cams?

90-92 is where I am not so clear other than it is again for a long stroke. Apparently the 90 does not use Shims which some claim is an advantage. Are there other differences in the 90, 91, 92 heads and how do I distinguish those?
Some claim (including Kelly Roberts) the 92 best suited for builds? What is different on the 92 from the 91?
Some claim the DOT is Head of choice while others say 90?

I understand some of this is subjective and it has ALL likely been hashed and re-hashed over the years. But as I mentioned, searched till I'm blue. Perhaps there is a definitive "Head Guide" I haven't found?
yes dot heads were used on 1st-gen katana 750's. same as the GSXR heads with the exception of milder cams (same that were used in 750 slabbies) they are made from the same castings as the 1100 and B12 heads, which is why you can install one of those on the larger motors and get a boost in power from added compression and steeper intake runners. you CANNOT run a dot head on a long-stroke 750, not without using the corresponding 748cc short-stroke block and going 815cc. more details here https://www.gixxer.com/forums/15-oil...1100-time.html. only downside is you are limited to 36mm carbs and those heads put the carbs high up to the point you'll have issues installing air filters as well as possible clearance issues with other stuff such as the fuel petcock. There's also been instances where cracks develop between valve seats and spark plug holes on high-power builds. I haven't had this issue on my 120-rwhp 815cc build

90-92 heads are same castings as the 1st-gen 750, I believe. as you mentioned, 91 & 92 heads use shims. advantage of these heads is they use the same valve sizes as the DOT heads along with steeper intake runners, and these heads were made for the 38mm carbs. limitation with these heads is shim-over-bucket design with the possibility of spitting shims at high revs. but chances are you won't be spinning out the motor several thousand more RPMS over the stock limiter with an aftermarket ignition, if you get one
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post #3 of 20 (permalink) Old 12-10-2018, 06:31 PM Thread Starter
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Re: Difference in Heads

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Originally Posted by Gixxerider86 View Post
yes dot heads were used on 1st-gen katana 750's. same as the GSXR heads with the exception of milder cams (same that were used in 750 slabbies) they are made from the same castings as the 1100 and B12 heads, which is why you can install one of those on the larger motors and get a boost in power from added compression and steeper intake runners. you CANNOT run a dot head on a long-stroke 750, not without using the corresponding 748cc short-stroke block and going 815cc. more details here https://www.gixxer.com/forums/15-oil...1100-time.html. only downside is you are limited to 36mm carbs and those heads put the carbs high up to the point you'll have issues installing air filters as well as possible clearance issues with other stuff such as the fuel petcock. There's also been instances where cracks develop between valve seats and spark plug holes on high-power builds. I haven't had this issue on my 120-rwhp 815cc build

90-92 heads are same castings as the 1st-gen 750, I believe. as you mentioned, 91 & 92 heads use shims. advantage of these heads is they use the same valve sizes as the DOT heads along with steeper intake runners, and these heads were made for the 38mm carbs. limitation with these heads is shim-over-bucket design with the possibility of spitting shims at high revs. but chances are you won't be spinning out the motor several thousand more RPMS over the stock limiter with an aftermarket ignition, if you get one
So does a 90 head have forked rockers or fingers? Also, I have a DOT head I purchased from a bike that was labeled as a "91" Obviously mis-labeled or someone put one on a 91. Either way, How do I figure out if it's from a Kan-a-tuna or Slingshot? Is there a reference guide for Heads / Cams in regards to markings to determine what a guy may have. Considering the age of these motors, who knows what may have been changed out?
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post #4 of 20 (permalink) Old 12-10-2018, 07:37 PM
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Re: Difference in Heads

https://www.gixxer.com/forums/15-oil...questions.html
Lots of info in here, regarding different combinations.
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post #5 of 20 (permalink) Old 12-10-2018, 10:44 PM
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Re: Difference in Heads

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Originally Posted by Metlhd View Post
So does a 90 head have forked rockers or fingers? Also, I have a DOT head I purchased from a bike that was labeled as a "91" Obviously mis-labeled or someone put one on a 91. Either way, How do I figure out if it's from a Kan-a-tuna or Slingshot? Is there a reference guide for Heads / Cams in regards to markings to determine what a guy may have. Considering the age of these motors, who knows what may have been changed out?
yes , 90 got forked rockers .
Must see which kind of DOT head you got
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post #6 of 20 (permalink) Old 12-11-2018, 06:50 AM Thread Starter
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Re: Difference in Heads

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Originally Posted by ghostrider.1127 View Post
Must see which kind of DOT head you got
so when you say "must see", is their something in particular you're looking for or I should take a pic of? Is there markings on the castings? How about Cam markings?
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post #7 of 20 (permalink) Old 12-12-2018, 01:34 AM
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Re: Difference in Heads

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so when you say "must see", is their something in particular you're looking for or I should take a pic of? Is there markings on the castings? How about Cam markings?
only difference would be the cams, '88 GSXR cams have "B" markings on both cams, '89 have a "G" marking on the exhaust cam
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post #8 of 20 (permalink) Old 12-12-2018, 06:53 PM
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Re: Difference in Heads

With the hope he did not got an F DOT head.
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post #9 of 20 (permalink) Old 12-12-2018, 07:19 PM Thread Starter
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Re: Difference in Heads

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With the hope he did not got an F DOT head.
I guess thats the gist of my dilemma, How do you distinguish the differences? ie "an F head" ?
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post #10 of 20 (permalink) Old 12-12-2018, 10:37 PM
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Re: Difference in Heads

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I guess thats the gist of my dilemma, How do you distinguish the differences? ie "an F head" ?
GSX-F, aka, katana. Those heads are the same as the GSXR ones with the exception of the cams.
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post #11 of 20 (permalink) Old 12-13-2018, 02:01 AM
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Re: Difference in Heads

Yes the DOT heads are all quite the same
Problem is in 2018 , how to get the proper camshaft of a R .
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post #12 of 20 (permalink) Old 12-13-2018, 05:02 AM Thread Starter
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Re: Difference in Heads

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GSX-F, aka, katana. Those heads are the same as the GSXR ones with the exception of the cams.
And... how do I know what I have?
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post #13 of 20 (permalink) Old 12-13-2018, 01:19 PM
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Re: Difference in Heads

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Originally Posted by ghostrider.1127 View Post
Yes the DOT heads are all quite the same
Problem is in 2018 , how to get the proper camshaft of a R .
No problem. Buy a set of used camshafts for bandit 1200. Send them to Kent camshafts for regrinding (grind no. SUZ7). They are better than all OEM GSXR camshafts and keep the OEM valve train.

Kent Cams - Product - Camshaft / Camshaft / SUZ7




Camshafts lift/IN Lift/EX dur./IN dur./EX
----------------------------------------------------------------------
Yoshimura stag-1 9.00 8.50 244 245
SUZ7 9.27 9.27 245 245
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post #14 of 20 (permalink) Old 12-13-2018, 03:02 PM
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Re: Difference in Heads

start looking into camshaft lift versus duration numbers. keep digging into this forum, the data is here. then you'll realize what you can do as far as what cams are nearly identical between katanas, bandits, and GSXR's and moving exhaust cams to intake cams and vise-versa with slotted cam gears and appropriate cam timing. I don't think cams from a shim head will work on a screw head, and vise versa.

https://www.gixxer.com/forums/15-oil...-cams-b12.html


if its performance you're after then my best advice is to just run what you've got in your 750. you'll only really notice a difference between OEM spec cams if you are big bore with high compression or on an 1100, not so much on a practically stock 750. if you want real performance from cams on a 750, go aftermarket. but even then, you'll probably only see a 3-4 hp gain on a stock 750. high compression, head work, and cams all work together. and you'll be spending loads of cash time and effort to get the same power that a very mildly tuned 1100 motor makes.

forgive me if I'm getting ahead of myself

Last edited by Gixxerider86; 12-13-2018 at 03:08 PM.
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post #15 of 20 (permalink) Old 12-13-2018, 05:22 PM
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Re: Difference in Heads

Cams from a shim head will not work on a screw head. Shim head cams have 8 lobes, screw head cams only 4.
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post #16 of 20 (permalink) Old 12-15-2018, 02:43 AM
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Re: Difference in Heads

Also with a dot head (due the ruber mainfolds ) you will be able to use just 36 bst ss or 34-36-38 mikuni rs.
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post #17 of 20 (permalink) Old 02-05-2019, 07:42 PM Thread Starter
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Re: Difference in Heads

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Originally Posted by ghostrider.1127 View Post
yes , 90 got forked rockers .
Must see which kind of DOT head you got
so here are picks of the "DOT" head that is labeled as from a 91 GSXR750. Any Ideas what it is or what it was off of? From what I understand, this wouldn't be a 91 or even a long stroke for that matter. Please enlighten me
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post #18 of 20 (permalink) Old 02-06-2019, 10:36 AM
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Re: Difference in Heads

dot heads were only on '88 and '89 model GSXR 750's and '88-'96 Katana 750's. those you can swap onto 1100 or b12 blocks since they have the same casting. '90 was the last year for screw rockers on the GSXR 750, '91-'92 saw shim-type heads
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post #19 of 20 (permalink) Old 02-07-2019, 08:51 PM
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Re: Difference in Heads

Yuo ^^^ Black color leads me to believe 89-97 Katana head. Definitely not a 91 750 head.
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post #20 of 20 (permalink) Old 02-07-2019, 10:28 PM Thread Starter
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Re: Difference in Heads

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Yuo ^^^ Black color leads me to believe 89-97 Katana head. Definitely not a 91 750 head.
could be, does appear to be a re-spray as some of the bolt heads are sprayed over.
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