rocker arm differences?

[antoniomota]

Greetings,

I've just joined, since it seems all SACS gurus are here (I've already browsed  some topics; and checked the Frankstein guide, many times). I have a kind of weird project in my hands, for my recently bought GSX750F ('99, as new as one can get: only ~3000 miles, 1 owner); stuff like *reducing* wheel size, *reducing* engine capacity; plus: political incorrect paint job (Lucky Strike cigarretts propaganda), maybe 4-2 mufflers vs. stock 4-1; etc.

So, to get to the point: I have several New Old Stock 600 heads; have new camshafts also; I know I must buy new valves, since my 750 valves are bigger and can't be transplanted to a 600 head; valve springs are softer on the 600; but all other head parts are the same, except the rocker arms!, see bellow:

model / rocker arm part number
GSX600F, Bandit 600 / 12840-19C00
GSX750F, GSX1100F, GSX-R1100, Bandit 1200 / 12840-27A01

Does any one know what's going on? Maybe different ratios? I really would like to avoid buying 600 rocker-arms (x8 = very expensive)... In short, my question is if these are interchangeble, or better not do do it (i.e. it's safe to use 750 rocker arms in a 600 head setup)?...

Thanks in advance. Regards.

-Antonio Mota

Edited January 14, 2018 by antoniomota

[Gixer1460]

Not sure a 600 head will transfer to a 750 block - best check first?

[antoniomota]

Forgot to mention: my plan is to use one of the 600 heads I have and to buy a 650 cylinder block, keeping 750 crankcase and its internals. I already have the 650 pistons. I have a 650 head, and it's exactly the same as the Bandit/GSX 600 (maybe 1 mm difference in exhaust port diameter (not really sure); but valves, combustion chamber diameter, etc. are similar). By "650" I mean the Bandit K5, K6. It's rarely mentioned that here we find the ultimate in SACS evolution (not counting the GSX1400). Yes, I'm talking about the Nikasil liners (I really believe it's the pinnacle  of SACS and air(/oil cooled) engines in general - once we forgot it's "only 650 cc", of course...). -A

Edited January 14, 2018 by antoniomota
misspelling...

[banoffee]

650 bandits and GSX1400s aren’t OSS bikes, so probably not surprising that they are rarely mentioned on here 

[antoniomota]

5 hours ago, banoffee said:

650 bandits and GSX1400s aren’t OSS bikes, so probably not surprising that they are rarely mentioned on here 

Not "old school" due to the SCEM(/Nikasil type) cylinders? Apart from that, the 650 (K5, K6, not later water-cooled) is similar to the SACS 600. And I see the GSX1400 also as "old school"; too big radiator, yes (but there's oil in there!); no carbs, but EFI was used by Suzuki in the XN85 turbo, almost 18 years before the GSX1400!; direct actuation valves (not rockers) unlike SACS engines, but similar to the old "GS" series; balance shaft like the GSX1100G... in short, I want one!! 

Edited January 14, 2018 by antoniomota
misspelling

[Gixer1460]

Don't try and convince 'de management' what is and what isn't Old skool - they don't like it LOL!

[wraith]

Welcome to OSS,

So let me get this right, you've got a gsx750f and you're down seizing it from a 750 to a 650 with a smaller port and valve head  why? Most people look at going bigger and more power not smaller and less power.

[vizman]

12 hours ago, Gixer1460 said:

Don't try and convince 'de management' what is and what isn't Old skool - they don't like it LOL!

on here, it's clear

[antoniomota]

> Don't try and convince 'de management' what is and what isn't Old skool - they don't like it LOL!

 

 

> you've got a gsx750f and you're down seizing it from a 750 to a 650 with a smaller port and valve head  why?

>Most people look at going bigger and more power not smaller and less power.

 

Yes, indeed well, I really like to mess with engines. But options for a capacity increase for the 750 don't fit my situation:

1) Wiseco 771 cc; that's basically for someone wanting to refresh cylinder with +1 rebore

2) APE solution (955 cc / +9 mm JE pistons and new liners): it's necessary to open crankcase, and I would like not to do it in such a low mileage engine; changing cylinder and head is easy; a "crankcase job" is another story....

To replace complete engine with a bigger one (1100): I don't really want to loose the stock air-box (1100 cylinder+head is taller and air-box must be trashed, right?). I've heard (from owners and also from Factory Pro website) that gen. 2 Katanas (>98) dont' like it (flat spots in some RPM ranges; it maybe some suction effect due to the fairing that spoil air flow to carbs when no air-box is there to "smooth" things).

So, my idea is a little different; I'm planing a lean-mixture setup, for getting as best fuel consumption as possible from a SACS Suzuki bike. My idea is to use GSX600F gen. 2 carbs (I already bought some used ones, good price) and use the 650 block. That's about 10% capacity increase from the 600, so mixture will be also ~10% lean from what Suzuki planed. A SCEM/Nikasil cylinder block is the ideal scenario (better heat dissipation than steel liners). The 750 oil cooler is bigger than 600.

Anyway, I'm putting a wide band sensor in the exhaust headers, to keep things under control and adjust the jets if danger approaches... don't want to burn the engine, of course.

Back to the rocker-arms: if I must buy the 600 rockers since the 750 are not compatible, I must spend as much $$ in those as a new 650 block that I really like to avoid, but...

Pics in attachment. Fairings are out for the Lucky-Strike paint job. The forks (covered with protection plastic) just arrived from Maxton (UK specialist); they were upgraded (now they are fully adjustable in compression and rebound).

Regards.

-Antonio

Edited January 15, 2018 by antoniomota
misspelling... bad english... ideas not expressed clearly...

[vizman]

all kool, keep on keeping on

however, take 5 to understand that (on here) that is a teapot.

[antoniomota]

4 minutes ago, vizman said:

all kool, keep on keeping on

however, take 5 to understand that (on here) that is a teapot.

Hmm, OK, "Katana" = USA. Europe = teapot? I thought only gen. 1 had that nickname...

[Oilyspanner]

Mark 2 still called a teapot, but had a ladies 'lovebud' as a rear light ! -  the Japanese have odd ideas sometimes....... calling the utilitarian gsx600/750f  'katana' was like calling rabbit droppings caviar, you can sell lesser items because of the association with something very respected - in this case the mighty GSX1100 and 1000 Katana helping the very different 'F' series and of course rabbit droppings could be called vegetarian caviar . People who adore the originals aren't going to like the tenuous link to the lesser items, kind of disrespectful even. Mind you, Kawasaki call almost all their range 'ninja' now (not so much in Europe) - started off as a class leading sports bike - gpz900r- now a commuter, pretend sports etc.

Can't help on rocker ratios - I knew the early 600f used individual arms and shims on top of valve retainers - like the last of the oil cooled 1100/750 GSXR's and that the B6 and later 600F used screw and lock nut adjusters, plus same rockers. 

The 750f actually rode surprisingly well, the 600f not so, busy little motor with underwhelming performance. A larger engine with more low end torque can be better on fuel than a smaller engine - dial the cams in for less top end, raise the compression ratio and raise the gearing - this will improve the mpg (make the bike lighter will help too). The engine was designed as a 750, has the internal friction of a 750 and isn't the lightest bike to start off with, reducing the capacity/power isn't going to achieve your goals.... just saying !

[antoniomota]

2 hours ago, Oilyspanner said:

larger engine with more low end torque can be better on fuel than a smaller engine

Oilyspanner, you could be right, but Haynes manual mentions 5.4 l/100 km vs. 6.7 difference in average fuel consumption. I know we shouldn't trust anyone about this kind of data (magazines say a XJR uses 8 l/100 km, and I get 5.7 in mine; XN85 almost 7, and I get 4.5! etc.). But Haynes also show a torque curve of the 600 with maximum just slight above 7 K. So, 600 cams seems less "hot" than 750?... -A

Edited January 15, 2018 by antoniomota
misspelling