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lb/hp is what it's about!
10,448 Posts
I'm curious about carb sizing between the models. Anything I ever found I had to hunt for hours to get and verify.

Here's my contribution for now. None of it really has any tech info but shows what can or maybe shouldn't be done. :LolLolLolLol:

Oil cooled 1100 into a unknown water cooled frame.

Here is a 600f engine into a 600w frame that I did.

For shits and grins I stuffed a gs750 engine into a cb360 frame. As you can see the plasma cutter got a workout. Haha


Discussion Starter · #3 ·
Time for a little more on wiring :)

The infamous bandit 12 "wheelie wire" ......
Utter bollox as far as I can make out, I've had a few b12's & cutting the blue wire makes no difference I can detect.

B12's run with the TPS disconnected just fine which is handy to know if you are using a 12 motor in a project

Later oil cooled bikes are equipped with a security device on the ignition that can be a pain if you don't know about it & change the ignition for something else as you wont get a spark, the solution is simple enough but I wont post it on an open forum, if any of you come across the problem PM me ...... Oh you wont find it in the wiring diagrams in either the Haynes or Suzuki manual so don't waste time looking :)

Coils are in the 2-3ohm range for all the air cooled bikes & 3-5ohm range for the oil cooled ones lots of people get this wrong when fitting dyna's etc .... gs's etc do run on gsxr/bandit coils but wether this is a good idea or not is beyond me
I have seen people removing the HT leads from GSXR coils to fit coloured ones, there is a clip holding the leads in but its is designed to break if removed so you are left with silicone to hold it in ...... not a good idea imho

Discussion Starter · #4 ·
I could name every conversion I've done using gs, gsx, gsxr, bandit & f engines :) the frames have been Suzuki Honda Yamaha & my own .........shafties as well as chain drives & using loads of different makes of wheels forks etc but trust me the list is way too long & complicated for a rough guide

What I'm trying to do here is give an insight & wont be able to cover every combination + I'm avoiding water as its for making tea :D

PS I will get to carbs eventually

Discussion Starter · #5 ·
Oil cooled wheel changes

Bandits 600 or 1200 rears are a direct swap but I cant remember if you have to use the caliper hanger & spacers that go with the wheel or not

Curved spoke gsxr slingshot wheels (20mm spindle) go in bandit 12's but you need the gsxr rear caliper hanger with the wheel in most cases (there are lots of different ones so make sure its the one for the wheel)
The front disc offset differs by 2mm, you can washer either the discs or the calipers by that amount to get it right no problem, obviously bandit ones go in slingshots as well just watch that brake caliper spacing both ends

GS rear wheel swap
the biggest you can easily get in the stock arm is a 4.5" off a b6, 600f etc etc but on some you may have to file out the wheel adjuster slots, do a wheel bearing conversion or sleeve the bearings ..... bigger that that you are looking at swapping the arm or serious mods

Front ends for GS
Anything you heart desires :) ..... its going to be (a) a bearing swap (b) a change of steering stem in the bottom yoke (c) a custom stem or if you are feeling really flush (d) full custom yokes
Things to watch out for ...... length.... gs forks are long compared to modern sports bikes so you are either dropping the front or making a custom top yoke or extensions
The gs gsx steering stems vary in size a little & are mostly welded to the bottom yoke rather than on a snap ring like the more modern yokes, those with a 30mm id bottom bearing wont always fit into a modern yoke with a 30mm id bottom bearing as they are slightly under (old tooling V new tooling i guess) that results in a prick in a bucket fit :) so taking the new yoke out a few mm & fitting a press fit sleeve is one way of getting round it but I prefer a new stem

Discussion Starter · #8 ·
Swingarm swaps for GS/GSX

By far the easiest is B12, on some models you can slip the gs bearing spacers into the b12 ones so you can use the stock gs spindle then make up a couple of equal spacers to centre it, don't forget to sleeve the centre spacer in the arm as well, on some models the arm will catch the rear footrest hangers so they will need to be tweaked or removed
On 99% of aircooled frames using the complete B12 swingarm, wheel & spacers will give you perfect wheel alignment
You can then keep it twin shock or convert to monoshock.........

Problems with twin shock are ..... the chain has a tendency to want to run through the L/H shock so your mount for the shocks need to be raised slightly & spaced out a little to clear .... if you are using a more narrow 530 chain that has smaller sprockets for the same gearing that helps too

Problems with monoshock are....... you are going to need to be able to fabricate the mounts obviously & they want to sit where the airbox & battery were so you will be running pod filters & relocating the battery...... monoshock conversions put a little extra strain on the weakest area of the GS/GSX frame so while you are doing the mounts I advise a little bracing as well

I have seen people bore the pivot bolt holes in frames to use the 20mm pivot bolt, the problem with this is getting it dead straight & it weakens the frames pivot point imho

Other arms
Sticking with the 80's & early 90's Suzuki arms (20mm pivot)
Gsxr slingshot & others go in with a little messing with bearings etc as above but you may have to slim the pivot point on the inside of the frame down a few mm ..... some of the first w/c bikes go is as well but after that it gets a bit more involved

Notice I have not included slabside arms here as the rising rate linkage on those is a real pain & not worth the hassle of fitting one, imho the gsx1100efe (1150 to you?) arm is very similar to the slabby & also not worth bothering with

Ali twin shock gsx1100 swingarms fit all the gs & gsx twinshock range 750cc up

Discussion Starter · #9 ·
A word on wheel alignment & chain alignment ....... applies to all

This seems to be something a lot of people struggle with, I have seen countless people worrying & trying to align the chain when doing a conversion the realise then wheels are NOT in line .....really bad idea imo

So here is my routine .......
Never rely on the marks on any swingarm to get the wheel straight, the best way when doing this sort of work is to bolt it up with it all the way forward in the slots & check its actually right before continuing

So so stick you chosen swingarm complete with a bolted up wheel in the frame as well as you can & have a look at WHEEL ALIGNMENT forget chains for now there is no point
If alignment is spot on you are good to go but on some arm & frame combo's a little messing may be needed ......
Example the wheel sits 10mm to the right so needs to me moved to the left to centre it & bring it in alignment with the front, you have 2 choices move the arm over on the pivot if there is enough room in the frame or move the wheel over in the arm, it up to you to decide which is best but GET THE WHEELS IN ALIGNMENT FIRST & leave them there

At this point you should have spent no cash on machining of spacers etc as simple bits of tube will work as temp alignment spacers

Next its chain alignment......
99% of the time its going to be off a fair bit 5 to 10mm is not unusual
Use sprockets made for the same size chain for this or you can be a few mm off & have to start again!
I clamp a stiff straight edge to the rear sprocket & measure in to the front to get an idea of offset needed, check & re-check to be sure!........ so for example I need 8mm offset on the front sprocket but cant get a sprocket with that exact offset & have to find another way....
....we will say I can get a 5mm offset sprocket which leaves me looking to make up 3mm there are a few ways I can do this ....

(a) use the 5mm offset sprocket & space it 3mm on the output shaft, this can sometimes be done although the sprocket nut sometimes needs slimming down
(b) use the 5mm offset sprocket & space it 2mm then turn the rear sprocket around so the dish in it gives you the other 1mm
(c) use the 5mm offset sprocket & take 3mm off the rear sprocket carrier
A combination of any of the above can be used within limits

Your next problem is ... will the chain clear the tyre & the frame? frames can be notched for clearance or maybe a 530 or 525 chain will give you the bit you need but make sure its up to the job as a chain in the back of the leg at 100mph stings a bit

Obviously the chain needs to be straight, look at how much sided to side movement you have with a new chain on a new sprocket & that's what you have to play with its either right or wrong !

note ..... 6" wheels are a right royal pain in the arse to get in most times so I stick with 5.5" & a 180 tyre

Got all that right ? you can now make up any permanent spacers you need :party-smiley:

Most of this will apply to other bikes as well as the best .......Suzuki's :)

Discussion Starter · #10 ·
Oil cooled engine to air cooled frame ...
Applies to all the oil cooled engines in any air cooled 4 frame 750cc up (with the odd 550 thrown in)

Yes they go as previously stated, you just need to decide where to put it ......

My preferred method is to stick it in on the stock bottom rear engine mounts & make the rest of the mounts to suit, with some models you will need to make 3 other sets with others only 2
Issues you face with that method are ..... (a) You will need to extend the exhaust downpipes out to clear the frame (25-30mm usually does it) ...(b) Most if not all oil colled exhausts will hit on the stock footrests or frame in that area....(c) Fuel taps on the stock tank can be close to or touching the carbs... (d) Expect plenty of carb fiddling as you will be using pods...(e) oil cooler lines may need to be extended & obviously mounts made

Option 2.....Stick it in on the front mounts & make the others
Issues with that are....... (a) Harder to get central as its wobbling about on the rubber front mounts while you are trying to sort it ...(b) Fuel taps on stock tanks can be close to or touching the rocker cover (c) the same clearance issues with the exhaust in the footrest area as above & sometimes worse (d) carbs & pods again

Option 3 ...... stick it somewhere in the middle & make all the mounts
issues ??? don't know don't like the look so never bothered to try :)

General stuff
Bandit 12's have a 12mm bottom rear engine mount bolt while most others have a 10mm, some people sleeve the engine bolt hole but I have seen cases cracked when this is done badly so advise drilling the frame to accept the 12mm

Stock tanks on some models can touch the rocker cover, raising it up a few mm at the back can cure this if you don't mind the look

If you hit any of the fuel tap problems listed above the choices are limited.... move it & re-weld it in a better place for clearance or fit an adaptor & something like a Pingel or move the whole tank slightly up down forwards or back

Bandit 12's are the tall one so although they go in easy enough as above access can be tight

There are at least 3 or 4 rocker cover breathers on these engines some are taller than others so finding a low one may help .... for example when putting a B12 into a 600F frame the breather catches on the removable cross brace so a smaller lower one means you don't have to notch so much of the tube away for clearance

All the rubber parts on the front engine mounts are the same & there are a couple of Kawasaki ones that fit too but are a little longer

:) tea time :)

Discussion Starter · #11 ·
Oil cooled engines

Some 600's will accept a 750 head & barrels bandit 6 with 750F top end is common, beware of the differences between the long & short stroke motors if thinking of doing this

The 750 "********" from some 750F's flows the most & also raises compression slightly

Gsxr 750/1100K cams have the highest lift & duration although finding good ones now is difficult

B12 gearboxes are straight cut while gsxr's are helical

Later engines use a Hivo cam chain while early ones use a plain chain

Bandit 12's with a bore will accept hayabusa flat topped pistons lowering the compression for turbo use but I cant for the life of me remember what the ratio ends up as, to get the compression back you would need to deck the head/barrels

As above with busa pistons but also using busa rods leaves the compression pretty much stock & gives you 1216cc, check it

With all of the above beware of the differences in gudgeon pin sizes across the range & check before you start

Discussion Starter · #12 ·
Now the difficult bit :)

Carbs for oil cooled engines
First it have to say this is the thing people seem to struggle with most & I fully understand why, I will try to keep it simple as every bike has slightly different needs for fuel supply depending on how fit the engine is & the level of tune

Keeping it stock for a start you have Mikuni bst (cv) carbs, the size ranges from 31's up to 40's depending on engine size.... I will restrict it to 31's up to 36's here as those are what I have experience with although I suspect the 38's & 40's are similar
Carb size is measured internally at the head side of the body

Note there are minor differences in jetting etc & on which models got which carbs in which year depending on the country the bike was intended for

With all these carbs getting smooth running throughout the rev range will always be easier with the stock airbox

Some US market carbs have different main jets for the outside 2 carbs & the inside 2, something to do with emissions I guess.... some US spec carbs have a metal bung over the mixture screw to prevent tuning, this can be removed, some also have a rubber bung under the pilot jet :nuts:I don't know why

All these carbs are very sensitive to the float heights being spot on forget the +or- 1mm you want it right ! all are also known to wear the emulsion tubes & needles over time & this can cause running problems especially if you are tuning for pod filters

My advice if you find yourself with either 31's or 33's is chuck the over the nearest hedge & fit some 32's off a bandit 6 or similar, there are many reasons for this, a couple being they are old & were poor from new, they are rare but basically worthless they are very difficult to set up .... I have never gotten to the bottom of why so if anyone can enlighten me please fill your boots :)

K&N Individual filters are harder to set up the carbs for than the K&N dual oval, I'm not sure why but its a fact proven by myself & others..... another option is Ramair foam individual filters which don't flow quite as much air & sit somewhere between the above types of K&N in the setup stakes ...... whatever you chose its going to be a pain to get it near right & a dyno run is the only real way of getting it 100%

Jet kits
There are 1 or 2 that are designed for use with the stock airbox that will clean up the fuel delivery nicely with minimal fuss but to be honest its nothing that cant be done with a selection of stock jets & careful work

Kits for use with pods .... on the whole utter bollox as there are way too many variables for any maker to get it right for you, for example who is running the exact same carbs, exhaust filters on a bike that is the same age as yours with the same milage & is reading the same on compression & vac ..... that will be nobody then :)

So the kit for use with pods will get you close after much messing around, frustration & anger, then you still need a dyno run or two to get it right ..... If you start off with a bunch of jets in various sizes & are willing/able to take the time you can get as close or closer than a jet kit will get you but will probably still need a dyno run for it to be 100%

Pilot jets rarely need changing unless we are talking a big power hike over stock or maybe if you have stuck some carbs on that with stock pilots are too big for your engine.... not as uncommon as it sounds, I once had a guy come to me with a fairly stock 600F sporting b12 36's with all stock jets :oops: yup it did piss fuel just a little :doh:

That me about done, I hope its of some use to someone ....questions ?????? :)

7,580 Posts

^^that one rarely gets used! :D

Whoa, that was one hell of an information deposit here on the forum! Haven't seen that much good, solid info in one place in quite some time. I can dig through some of my old notes and add some turbo info if you would like? Pretty basic stuff really, nothing of the technical engine build sort, but enough to get anyone pointed in the right direction. There is far more out there than I could ever retain, but the standard formula is pretty direct and to the point.

Discussion Starter · #14 ·
Yes please Ratfighter I'm getting the urge for a turbo so anything related would be great for me mate :)

7,580 Posts

I'll get into all that later on this evening or tomorrow morning. My info is strictly related to blow through turbocharging on the Bandit 1200 and GSXR1100 air/oil engines and the 36mm carbs that came on them. I'm sure there is plenty that relates well to almost anything, but my info was gathered from months and months of conversation with Toni (Motohorho) and a few local guys (gifted motorcycle builders at that!) that ended up impressed with the things I knew that they didn't. As well as the decade of research and internal combustion engine destruction, I'm pretty confident I know what I need to know at this point. Got quite a few turbo's laying around the shop from the baby IHI RHB31, up to the monster Holset H1C, and a good lot of them in between too.

Threads are worthless without pics right? So here's my GS1000C with a GSXR1100 engine and a turbo kit, sporting GSXR750W forks, '95 CBR900RR wheels, and a '81 GS550E tail, and '91 GS500E headlight. Suzuki lego set of a parts bin I've got going on! :D

I'm off to go finish up a GS850G build in the shop for the day. Turbo info coming soon!
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