Naim Posted October 28, 2019 Posted October 28, 2019 I decided to swap gsx-r1100 carbs to my GSX1200 Inazuma. I'm aware that these carbs uses gravitation fuel supply while my old CVK32's used a fuel pump. What happens I use fuel pump with Mikuni carbs? Quote
Oilyspanner Posted October 28, 2019 Posted October 28, 2019 Fuel pumps for carbed bikes only operate at very low pressure, not like injected bikes - healthy float valves /seats should stop the fuel flow easily enough - do you actually need a pump on the In. 1200 ?.....maybe there's very little distance between the fuel tank and carb fuel inlets ? Are you tuning the motor ? 40mm carbs are good for mid-range up power. but you will lose some power lower down, if you big bore and flow the engine they're good - sorry if you've posted engine work being carried out in another post listing what you're doing. You'll need 41c00 inlet rubbers for the carbs and you'll need to match the inlet port entry to the diameter of the inlet rubbers ……. you probably know this and it's listed in your post somewhere ! Quote
Gixer1460 Posted October 28, 2019 Posted October 28, 2019 And they are a barsteward to get right Quote
Naim Posted October 28, 2019 Author Posted October 28, 2019 36 minutes ago, Oilyspanner said: Fuel pumps for carbed bikes only operate at very low pressure, not like injected bikes - healthy float valves /seats should stop the fuel flow easily enough - do you actually need a pump on the In. 1200 ?.....maybe there's very little distance between the fuel tank and carb fuel inlets ? Are you tuning the motor ? 40mm carbs are good for mid-range up power. but you will lose some power lower down, if you big bore and flow the engine they're good - sorry if you've posted engine work being carried out in another post listing what you're doing. You'll need 41c00 inlet rubbers for the carbs and you'll need to match the inlet port entry to the diameter of the inlet rubbers ……. you probably know this and it's listed in your post somewhere ! Another question was supposed to be regarding inlet rubbers. I got the original ones from 1100 with carbs but its rubbish, all cracked. Found this in amazon...but looks nothing like the original https://www.amazon.com/gp/aw/d/B07CYJF1FH/ref=ox_sc_act_image_1?smid=A2UR5TWQRNTCTM&psc=1 On the other hand I found these but as per catalogue number they don't match Another question was supposed to be regarding inlet rubbers. I got the original ones from 1100 with carbs but its rubbish, all cracked. Found this in amazon...but looks nothing like the original https://www.amazon.com/gp/aw/d/B07CYJF1FH/ref=ox_sc_act_image_1?smid=A2UR5TWQRNTCTM&psc=1 On the other hand I found these but as per catalogue number they don't match https://m.olx.pl/oferta/krociec-gaznika-suzuki-CID5-IDy9Hvi.html#position=1&page=2 Quote
Gixer1460 Posted October 28, 2019 Posted October 28, 2019 The only ones that will natively fit 40mm CV carbs are from GSXR 1100 M or N (1991 and 1992) The largest 750 rubbers were 38mm which sometimes can be stretched but it's painful to do! Quote
Naim Posted October 28, 2019 Author Posted October 28, 2019 2 hours ago, Gixer1460 said: The only ones that will natively fit 40mm CV carbs are from GSXR 1100 M or N (1991 and 1992) The largest 750 rubbers were 38mm which sometimes can be stretched but it's painful to do! Kinda wierd, Over 42mm for 38mm carb? Quote
Askamaskinservice Posted October 28, 2019 Posted October 28, 2019 38mm carburettors are measured inside, the outside is bigger........ Quote
Gixer1460 Posted October 28, 2019 Posted October 28, 2019 2 hours ago, Askamaskinservice said: 38mm carburettors are measured inside, the outside is bigger........ ALL carbs are measured internal bore size! Quote
Dezza Posted October 29, 2019 Posted October 29, 2019 I recently fitted some 750L rubbers to a Blandit 12 head so as to accommodate RS 38 carbs. These carbs have an od of 42 mm and fit perfectly with these rubbers (which are not easy to get secondhand, surprise surprise). If you imagine an id bore size of 38 mm and a metal thickness of 2mm, then this is where the 42mm od comes from. So measure the od of the carbs you want to fit and go from there. If the BST 40s have an od of 44mm then you'll need the 1100M,N rubbers as stated above. Alternatively, apparently the rubbers can be enlarged by the use of a rotary sanding drum. I think noclass has done this on his build thread so search through the projects section. Quote
Naim Posted October 29, 2019 Author Posted October 29, 2019 Had anyone bought one of these? https://www.amazon.com/gp/aw/d/B07CYJF1FH/ref=ox_sc_act_image_1?smid=A2UR5TWQRNTCTM&psc=1 I should be going for geniue and/or aftermarket , just considering it price wise. Quote
Gixer1460 Posted October 29, 2019 Posted October 29, 2019 We still haven't established what carbs you have - early GSXR's had 34mm, most had 36mm inc Blandits, some 750's had 38mm and the latter 1100's had 40mm - all bore sizes. That advert is confusing as a single rubber seems to fit multiple size carbs! Also its not just the diameter that is an issue, the mounting angles should be correct for an easy fit! Yes OEM are expensive but they are designed to fit correctly! Quote
Naim Posted October 29, 2019 Author Posted October 29, 2019 I have a 40mm gsxr1100 mikuni carb as you can see in the topic :-) Quote
Gixer1460 Posted October 29, 2019 Posted October 29, 2019 22 minutes ago, Naim said: I have a 40mm gsxr1100 mikuni carb as you can see in the topic :-) But for us - are they the 36mm bore (40mm OD) GSXR1100 from J - L models or 40mm bore from M/N models - as there seems to be confusion what is measured for description! Quote
Oilyspanner Posted October 29, 2019 Posted October 29, 2019 1 hour ago, Naim said: Had anyone bought one of these? https://www.amazon.com/gp/aw/d/B07CYJF1FH/ref=ox_sc_act_image_1?smid=A2UR5TWQRNTCTM&psc=1 I should be going for geniue and/or aftermarket , just considering it price wise. The Americans didn't get the 40mm BST carbs on their GSXR1100s like the rest of the world in 1991/92, so all their 1100s had 36mm carbs - the ad. being from the U.S. will mean the rubber inlets will be too small. I bought a new old stock 41c00 inlet rubber a few years ago on #bay, they rarely come up for sale at a reduced price - each of the four are numbered and are all differently angled - so you would need a set. 36mm bst carbs are much easier to tune and parts are easier to find as many of our engines used them. I like my 40mm bst carbs, but they are sods to tune if you move away from the standard set-up. I tried to use after market filters (not the airbox) and despite liking a challenge I couldn't get the power delivery anywhere close to being decent - I refitted the airbox, fitted smaller jets and I had loads of torque, with a power curve with no drops - it felt twice as powerful in the mid-range and had more top-end ! I don't know if you'll be able to use the Inazuma's airbox with the big carbs - but as the saying goes - nothing ventured nothing gained.... Quote
Naim Posted November 12, 2019 Author Posted November 12, 2019 Two more things came to my mind: My regular CVK's have a trottle position sensor, mikuni's don't...how do I deal with that? Also I have two cables connected to trottle while mikuni's have one cable only. Quote
manden Posted November 16, 2019 Posted November 16, 2019 Get tps from 36mm bandit mikuni and remember there is a light pressurized part of the 40mm carbs Quote
Naim Posted November 18, 2019 Author Posted November 18, 2019 On 11/16/2019 at 12:55 PM, manden said: remember there is a light pressurized part of the 40mm carbs what do you mean by this? Quote
CockneyRick Posted November 19, 2019 Posted November 19, 2019 Given the issues you're facing, why bother? If you must change em, go for 36's Quote
Fatmama Posted December 25, 2019 Posted December 25, 2019 Inazuma 12 swoping the original 32mm Keihins to 40mm Mikkaroonies from gsxr 1100... Been there, done that. It works. Question why would you do that? I did it because i changed damaged headers to unrestricted, stepped headers from Holeshot (Dale Walker) and with them i wasn't able to dial in the original carbies. In retrospective i should have just gotten another stock header and done. The Ina 12 in standard trim got best low down torque from all oil boilers... My working set up was: Airbox removed 4 metal mesh pod filters Mikuni 40mm from a gsxr 1100w with their intake rubbers (can't remember jet sizes) Standard engine Unrestricted exhaust system with stepped headers. No fuel pump. (tank wouldn't fully empty anymore but no biggie) Inazuma 750 doesn't have fuel pump, the 12 needs a pump to empty its tank. She ran and sounded fantastic (loud as hell) with that set up, but is changed now to flat slides. Good luck and have fun with your Inazuma. Quote
Gixer1460 Posted December 25, 2019 Posted December 25, 2019 Whether it's been done now or not - the 40's are a total PITA to tune without std airbox and exhaust - Suzuki San got it pretty right in the factory. A super top end and shite mid range is not tuned IMO - the 36's are sooooo much better at doing everything and will still represent a decent hop up from 32's. Quote
Fatmama Posted December 25, 2019 Posted December 25, 2019 16 minutes ago, Gixer1460 said: Whether it's been done now or not - the 40's are a total PITA to tune without std airbox and exhaust - Suzuki San got it pretty right in the factory. A super top end and shite mid range is not tuned IMO - the 36's are sooooo much better at doing everything and will still represent a decent hop up from 32's. Agreed, that's why i would stay with the originals. My 40's ran surprisingly well, mid and top range. Contrary to everything read here. Guess i was lucky. Quote
R1guy Posted December 26, 2019 Posted December 26, 2019 On 10/29/2019 at 9:49 AM, Naim said: Inside OD is 40mm. Erm? Quote
Wagola Posted December 27, 2019 Posted December 27, 2019 On 10/29/2019 at 9:49 AM, Naim said: Inside OD is 40mm. Well that clears that up !! 1 Quote
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