wsn03

My GSXR 750 f has been sat idle for almost a couple of years. Everything good (fuel stabilizer; battery) - indicators not blinking. New relays are 75 quid if oem. Is there a way to fix it?

Yes the high rpm is crucial when carb balancing, and rough idle will happen with badly syncd carbs. Sync 1 & 2 together..... then sync 3 & 4 together..... then sinc both pairs by using the middle adjuster (sorry if you know this already, trying to eliminate all your issues) When you adjust the screws don't lean on them, make sure you lift off before you confirm they are sync'd. Tiny amount of lean upsets it.

I got a jewellers viewing think, brilliant for stuff like jets

Eblag and Amazon have them at half that price

How does it work? Is it like the Gunsen, or better?

I think what you are doing is right - you have to try all these things. Look at the difference between the new pilots and the old - hopefully the hole is bigger. Maybe a Gunson colour tune would be a good idea - you can actually see your pilot is set up correctly, and they are quite cheap. Looking at them and reading the reviews I think I might set up my Bandit pilots with them.

I find thinners or something as strong is always required, you will be surprised how bigger the hole is after soaking in them. They could be partially blocked. I soak them in thinners overnight

Did you take pilots out and look through them? You should be able to see right through them against a light

I soak my pilots in thinners every time - obviously taking them out to do it

I used a colourtune, in the end I set screws the same. Perhaps I should have persisted, got quite tired of the thing to be honest! Your theory makes sense though

So 3 possible issues: 1. Coils - are your aftermarket ones any good? ACTION - try to research reviews on the coils you bought, do seem a bit cheap to me! 2. You have a leaking airbox, not sure why it should cause a change in performance as its before the filter, but it is when you spray it. Action - To me then that needs sealing before you do anything else 3. There is a question mark over your pilot / damage where it is screwing into. That will cause excess air leak which will mess up everything. Action - Can you get another set of carbs?

I know nothing about those coils, the only make I know people recommend is DYNA coils - that is what I have. However they did have some problems when production went to China, don't know if this is ok now.

Whoaoh! Somethings wrong there. The revs changing. Not good. So that box leaking is causing a surge of air. Can you seal it?

I've always known them to need to be the same

If it was me I'd want a decent set of new coils - DYNA preferably - it cured my erratic idling.

You mentioned you were trying to change coils. Are coils a weak spot on yours? I presume they must be as I guess your bike is pre-GSXR F. Did you try different coils? My concern with the crap coils is they change behaviour as you are riding around on them - that's what happened with me. I presume your readings in that case might not mean a whole lot

So all screws turned out the same then. I have 2.5 on my 750 F and Bandit 1200. Is 3 too rich or the norm for your model? Have you checked valve clearances? Critical. When I had a surging problem it was an airleak, I actually eventually found it was caused by a screw for the scottoiler coming loose (fucktard who put in did it with pliers, idiot). My other port of call - Coils. I only have experience of Slabbies - my GSXR 750 F ran like a pig until I fitted aftermarket coils and leads - DYNA in my case, but I hear mixed things about them these days - the slabbie coils are known to fail, is that the same for your model? Also have you balanced the carbs? That will really affect things, they go out of balance quickly. I don't know what to make of your photo. My concern is any air getting past the pilot more than allowed by normal? Sorry I haven't been back through your original post, just trying to go through the obvious.

No worries. In all the ones I've tested the longest I ever found one hold out before leaking was 40 mins, most are pissing fuel out within 10 mins as the fuel fills the bowls then gets past the valve which is supposed to be a cut off. If leaking within 5 minutes this is your idling issue, it is over fueling when on tickover / low or no throttle. If like me you have gravity fuel tap that you forget to switch off, double trouble - diluted oil!!! Scary. I once found an airbox filled with petrol - took the lid off with a lit cigarette in my hand! I'd have lost all my bikes in that inferno, still scares me now. I always have a fire extinguisher since that episode. Plus I don't smoke For anal retardedness like I suffer I actually go for overnight - I just like to know that gravity fed fuel was held at bay for a long time, even a tiny leak means the valves are on their way out, so no leak overnight means perfect. Don't put too much fuel in your remote tank, if they are fooked it will make a mess. This check should always be done on all carbs, these little valves work hard and when they fail they help to destroy engines by filling the crank with petrol - nightmare! Good luck, hope it goes well

That's not the same thing I'm talking about - I'm talking about checking the needle float valves for leaks. You have to load them with fuel and make sure they don't flood. The machining on them is microscopic precision, so they wear and then fail, and that's when your problems start. They're also very expensive. On by Bandit 1200 they were fooked by about 9000 miles only. I noticed the oem replacements were quite different looking (clearly re-designed)

It looks to me like you haven't done anything to check the needle float valves - they are a big fail point. They start leaking and over fuel the engine - this will be fine on open throttle, but poor on idle. What to do: Put carbs in a biscuit tin or some sort of metal tray. Connect a remote fuel tank (e.g. from Demon Tweeks), note the level of fuel in the tank (I use masking tape) then turn on tap - leave for a couple of hours, checking occasionally. If level is the same after that all good, if not you have leaking valves. I have seen new valves not start leaking until after 40 minutes?!? If they are shagged they will start leaking immediately, and petrol will start pissing out. I buy Mikuni oem only, but some say Wemoto are good. All other aftermarket ones appear to be made of cheese. Hope this helps - it is the first check I do on any carbs

For some reason no one can explain Bandit plugs are a weird and delicate science. They seem to last 5 minutes, and for some reason no one understands they never recover from being wet. They tend to be the home of all electrical problems (I've had a mk1 1200 from new, 12000 miles and on my third set!)

I've done a million carbs over the years, and left bikes in long term storage most of the time. My 10 pence worth: I soak jets in thinners I wash carbs in a bucket of petrol (probably no longer a clever thing to do but its how I was taught). If it was me I'd leave soaked in a tray of petrol for a couple of days - obviously rubber seals binned first and diaphrams out. Rubber inlets I replace because on my slabbie they are the biggest bastard cunt fuck pig wanker asshole of a thing to work with ever - bollocks! New ones are nice and soft and easy to work with, its like a whole new way of life. I have screwdrivers ground down to fit the pilots exactly - they break so easy. Also rig up a remote tank to test your carb float valves aint leaking over 24 hrs - needle float valves, the weak spot - even aftermarkets will fail except Wemoto, but I always buy oem Mikuni myself (sell a kidney) BTW check diaphrams - my low mileage Bandit 1200 started stuttering all over the shop in Holland - when I held diaphrams up to the light full of little holes - they do go, check them. Finally - to store fill with Super unleaded (less or no ethanol), add STABIL 1 MARINE - it works a treat, stops the fuel going off and stops moisture getting into your tank. Tank is always full to stop rusting. Filter between tank and carbs. No issues except when I forget to do any of that.

Thank you, that's a good call. We had to do some frame work, so the loom was all apart, connectors cleaned and a blob of vaseline smeared in each, so as far as I recall all good. That's 3 people theorising carb - so we'll see what happens when she's on good fuel only

Thanks chaps. I'm ok with the carbs, needed to check on the electrics - the GSXR coils were known for failing even at low miles. Thanks for confirming Bandit coils have a better reputation - I wasn't sure if they were crap as well. I overhauled leaking fuel valves at only 9000 miles (unbelievable!!) - the miles are real, I've had the bike from new. Diaphrams also full of holes around the same time! Carbs are bang on, and I flood tested them too just to be properly sure (I hook up a remote tank and leave it for 24 hours - if no fuel level dropped the valves are good). Didn't think about needle wear - one to remember to check for next time. I'm guessing at only 12k though this shouldn't be an issue yet. I'll run through the fuel, as I think about it some of it is 2 years old I think. If the problem persists I'll take the carbs out again. However it ran really crisp on the way home like normal with more new fuel in it. So I'll see what happens.

Bandit 1200 mk1, parked up for 4 months in Jun after months with normal unleaded after a rebuild, however I think some of that unleaded was already almost a year old - didn't mean to lay it up in June but another job took over my life. Come to start it in Oct, can't get it to fire. Assuming blocked pilots (so tiny) from petrol turned to shite, overhauled carbs - all good. Balanced carbs. Changed plugs. Put in fuel stabiliser - cack fuel plus some superunleaded. Bike runs ok, but I notice cold starting is a bit of an issue (though its not cold in the garage yet) Bike has 12000 miles. 6 months later - bit of a pig to fire up, stuttering and spluttering. Can't rev it for what seems like an age, definitely missfiring like crazy. Cylinders 2 and 3 exhausts colder than others. Get on the dual carriageway for 10 mins and running well. Ever so slight lumpiness - however, most of the fuel is old. I manage to squeeze in £8 of super unleaded for the journey home, opened her up, running well, not 100% but pretty close. I'm thinking either - this will fix as I get decent fuel through, perhaps I'll do another balance of carbs after next fill up. OR Coils? Plug leads? My GSXR F is famous for having crap coils, and life changed when I fitted Dyna coils back in the day before they started making them in China (still going strong). This bike is low miles but could the coils corrode / breakdown - you can see she doesn't get a lot of use. Same question for plug leads and caps? If the problem doesnt go away with a refill of good new fuel I'm going to have to look at leads and coils - what type to get, oem? Are Dyna still unreliable since being made in China? Thanks