Katana Owners Club U.K.

you'd need to re-jet for the harris pipe, also will probably need to adjust the pilot screws aswell as the tickover.

Does sound like the jetting is out. The easiest and most successful way to rejet is to take it to a dyno.

However the dyno jet website may list the kit req.

Have the carbs been apart and have they been balanced since.
this would only affect tickover , but if you raise the tickover screw and the balance is well out , when you apply throttle to set off 1 or 2 carbs may be over fulling in comparision to the others , richening it a touch till you get on to main jet.

ha ha , Now if we remember the last owner had it parked up for a long while, so maybe the passage ways are a bit clogged up .

Best to give it some , in the interest of mechanical testing you understand.

You could try going up a couple of jet sizes, i don't know what std jets you have but for example if it has say 120 main jets go to 125 and see how it is, it's a bit of trial and error, better to be slightly rich than lean, with the pilot screws make a note of the std setting and try going out 1/4 turn then adjust the tickover to the correct level...When doing this first off make sure the carbs are clean and balanced to start with..You should be able to get it running good. jets will cost around £10-15 for four much cheaper than a dyno even if you have to try a couple of different sizes. Don't change the air filter as you'll need to rejet and tinker even more, with a Harris pipe you'll always need to rejet.

Hi Mick
Well if you run it and the mixture is too lean, you might just do that Mick.

You really need to do a Plug Chop to see what the mixture is doing! Give it a good thrashing in 3 or 4 gear at full throttle for a mile or so..............kill the engine and coast to a stop and whip out a plug and see what colour the plug electrode is.............if its white its to weak or lean. If its black and sooty its too rich................but my money is on it being to lean or weak!

I would whip the carbs off and see if it has standard jets fitted.........whilst you are there buy a tin of carb cleaner and give the carbs a clean and blow through. Then fit some bigger jets if yours are still standard ones and you have a harris pipe fitted. Go up by at least 10 on the mains or 4 sizes ( Suzuki mikuni # jets go up in 2.5 increments) and lift the needles 1 position to richen midrange. Screw your fuel metering screws in until they just bottom out and back them out 1 1/2 turns.

TTFN

Confussed ?, you will be

Go with the mains and pilot/mixture screw first then see how it is, too much in one go and it's hard to tell whats working or not, it shouldn't be too hard to find a decent setup.

And It's Mal

That looks like your mixture screws, if you have a manual it'll state how many turns out they should be as std (as a starting point) tickover i would think should be 11-1200rpm.

From what you say about the plugs it sounds like the carbs need a good clean out, not forgetting the needle valves and their holders, also check and set the float heights (i would still rejet while they're apart. 2 sizes should do it imo), once all done balance the carbs and hopefully you'll have a sweeeet running Kat

pretty sure the manual doesn't give a setting for the mixture screws as they"set" at the factory... 2.5 out is a decent starting point.

do you stil have the std airbox? if so i'd go 1 size up on the main and raise the needles a notch. sounds like it's leaning out between needle/main thus why it's not pulling past 75-80

if it's lean it's gonna be running hot... which isn't a cool thing on a 200 mile ride imo.... i'd def try to get all plugs looking the same and do a plug chop!..... before ya leave home on friday

std unleaded is all you need for your bike.

That,s the spirit aim for the tale of woe trophy!!!!!!.
seriously when I got s2 and used it the first time it was much like yours. Did a few hundred in a vain hope it would sort it self which it clearly didn't got better but still iffy.
Took carbs off got new pliot jets and float needles and seat from ( £40 NRP) cleaned carbs through and bingo robert is your parents male sibling.