Bandit 1200 - to dyno or dynojet?

[Ernie]

Hi

Just finishing odd jobs on my bandit 1200 special. Its a mk 2 with standard carbs. It has K&N dual pods and a straight through black widow exhaust, a few inches shorter than standard.

I've gone slightly richer on the pilot jets and lifted the needles as high as they will go to richen the midrange. I did this all in the hope I could avoid the cost/hassle of taking it on a dyno. Truth be told its not running well and I am contemplating spending £130 on a stage 3 dynojet kit but would like to know if people have had good results out of the box with this kit? If the consensus is no then does anyone know a good dyno/tuner in the Weston Supermare area of the UK and what should I expect to pay to get it set up?

Thanks in advance and sorry if this is the 10 millionth time this question has been asked...

[banoffee]

You’ve gone up several sizes on the mains too, right?

I found the recommend main jet size in those kits to be a ball park only. Needed a dyno run on my GSXR to get closer to perfect.

[Gixer1460]

Pretty good ballpark though! I've done a couple of GSXR's and a mate did a 1st gen Bandit - all worked out of the box, following the instructions and got dyno'd just to check they were right - my 1186 was within 2 points of correct on the mains, nothing else needed changing! You could spend hours faffing around on a dyno only using std jets and needles etc IMO!

[bluedog59]

I'd put the extra inches back in the pipe as well.

[Captn]

Do yourself a huge favor.  Install a O2 sensor and gauge, even if temporary, to see which way your changes take you. You'd be surprised how much of a difference little changes make. Jet/ tune to get close to 14.7:1 stoich.  If you keep building and tuning bikes it is a must. Reading plugs isn't an exact result as is O2 reading are. I've ran them on bikes for years and can imagine trying to tune without one.

Edited May 11, 2020 by Captn
Pic added

[Gixer1460]

Not bad advice but the 14.7:1 ratio is not a 'one size, fits all' and correct for every scenario! Firstly you need a wideband sensor & controller not a narrowband, a tuned bike will likely need figures in the region of 12:1 at idle, 14.7:1 (lean cruise) and 13.2:1 WOT max power. Obviously a Turbo / nitrous engine will be different and used with carbs is notoriously difficult as the fuel metering is quite course.

[Ted M]

Hi Ernie I have got the basic set up you have, I'm running mk2 carbs with dual pod filters and an Akropovic full system. I put a dyno jet stage 3 in and it worked sound. I put it on a dyno and it was fine just a bit if tweeking with the needles. So in answer to your question yes it is worth a dyno jet and a bit of dyno time. If you don't go down the road of a dyno jet system you need bigger mains and a dyno run minimum to sort your fueling. I've just checked the DJ kit and this should give you a good starting point all info for the stage 3 kit:

Main Jet size : DJ 144 equates to Mikuni 135

Pilot Jet DPJM018 can't find the Mikuni equivalent

Mixture screw 2.5 turns out

Edited May 12, 2020 by Ted M
Biff

[Dezza]

I agree with Bluedog. If the BW downpipes are designed to work with a specific length can, cutting it down could be adding to the problem. Also, changing several things all at once never makes fault finding any easier.

[Ernie]

Thanks All, I'm going to buy the kit. I've seen a comparison of the Mikuni and DJ needles, they are really different even to the naked eye so I'm expecting a big change in the midrange,  I hear what you say about pipe length, I'll try the DJ set up as is, can always add a bit to the Link pipe but I may be too vain, the pipe looks good, hate to spoil it!

Much apreciated

[Captn]

Of course a wideband O2 sensor. Thanks to @Gixer1460for pointing out my several rookie mistakes. 

[Wagola]

14 hours ago, Captn said:

Of course a wideband O2 sensor. Thanks to @Gixer1460for pointing out my several rookie mistakes. 

@Captn@Gixer1460read through this, where can I get a wideband O2 sensor and gauge from ? Looking at going this route for my own bike, to see what it tells me about the state of my own bike.

[Captn]

@Wagolathe unit that's shown on my bike pic is an Autometer wideband. Part number is Autometer 4370.  It is a complete kit with sensor and controller/gauge. Easily wired. I have had it on 4 bikes over a period of 6 years. Great piece. You will need to get a weld in 18mm bung for either steel or stainless steel depending on your exhaust material. This kit makes jetting much more accurate to establish a baseline. Combine this with a dyno pull and you'll get the best performance. Look on fleabay or your favorite auto parts performance parts site.  Should be an easy find. Let me know if you need any more data.

[Bobbermarc]

Hi what do people do with the breather /vent pipes after you take the main air box out

and put k&ns on thanks 

[Gixer1460]

3 hours ago, Bobbermarc said:

Hi what do people do with the breather /vent pipes after you take the main air box out

and put k&ns on thanks 

Holy Thread resurrection Batman LOL!

Run them to a nice fab'd catch can or a tin can if you are tight or dumpy K&N vent filters if you don't mind the mess !

[Bobbermarc]

Would I have to put a crank breather on it

[wraith]

As @Gixer1460says you ever.

1. Leave the pipe off at the top of the engine.

2. Run pipe and leave it to the open air.

3. Put a new longer pipe on (from top of engine breather) with a air/oil filter on the end, can be got off eblag.

4. Put a longer pipe on (from top engine breather) buy a oil catch (eblag or elsewhere if you want) run new pipe to that, or use you favourite drinks can, make sure air can flow freely from can so engine can breathe 

have a look through the projects section or do a search 

[wraith]

Ps.

Welcome to OSS 

[Gixer1460]

12 hours ago, Bobbermarc said:

Would I have to put a crank breather on it

Yes you do, otherwise even as std., crankcase compression / blow by will push gaskets and / or oil seals out, so leading to leaks!