Jetting Thread

[andrewsw]

my understanding (limited as it is) is that the electronic restriction is on later bikes (like the '93) but the whole thing is questionable. *If* you're restricted, I think it only applies to 5th and 6th gear, but that's mostly speculation too.

A

[Nickelodeon]

I wanted to leave my previous jetting information up, but include the below new jetting information based on using a Yosh "tri-y" header(I believe there were three different header styles done for the Bandit 400 by Yosh, a 4-1, and 4-1 with a welded on balance pipe just under the head flanges, and my version which is a tri-y) mated to a "tyga perfomance" stainless oval silencer "EXSL-0017" via custom mid pipe:

Yosh Tri-Y w/ custom mid-pipe & tyga SS oval silencer(EXSL-0017)
32mm BST's (Rebuilt w/ new o-ring kits)
Factory Pro 1.0 kit
Alt: ~ 360ft

Setup:

180 deg. CBR F3 Thermostat(idle hunts a little less)
Stock airbox(well sealed, had to use tape due to warpage), K&N filter and stock exhaust
97.5 MJ (95's too lean)
Needle Clip #3 position from top(Factory Pro needle)
Fuel Screws 2-3/4" turns out
Iridium Plugs

Picked up a little more top end acceleration and now it tops out around 115mph(gained 4mph). The mid range is a little fluffy around 6K now, with more roll on it's "ok"...but seems a little off carburation wise in that area(too rich?). I'll start with turning the fuel screws in a 1/2 turn in and see what that does. I have to wait a bit on the plug check as they were showing lean with the 95's in and I want to ride it a bit to see how they come out with the 97.5's.

****UPDATE****

I'm now busting over 120mph(not sure how much further it will go yet)...with 32mm's none the less and I actually raised the gearing to reflect GSXR400 spec....go figure. There's a chance this increase was due to using synthetic(Rotella T6)...or maybe I've been "breaking in" my bike as I acquired it with 18K miles and now have over 21K with "hard use".

[andrewsw]

[...]The mid range is a little fluffy around 6K now, with more roll on it's "ok"...but seems a little off carburation wise in that area(too rich?). [...]

I have a fairly similar setup to yours, and this mid-range "fluffy-ness" is the bane of my existence. It *seems* like a rich problem (and I've had people report black smoke out the tailpipe when rolling on) but Marc at FP says it might be a problem with a too small pilot jet. I haven't gotten around to trying it yet, but thought you should know. Some experimentation with fuel screws suggests that it would run better with larger pilots (37.5) but it didn't really seem to take care of this particular symptom. I'll probably fiddle with the needle a bit and see if that's it. Also, I suspect my needle jets are out of round, which might contribute to this problem.

very much my uneducated 0.02.

A

[Nickelodeon]

Thanks for the note Andrew, I appreciate it. Have you topped out your bike? I'm curious what it hits with 105 mains.

Nick

[andrewsw]

I'm not running 105s. I think they're 97.5s but honestly it's been a while since I looked. My top end has never been more than about 110-112 and it's hard getting up there. Seems to run out of steam around 100mph. I haven't played with the top end much because I just don't need it and don't have much opportunity to explore it. Also, the gas mileage was pretty bad with those 105s, if I remember correctly. One of these days I'll take the time to really work on it, but with no garage space and precious little time... shrug... If I do, I'll be sure to report in with the results.

A

[Nickelodeon]

Your post in 07' says you have 105's...that's where I got that.

:)

[wildwhl]

...and I was just about to post a jetting question - great thread and thanks.

WW

[wario]

Im hoping for a little input from the Bandit400 owners... where can I find a pipe or a slip-on muffler for my 93? I have been unable to find ANYTHING here on the US side of the pond... 

[andrewsw]

A few posts back we were talking about mid-range "fluffiness" (whatever that means). Turns out my problem was overly worn needle jets. Replacing those helped a whole bunch. my current setup is 102.5 mains, #35 (up 1 size) pilots, 3.25 - 3.5 turns out on the fuel screw, same 4-2-1 Yosh Exhaust (now with no rust!), no snorkel in airbox, K&N filter. Runs pretty well, but I might move up to #37.5 pilots to clean up still-unstable idle and the large amount of fuel screw. Sorry, no top end report, but it's pulling very well still at 90mph.

[stormi]

Im hoping for a little input from the Bandit400 owners... where can I find a pipe or a slip-on muffler for my 93? I have been unable to find ANYTHING here on the US side of the pond... 

Hey Wario,  I think you'll have a hard time finding something dedicated for the B4, but there are other options.   I posted this back in 2007 when we changed the exhaust on Dita, our little B4.
http://forums.banditalley.net/index.php?topic=8930.0

A few posts back we were talking about mid-range "fluffiness" (whatever that means). Turns out my problem was overly worn needle jets. Replacing those helped a whole bunch. my current setup is 102.5 mains, #35 (up 1 size) pilots, 3.25 - 3.5 turns out on the fuel screw, same 4-2-1 Yosh Exhaust (now with no rust!), no snorkel in airbox, K&N filter. Runs pretty well, but I might move up to #37.5 pilots to clean up still-unstable idle and the large amount of fuel screw. Sorry, no top end report, but it's pulling very well still at 90mph.

Yeah! That sounds like you got a little seat time at least?

[wario]

Im hoping for a little input from the Bandit400 owners... where can I find a pipe or a slip-on muffler for my 93? I have been unable to find ANYTHING here on the US side of the pond... 

Hey Wario,  I think you'll have a hard time finding something dedicated for the B4, but there are other options.   I posted this back in 2007 when we changed the exhaust on Dita, our little B4.
http://forums.banditalley.net/index.php?topic=8930.0

[/quote]

Thanks for the suggestion - I've been figuring that I'd need to fab something if I continued on this dry spell... I "punched" out the inner baffle this past weekend with a 3/4" pipe - the bike sounds better and revs snappier and I haven't had to change the jets. I may have found a real nice "good enough" solution that will help me be more patient until that scrapyard B4 with a pipe comes along...  Again - Thanks.

[stormi]

Thanks for the suggestion - I've been figuring that I'd need to fab something if I continued on this dry spell... I "punched" out the inner baffle this past weekend with a 3/4" pipe - the bike sounds better and revs snappier and I haven't had to change the jets. I may have found a real nice "good enough" solution that will help me be more patient until that scrapyard B4 with a pipe comes along...  Again - Thanks.

Are you using the stock exhaust still?  Suzuki put the drain holes at the wrong part of the exhaust, so it's likely rusting like crazy too.  I would haunt fleabay and see if you can find any exhausts with the mid pipe.  Even used would be better than stock.  It was unreal what it weighed too. 

[andrewsw]

Yeah! That sounds like you got a little seat time at least?

I'm daily commuting now -- have been for a year and a half. The ride isn't very far, current commute is only 8 miles, but it keeps both me and the bike in decent tune. :)

[wario]

Thanks for the suggestion - I've been figuring that I'd need to fab something if I continued on this dry spell... I "punched" out the inner baffle this past weekend with a 3/4" pipe - the bike sounds better and revs snappier and I haven't had to change the jets. I may have found a real nice "good enough" solution that will help me be more patient until that scrapyard B4 with a pipe comes along...  Again - Thanks.

Are you using the stock exhaust still?  Suzuki put the drain holes at the wrong part of the exhaust, so it's likely rusting like crazy too.  I would haunt fleabay and see if you can find any exhausts with the mid pipe.  Even used would be better than stock.  It was unreal what it weighed too. 

Well, I figured that I needed to be very careful to swap out exhausts considering the overwhelming number of horses that are clawing to get out... 

I like the bike relatively quiet - it makes it easier to sound like Im not speeding, even if I am. Waking all the children in the neighborhood by reving to 13k in the first three gears just to get up to 60mph is far from optimal  - but, sounding like a sewing machine that just had the oil changed is not too cool either. My goal is not to mod the bike until it's unrecognizable - but rather to slightly improve it to the point where I feel like Im getting the most I can out of it for the money I have into it. My B4 is a true "2nd" bike that is (almost) only used on nice days and for Sunday get-together events with like minded friends. I've got an awesome daily rider and have built my share of street fighters - so, my need to make it into something it's not or to extract every possible ounce of power from it are not in this bike's future...

And besides... I'm carrying more extra "excess weight" than the Bandit, so losing 10lbs off the pipe is negligible when put into the scope of total weight reduction 

[Squishy]

So today I tried 110 main jets on recommendation by Thief100.

Setup:
Stock airbox (removed snorkel for this)
Stock BST33 carbs, needle position +1 rich
Main jet 110 (stock was 100)
Slip-on exhaust
Altitude: 0ft

On stock settings my 400 ran fine without flat spots (if I richen the needles) but wouldn't go above 185km/h and dropped in power above 12000rpm.. So I figured to give the 110 main jets a try. I completely cleaned the air filter and removed the snorkel just in case.

On my testrun I ran with the silencer in the slip-on like I always do. Mid range was very strong but above 8000rpm at full throttle it almost stalled.
I removed the silencer from the slip-on and now it's much better. I can really notice it pulls harder and to a higher RPM, but it's still too rich and a bit jerky above 8000rpm full throttle.

Is there anything else I can do?
Can I run without the airbox cover or any other solution without having to immediately make holes in the airbox?
Or should I just try 105/107.5? (but will need to buy the jets and remove carbs again....)

Thanks.