which jets for modified airbox on Tiger 900

[Germanski63]

Hi Chaps

What jets should i use on this modified Tiger 900 Airbox P reg with a Mikuni Carb and a K&N Filter in it
Doesn't like it on standard jets as pulls great for a while then doesn't seem like its getting enough fuel as it stutters if you give it a lot of throttle,but if you wind it up gently its a bit better but not really crisp all the way up the Revs
Any ideas?
Ps I haven't put the other grid on yet
just run it up the road for a quick test but alas felt like not enough fuel .
Carbs have been cleaned out .

[Sin_Tiger]

Hi. Welcome 

Stop what you're doing now. Drain the fuel tank, by which I mean take it off and empty it completely, I'd guess you've taken it off already judging by the photo's.

Remove the fuel tap being careful with the screws into the tank.

Flush all the crap out of the tank, there will be plenty if you haven't done it already.

Clean the little nylon mesh strainers, my personal choice is to bin them and fit an external filter in the line between the tap and the carbs.

Now take the carb fuel inlet tube off and take out the little filter cunningly hidden inside the tube. If you've fitted a good quality in line filter you can safely bin that or clean and replace if you feel that way.

Now put it all back together with some clean fuel and go ride it again.

The air box mod you're doing is a whole topic in its own right, spend some time reading up on it as there's plenty on here and elsewhere on the subject. If you do that and don't come to the conclusion that what you're doing is ill advised I'll be very surprised. Save yourself some money and a lot of grief.

Lastly, a short introduction of yourself and the bike helps other members put everything in context. A couple of photos in the gallery are always welcome, nothing we enjoy more than looking at Steamers watts and all.

[Mustang]

  what he said  ..........................

[JayDub]

  Yup... you'll be sorry, steamers prefer the air intake system as standard.  Any change to the air box volume, auxiliary chambers and even the snorkel will only bring you regret... and a headache. 
Learn from our experience 

[nickjtc]

Learn from our experience 

What he said, x2. The po of my Steamer messed around with the air box, carbs, and exhaust and although it ran ok I was never 100% happy with it.

[Sin_Tiger]

While you've got the tank off and empty, open the filler cap and turn it upside down, to stop any cr@p going into the tank, and check the drain pipe is clear (rear right corner on the underside) by blowing gently through from the bottom spigot. If it's blocked don't be tempted to try to poke it through with a sharp wire, the pipe runs through the inside of the tank and is easy to damage being plastic.

[fishnbiker]

If you decide to ignore all that previous rambling, I may have some insight for you.

Back around 1999 I did the same cuts on my airbox with a K&N filter. Main jets on cut airbox around 122.5 . Now running a full K&N unit modified to fit. Main jets on the Mikuni went to #125, needle boosted 1 or 2 notches (so long ago I'm not sure). Over 100,00km on my airbox upgrades.

More HP with some loss of torque below 4,000 rpm. Need to keep revs above 3,000 when chugging on gravel. Fuel consumption dropped from 53mpg to 47mpg(UK) Still able to get 300~330km per tank fill depending on how I ride.

[threepot]

ST....stop rambling!!!!

[JayDub]

More HP with some loss of torque below 4,000 rpm. Need to keep revs above 3,000 when chugging on gravel. Fuel consumption dropped from 53mpg to 47mpg(UK) Still able to get 300~330km per tank fill depending on how I ride.

If you're happy with that, and don't go nuts due to taking the carbs off too often in the quest for 'acceptable' fueling....   

[BruKen]

The above sounds lean to me. Considering they run rich when WOT, you're being saved by default. I appreciate it works for you but keeping revs above 3k on the gravel is going to be hard work with plenty of stalls cos you've obviously lost torque and a recipe for gravel rash. I'm glad it's worked out for you. Tough old birds these Tiggers.

[fishnbiker]

I did not say the loss of torque was an issue, just noticeable. I have been able to run it as low as 1800 rpm going up switchbacks (with 19 tooth front sprocket) but it's a little jerky/chugging that low. Starts to smooth out around 2500, but right into the full useable range at 3000. Has been fine in this final configuration since around 2001 (?) for 100,000+km. The first 2 years I used a cut-up stock similar to Germanski63's  for 2 years before going into full tinker mode with the Porsche K&N unit.

The main reason for going this route was to make filter cleaning a 10 minute job instead of an couple of hours or more. No more pulling the tank, snorkels, carbs, then the stock airbox. I can now do it on the road with a cup of gasoline (petrol) & some soapy water & filter oil.

Mine is no longer ridden on single tracks as it's now too heavy for me to pick up if tipped. A Suzuki DR650 does the rough stuff now.

7,000 ft rise on these switchbacks done at 1800rpm (Copper Canyon Mexico) ...



More pix at ...

https://fishnbiker.smugmug.com/Motorcycles/Motorcycle-Travel

[nickjtc]

That 'shortcut' on the second switchback up the hill looks like it would be interesting to attempt.....

[Beernard]

G'day. Every chance I don't have a clue here. Sorry bout that! Can't help wondering about the airbox mod. It would seem to me that if you were to go against all wisdom and chop it up - why not go the whole hog? Why shouldn't the centre pot get the kind of feed that the outsides get? I say this because when the frail, brittle, ridiculous airbox on my 92 Trophy fell to bits, I had to find a replacement. Down here in the Antipodes, not real easy. I found an airbox with both side "snorkels" chopped, but the piece over No2 still there (like yours). Looked fucked to me. I hacksawed the rest off, glued in a stainless shield (got a pic if you like), jetted them even. Also, sealed the leaky and shithouse intake with silicone. OK, not same bike. I jetted my Trophy to crack - lucky!! My point is, if you are going to modify, I don't think the mod you are displaying is the go. I reckon if you go that far, open the whole shebang.
Regards in all ways, Beernard.

[fishnbiker]

..... My point is, if you are going to modify, I don't think the mod you are displaying is the go. I reckon if you go that far, open the whole shebang.
Regards in all ways, Beernard.

I did the same as Germanski63 & it was still OK after 2 years. I only went the K&N route as an exercise in fabrication with a cheap price on the Porsche airbox. Mine has near 15 years~100,000km. I think the chopped version would be adequate if properly supported, subject to yearly inspection. On the chopped airbox I glued a cube of hard plastic foam to the bottom of the airbox & resting on the alternator drive gear casing for extra support. The "bridge" across the centre would also give some more support to resist twisting or warping.

If you look back at my K&N version you will see a small heavy wire bracket hanging down to a stud on the K&N plate. That was part of what I meant about extra support. The cut up stock unit is probably light enough to get away without it. The K&N dragged the carbs down a bit out of alignment with its extra weight.

His looks good like he's done it.



This was also part of the plan, a 3 into one Girly header modified to fit along with a GSXR Titanium & ally 2kg can for a weight saving of some 9kg. The black barbecue paint only lasted a week or so. Now running the tan stainless colour ...