Oh yah, I unfortunately have the Keihin carbs that Dynojet doesn't make a jet kit for. All the 1997-1998 Tiggers and many of the California bikes (Sprints, Trophy, T-Birds, etc.) share the same engine and setup. Poor bastards!

Dynojet said that they don't think they will make a kit in the near future. Due to a lack of response from Triumph UK....   Shit ! ! ! !

This bike just won't let me do anything the easy way!
I love her and hate her!

The Tigger is set up rather lean for EPA reasons. This translates into a visible performance problem that the dynamometer displays.

In the real world it is most felt when the bike is rolling along at 4-5k RPM's and whack the throttle open. Results in a pretty noticeable bog before the fuel flow catches up with the increased airflow.

So decided to do what is possible to the stock carbs to richen the mix. This included shimming the needles up .025", opening up the main jet size, removing the low speed circuit plug and resetting the adjustment, and finally readjusting the float bowl float to increase the fuel level. Also, the addition of a K&N air filter instead of the factory oiled foam crap.

We removed the fuel bowls and exposed the pilot and main jets and the fuel float. Here is what was found and all three carbs were found to be the same.

Main jets -> #98     Fuel hole diameter is measured at .038"
Pilot jets  -> #38     Fuel hole diameter is measured at .015"

Low Speed Jets:
Drilling out the anti-tamper plugs was not a problem, they are made of simple aluminum. But be sure not to drill and break through them quickly - since the screw lies just on the other side of the plug!!!

They will all be turned inwards until bottoming and then all unscrewed 3 turns as per Triumph FAQ and other's recommendations.

Carb #1 was at 2.5 turns out.
Carb #2 was at 2.25 turns out.
Carb #3 was at 5.5 turns out!!!!

I never have suffered from cold starting problems and drove my bike all last winter. Start it up and leave the choke on for the first mile or so, then take it off and no problems.

Fuel Jets:
It was decided to open the main jets to .039" which gives about 5.3% greater fuel flow over the .038" originals.

Follow up:
A friend of mine had his mains opened up to .040" from .038" and has had no negative problems to report. His mileage also did not change a noticeable amount. So with this information I would recommend that the mains be opened up to .040" instead of .039".

The pilot  jets were left alone with for now, due to erratic results.

Fuel Floats:
The fuel floats are measured at 17.5mm when the carbs are held on their side with a minimum of pressure on the seats. The manual did not specify how far the recommended float set height (only a fuel height that was just to much to check at that point, getting a bit to fed up), so they were lowered to 16.5mm to increase the level of fuel in the bowl by 1mm (17.5mm - 16.5mm = 1mm - bend the floats upwards and the fuel level increases) over the stock setting.

This will flow an increased amount of fuel, but how much?

Who knows?

Just that it will flow more gas than it used to..... ;)

Needles:
This turned out to be the bitch of the job. They are not the standard design with clips and shims on a notched shaft. They are designed to be non-adjustible with the needles being swaged into the "washer" that holds the needle at the proper position.

You cant just drop a shim washer under the needle due to the .010" or so of freeplay in the system would be eliminated between the top of the needle and the plastic cover/spring retainer. Remove the freeplay and the carb's slide  movement would bind the needles up.... BAD!

So, if you shim the bottom up you have to increase the top clearance the same amount. We did this by grinding off the top .025" of the top of the needle/washer swaged combo.

However, when this is done the swaged portion is also ground off. And the needle is free to leave the retaining washer and fall through!

BAD!

So, the washer's inner diameter was chamfered. Then the center of the inserted head of the needle was upset with an automatic center punch while being held in a vise. Oh yah, a drop of loctite was used on the joint too.

Upshot -> Add a .025" washer under the needle head and grind the top off by .025" and resteak/loctite the now free unit back together. Trust me, it is obvious what to do when you have it all apart on the table.....

FLASH!!!! A bit easier method of doing this process has been found by John McMahon. I have not personally performed it on any bikes, but logically it seems like a bit easier way to accomplish the needle adjustment.

Final:
Now that it is finished, replace the old air filter with the KN. unit and place the airbox back in position. Squeeze the carb stack back in and reinstall all lines.

Tighten all connections, and you are done!!!

The whole reason to do this is to get the lean out and add a little fat into the equation. The bog with rapid throttle opening is the major target of the operation. This has been attacked in a rather conservative manner. And the idea was to increase fuel enrichment without going to excess.

The gas consumption on my bike is between 32-39 MPG. And I did not want to reduce it from it's current bad to outright poor! A slight penalty is expected, but it is hoped to not be reduced to less than 30 MPG. I will keep a log and see what happens....

The Tigers have another air intake/resionator on the right side that is closed off with a rubber cap/cover. And it was hoped that with these mods the right side intake could be unsealed and allow a little extra air in to mix with the extra fuel, oh baby!

All the parts went back in correctly, thank god, and the carbs seemed to have the proper movements and feels. Place the gas tank on and rehook everything, turn on the petcock, and go for ignition!

Starts right up! This is great!

Warm it up for a minute and give it some gas -> Ackkkkkkkkk !!!
(the sound of Bill-the-Cat coughing up a hair ball)
"Houston we have a problem."

OK.

G.U.M.P. - Gas, Undercarriage, Mixture, Prop. (aircraft checklist shit)

What the fuck?

Spark - good, because the engine is still running.
Gas - it's in there, because fuel bowls are full.
Mixture - questionable.....
Air - good due to new K&N filter installed!!!

What is wrong?

Fiddle with the carbs. OK, everything seems fine. All the needles are loose and seem to be moving nicely.
Idle is great. Whack the throttle open and blehhhh..... Slowly open and it seems to run ok..... Hmmmmm....

Try different things for a while, and finally put the cap onto the right side air intake, because it was on there in the first place.,,,,

Throttle snap -> VRROOMMM!!!

I never thought that such a little thing would make such a big difference, but it does!!!!

Ok. Here is where we either shit or get off the pot!

The whole reason for doing this is that the bike ran really lean, causing the bog on throttle snap open. Cold starting was no problem on my bike, verses other people who had this common problem.

The dyno runs confirmed the lean running condition and graphically demonstrated what I was feeling while running the bike on the road.
 

Throw on the riding jacket. helmet, and gloves and head out onto the highway!

The bike is felling much snappier, almost predicting what I am going to do!
:-)     LOVE IT!

Taking a more analytical approach, I decided to go find a quiet road and do some testing. Oh yah!

Riding along at about 4,000 RPM I would whack the throttle open to WOT, This would cause a very noticeable bog before the acceleration would kick in.

Now there is just a hint of a hesitation when the throttle is snapped open. Still the faintest hint there, but almost completely gone!

Now let's see how she feels when her legs area really unleashed!!! I set course to the west and arrive at the northern section of Route 8 in Connecticut. Nice open highway that goes basically north-south and has lots of visibility and not to many cops. ;-)

Nice clear, dry day and little traffic on the highway. Do a pass up and down where the "test track" is to be set up. Road looks good and no hazards are seen upon inspection. Let's go!

Pull over and wait for a very long period of no traffic.
Ready.........Set.........GO!!!!

Rev it up and let the clutch out. Yah!
Near red line go for 2nd. Whoa there girl.....Keep the front down......

3rd, the roar of the engine, transmission and exhausts are being lost to the slipstream noise....

4th, 5th and finally 6th!!!

110 MPH, 115 MPH, Wow really fucking windy out here!
Hold on tight and keep down! Wonder how much it would hurt to crash now......

120 MPH, 124 MPH, 126 MPH, curve is coming up in a bit, have to slow down soon!
128 MPH, 130 MPH, 132 MPH indicated finally.....

Off the throttle and onto the breaks! Like right NOW!

What is this thing? Is this a squid maker? Oh my!

The actual speedometers seem to lie a bit on the Triumphs and give a higher reading then actual. Must help for you speeders out there.
But I am sure that even a calibrated speedometer would have indicated well over 120 MPH.

Much better!!
 
 

Put two full tanks of fuel through the thirsty old girl and have some new data :

Ok, not bad!

This is with some squidly around the town thrashing and some 75 MPH highway driving as well. A bit colder weather and some idle for warm-up time as well. The fuel mileage has not changed much from stock.

Idle smells a bit rich, however, and will have to get to a CO meter in the near future and do some low speed circuit tweaking. But it is not a major imperative.,.

But i am very happy with the mileage remaining at a reasonable level, and this has convinced me that the modifications have been correct for the bike's current setup and operating conditions.
 

DO IT!!! IF YOU HAVE NOT ALL READY DONE IT!
 

1) The Tiger is a much snappier road performer after I have done these mods.

2) It has a minimal cost in materials and can be completely finished in one day with some good work.

3) Mileage had not been greatly reduced from stock levels.

4) The bike will run a bit cooler at moderate power settings, due to moderate mixture enrichment.

5) See #1 - Cuz, it's an incredible difference!

Some comments from another Tiger owner who did the mods!

Future plans will be a trip back to the dyno for some more testing and some hard data.