Finnish Katana dies on throttle

[Sami]

Hello from Finland!

This is my first post and of course its about carbs. I bought non-running U.S. imported Katana last winter and finally got it running. She had many problems, water in oil pan, vandalism, died shocks etc. Now there is only one, she dies on throttle. If i open throttle really really slow revs go down and then little higher than it was.

Here is some facts about her:

- She is 750 from 92. 49-state model.
- Carbs have been cleaned twice.
- Bike has stock air filter and exhaust.
- Float height is 14.6 mm, before adjusting it was less.
- Before cleaning idle speed was about 10000 rpm! Blocking air filter did lower rpm.
- Now idle speed is about 1100 rpm without "choke".
- Pulling choke rises rpm.
- If i put my hand over the air filter, rpm rises.
- All 4 cylinders have spark and exhaust pipes are evenly hot.
- I have sprayed starter fluid around all possible vacuum leak areas, without any effect.
- A/F screws had plugs and i removed them.
- I have tried a/f @ 1.75 open and 2.5 open. 2.5 feels maybe little better.
- Rpm drops kinda slowly.
- 1, 2 and 4 have 105 main jet. 3 is 110.
- Someone has changed jet needle. It should be 5EZ62 but its 5EZ61 which is little thinner (from euro carbs)
- Needle jet is still Y-1
- Jet needle is adjustable, i have tried middle and and top slots. Both feel same.
- I have adjusted valve lashes. Intake is 0.10 mm and exhaust is 0.20 mm.
- I have read carbs 101 and 102!

And here is the questions:

- Whats wrong?
- How long is stock jet needle? if i could adjust mine to stock setting...
- What about a/f screw, could it affect this way? Should i open it more or less?
- Is it rich or lean?
- Does carb number 3 need another setting because 110 main jet?
- How tight fit jet needle should be in needle jet?
- If nothing helps i will clean it again in ultrasonic cleaner, but could it be something else?

And here is a low quality video about symptoms:
[ame="http://www.youtube.com/watch?v=yL4dZecj1Y4"]YouTube - Katana problems[/ame]

Thanks and sorry about my bad english!

[Kreylyn]

Not sure from the info provided, but...

Were the a/f screws removed as part of the cleaning process? If not, the carbs were not fully cleaned. If yes...

Set them at 2.5.

Have the carbs been synced?

If no... sync them, this has to be done to even the fuel for each carb, otherwise you have some that will run richer/leaner than the othes and cause a very delayed or even stal on quick throttle response.

Krey

[Sami]

Yes a/f screws were removed and screws are set to 2.5 out. Carbs have been synced visual (holes + vernier caliper + light + unorthodox way of sucking each carb... )

[vco123]

Not that I have much to add, but whats the deal with the "1, 2 and 4 have 105 main jet. 3 is 110." ?

Is this a Euro thing, or is something a little off?

[Kfreak]

You covered air inlet to air box with hand and idle increased. You are sucking air from another area. A/f screws were out? Are the little "0" rings in place on the a/f screws? Factory needles are not adjustable. RPM's dropping slowly indicates a vac leak. Did you re-connect the drain hose on the bottom of the air box? I'm just thinking off the top of my head on possible stuff you may have forgotten to do.

Not that I have much to add, but whats the deal with the "1, 2 and 4 have 105 main jet. 3 is 110." ?

Is this a Euro thing, or is something a little off?

Check your manual, these bikes come from the factory with a different jet in #3 carb.

[Wolfe_UK]

All except US models have 105 main jets. US models have a 110 in #3
US pilot jet size 32.5 - Others 37.5

- From my workshop manual

[Sami]

Ok i have to double check choke plungers for vac leak... What about carb overflow tubes should those be plugged? Could vac leak be there? I think those should not be plugged but there is some indication that someone had those sealed before... Drain hose is connected and plugged.

Yes rpm goes up if i seal air inlet but before i cleaned carbs it was only way to lower rpm, so now its kinda inverted... Right behavior would be engine stalling?

Does anyone know stock needle length/height? I mean this part:

I gonna clean em again...

[hardlydangerous]

carbs need serious work
broken down, seperated, soaked and rattled for a while in an ultra sonic cleaner.
its too lean way too lean

[Kfreak]

Ok i have to double check choke plungers for vac leak... What about carb overflow tubes should those be plugged? Could vac leak be there? I think those should not be plugged but there is some indication that someone had those sealed before... Drain hose is connected and plugged.

Yes rpm goes up if i seal air inlet but before i cleaned carbs it was only way to lower rpm, so now its kinda inverted... Right behavior would be engine stalling?

Does anyone know stock needle length/height? I mean this part:

I gonna clean em again...

Vents tubes need to be open. Do you by any chance have a California model that someone pulled the emissions stuff off of? Can't give you the needle length. I can tell you that the needle in the pic is not stock. The "c" clip belongs in the 3rd slot from the top.

[Sami]

She might be from Cali, but i dont know for sure. Some magical solutions if she is ? Needles have two small squares and text "5EZ61" which is type number for UK kat needles. Maybe because european sellers dont have correct needles, atleast not in finland. If clip is in 3rd slot, needle lenght is 52mm... anyone with set of stock needles (5EZ62 or 5EZ63) to measure?

Could incorrect float height affect throttle response? I did the "Haynes way" when i adjusted those... meaning carbs upside down. Clymer says to measure in slight angle, but is there any difference?

Anyway carbs are in parts and again in dip. Tomorrow is third spin in ultrasonic. Maybe third time is the charm. I will also look again for vac leaks.

[Wolfe_UK]

To the best of my knowledge the UK spec. and European spec. machines are the same, just with different clocks for mph/kph.
The US needles are different to the the UK ones, and the ones you have are UK spec needles so I would guess that given they all use the same jets and hight can be adjusted, it shouldn't matter the length of the needle really, if they even are different which I don't think they are.

[Sami]

Carbs were cleaned and all seals were replaced, but still the same problem... Then i found my vac leak, loose spark plugs So now throttle works, but rpm drops slowly. 3k and over its ok, but from 2500 to idle its very slow. Maybe some a/f adjusting? Float height is now about 13.7mm.

[Kreylyn]

Carbs were cleaned and all seals were replaced, but still the same problem... Then i found my vac leak, loose spark plugs So now throttle works, but rpm drops slowly. 3k and over its ok, but from 2500 to idle its very slow. Maybe some a/f adjusting? Float height is now about 13.7mm.

Now that you found an issue and corrected it, I would go back to the 14.7mm on the floats and 2.5 turns on the a/f screws.

Krey