250r barely runs after K&N pod install

[max427]

Ok i just installed K&N dual pod filter and shimmed my carb needles. Bike barely runs. It was chugging and basically wouldn't run under throttle, if i try to rev it up it gets to like 3k, starts to bog, then when i left off it dies.

Link to original page on YouTube.

I pulled the carbs back off, removed mixture screw covers and checked the needles. They were both sitting up- away from the bottom seat of the diaphragm. i pressed them both back down, made sure they're fully seated. Still runs like sh*t. !!!! SOOO nice out today too.
Anyway, is it possible that the washers im using are too large (outside diameter) for the needles to be properly held down? Would this cause it to run so poor? Chugs black smoke by the way, i tried adjusting the mixture screws while running and it does nothing.

[setasai]

Originally Posted by max427

Ok i just installed K&N dual pod filter and shimmed my carb needles. Bike barely runs. It was chugging and basically wouldn't run under throttle, if i try to rev it up it gets to like 3k, starts to bog, then when i left off it dies.
http://www.youtube.com/watch?v=R7fWfR6X0N0
I pulled the carbs back off, removed mixture screw covers and checked the needles. They were both sitting up- away from the bottom seat of the diaphragm. i pressed them both back down, made sure they're fully seated. Still runs like sh*t. !!!! SOOO nice out today too.
Anyway, is it possible that the washers im using are too large (outside diameter) for the needles to be properly held down? Would this cause it to run so poor? Chugs black smoke by the way, i tried adjusting the mixture screws while running and it does nothing.

What size washers?

[greg737]

Chugs black smoke by the way

That means you're running way too rich.

Anyway, is it possible that the washers im using are too large (outside diameter) for the needles to be properly held down?

For shimming your carb needles you need to look for #4 washers. These have the following dimensions, listed in decimal, fractional, and metric sizes:

ID = 0.1250" , 1/8" , 3.175mm
OD = 0.3750" , 3/8" , 9.525mm
thickness = 0.0400" , 1.016mm

If you can't find #4 washers, try to get an assortment that is close in dimension. Those with 2.5 - 3mm inside diameter, and not being too much larger than 3/8"/9.5mm outside should be fine.


The problem with carb adjustments is the complexity of the situation: one adjustment will affect idle, another adjustment affects acceleration, another affects mid-range, another affects top-end. And there's overlap between them.

The old-time wisdom is to only change one thing at a time. This is hard to make yourself do.

[greg737]

Watched your video on youtube. Sounds like it's running too rich.

Doesn't surprise me that it won't rev past 3 or 4 thousand. An overrich situation is made worse by the fact that the bike's ignition system is really ramping up the advance between idle and 4000 rpm (the pre-gen bike goes from 13 degrees BTDC at idle to 42 degrees BTDC at only 4,200 rpm).

Also, if you've been it running at "black smoke" levels of rich you should pull the spark plugs and look at them. It's possible to end up with the plugs so carboned up that even if you guessed right and got the carbs perfect, the bike would still run like crap.

The only way to know if you're correcting things with the carbs is to be sure that the bike is running on clean, properly gapped spark plugs.

[alex.s]

+1 too rich

[DaBlue1]

Originally Posted by max427

Ok i just installed K&N dual pod filter and shimmed my carb needles. Bike barely runs. It was chugging and basically wouldn't run under throttle, if i try to rev it up it gets to like 3k, starts to bog, then when i left off it dies.


I pulled the carbs back off, removed mixture screw covers and checked the needles. They were both sitting up- away from the bottom seat of the diaphragm. i pressed them both back down, made sure they're fully seated. Still runs like sh*t. !!!! SOOO nice out today too.
Anyway, is it possible that the washers im using are too large (outside diameter) for the needles to be properly held down? Would this cause it to run so poor? Chugs black smoke by the way, i tried adjusting the mixture screws while running and it does nothing.

Shimming the needles is not going to add enough fuel if you are using pods. You really need to go up a few sizes on the main jets. From the video, it sounds like you are getting to much air at throttle. When you add shims the needles will sit up slightly, they do not hold the needles down. BTW brown smoke means the main jet is too small or the fuel level in the float bowls is too low. Adjusting the mixture screws won't do much if the main jets are too small

Recheck your needles & shims and change your main jets or put the air box back in.

[greatwhiteninja]

with no airbox and pod filters in you need more fuel.. my bike wouldnt rev past 7k when i did pod filters and 105 mains! needles were shimmed and evrything.. needed 110 mains. the mixture screw just leans/richens the throttle response.. like how fast it returns back to idle.. to lean it hangs before going back to idle, to rich it drops below the idle speed.. or vice versa, cant rember lol!

[max427]

Found the main issue. Pulled carbs again and found that the washers I'm using keep the spring retainer from holding needle down. Removed washers and it started and idled much better, took it for a quick ride, def needs jets (which you guys already knew lol)
got to find smaller o/d washers to shim needles and prob 110 jets. By now many screws are beginning to strip, gotta replace that hardware and carb to engine boot clamps.

[greg737]

By now many screws are beginning to strip

If you're using an American/English Phillips head screwdriver on your carbs, you're making a mistake. All the screws on the carbs are Japanese Industrial Standard screws ("JIS" for short). Look at them carefully and you'll see the little dot on the top of each screw.

The only screwdriver bit profiles that won't strip them are: Real JIS drivers (of course) and the other, believe it or not, is a small sized drywall bit.

[greg737]

BTW brown smoke means the main jet is too small or the fuel level in the float bowls is too low.

No, Brown smoke means Chief Wild Eagle has decided that the Hekawi tribe will attack at dawn.

Or... maybe it means you're burning some really high-resin BC-bud.

[max427]

Jets came in today so I ran home on lunch, swapped bikes and rode 250 back. Got 108 to 115 from jets r us. Started with first installing washers that actually fit, as opposed to ones that held spring hold down up, allowing needles to pop up. 2 washers to start. threw In the 115's to start, figuring I would work backwards rather than start at 108 and work up. Well it started great, once it warmed up I adjusted idle speed to about 16-1700, then tried blipping throttle and it basically hung at 3k. Turned screws all the way in and started backing them out little by little. Now the throttle drops from say 6k, unbearably to 2200 or so,then after 3 seconds or so it comes back to idle, ok I can live with that until I get more time to play with it. Drove much much better than before, still feels like a weak midrange, might go to 112s and ride again. Anyway, are mixture screws just for idle?

[94fiveohvert]

a hanging rev sounds lean.. have you done anything with the pilot jet? sounds like you need a bigger pilot. you can only do so much with the mixture screw.

[NathanUc]

When I swapped out my airbox for the pods, I first tried the following

Factory Pro Stage 2 (very nice because it replaced those JIS screws with hex)
Pilot: 40
Main jet: 110
Needle: clip in3rd, 2 washers, clip on top

First run It would get really boggy around 7k. After less than a mile the engine cut and wouldn't start again. Don't know if maybe something was clogging the carbs or what, but I know it wouldn't start no matter what I tried.

Pushed it home and jumped straight to 115 mains. Runs great now (slight hickup between 8-9k). I have a feeling it's running a little rich and I plan to try the 112.5 again now that the weather has changed a bit, but for now I'm happy with it's performance and not really in the mood to pull it apart. A little rich is better than a little lean.

You should really consider a 40 pilot.

[Kevin2109]

Make sure the runners are completely open, Mine weren't at first and my bike barely ran