i have a cr twist throttle and cable on my 500 with a pwk 39mm.

you don't need a spacer for the intake boot when you install that carb. it fits in like a glove, and both rubber boots fit, and reach fine.

did you bore the 250, and install a new piston?

 

yeah i bored it and put a new piston in it
I have an 87 lt 250r with the carb for that year although the jet needle and needle jet are for an 88 I don't think that that matters In the manual the optional jets for an 87 or an 88 are a 200 220 and 250 I have a 240 i need to lean it out when i switch to a 220 should i mess with the needle jet before i put in the new main or after and why the need to mess with the jet needle if you can just switch mains
Is the jet needle for small adjustments and the main for big ones
Before the rebuilt it it barely put out any smoke now it makes a cloud every time you hit the gas and when you get to full throttle it just starts to bog out
Just some fine tuning i think it needs

Thanks for your help

Oh and to reply to the battle between stock cable versus aftermarket cable:
The stock mikuni on a 250 has a top adjustment so the shielding on the cable stays outside of the carb.
On the 500 there is no adjustment on the carb and the shielding goes inside the actual carbeurator.
The keihin is set up just like the stock mikuni from a 250 with the top adjustment

 

What Gas are you running?

 

i am running 20 : 1
I have a 170 main and a 50 pilot
It does not operate well at high throttle and will stall at low throttle any suggestions
But all in all the engine responds a lot better with the keihin on when i let the throttle close the engine comes right down quickly where before it would slowly come down

 

When you tried two different stock carbs I'm betting you used the same slide. I believe f250r was correct about your slide being worn. Before buying the PWK I have now, I had to replace the slide in the stock carb. In my case, I believe most of the problem was with the part of the slide that makes contact with the idle screw. That area was ground down so far that the slide could no longer be held up far enough. If the stock slide is too low, the engine will race just like a lean (leak) condition. I know this sounds bass ackwards but it is true. Also, flat slide carbs have alot more leakage around the slide than do round slides (and probably D-slides like the PWK). This causes the r's to take longer to come back down to idle when the throttle is let off and is a common occurrence with sleds. Therefore, when the LT's slide wears on it's outer surfaces, it is more prone to wild idle.

BTW, I disagree with f250r about the throttle cable. I had to replace mine when I attached the PWK to the thumb throttle.

 

What Octane??

 

Hi,
IMO I would take it to someone who knows how to jet/adjust a 2-stroke carb.
You obviously don't want to listen to those who have actual experience w/Zillas like DuneAddict, Donzilla or myself.
(Yeh, Ive built HUNDREDS of Zillas.........................been doing it since the first day they came out.)
If you are not careful you will "stick" the piston w/a 170 jet in that carb.
Please understand, I'm not putting you down................... I just don't understand why people ask for advice and then don't listen to those that know.
You could have just put a bigger pilot jet in your stock carb 2 mos ago and be riding w/ the $$ in your pocket you spent on the Keihin.
I truly wish you good luck,
RK

 

Please respond...

Did you use the same slide for both stock carbs?

Also, replacing the stock carb for a 39mm PWK was DEFINATELY not a waste of money. The difference it made with my quad was HUGE! After adding the carb I had my motor ported. The carb made a much more noticeable difference (seat of the pants) than did the porting. The stock carburetor is junk in my opinion. As a side note, my Paul Turner pipe made the second most improvement. This was compared to the PSI pipe I had, not the stock one. The PT pipe lives up to the hipe of giving you alot more power in the upper r's.

 

Hi.
Since you've extensively rebored your atv it's hard to say which will be the cause of the problem. However.

Unmodified Kawasaki bayous had the same problem that when they got warmed up (hot) they started reving (idling very fast) one had to tune down the throttle screw (a-lot). Bayous with lot's of milage BTW.

Caused by higher compression . Piston rings (collars) would expand too much (due to the heat), no matter how new and clean your oil was or well your (cooling system) was running.

Changed the rings for a new "good set" and it solved the problem.

It's possible that you ran into a defective set of rings (collars). It happens.

Air leak is possible. However that would mean you have (probably) metal that is expanding causing the leak. Check your carb manifold seals.

Other than that i can't think of anything right off the bat.

 

ok to answer everyone

i am running standard 87 octane unleaded.

I had tried the combination of both slides various jet needles and a brand new throttle idle screw. The slides were the same size as well as the interior size of the carbeurator down to the 1000dth of an inch. If i didn't listen to the people who have built hundreds of zillas then i wouldn't have bought the pwk. Also the new slide was back ordered for two months indefinately and was 80 dollars and i had no idea what the factory dimensions were so i did not know what the effect would be with a new one.
I had checked all the seals and had done a leak down test which performed better than others who had no problem with their zilla.
I had also done every dif adjustment with the idle screw and it would make no difference it would only sometimes help when i lowered the idle screw.
Also let's just look at basic physics in order to get a lean condition you have to be getting more air than you are fuel if my slide goes all the way back down and i am getting high rev with a lean condition i have to be getting air from somewhere and i doubt that the pilot will allow that much air through. Also if that was the case how come it does not do it when it is idling only when i rev the engine up high.
I have had the majority of people tell me to buy the pwk and i have bought the jets that have been recommended by your profesionals.
So i thank you for your wishes of good luck but like i said in the beginning I am not an idiot and it is a carbeurator not rocket science i asked for the recomendations of jets because they are five dollars a jet and i don't want to spend 80 dollars on jets.

I would consider that jet rings might be bad but for the rings to be defective three times in a row is highly unlikely

Also again like i said even though the jetting is off the zilla does not respond well at any rev while in gear but when i rev it high in neutral when i let off the throttle the engine comes down fast as if the carbeurator is cutting if the flow of fuel and air which is what a carb should
do which is what my keihin with any combination did not do it would take a long time to come back down if it did

So again thanks to everyone who has helped me by just throwing out ideas. I will try to jet the carb this week and respond to let everyone know the outcome