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PW-80- jetting

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I have a pw 80, it runns well...But only if the choke is on...It will die if the choke is off. Everything in the carb looks fine, any sugesstions?

Float? affect this problem? Any ideas?



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Sounds to me that your carb needs to be cleaned. At least, that's the first step to diagnosing any problem like this.

There's two ways to do this.

The best method is to remove, fully disassemble and soak all metal parts in parts cleaner.

First, turn off the gas. Drain the carb bowl by loosening the drain screw, it's probably stripped, but worth a shot to keep your work area clean. Have a paint can cap or something ready to catch the gas.

There is a black hose with a brass collar on it on the right side of the carb, this is the oil-injector pump outlet hose. Slide the collar back and then pull the hose off.

The choke cable is held on with a plastic 17mm nut, after you've loosened it, the cable will rotate allowing you to slide the cable out.

There are two screws on the left side of the carb that need special attention. One is in the center and one is towards the front. Turn these in until they bottom out LIGHTLY counting the number of turns till they stop. Write these counts down, you'll need them later.

The slide is held in with a phillips head screw, after you've loosened the airbox and intake boots, you should be able to pull the carb out, but it will be held on by the cables. Remove the slides, you can leave these dangling.

I like GUNK brand 1-gallon can size that comes with a parts dish. Do not put anything plastic or rubber in it.

While it's soaking, take any O-rings that you removed to the hardware store and visit the plumbing section. Find O-rings that are as close as possible and head home.

Remove the parts from the parts cleaner, use an air gun to blow out all the orifices and passages. Keep your face away from the carb when you do this. I got cleaner in my eyes once, you've never seen a blind man run so fast to water.

Also blow out the jets, the large hexagonal one (technically a Mikuni small hex) is the main, it may have come out with the needle jet. It uses a 6mm wrench where the needle jet it's connected to uses an 8mm wrench.

The small one which uses a jeweler's screw driver to remove is the pilot. This is most likely where your problem is. I should have mentioned this earlier, but look through the pilot at a light source, it's got a teeny tiny little hole although yours originally may have been completely clogged. After blowing it out it should have a small but visibly larger hole.

Now rinse all the parts off in water and let them dry. Technically you're supposed to catch the "rinsate" and evaporate it off, but I won't tell the EPA or your wife that you did it in the kitchen sink.

After everything is dry, reassemble the carb.

Put the slides back in and tighten down the keeper screw.

The two screws you were paying close attention to during disassembly need to be turned all the way in and then back out the same number of turns as you wrote down.

You didn't write it down, did you? Ok, try setting the one towards the front the mixture screw to 2.5 turns out and the idle screw turn it out about 5 turns from bottomed.

I hope you wrote that down the first time cause the idle screw is going to require fiddling with to get it right.

Reconnect the oil injector hose and the choke cable.

Put the carb back in the intake and air box boots, make sure it's straight and hold it tight against the intake (back side) when you tighten down that screw.

Your bike should fire up in a couple kicks.

There are better, more detailed instructions with photos available at http://articles.superhunky.com/4/21 and also a good jetting guide available at http://articles.superhunky.com/4/55

The half-assed but sometimes effective carb cleaning method is to drain the gas from the carb bowl using the bottom bowl screw, loosen the intake and air box screws, remove the oil injector hose, rotate the carb, remove the four bowl screws. Carefully remove the main and pilot jets and then soak those in parts cleaner, blow them out. Reassemble. Rotate the carb back. Reconnect the oil injector hose and finally tighten the clamps on the air box and intake - again, hold the intake side towards the back to get a good seal. I've done many half-assed cleanings, but I'd recommend the best method especially if it's a new to you bike or you've never cleaned the bike's carb before. Do not attempt any jetting changes until you've cleaned the carb completely and also checked the needle position (discussed in the second link I posted above).

Good luck and welcome to the forum.

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