Keihin 28mm PWK

[WarpAssassin]

I took the advice of royalt67 and the rag has been off for every attempt and the above mentioned were the results.

I feel like I need to strip the carb down to see what's going on inside. Could it be a stuck float?

 

[royalt67]

I feel like I need to strip the carb down to see what's going on inside.

That sounds like a good plan, not that you should need to do this on a new carb. Hey, there's a good question. Is this a new or used PWK28? (it looks new)

The whole "revs high and dies" thing sounds like you are really lean, like maybe something is plugged. Pay special attention to spraying out the jets and passages. I doubt the float is stuck or you would bog and have fuel leaking out, but clean it too (the float needle). While you are in there take note of what jets are in it. Measure your float level too, should be 19 mm with the float just barely touching the needle.

You might end up needing to go up on the pilot and main jets. When I jetted mine, I ended up with a 45 pilot and 162 main.

One more thought, when you take the float bowl off, keep the carb upright so you can check out the fuel in the bowl. Look for dirt or little "bubbles" that would indicate water.

 

[Braaaptor]

That sounds like a good plan, not that you should need to do this on a new carb. Hey, there's a good question. Is this a new or used PWK28? (it looks new)

The whole "revs high and dies" thing sounds like you are really lean, like maybe something is plugged. Pay special attention to spraying out the jets and passages. I doubt the float is stuck or you would bog and have fuel leaking out, but clean it too (the float needle). While you are in there take note of what jets are in it. Measure your float level too, should be 19 mm with the float just barely touching the needle.

You might end up needing to go up on the pilot and main jets. When I jetted mine, I ended up with a 45 pilot and 162 main.

One more thought, when you take the float bowl off, keep the carb upright so you can check out the fuel in the bowl. Look for dirt or little "bubbles" that would indicate water.

Agreed! Also, pull the fuel line off the carb and at least make sure you're getting a steady stream of mixed fuel out of the tank. Sometimes the screen inside the fuel petcock will be clogged, and you'll only get a trickle of gas out the fuel line to the carb. As long as the fuel line isn't pinched and the fuel weiner clean, you should get plenty of gas to the carb.

Keep in mind that your PWK carb may not be jetted for a Blaster, either. This carb is used on all types of bikes and quads, and whow knows? You may have gotten one jetted for an 80 or 100cc engine, not your 200cc Blaster. It may be jetted so lean that, as mentioned, the engine won't run well until you go richer on the main and pilot. I run a 28mm PWK on my Blaster, and it required lots of jetting changes to finally run properly. MY final, properly-tuned carb. settings are in my sig. Try those jets and see what happens. I run a pod type K&N air filter on my machine, and the engine is all stock inside, so that jetting should be pretty close to what you'll need (elevation and final tuning not included)... I:I

 

[royalt67]

Yep. A basic aftermarket PWK28 comes with a 38 and 135, but I don't know of anybody who has stuck with that.

 

[WarpAssassin]

Just spoke with my trusty moto shop guy Randy, and he said I should be running a 32.5 slow jet and a 230 main. He also said elevation has alot to do with it. I'm not sure what's in the carb right now, foolish of me not to strip it down when I first got it. I guess you could say I was a bit over anxious. At work at the moment and I'll be here all night and look forward to stripping it down tomorrow to see if i have any debris in there as well as the jet ratings. I'll post again once I find out.

It did run mad crazy when I first got the machine, but I was having probs with the stock TORS setup.

 

[super noober]

Just spoke with my trusty moto shop guy Randy, and he said I should be running a 32.5 slow jet and a 230 main. He also said elevation has alot tomdo with it. I'm not sure what's in the carb right now, foolish of me not to strip it down when I first got it. I guess you could say I was a bit over anxious. At work at the moment and I'll be here all night and look forward to stripping it down tomorrow to see if i have any debris in there as well as the jet ratings. I'll post again once I find out.

It did run mad crazy when I first got the machine, but I was having probe with the stock TORS setup.

i belive thats stock jetting on the stock 26mm carb

 

[royalt67]

Ditto on that Noober. It doesn't sound like "trusty moto shop guy" knows the diff between a mikuni and a keihin.

I'm not even sure Keihin MAKES a 230 main jet, but if they do, you could flush something very large and solid through it!

 

[Luni]

Yeah, jetting on a Keihin is different than a Mikuni.

I think Im running a 35 pilot and a 128 main. I ride between 6 and 9k feet usually. Sometimes over 10. My jetting works everywhere I ride in my area.

Richen it up for lower altitudes jet sizes at a time.

 

[scotj77]

when you measure the stock carb on the outer edge of the outlet side it measures 28mm. but that is not the measurement that counts. you have to measure back into the carb just after the slide chamber.(don't know what to call that area so i made somethin up)

 

[royalt67]

when you measure the stock carb on the outer edge of the outlet side it measures 28mm. but that is not the measurement that counts. you have to measure back into the carb just after the slide chamber.(don't know what to call that area so i made somethin up)

Really, Scot? That's good to know. I never bothered measuring the stocker.

 

[Awk08]

dont know if this is gonna help here, but, just had a 28mm pwk pass thru my hands, supposedly came of a running blaster with a pipe and filter,
it had a 50 pilot/155main ???? and fit right into a stock boot that came off my sons stock carbed motor