125-200cc PWK 36mm

My 2009 165 has the standard Mikuni carb. My bike idles at a highish rpm and when lowering the idle speed a little it stalls/stops. I went riding on a mx track yesterday the track was sand with wood clip mush (loomy). I was killing the clutch on every corner more than i've ever done before running a low gear and unless i was in the power the bike would struggle to rev.

My KTM 300 has a 36 keihin carb (flat slide). On ebay i'm seeing two types of 36mm carbs. Which one are you guys using?. Also, is it worth a look at the powervalve springs?

The powervalve springs won't effect the idle or bottom end. Really sounds like a jetting issue. The 36 will help especially if you go to a PWK. You just need to make sure you are getting the right one. If it has a screw top it will be longer than the TMXX. The carb that the late model KTM's use has a different style top that doesn't resemble the screw top at all and is the right dimension. I don't know if I would invest in a different carb until all the comparisons have been done with the APT/Lectron carbs. It really sounds like either of those will completely cure your problems.

Thanks guys.

Just been surfing the net and found another carb manufacturer making copies of the keihin flatslides. The carbs are called OKO, do you know anything about them i think they are a chinese and the reports read well.

If you ride mostly mx and have the 165 kit, I think I would stick with the mikuni and work on the jetting. I do believe the 36 PWK pulls better just off idle and has a little more low end. I have done some tests crawling up a hill at just above idle and with the mikuni the auto clutch is quick to start slipping a little. Pwk the clutch stays hooked up more which tells me the motor is making more power at that rpm.

I normally ride Enduros, but my nine year old son has been nagging me for a bike, so he's got an early christmas present in the shape of a suzuki rm 65. although i'm an enduro rider i'll be on the MX scene a lot more now.

my mikuni is worn the float needle has clear wear makes and the slide has seen some action. I've a 449 which i race and rev that bike hard so the 165 lives in the power when cornering the clutch is being used to keep it in the power and not allow it to drop into the mid revs. I'm very much a learner when riding MX, but I can circulate over taking slow riders

Hey Guys,

The Mikuni is a decent enough carb, however the PWK is a fantastic carb. The OKO copies are okay, and the newer ones are much better than what they use to make. The differences between the two PWK's have to do with the Power jets. A power jet affords a bit of a boost once the carb is fully open. These take a bit more tuning that the standard carbs, but it's not really all that much harder to tune as long as you have a decent understanding of carb tuning.

The Lectron carbs have been around for ages. They offer some unique advantages in regards to tuning because they don't have jets in the traditional sense. However, until you understand carburation it really isn't worth while for you to spend that kind of money.

I've got bunches of carbs including Keihin, Dellorto, Mikuni, OKO, and others--they all have advantages here and there. The thing is learning what's going on with the carb and how to determine if it is rich or learn (and they can be both at the same time!), and how to adjust for it is more important than switching brands/models in most cases. That said I really like the PWK.

Spud it sounds like you need to work on your idle air/fuel mixture to allow the bike to idle at a lower rate. It is also quite possible that you have an air leak that is causing your issue. Chances are high that your carb is just mis-tuned and replacing it is really only going to force you to learn how to tune anyway.

Some of the best two stroke tuners in the world are Moped riders. They all have 30 year old bikes that they some how figure out how to keep running. That takes skill. The moped folks are also all about sharing knowledge. You can find over on the Moped Army Wiki excellent information on how to learn how to tune a carb.

For new tuners I generally suggest that they read:
How To Tune PHBG Carburetors
PHBG tuning made easy

Granted these are for the Dellorto PHBG, but most of the carbs you will ever use on these bikes act in very similar ways, and those tutorials will get you off to a very good start.

I'm not a fan of the Plug Chop tuning of carbs though because they really only tell you about one state, and that's just not enough for the two stroke. For this learning the HFFS method is preferred. Now when a moped person says "four-stroking" what they mean is loading up such that the engine misses a power stroke and thus starts to sound like it is "four-stroking."

If you have more questions you can find me over at BATS (a two stroke website focused mostly on two stroke street bikes)--I ended up over here while looking up some Husky info and noticed you cats could use some carb learning action. Us two stroke riders have to stick together these days!

Carbs really are pretty easy once you grok them--the most difficult thing with carbs is that for most people nothing you've ever done is similar and thus you have to learn a lot before any of it starts to make sense. There's some serious physics, chemistry, and many other things going on at the same time. Still to learn the basics is pretty simple, and you can figure it out. ;P