PWK Cr500 Jetting tips?

[Nikel]

Hello.

Bought myself an Keihin PWK 39 carb to put on my :87 CR500.
Is there anyone who have this carb and maybe have some guidelines that I can go after.

Kind Regards.
Niklas

 

[2premo]

wow interesting to hear how it ends up, have a 38 mic on mine works great

 

[Nikel]

Hopefully it will turn out great.
The Vm40 are giving me some problems with fuel starvation and is an old carb.

Many Honda cr500 guys us the PWK and they say it's amazing.
I got the carb for 50$ so why not.

 

[Martint93]

I would say, start With a 178-180 main jet.

my 87 500 recently got a 38mm pwk and I use a 175 main jet at the moment..

 

[2premo]

just because something is old does not mean its bad
the fuel starvation is usually a jetting issue, my brother had to rejet his 40mm and said people with experience help, prior to running a GP he had his done and could pull the other big bores everywhere, tis was about 1990 and he was on a 1985 CR500 with the six speed change out, originally his was 4 speed

 

[Martint93]

mine is also a six speed
any one else think that their LC 500s is a bit flat on top? doesn't rev that much? mine is like that

Nikel, I think you will like the pwk. it did Wake up my husky!

do you have a intake and air Box boot to fit the pwk?

 

[Nikel]

@Martint93
I think the Carb is fitted with a 175 now so that would be a great start then.
And yes, they are more like a Diesel.
Mine revs about 6500rpm and then it just stop.
But it is a shit load of power under.
No I don't have any fitting.
Put I figure it out. =)

Thank you.

@2premo

I have tried more or less ewverything in the book.
Stock jetting doesn't work.
Bigger Jets make it run out of fuel even faster.

 

[Martint93]

jeg er fra Norge, er meg du kontaktet via youtube

 

[Nikel]

Haha. Vad roligt.
Jag vill också ha sex växlar.
Då borde dina settings passa ganska bra på min.

 

[Martint93]

I Guess we have to take it on English so the rest of the world can understand
I just bought a Complete transmission on ebay and put it in when I rebuild it
my bike is a 87 wr 400, but I have put a 86 cr500 engine in it With a wr six speed transmission, pwk 38mm carb of a ktm 300, home made silencer, sem ignition an sligthly ported exhaust port. squish is set at 1,2-1,3mm.
I still don't feel it has the power a 500 should

but the 38mm pwk is a fairly New mod, so the jetting is not 100%
currently:
main 175
pilot 45
needle n2zw #1
slide #7
air screw 1 out


gearing is 15/48 on 18" rear Wheel.

 

[Nikel]

That sounds weird.
My bike is completely stock except for a TurbineCore 2 silencer.
And it has a lot of power.
Slightly slower than my friends Aprilia sxv550 with 70 rwhp.

I noticed in your video that you started the bike without any problems with your left foot.
My bike just says Fu if I try that.
How is the compression?

 

[justintendo]

I Guess we have to take it on English so the rest of the world can understand
I just bought a Complete transmission on ebay and put it in when I rebuild it
my bike is a 87 wr 400, but I have put a 86 cr500 engine in it With a wr six speed transmission, pwk 38mm carb of a ktm 300, home made silencer, sem ignition an sligthly ported exhaust port. squish is set at 1,2-1,3mm.
I still don't feel it has the power a 500 should

but the 38mm pwk is a fairly New mod, so the jetting is not 100%
currently:
main 175
pilot 45
needle n2zw #1
slide #7
air screw 1 out


gearing is 15/48 on 18" rear Wheel.

wow, that is some seriously tall gearing on a 500...how fast do you want to go? the husky 500 doesnt rev very hard either. where does it feel like its underpowered in the rpm range?

 

[grouty]

The last fuel starvation problems I had on a big Husky 2 stroke was down (in the end !) to the fuel tap and fuel line not flowing fast enough.
Replaced the tap, along with a bigger fuel hose, new fuel needle valve, and the job was a good-un.
It may not be the case with your problem, but it solved mine.

 

[Nikel]

wow, that is some seriously tall gearing on a 500...how fast do you want to go? the husky 500 doesnt rev very hard either. where does it feel like its underpowered in the rpm range?

I have 16/48 on mine now, but I will change the rear sprocket to a 44 when we have some time over at work.
Mine does 150 km/h at 6500 rpm/5th gear and the engine only say.
-Meeh, is that all you got.
I'm in need of a 6th gear.

 

[Nikel]

The last fuel starvation problems I had on a big Husky 2 stroke was down (in the end !) to the fuel tap and fuel line not flowing fast enough.
Replaced the tap, along with a bigger fuel hose, new fuel needle valve, and the job was a good-un.
It may not be the case with your problem, but it solved mine.

I have fitted a fuel pump on it.
But now the problem is on the other side.
It pukes fuel everywhere

I have manufactured a couple of restrictions that I will hopefully try tomorrow.

 

[justintendo]

didnt notice this is a motard...now i understand your gearing choice..

 

[Martint93]

wow, that is some seriously tall gearing on a 500...how fast do you want to go? the husky 500 doesnt rev very hard either. where does it feel like its underpowered in the rpm range?

Mine is not a motard.

I would like it to do about 170 km/h

I feel it lack power everywhere actually...

With 15/48 gearing, it will only power wheelie in 3rd if I give it full throttle at the right moment..

 

[Martint93]

That sounds weird.
My bike is completely stock except for a TurbineCore 2 silencer.
And it has a lot of power.
Slightly slower than my friends Aprilia sxv550 with 70 rwhp.

I noticed in your video that you started the bike without any problems with your left foot.
My bike just says Fu if I try that.
How is the compression?

Last I checked ( november 2013 after fresh bore and piston ) it was at 155psi or 10.8 bar

 

[Nikel]

So this is how it went.

I got the carb today and thought.
What the heck, I just try to fit it and see whats happens.

The PWK has a much smaller diameter on both the front and the back,
but the Husky intake and box was flexible enough so i just tightened the clamps.

Rolled it out.
Gastap on.

Leaaaking like hell.
The Snowmobile is fitted with an ACCS system (Altitude Compensation Carburetor System)
Witch is a hose that goes from the bowl to some thingywingy, but I don't have that system so I just priming my lawn.

Anyway.
After some reading in the Polaris service manual i found out that the ACCS system is at atmospheric pressure when riding in normal Altitude = I just connected a hose and mounted it up in the rear fender.

Second try.
Gastap on.

No leak.

One kick.
Wham.
And it started.

I could not believe what i was hearing or seeing.
It has NEVER happened before.

I let it idle when I get dressed.
Didn't die.

Weird.

Time for a spin.
Whooaaaa, what the heck happened to my nice bike.
Before my bike was very kind under 1/4 throttle.
Now it just said brapp and aimed me right to the bushes.
The response is AMAZING.
It runs like a dream.

Full throttle runs, no problem.
Crusing, no problem.


THIS WAS A GOOD BUY!

 

[2premo]

I have 16/48 on mine now, but I will change the rear sprocket to a 44 when we have some time over at work.
Mine does 150 km/h at 6500 rpm/5th gear and the engine only say.
-Meeh, is that all you got.
I'm in need of a 6th gear.

what you need is an 87-88 XC gearbox, 6 speed wide ratio