72 xs2 bogs down and backfires out of carbs, out of ideas

Alright, just came back from a test start. The carbs both still dumped fuel out but I decided to start up anyway. I left the petcocks closed.

Started perfect, still had the same bog. I opened both petcocks and suddenly it would rev all the way up like normal, besides the fuel dumping on the ground. The bog was completely gone, I repeated this several times with the same results.

Does this mean it was a float bowl issue? I set the bowls to 19mm spec from the write up I posted, but I guess I will have to adjust them again. Do you set them lower when they flood out like that?

IMG_0112.jpeg
 
So with opening and closing petcock it comes and goes
It ( machine ) has been working ..and no major changes done
My guess it is the float valves not operating
Dirt or Sticking
On stock carburetors there is the possibility to flush through from under
And via closing the petcock to let it run lower the level till stumbling and then open see what happens
be careful with not catching fire

Tap with something on the outside float bowls like screwdriver handle can change it

Others chime in on the level adjustment
 
PROBLEM SOLVED: after getting fed up messing with the carbs I ordered two Chinese knockoffs of the PWK 32’s I have from Amazon and plugged them in.
IMG_0115.jpeg


Fired up right away and revved with no bog, it’s been too cold for me to do a real road test but everything seems perfect revving in the driveway. I would like to know how to fix the old mikes carbs though, they cost over $400 vs the Amazon $60 for both. Definitely very overpriced.

Thanks for all the help from everyone here.
 
FWIW, a search on Amazon for PWK 32 finds them.
Thank you ..
I did look ..but since some are not good and these appears to work out of the
box .
At low price and others not work at high price being troublesome according to reputation
or are these risky also
Can also ask would PWK 34 be better suited
Am I thinking wrong here ? at $ 60 for new or is it junk ?
 
Thank you ..
I did look ..but since some are not good and these appears to work out of the
box .
At low price and others not work at high price being troublesome according to reputation
or are these risky also
Can also ask would PWK 34 be better suited
Am I thinking wrong here ? at $ 60 for new or is it junk ?
I "think" these are the PWK 32 that the owner above bought -

https://www.amazon.co.uk/Carburetor...1736283716&sprefix=pwk+32,aps,620&sr=8-1&th=1

On a stock motor, a 32mm flat slide should be fine. I think.....
 
thank you Sir
Keeping on like a drunkard Ill blame the shots for later dinner " Schnapps " Still thinking One needs 34 -s for an 80
having BS 34 .s
for the US enthusiasts

https://en.wikipedia.org/wiki/Snaps

Correct me if I am wrong if the Carburetors are not garbage / junk it appears having a lot included for the money
Plug and Play and drive on to the sunset --NEW

Or am I missing something
 
@Jan_P I had shot of Swedish Schnapps once. As soon as it hit the back of my throat, I coughed immediately and nearly spat it out! It took all my will power to get it down. All my Swedish friends laughed like crazy. LOL skål
:cheers:
 
thank you Sir
Keeping on like a drunkard Ill blame the shots for later dinner " Schnapps " Still thinking One needs 34 -s for an 80
having BS 34 .s
for the US enthusiasts

https://en.wikipedia.org/wiki/Snaps

Correct me if I am wrong if the Carburetors are not garbage / junk it appears having a lot included for the money
Plug and Play and drive on to the sunset --NEW

Or am I missing something
I got 2 of these in size 32mm: https://www.amazon.com/dp/B083RMKS5...B40N3SVSKT8PZZ9_1&starsLeft=1&skipTwisterOG=1

Plug and play, but I haven’t done a proper road test (it’s snowing here). The machining seems much better than on the Mikes carbs. I just sprayed some carb cleaner through them and put them on.
 
thank you Sir
Keeping on like a drunkard Ill blame the shots for later dinner " Schnapps " Still thinking One needs 34 -s for an 80
having BS 34 .s
for the US enthusiasts

https://en.wikipedia.org/wiki/Snaps

Correct me if I am wrong if the Carburetors are not garbage / junk it appears having a lot included for the money
Plug and Play and drive on to the sunset --NEW

Or am I missing something
If you want your mind to be truly exploded, enter PWK 32 into Ali Express. I just did. And my mind is truly boggled :whistle:
 
UPDATE: went for a test ride but had a massive lack of power, checked the jet size and it was 130, 100 or 105 is what I ran in the old carbs, so I swapped the main jet and got an improvement but it is still very underpowered so I will swap pilot jets and do another ride tomorrow.
 
During the test ride after re-jetting, the bike has very slow acceleration and still bogs towards the end of gears and doesn’t get above 30. I have heard some associate this with worn clutch plates. It will start off very slow then the carb will catch up and it will fly forward. Changing the needle height made it better but it’s maxed out (top clip position). Any ideas for carb tuning?
 
So where are we with the capacitor ?
From a methodological viewpoint
It would be strange 2 sets of Carburetors going bad on both sides even though they flooded

Thinking it over and then perform an action and then reevaluate 1 set carbs then a new set no major solution
Normally it points to the fault being somewhere else
Is power feed to ignition + coil good ?
Ignition timing ?
A picture of the spark plugs ?
 
So where are we with the capacitor ?
From a methodological viewpoint
It would be strange 2 sets of Carburetors going bad on both sides even though they flooded

Thinking it over and then perform an action and then reevaluate 1 set carbs then a new set no major solution
Normally it points to the fault being somewhere else
Is power feed to ignition + coil good ?
Ignition timing ?
A picture of the spark plugs ?
The capacitor is replaced, It has to be the carbs, the problem only occurs under load, and it gets up to speed eventually. I will get a spark plug picture.
 
what is your opinion on it being the clutch? Since it only happens under load. Some other members have the same symptoms: https://www.xs650.com/threads/clutch-slips-at-high-rpms.7933/

https://www.xs650.com/threads/acceleration-problems.39994/page-2


The Clutch has usually that symptom


do your revs climb with no speed gain...maybe you need new plates and springs.

The creation of power and the transmission to the rear Wheel when the clutch slips there is less resistance to the motor.
and the revs increases
Remember first time heard of it a sailor had a Triumph out of the corner full throttle to me it sounded as in shape moving away with a roar
a more experienced friend said
That clutch is slipping It can sound as if bike is Fast / Tuned / Souped up for some.
As far as I know -- there can be other problems but The throttle response should be there.

We had a discussion here about the gear box giving the symptoms A first for me But I believe it depends on the gear
 
The Clutch has usually that symptom


do your revs climb with no speed gain...maybe you need new plates and springs.

The creation of power and the transmission to the rear Wheel when the clutch slips there is less resistance to the motor.
and the revs increases
Remember first time heard of it a sailor had a Triumph out of the corner full throttle to me it sounded as in shape moving away with a roar
a more experienced friend said
That clutch is slipping It can sound as if bike is Fast / Tuned / Souped up for some.
As far as I know -- there can be other problems but The throttle response should be there.

We had a discussion here about the gear box giving the symptoms A first for me But I believe it depends on the gear
Yes the revs are there in first and drop and bog in second as it starts to lose power… I will order new clutch plates and springs from EBay to install.
 
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