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

[gggGary]

Put on a decent set of airfilters and report back.
Heck as an experiment run without any, see what happens.
Just for entertainment lets see what they look like looking in the throat?
riffing on others concerns, confirm the carbs are in sych visually. Both slides at the same height on the idle stops and raised up to say 1/4 throttle.

 

[gggGary]

Confirm all your carb vent lines are "still" open. 'Round here mud daubers love to plug carb vents with their babies.

 

[gggGary]

Yeah I'm guilty of not looking back through the thread, sorry.
Valves checked and reset? Compression test done?

 

[gggGary]

Not much fuel in the line/ filter remove the fuel filters, make a difference?
Open float drains check for strong consistent fuel flow.

 

[Wingedwheel]

While I agree with Jan P that it’s odd both carbs developed an issue at the same time and the new carbs are causing issues as well I’m not convinced it’s electrical. I also agree with Gary that checking the carbs under different conditions may provide a clue. Fuel flows through the lines with no restrictions?

 

[Its been a long time]

Sorry to say, I'm not convinced by Ali Express (or same thing from elsewhere) carburettors. Those very small pleated air filters are the first thing I would remove though.

 

[RaceCar1983]

I’ve tried it without the filters with the same result, tried velocity stack type as well same thing (there is not room for normal long air filters, but the bike ran fine with the shortys for a long time). Fuel flows good, I have tried with and without filters, same thing. I have tried vented gas cap and opening it he gas cap while running.

I think it is electrical, to go through 2 sets of carbs with the same results regardless of jetting makes me nearly certain. The question I have now is, what electronic ignition will work with my xs charge PMA?

I plan on getting some vm34 Mikunis if that doesn’t work.

 

[Jan_P]

So electrics
I sometimes when nothing else works pull separate wires all the way from battery to ignition and coils and a separate ground
Not sure if you have that possibility
That way one can be sure the ignition gets full power ---Sometimes that changes things

 

[gggGary]

Valves checked and reset? Compression test done?

Please excuse my rudeness but while working through issues remotely we often find the questions not answered are key to the problem.

I think it is electrical,

As long as I'm being an ass.
That's not how you find illusive issues but it is a good way to cure right hip sores.
With the plugs off and grounded do you have strong bright blue spark?
As others have mentioned replacement ignition parts can often be a step backwards from 50 year old OEM components.

 

[RaceCar1983]

Please excuse my rudeness but while working through issues remotely we often find the questions not answered are key to the problem.

As long as I'm being an ass.
That's not how you find illusive issues but it is a good way to cure right hip sores.
With the plugs off and grounded do you have strong bright blue spark?
As others have mentioned replacement ignition parts can often be a step backwards from 50 year old OEM components.

Valves done, comp test done both good, spark is bright and good, tried different plugs as well.

 

[RaceCar1983]

I plan on getting a rawhide cycles dual coil ignition system and mikuni vm34 setup. Killing an ant with a sledgehammer if you will (I will try the ignition system first just to narrow the problem them move to the carbs if need be). Will the rawhide system work with my mikes xs PMA?

 

[RaceCar1983]

I found on another thread gggGary you have experience with the eBay tytronic ignition setup. Does this work with a PMA and would you recommend it over the rawhide system? They are nearly 1/3 the price of the rawhide.

 

[Jan_P]

Thinking out loud 1
A video of it running with sound would help

Thinking out loud 2
can it be a coil shorting out at higher rpm ? have no experience putting it out here others to chime in

Assuming stock coils these can be found I believe since other ignitions are used

 

[gggGary]

I found on another thread gggGary you have experience with the eBay tytronic ignition setup. Does this work with a PMA and would you recommend it over the rawhide system? They are nearly 1/3 the price of the rawhide.

It didn't go well for me but think I had an early version, they did change them, I didn't try the newer one they sent me, it might work if you are careful to find a coil with a 4 ohm (no less) primary. @5twins is exploring that setup.

 

[RaceCar1983]

It didn't go well for me but think I had an early version, they did change them, I didn't try the newer one they sent me, it might work if you are careful to find a coil with a 4 ohm (no less) primary. @5twins is exploring that setup.

And they work with a PMA? Or did you install with a stock alternator?

 

[gggGary]

And they work with a PMA? Or did you install with a stock alternator?

stock; a Vape charging/ignition system is the gold standard. Function AND price LOL

Do you currently have a battery? (bad pun?)
If not I'd be trying a battery in place of the cap for testing purposes.

 

[RaceCar1983]

stock; a Vape charging/ignition system is the gold standard. Function AND price LOL

Do you currently have a battery? (bad pun?)
If not I'd be trying a battery in place of the cap for testing purposes.

I’m already running a battery. Voltage at idle was 13.5 and went up to 14-14.5 when slightly given throttle. I have also tried another battery with same result.

Does anyone know what electronic ignitions will work with a PMA? Is it worth making a new thread to discuss this subject?

 

[Its been a long time]

I’m already running a battery. Voltage at idle was 13.5 and went up to 14-14.5 when slightly given throttle. I have also tried another battery with same result.

Does anyone know what electronic ignitions will work with a PMA? Is it worth making a new thread to discuss this subject?

If you have a battery, any aftermarket ignition should be suitable as far as I'm aware. The ignition system runs from the battery, in turn the battery is charged by the alternator. Your voltage sounds just fine.

 

[RaceCar1983]

If you have a battery, any aftermarket ignition should be suitable as far as I'm aware. The ignition system runs from the battery, in turn the battery is charged by the alternator. Your voltage sounds just fine.

Ok, the reason I ask is the eBay Tytronic ignition has a review stating it won’t work with a PMA setup. I guess I will bite the bullet and go with the Rawhide double pickup unit (better customer support).

 

[Its been a long time]

Ok, the reason I ask is the eBay Tytronic ignition has a review stating it won’t work with a PMA setup. I guess I will bite the bullet and go with the Rawhide double pickup unit (better customer support).

From memory, I seem to recall that the Rawhide system is a relabelled Tytronic? Apologies if I'm wrong on that, but I seem to recall that part from the plastic molding colour the two systems are pretty much identical?