MikeXS Keihin flatslide PWK installed --- now troubleshooting

[ukie eagle]

OK... so I mounted the carbs, hooked up gas lines, put in fresh plugs, etc., and connected the throttle cable.
I turned the air screws in until they seated and then turned them out 1-1/2 turns and upon starting her up she was running rough.

This I expected, but while waiting for her to warm up to the point where I could start "fine tuning", when she started to drop in RPMs [to the point where I thought she would stall], I would naturally try blipping the throttle to keep her from stalling.
At that point, the RPMs would jump way up --- and not go down at all when I released the throttle --- so I would have to shut her down.

See, the problem is, I just had the rings replaced so I'm kinda "breaking in" the motor [only 10 miles on the motor since new rings], and feel I don't have the luxury of letting the engine run at higher RPMs while I mess with it/tweak the carbs...

Having read the other threads on these carbs, I'm thinking there may very well be an issue with the throttle cable/splitter --- is there a readily available throttle cable assembly that will work better?

FYI, I don't have the stock "wheelbarrow" handlebars on the bike, and with the bars I do have on her, I had quite a bit of slack as far as the cable length, so didn't have to worry much about how to rout the cable that came with the MikeXS carbs to get it to reach the handlebar/throttle grip...

Thanks!

 

[mrriggs]

I'm pretty sure that the PWKs can use the same throttle cable as the VM34s. I can't guarantee that since I haven't personally tried it. If anything, you may need to modify it a bit but that could be the case regardless. The cable I bought was advertised as being compatible with PWKs and I still had to modify it to fit.

Your problem may not even be the cable. You really need to sync the carbs before doing much else. Do you have plenty of free-play at all ends of the cable? Also verify that the ATU (ignition advancer) is functioning properly.

 

[ukie eagle]

I have more than enough cable length to work with [didn't have any problems routing it], so I don't think that not enough free play is a problem.

Could having too much free play be the issue?

What's frustrating is that I just want to let the engine warm up to normal temp so that I can start to sync/tune the carbs, but when the RPMs jump up like that, I get nervous & shut her down.
Call me overly cautious, but with only 10 miles or so on the ring job, I don't want the engine revving like that.

And how do I check if the ATU (ignition advancer) is functioning properly on this '80 with the stock electronic ignition?...

 

[hutch08]

I bought a set of cables for vm34's but had to use a combination of pieces from each to get them to work properly. My bike isn't running yet so I can't help you with the tuning issues. Try bench syncing them the best you can first. From my knowledge a rapid jump in rpms usually means a lean condition, make sure you have no air leaks.

also, from what I've read... These carbs have a tendency to have sticky slides, pull your filters and make sure the slides are returning. One trick is to stretch the springs so theres more tension on the slides.

 

[ukie eagle]

"Bench syncing"?...[forgive my ignorance], but what's the best way to do that?