82' GPz 750 BS34 float issues - dies at 5K rpm

Well - not a tank vent issue. Dies at exactly the same spot with or without the tank cap open.

I still think this is due to the float levels, but am hoping to borrow a bank of carbs for this bike off a buddy with the same bike to confirm it's in the carb and not some other issue.

Doesn't sound like these plastic floats have issues with losing buoyancy - but that would explain my issues. I've read of the same symptoms with too high of a float level (which I have) so that's why I'm leaning this way.

The other thing I'm going to look at is the coil power mod to get the best spark possible... Spark was weak, so they could be flaming out at higher RPM.

Messing with the float levels did get the bog point from 4K to 5500 - so I'd like to get that sorted no matter what.

Damn old bikes...

Rabin

Rabin



Rabin

bean wrote:

The other thing I'm going to look at is the coil power mod to get the best spark possible... Spark was weak, so they could be flaming out at higher RPM.

Messing with the float levels did get the bog point from 4K to 5500 - so I'd like to get that sorted no matter what.

Damn old bikes...



Rabin

Maybe it is an ignition problem... cutting out at aproximately the same RPM every time - if it were the floats/carbs, you'd think it would do it (act up) at random speeds & RPM's?

Would determine coil primary voltage (and compare with voltage across battery terminals) at 3000~4000 rpm before adding coil mod or further addressing carbs. Absent this knowledge, the coil mod seems a blind gamble (but Lady Luck might smile).

Remains a mystery why the float tangs can't be adjusted far enough to lower the fuel level a little more. This by definition is screwy. :huh: Maybe a P.O. installed the wrong parts (needles,seats and/or floats). Am presupposing the seat 0-rings were checked and found to be in position.

Good Fortune!

I just picked up the *right* air filter from the local bike salvage place (Regina Motorcycle Salvage) and when discussing the issue with them - he's guessing air filter missing is the cause...

I'll find out tonight when I drop it in, up till now it's just been short rides with a thin bit of foam over the airbox lid...

He didn't have faith in the clear tube method, and said the BS carbs were REALLY sensitive to air box, and air flow.. He's also never heard of the plastic floats acting up, and if the fuel stops with the float needle closed that should be good too.

If he's right - it's an easy fix, and I just wasted a whole lot of time...

Well - I'm speechless. Put the air filter in, buttoned it up, and the damn bike revved to 10K perfectly... (once warmed of course)

I had never heard or read that CV carbs were so sensitive to the airbox, and never would have thought not having the filter would have caused this issue.

Wanted to post this just in case anyone else ever ran into it.

Thanks very much for all the suggestions, and advice.

Rabin

bean wrote:

Well - I'm speechless. Put the air filter in, buttoned it up, and the damn bike revved to 10K perfectly... (once warmed of course)

I had never heard or read that CV carbs were so sensitive to the airbox, and never would have thought not having the filter would have caused this issue.

Wanted to post this just in case anyone else ever ran into it.

Thanks very much for all the suggestions, and advise.

Rabin

We appreciate you taking the time to post the 'fix'...it does add to the database and will save someone some additional grief in the future.

I was considering replacing my air filter because it's looking a little shabby, I will MOST certainly replace it now for this reason. Thanks again Bean for taking to time to post this fix!