Popup carbs

[Bikeazoid]

Thank you, especially for the video, that rocks. I was wondering what pop up was on the main site....

[SamK]

I might have a set though I can send FoC, I'll need to check if I can find it

UB

Thanks Rob
Don’t worry if not, I’ll put together a bigger order to negate the ridiculous postage charges.

I’ve taken the carbs apart this afternoon..
a T15 torx bit is a perfect sized drive for the roll pins

Now nothing I can do except clean them while I’m waiting for parts...

Sam.

[Uncle Bob]

Hi Sam - Sorry about delay, took a while to find things in my garage! I did find the LiteTek throttle shaft if you want them:

Rob

[SamK]

Hi Sam - Sorry about delay, took a while to find things in my garage! I did find the LiteTek throttle shaft if you want them:

IMG_20200503_145505844_HDR-F800x600.jpg

Rob

Thanks for the offer Rob, but I did an order with some other bits n pieces.
Actually just arrived yesterday.
Plan to rebuild the carbs tomorrow.
Here’s hoping

Sam

[SamK]

Update...

Throttle shaft seals have been replaced but the problem persists.

Any further suggestions?

Sam.

[SamK]

Managed to catch it on video -
Vimeo video

Sounds worse in real life.

[Lexdba]

That's definitely air leaking somewhere into the inlet trajectory by itself.. but the shaft seals.. ?
Have you tried to pin-point your problem by spraying brake cleaner on certain spots around the carbs? (do this outside, with a bucket of water near, I've had a bike backfire and light the cleaner ).

By methodically spraying on certain parts (c.q. filterbox to airbox, airbox to carbs, shaft seals, carbs to head etc.) you can hear where the mixture gets enriched by the highly combustable brake clean. That's where your leak will most likely be!

Also; after listening to your video a couple more times it definitely sounds like a proper vacuum leak that causes the CV slides to slide up and stay there. I've had a GS500 that did the same thing. Could you try putting it in gear whilst it is happening and slightly release the clutch to get the motor to load up a little? If they drop right down it'll definitely be a vacuum leak.

[SamK]

Also; after listening to your video a couple more times it definitely sounds like a proper vacuum leak that causes the CV slides to slide up and stay there. I've had a GS500 that did the same thing. Could you try putting it in gear whilst it is happening and slightly release the clutch to get the motor to load up a little? If they drop right down it'll definitely be a vacuum leak.

Yes, I’ve done the spray test... but once it’s up to temp it’s too erratic to notice if it’s doing anything.
The throttle shaft seals were changed after reading of a similar issue on another forum.

Inlet rubbers look quite new. Certainly no visible ageing on them and still quite flexible.
I’ve also replaced the screws and brass washers on the head for the vacuum feed and the clamps on the rubbers

Putting load on can reduce the high revs.. but not always.

Sam.

[Lexdba]

And does it react to anything when ice-cold? If it's a leak it should definitely pick up rpm's.
Are all of these present?

[SamK]

And does it react to anything when ice-cold? If it's a leak it should definitely pick up rpm's.
Are all of these present?

plugneedle-jet_medium1335744080-01_e5c9.jpg

I spray tested both when just started and ticking over and after a run with no noticeable Rev increase.

I’ve not been in the float bowl at all.
I assume if that plug isn’t sealing, or missing, it could draw fuel up into the mix?