Carb rebuild woes... Won't rev past 3k

[bigbadjonno]

Soo, long time coming, first ride today after the winter rebuild.
Forks - lovely.
Swinger/shock linkage - lovely.
New Michelin PR4 - lovely.
Carbs..... Not so lovely. I stripped them originally due to age and the low speed fuelling was awful.
Spotlessly clean when rebuilt. All standard, standard needles, jets etc. They're like new.
Put it all back together. Balanced the carbs, set the fuel screw using the idle drop procedure in the Honda workshop manual. The low speed fuelling is now sublime, like I remember my original 'Storm being.
But.... Get to 3k and it just won't go. No power at all. It will eventually get to 9k rpm, but it's not happy.
Now, I've not touched the plugs (new last year) or the cam timing (sorted when I bought the bike due to previous owners attempts at cam timing...).
So, any ideas, before I go crawling to the local spanner man? It's definitely carb related, but not sure where to start.

[fabiostar]

god i feel your pain i really do. mine had problems a bit like yours and i changed everything but the garden gate and it didnt help. mine has for some reason cleared its throat on its own.. clean as the carbs are i would go back into them again just incase dirt from the tank has made its way into them.. sorry cant be of more help but its a starting point, and junk your plugs.

[sirch345]

Have you put the vacuum pipe on the petrol tap on the right outlet (assuming you have the earlier version bike with 16ltr fuel tank). The outlet you need sticks out to the side of the tap, not the drain outlet that points down to the ground, although I wouldn't have thought it would rev to 9K if that were the case, even if it is eventually,

Chris.

[VTRDark]

or the cam timing (sorted when I bought the bike due to previous owners attempts at cam timing...).

Have you ridden it since then?

[8541Hawk]

Sounds like one of the carb slide diaphragms isn't seated properly.

[bigbadjonno]

or the cam timing (sorted when I bought the bike due to previous owners attempts at cam timing...).

Have you ridden it since then?

Yeah, done a couple of thousand miles since then. Not touched the motor, just carbs.

[bigbadjonno]

Have you put the vacuum pipe on the petrol tap on the right outlet (assuming you have the earlier version bike with 16ltr fuel tank). The outlet you need sticks out to the side of the tap, not the drain outlet that points down to the ground, although I wouldn't have thought it would rev to 9K if that were the case, even if it is eventually,

Chris.

Cheers Sirch, 19 litre tank on mine (2003 bike).

[bigbadjonno]

Sounds like one of the carb slide diaphragms isn't seated properly.

Yes.... Thought had crossed my mind. Perhaps I should have run it up with the airbox off first...

[Stephan]

Sounds like one of the carb slide diaphragms isn't seated properly.

Yes.... Thought had crossed my mind. Perhaps I should have run it up with the airbox off first...

No need to start, just remove the filter, open the slides fully, release, and check if they return the same time or for some unusual sound.

[tony.mon]

When you took the carbs off for cleaning, did you stick a rag down the intakes?
Did you take them out again?

[bigbadjonno]

Sounds like one of the carb slide diaphragms isn't seated properly.

Yes.... Thought had crossed my mind. Perhaps I should have run it up with the airbox off first...

No need to start, just remove the filter, open the slides fully, release, and check if they return the same time or for some unusual sound.

Yes, did that a few times. They both seemed to be fine, unless of course they've both got the same issue

[bigbadjonno]

When you took the carbs off for cleaning, did you stick a rag down the intakes?
Did you take them out again?

I used some plastic caps that I found, so definitely not left in there

[tony.mon]

Clearly something wrong, it won't fix itself, do strip and rebuild.

[sirch345]

Have you put the vacuum pipe on the petrol tap on the right outlet (assuming you have the earlier version bike with 16ltr fuel tank). The outlet you need sticks out to the side of the tap, not the drain outlet that points down to the ground, although I wouldn't have thought it would rev to 9K if that were the case, even if it is eventually,

Chris.

Cheers Sirch, 19 litre tank on mine (2003 bike).

Chris.

[bigbadjonno]

Just an update on this, should anybody ever reference it in the future.....
I'd not got the diaphragms seated very well for the slides so they weren't opening.
Once I'd remembered the correct way to install them (with that goddam spring....) they were fine.

Originally I'd installed them by inserting the slides into the carbs, then the springs, then the caps. Nigh on impossible and hence the above result.

Much easier to insert the springs into the cap spigot, place the slide assembly into the cap with the diaphragm rib sitting on the cap, then inserting the whole kaboosh into the carb. Tricky to guide the needle in whilst holding back the spring, but much more reliable way to get the diaphragm to seat correctly.

D'oh.