Fazer thou rpms sticking when clutch pulled in changing down only...

[will6576]

As Title, loving my thou but this niggle is doing my head in, bike is 04 with 60k on it, full service recently and clutch strip assemble all good, new clutch cable, Ivans Full monty goes well,
seems to happen when over 4000rpm changing down from 6/5/4/3 when clutch pulled in the rps stick for a second then drop, changing up is a dream short shifting or with clutch pulled, seems worse when bike is warm and better at low rpm's. throttle cable is good and not sticking neither is the clutch cable. you have to plan well ahead when changing down and to allow for that second before the rpms finally drop to change gear,
Thanks for any advice in advance, Motul semi synth 5100 a month ago.
Mark.

[unfazed]

Could be a few things, but sounds like an air intake leak
Cracks on the vacuum take off caps, Replace them as a matter of course as they are only about a tenner for 4
Cracks starting to go all the way through on the intake manifolds,
To much cut off the the diaphragm springs when doing the Ivans modification causing the diaphragms to float.
Carbs not fully fitted on the rubbers when carbs replaced.
Sticking throttle shaft on the carbs.
Dodgy TPS
Incorrectly set pilot screws after Ivanising.
Carbs not balanced properly

As a start point check for intake leaks try dropping the idle speed, balance the carbs and reset the TPS

[will6576]

Thank you for that, done the carb sync and TPS, the vacuum caps were good, if an air leak, would it present itself through out the rpm range? i understand that the ivans full monty is a complicated procedure so might bite the bullet and get a stock set of carbs and sell mine on as too many variables to check. ive rejetted bikes before but this kit seems like rocket science lol...

[unfazed]

Yes it will effect it accross the rev range, and maybe run a bit hotter than usual, but not enough to notice and can cause the carbs to be slow to settle.
Who did the Ivanising?
Not too unusal for carbs not to be fitted incorrectly and have the inlet manifolds fold in when the carbs are being refitted.
Check to see if the vacuum vent pipes for the diaphrams are clear, there are two, under the tank on the top of the carbs between 1 & 2 and 3 & 4. There is a a little mesh type filter inside the fat tube part and if restricted, could cause the diagrapms to be slow to drop as it would not be able to equalise the air quick enough, although this would also make it slow to respond to the throttle.
If the AIS is still fitted try blanking off the connection to the air box.

[Falcon 269]

If it's one of the many that I've 'Ivanised', I promise you it won't be a problem caused by over-cutting the throttle slide springs (I deliberately do them less than Ivan recommends), or incorrect setting of mixture screws (unless someone has messed with them later - perhaps when it was serviced recently?) or improper refitting of the carbs back into the intake stubs. 

If you decide to fit stock carbs again, you would hate it.  Not only would you have to do much of the same work necessary to check the Ivan's installation anyway, you'd lose all the torque and peak bhp gains that come with the Full Monty.  It's a lose-lose proposition.

Try adding a bit more throttle slack at the adjuster at the throttle end and see if it changes anything.  While hanging revs typically suggest an air leak, this sounds like it could be mechanical to me.

[unfazed]

Mike, That was the very reason I asked who did the Ivanising, knowing it was you would have ruled out a few problems

[will6576]

Thank you all for your inputs, i am in love with the power so a bit hasty of me to give in lol...will check the vacuum pipes+filter also will check to see if the AIS is still in operation and get back to you.
Good to have experts on tap ;-) much appreciated.

[will6576]

i have checked and cleaned both Vacuum pipe filters and proceeded to block the AIS and found no pipe there so already removed apart from where the AIS enters the airbox, the hole was left open, surely this would have forced more air into the system affecting performance?
will get out later for a spin and check back in.

[will6576]

This cap was left off and hole open 

[Falcon 269]

That's the AIS outlet from the airbox.  Leaving it uncapped would just have allowed a tiny bit more air into the airbox (and possibly made a bit of a whistling noise) but it won't have made any difference to performance and certainly isn't the cause of your problem - sorry.