Thunderbird 900 1995 Won't Rev Up

Sounds like one of the other jets?

 

Sounds like you’re gonna have to bite the bullet and strip and clean the carbs properly mate
It’s what I would do first otherwise you’ll never be able to balance them properly

 

My T100 had had an on and off life. It stumbled a bit. When I dropped a carb bowl I found I had fine‘red sand’ everywhere (tank corrosion). I bit on the bullet and bought a 3 litre ultrasonic cleaner for about £60. It will take a pair of stripped carbs and they came out gleaming with all orifices pristine
I have used it for loads of detail cleaning jobs since - not least SWMBO’s jewellery (but NOT set with soft stones!! - don’t ask)
I have thrown in rusty nuts and bolts with soapy water and saved labouring with a wire brush where it won’t properly fit anyway....

 

Yep...sonic cleaners are excellent
Got one at work so I get all my mates carbs to do
Just did the carbs off a mates zephyr 1100 on Monday

 

The pilot jets are next to main jets not to be confused with pilot screws. These have 75% of all carb problems. Have you cleaned out the duck billed shape filters in the fuel pipes.
Btw I make pencil coil kits that really help to engines
Pm if interested.

 

If you’re happy that you’ve cleaned the carbs correctly I’d make sure the air filter is clean before trying to balance the carbs. A dirty filter will restrict air flow and could give the symptoms you describe. When balancing the carbs it won’t really matter what readings you get so long as they are the same.

 

Have you checked valve clearances? Inlets can go negative

 

Are the inlet rubbers starting to perish? Drawing air in, between the carbs and the cylinder head, will not be conducive to good running. With the engine running spray Easystart, or similar (I do believe WD40 has the same effect), over the inlet rubbers. If the revs rise then the spray is being sucked in via cracks in the rubber, or even the loose retaining clips.

Just a thought.

 

In a similar vein how are the carb diaphragm rubbers?

 

I think I would be for polishing the carb bore and slides with Brasso to remove any oxidation of the alloy and minutely checking the rubbers for tears or splits as well as ensuring they are properly seated before bolting up.
If the vacuum circuit is not working properly a fully open butterfly will not help the slide lift all the way. Likewise all the vacuum caps are intact.

 

Now it is running okay, give it a regular slug of fuel system cleaner to keep the carbs clean and shiny inside. I use Redex which works well on my Trident. Others herein have their own favourites. The only time I had a problem was when, one winter, I forgot/couldn't be bothered to dose it up before it was put into hibernation. A dollop of Redex soon had it purring again.

 

Nothing new then. Same old culprits time after time.
Glad it'srunning ok now