Revs don't drop!

[threepot]

I've put a good few hundred miles on since I did that work. Pulls cleaner from low rpm's,but seems to rev higher at speed,as if its not in top gear? The only adjustments I made  to the carbs was to reset the idle mix screws to 2 turns out. They were about 3-31/2 ! I've read that k&n's work better when they start to get dirty? I give it a clean before fitting. Too much airflow? 

[Sin_Tiger]

Can't say I noticed any great difference.

[JayDub]

Unless you changed the gearing, them it's exactly 4,000 rpm  @ 60 mph in top as standard.  Maybe it's just a happier motor now?

[BruKen]

I've put a good few hundred miles on since I did that work. Pulls cleaner from low rpm's,but seems to rev higher at speed,as if its not in top gear? ..........

My brain just BSD'd  Can you describe it differently?

[GavD]

Unless you changed the gearing, them it's exactly 4,000 rpm  @ 60 mph in top as standard.  Maybe it's just a happier motor now?

If I remember rightly TP has a 3 spoke wheel in the back, so if circumference of the tyre is different from a spoke wheel then revs will change slightly from JD's, but I don't think that'd make too much difference.

You may be imagining things TP. Been smoking dried leeks again?

[threepot]

Got STD wheel on Gav.
BruKen..it just feels its reving higher than it was before I did that work   As if I've lost about 10/15 mph?
The idle mix screws wouldn't effect 'high' revs would they? They're now 2 turns out.

[GavD]

Carb tinkering cannot change the revs of the engine for any given speed/gear.  If you're in top and your revs are higher for a certain speed then you must have changed something mechanical i.e. sprockets, gearbox ratios or circumference of rear wheel.

[BruKen]

Got STD wheel on Gav.
BruKen..it just feels its reving higher than it was before I did that work   As if I've lost about 10/15 mph?
The idle mix screws wouldn't effect 'high' revs would they? They're now 2 turns out.

As said carbs will not change rpm for a given speed. It's simply not possible. You're either not engaging top gear or its in the mind. I'd say mind. The brain does a wonderful task of interpreting incoming stimuli but sometimes gets it wrong. I postulate that the engine is now running lean because its not getting fuel and so you are winding the throttle open more. This exacerbates the issue and starts a chain reaction of more throttle twist. Meanwhile the engine tone changes. The two together makes your brain think higher revs.

Now back to basics. The pilot jet and not idle jet you call it is functional until the pressure wave in the venturi closes it. This should be around 1/3 throttle and so as you can reach cruising speed on one third throttle is still very much in play and so their setting is actually the most crucial setting. Next comes the butterfly valve. Is it engaging correctly and shutting correctly. Are the slides free to move without sticking and without punctures in the diaphragm? Check by blowing in each of the large rear ports per carb.  Finally if you've buggered about with jet sizing, airbox mods etc etc. You're on your own. Is the airbox capped on one side? Some people think they know more than the designers and fiddle. Sometimes they get it right, most times they delude themselves. Finally these carbs have a habit of sticking chokes. You cant tune the carbs with the chokes on.

If my postulation is correct I'd suggest you check the carbs are in good order then redo the pilot jet. This can be done ham fisted by running the bike to temp, ensuring idle adjusting screw is tuned out to 800 rpm,and then adjusting each pilot jet individually till the highest rev is reached on each carb/ cylinder. Check with carb balancer and hand held tachometer. After each adjustment wind out the idle rpm adjuster back to 800 rpm.  One all is balanced and highest rpm is reached back off a 1/4 turn rich on each pilot jet screw. Wind in the idle adjuster to 800 rpm. Repeat in finer increments. Rebalance carbs. Set idle 800 rpm. However if you've been fiddling with jets etc this wont solve your issue.

[BruKen]

Before you do all this check the rubber manifolds and airbox manifolds are good and airtight. Sometimes tightening the jubilee clips cause the carb to slip out. This will definitely cause a lean scenario if its the front manifold and mess up the venturi and slide calibration if airbox side.

[threepot]

Thanks BK,I'll take that 'on board' . I checked diaphragms, and they looked OK.  I'm wondering about the kn filter? What effect would it have if it was allowing too much air through,now that it has been cleaned? I took it out of my Super3 before I bought my tiger. I wasn't convinced the s3  ran any better with it in?      And one side is capped.

[BruKen]

These are pure venturi carbs and with no cable driven slide. They work purely off air pressure and pressure bubbles. So just like a tuned pipe on a two stroke any change in pressure will have a dramatic effect on performance. So critical is this triuph wonts sell you just a filter element. You have to buy a whole airbox. Again some people know better. Kudus to them. I'd not advise it. See previous post re front and rear manifolds. Theyre a right bugger and more often than not also the culprit.

[ssevy]

BruKen has given some great suggestions here, and getting your carbs sorted will probably cure it.
I have a couple of suggestions that are definitely out of the box if it doesn't:
If for some reason you are actually revving higher, maybe your clutch is going south? Old fluid may have attracted some water and corrosion might cause sticking?
Are you dragging a brake, which would feel like a lack of power?
Probably neither applicable here, but sometimes random causes can feel like something else?

[threepot]

BruKen has given some great suggestions here, and getting your carbs sorted will probably cure it.
I have a couple of suggestions that are definitely out of the box if it doesn't:
If for some reason you are actually revving higher, maybe your clutch is going south? Old fluid may have attracted some water and corrosion might cause sticking?
Are you dragging a brake, which would feel like a lack of power?
Probably neither applicable here, but sometimes random causes can feel like something else?

Clutch feels OKand fluid is fresh.,and brakes not binding,  Thanks

[threepot]

These are pure venturi carbs and with no cable driven slide. They work purely off air pressure and pressure bubbles. So just like a tuned pipe on a two stroke any change in pressure will have a dramatic effect on performance. So critical is this triuph wonts sell you just a filter element. You have to buy a whole airbox. Again some people know better. Kudus to them. I'd not advise it. See previous post re front and rear manifolds. Theyre a right bugger and more often than not also the culprit.

Now you've mentioned 'air pressure', could this be the cause??

[Bixxer Bob]

   Not a carb man as you all know, but my guess is that would do it.....