Engine "pop" blipping throttle from idle
 

Now that I go to track sometimes with my Aprilia RSV 1000, I try to quickly accelarate (clutch lever engaged of course) before descending a gear to reduce engine braking and control rear wheel.

On the road, I'm training to do it right with my VTR.
But, 20 to 30% of the time, when I use to throttle to take more revs just before downshifting : the engine does a "pof" sound and does not take revs.
Am I doing something wrong ? (It never happens on my RSV 1000 ..)

Huh??

Re: Changing gears down with gas, engine sometimes do a &quo
 

I may have badly explained ...

To reduce engine breaking and avoid blocking rear wheel during high braking and quick downshifting, you do have to :

- brake firmly and doing that :
- dis-engage the clutch
- Open throttle for the engine to take more revs (as it is like on neutral)
- down shift
- re-engage the clutch
and so on until you reach the right gear.

You cannot downshift quickly and avoid rear blocks if you don't do that specially on a big V-twin bike.

My problem is : Sometimes, when I open throttle, the engine does not take revs and instead do a "pop".

Yes, I see what you mean. Rather than repeatedly engage the clutch for each gear (the slow way) I stay on the gas as much as possible, brake as late as possible, then crack the throttle to match wheel speed and decrease engine braking after downshifting.

Regarding the pop when you blip the throttle, my guess is that you need to shim the needles in your carbs, to richen the low-mid mixture.

Re: Changing gears down with gas, engine sometimes do a &quo
 

You think I need to shim up my needles ?
I'm completetely stock (airfilter/exhaust/jets/pilot screws/etc)
It's a 2001 model.

Can you explain a little more how you brake and downshift ?
You downshift several gears without reengaging the clutch ?
So You don't use engine breaking at the rear wheel ?

I admit it depends how quickly you arrive at the turn, at which speed and gear ration you can enter it, sometimes I downshift 2 gears at a time, sometimes I do the whole thing, sometimes I just downshift normally ;-)

I've to work to do the whole thing right, so I'm training with the VTR on the road ;-) But sometimes the "pofff" sound occurs and it is even more ridiculous on the road ...

It is a common problem with the needles. I would guess it is for US emissions, that the mixture be lean. There is also a lean area around 7k RPM, where emissions measurements are made. Rejetting is helpful even with a stock exhaust. The easy fix is to install a thin washer under the needles as described in other threads here.

When downshifting, blip the throttle before each downshift (standard practice), hard to do when hard on the brakes, no clutch between downshifts, then just cracke the throttle and release the clutch slowly, while entering the turn. A lot of stuff going on at the same time.

I have found that to eliminate the problem of wheel hop with the big twin. It is a lot to think about and takes practice. Sliiper clutches are for sissies :P

Yep lots of stuff :wink: Have to train on road with my VTR ! :wink:

What do you mean by "cracke" ? open throttle a bit and keep it or 0 throttle opened ?

I just mean the throttle is not closed as you let out the clutch. I can't say specifically how much. I do it by "feel".

Re: Changing gears down with gas, engine sometimes do a &
 

ok.

I has tested it again and take care of it returning home this evening.
It does it from idle too at neutral "blipping" the throttle.

It doesn't "pop" at low/mid temperature but after riding into traffic/town and at high temp (100°c) it does several time.

Does it tell us something more precise ? :roll:

If I'm not mistaken, if it's better when it's cold, it's probably rich, although that would contradict what's been said. Is it possible the PAIR could be the culprit? My bike seems to rev fine, it's mostly stock. I don't hold the throttle open though, but sort of "rip" it to match the revs, and let out the clutch when it's where it wants to be

Re: Engine "pop" blipping throttle from idle
 

I've seen another thing :
blipping throttle at neutral, the revs seems to return to idle pretty slowly...

Re: Engine "pop" blipping throttle from idle
 

Is the pop I have blipping throttle also called "carb backfire" ?

I think the "hunting" returning to idle is a mixture screw adjustment?

jschmidt?

I like that suggestion. It makes me realize I've been too ginger with the rev matching. That should help a lot with corner entry. Thanks!

sure thing, I love downshifting manual trannys, and the satisfying noise of blipping the throttle. Just make sure you don't overshoot your target revs, or when you let out the clutch 'while the revs are on the way up past' it will jerk ya, while if you're too low, the opposite thing will happen.

Happy downshifting!

Re: Engine "pop" blipping throttle from idle
 

Pair system disabled, carbs sync done.
No changes (carbs was pretty well sync'ed)
Blipping throttle at idle, returns to idle with a small step at 2000 rpm.