Idle dropping at stops/lights

[docc]

Being a bone fide old git , I love my mercury sticks. The bumping about, the toxicity, the danger of sucking it all up into the intake, the toxicity,  . . .

 

Oh, did I mention the toxicity? 

 

motowfo and I did a back-to-back comparison with the mercury sticks (reveling in all their toxicity) and the "TwinMax" device. A pleasant surprise to see the digital device is quite reliable.

 

With only two (really big) cylinders, balance is quintessential. I'm not sure entirely what that means, but it's fun to post and, I can say the experience of rolling the throttle on a properly balanced twin is . . .  je ne sais quois . . . ?   Worth every effort!

[68C]

I also have a small jar of mercury tucked way to use when balancing carbs/throttle bodies, I reckon old age will take me before the mercury does.

 

The good thing about mercury columns is their accuracy, assuming gravity is fairly constant where you live.  Oil rig, house boat, San Andreas?

 

If using gauges always connect them with a 'Y' piece and check they both read the same when you suck on the joiner, It's not the end of the world if they don't but would be worth making up a correction chart if you can't adjust them.

[vuzzi]

Not sure how, but 1 turn out on the air screws made the idle stumble even worse. 

 

This shouldn't make a difference at idle since you compensate by a slightly more closed throtle while setting the TSP at 530 mV again.

 

Note that at step 4 in Tom's post, the right hand idle screw should be backed out. Also check that the "choke" is free at the right hand throtle body when balancing and setting tps and so on.

 

Opening the air bleeders in step 2 leads to higher revs and must be compensated in step 4 by backing out the left hand idle screw.

 

Opening the air bleed screws more in step 2 leads to a richer mixture at bigger throtle openings because the slightly smaller throtle opening is not fully compensated by the air bleed screws at bigger throtle openings (no lineair relation).

 

After step 5 the idle rpm's may have changed so step 4 and 5 may need to be repeated.

[thebronze]

Does anyone in the states know where you can buy a carb synch tool?  I like the motion pro w 4 sticks.  Most of the modern bike shops look at me funny when I ask for tools.  Asking for something that bucks the disposable economy doesnt register.

[docc]

Amazon?

[vuzzi]

try this one: http://www.carbtune.com/

 

works great

[moto fugazzi]

I have one of these. http://www.advrider.com/forums/showthread.php?t=701625  Works great, and also tells your RPM's (based on the impulses from the TB's).

I also have a motion pro, and it works well, but you have to calibrate it every time before you use it. Not hard to do, but it adds a little more time to the process.

Ken

[thebronze]

Carbtune is really nice.  I borrowed one from a friend and synched it up around 2k.  The bike is a little better but still has a slight hiccup around 3-4k.  I reset the TPS and everything but the idle trim has been verified.  I'm waiting on a USB cable to arrive.  Thanks for all the help folks.

[docc]

Sounds like it keeps getting better and better! 

[Welshguzzi]

Carbtune is really nice.  I borrowed one from a friend and synched it up around 2k.  The bike is a little better but still has a slight hiccup around 3-4k.  I reset the TPS and everything but the idle trim has been verified.  I'm waiting on a USB cable to arrive.  Thanks for all the help folks.

I used a Carbtune when I had the Ducati - nice piece of kit. When i ahev worked out hw to use it on the Lemans, I will! Any queries are dealt with very swiftly by John Morgan who appears to be a very knowledgable and helpful chap.

 

I have an identical problem with the Lemans - cutting out at stops/lights, and an intermittent and momentary loss of power at cruising speeds. Just applied copper slip to the temperature sensor so will see if this has any effect. I bought the bike with a PCIII fitted - not sure if this has anything to do with the problem.

[luhbo]

I bought the bike with a PCIII fitted - not sure if this has anything to do with the problem.

Disconnect it and watch what difference it will make. This would be a quick answer to your question.

Fiddling with the head temp. sensor often leads to further pain - as the plastic parts of it are rather brittle.

 

Hubert

[moto fugazzi]

Carbtune is really nice.  I borrowed one from a friend and synched it up around 2k.  The bike is a little better but still has a slight hiccup around 3-4k.  I reset the TPS and everything but the idle trim has been verified.  I'm waiting on a USB cable to arrive.  Thanks for all the help folks.

What are you doing when the bike hiccups at 3-4k? Are you using slight throttle  at cruising speeds, or is it moderate or heavy acceleration?

 

I noticed on my AFR meter that there are huge lean spots at 2.8k, 4k and 4.2k, and it's not really noticeable unless you're cruising exactly at those RPM's for a little bit of time. Keep in mind the the factory tach (at least on my bike) reads about 200 rpms higher than my digital tach. Your bike may vary.

 

Ken

[Welshguzzi]

Application of copper slip to the temp sensor bore no fruit......... the problem remains.

Next, changing the ageing FI inlet manifolds, and a new set of relays from Pyro Dan to be installed over the winter.

[Bob Hartman]

I desperately try not to reply unless I've had exactly the same problem, but here we go anyway.

 

When I bought my '02 Le Mans last summer it hadn't been ridden in yonks.  At first it had off-throttle cutting out issues, usually when entering a slow corner or crossing over a lane into a drive.  Or it hunted and stalled at a light.  Or a cough and a stall while downshifting.  Sometimes it was frightening.  But with use it cleared up; all fine now.  Clogged fuelways?

 

One of the usual Ducati fixes for your problem is to look for knackered, clogged or compromised injectors/fuelways.  Could there be some schmutz in there making liars of the rest of your system?