Ron Moss - Avanti TT3 - Cylinder Kit - Review & Test.....

[Special X]

Coaster . . . I wasn't on about Ron when I made the racer comment I realize it might have looked like that - sorry Ron. What I meant was that racers would deliberately make their engines uber rich at the bottom of the range to prevent seizure in the event that they have to back the throttle off.

[carbon lammy]

Kit no. 122 up and running only done about 20 miles but pulls really well and very smooth,just need more miles now

[nelson pk]

"Augusto", yes, this will change jetting considerably over what is needed for the same motor fitted with static timing.

What has cracked me up about recent features on advance retard ignitions is that statement that a good advance/retard ignition will allow a motor to run cooler throughout the range (!). This is not true, if a static ignition is set to 17 btdc and an auto advance/retard ignition is set to range from 20 to 16 dbtdc then the motor will actually only run cooler once the ignition has retarded beyond 17 and is working its way towards 16 (or less, depending on range and starting point). From 20 (e.g.) to 17 (same as static) the advanced spark will cause the motor to run hotter, which will need to be made richer to keep the temps down and stop it from getting too hot.

The benefit of the advance at lower revs is that torque and power will increase and help the bike to pull better at these lower revs, however, it will not result in the motor running cooler. Indeed, if you start at too advanced a setting, or have too great a range of advance/retard, then you could well find that your motor is considerably hotter at cruising speeds than it would have been with the 17 dbtdc static ignition!

Auto advance/retard is the way to go if you want a motor that pulls better under a wide range of conditions (so a big thumbs up from me) but running cooler across the range is not what it offers.

Adam

Not entirely true Adam.....................................lets look at an Augusto 6000 for example. if you set your max advance at say 19/20 degrees, when you hit 6000 revs (where motors start to pull really hard and where most people cruise) your ignition would be retarded to about 14/15 degrees which will be significantly cooler that a static set at 17 degrees without sacrificing hardly any performance because the motor at this point is generating enough heat itself.
Most people will get overheating problems when the motor starts to pull hard....about 5500-6000 revs and this is right where an advance/retard system can help against overheating issues.

[Adam_Winstone]

^... totally true... but you've highlighted what I've said about where you choose to start and where you end. What you've suggested is starting with less advance so that more of the range is at the same (or less than) as static would have been. It doesn't actually matter where you start/finish, the important thing to remember is that everything greater than the static position will be hotter. Indeed, if you are never running with extra advance at lower revs then you've missed one of the biggest benefits of 'advance'/retard timing. The advance (whilst hotter) gives the additional low rev grunt, with the retard giving the benfit of cooler running at higher revs... but, as was my point, the motor will not run cooler throughout the range... only when the firing point is less than static would have been. You're supporting my point by suggesting a lower starting point, which results in more of the range (but not all) being less than static.

What a few people with ETGs are also stating is that they're having issue when riding with slower groups, especially as the current trend seems to be towards trying to run torque'y motors on higher ratio gearing. The combination of low revving motors, and then riding with slower groups is causing EGTs to sky-rocket when using advance/retard ignitions, with riders needing to get revs higher to retard the timing back to cooler running. However, this is a completely different issue and unrelated to the point that I was making previously.

Don't get me wrong, I'm all for auto advance/retard ignitions... I just hate people stating that they make a motor run cooler throughout the range, which they don't.

Adam

PS - All good debate though and I'm just talking through the point, not having a pop at anyone or any of the ignitions available

[warts]

So you are saying that in addition to an engine speed component to the ignition advance, there should be a load sensitive component too?
Or ride with due care until such a thing is available?

[coaster]

^...
What a few people with ETGs are also stating is that they're having issue when riding with slower groups, especially as the current trend seems to be towards trying to run torque'y motors on higher ratio gearing. The combination of low revving motors, and then riding with slower groups is causing EGTs to sky-rocket when using advance/retard ignitions, with riders needing to get revs higher to retard the timing back to cooler running. However, this is a completely different issue and unrelated to the point that I was making previously.

PS - All good debate though and I'm just talking through the point, not having a pop at anyone or any of the ignitions available

As always very detailed and thorough input Adam but in the interests of healthy debate and sorting out my very tentative understanding of ignition timing and EGT readings, I THOUGHT that advancingthe ignition kept the flame front above the exhaust port and tended to give higher cylinder temps but lower exhaust temps. Retarding the ignition tended to allow the flame front to enter the exhaust port which lowered the head temp but raised the exhaust temp. Therefore what your being told by the guys being forced to run at lower revs doesn't make sence unless there is some other factor involved such as the static timing you mentioned or maybe the wrong type of retarder i.e. Augusto 7000 or 8000?

Cheers

Colin

[nelson pk]

^...
What a few people with ETGs are also stating is that they're having issue when riding with slower groups, especially as the current trend seems to be towards trying to run torque'y motors on higher ratio gearing. The combination of low revving motors, and then riding with slower groups is causing EGTs to sky-rocket when using advance/retard ignitions, with riders needing to get revs higher to retard the timing back to cooler running. However, this is a completely different issue and unrelated to the point that I was making previously.

PS - All good debate though and I'm just talking through the point, not having a pop at anyone or any of the ignitions available

As always very detailed and thorough input Adam but in the interests of healthy debate and sorting out my very tentative understanding of ignition timing and EGT readings, I THOUGHT that advancingthe ignition kept the flame front above the exhaust port and tended to give higher cylinder temps but lower exhaust temps. Retarding the ignition tended to allow the flame front to enter the exhaust port which lowered the head temp but raised the exhaust temp. Therefore what your being told by the guys being forced to run at lower revs doesn't make sence unless there is some other factor involved such as the static timing you mentioned or maybe the wrong type of retarder i.e. Augusto 7000 or 8000?

Cheers

Colin

Your right coaster. If you advance the ignition timing the EGT's will go down because as you quite righly state its putting cylinder head temp up and exhaust temps down. If you retard the ignition, the flame is still partially burning when its getting thrown out of the exhaust leading to higher EGT's. I have experimented with this and it is absolutely true.

The fact that people are getting high EGT's when at low revs could point to a jetting issue. At low speed and small throttle openings the air velocity going through the carb is slow so will tend to pull a lot on the pilot system as this is further down the carb and designed for low revs/small throttle openings. As you increase air velocity at the same amount of throttle opening (more revs) it will draw a lot more on the atomiser and needle therefore enriching the mixture? So for example if your needle atomiser combo was rich enough but your pilot was a little lean you could get that issue.
Just a theory and an opinion, not gospel!

Adam, we do seem to be on about the same thing with advance/retard sytems but just have approached it from different angles.
As you quite rightly say its how you use the advance/retard to suit your purpose.

[CANbus]

Hi guys, thought I'd give you an update. Number 46 running fantastic, about 300 miles.

Phbh
50 pilot was 55
X13 2nd clip
Av266
40 slide
125 main

Remote filter, JL, agusto

[soosh]

Hasn't anyone done over 1000mls yet and really putting this kit through its paces? What's happened to the Scooterotica built Avanti?

[Muppet]

if anyone wants to lend me their avanti i can do the miles and put it through its paces :baddevil:
muppet,