Ignition advance

[tomacGTi]

I know that you can slot the pickup on the LH cover to get something like 2* advance. Reading around on the wonderful internets gives plenty of mixed reviews all around.

Is there any benefit/loss to doing this?

Basically a free and reversible mod but I'd like to know before wasting my time.

[mosquito]

Interesting idea.  Have any links handy?  Dunno, but guessing:  

Assuming the stock timing is exactly right throughout the RPM range and the bike is stock it'll make it always run worse.  If the mix is substantially richened -- whatever that means, but maybe rejetted for cold, dry weather at sea level and an exhaust change, or maybe including an overbore -- it seems like it would help because a lot more fuel could need more time to burn.

How much timing would need to be changed for best performance though would be tough to guess at without research.  I don't know if a 2° advance counts as a roughly 13% change (assuming previously at 15° BTDC) or a 6% change (assuming 15° BTDC + 20° ATDC for completing the burn).  Changing the main jet from 102.5 to 107.5 should be about a 5% change in the amount of fuel, but I don't expect the relationship in fuel change to timing change to be linear at all.

Knowing nothing else, if I had a heavily modded bike I'd probably want to figure out some way of making it adjustable without having to remove the cover so I could actually tune it.  Figuring out how to do this through the case or cover and seal it would be tough, but so would building an electronic pulse modulator to change the signal the igniter actually receives.  (And that would probably run into limiter issues.)

If you do it, I'd like to hear the results.

ETA:  Just looked for and found this thread: http://forums.banditalley.net/index.php?topic=7767.0 . That makes me think the best thing to do would be to find an adjustable igniter.  Unfortunately I'm not finding diagrams / details about the internals of them to know how easily making one adjustable would be.  I'm expecting it would require changing the ROM / map each time.

[tomacGTi]

When you advance the timing, you bring the motor up on it's advance curve sooner, advancing the flame front. This usually results in a little more torque below the HP curve as well as a more responsive throttle.

The downside is you're stealing from Peter to pay Paul: the advance you have below will take away up top, so there is a delicate balance between it all. Typically, the faster the engine spins, the less advance it needs to get the combustion started which is why if you advance too far, you'll ping.

5* advancers are the norm for the bigger Bandits, I know if you modify the pickup on the 400, you can gain +2*. I'm just wondering if it's worth it from a performance point of view. I know some have done it here before, I just want to know if it's worth the trouble.

[Red01]

Since it is free and reversable, the only thing it costs you is the few minutes of time to give it a shot, so why not?

[tomacGTi]

Because it's 55 and raining and I don't have a garage...

But I did modify a spare pickup I had from an old "ventilated" case.

[tomacGTi]

2* made it the midrange smoother and gave the bottom a little more grunt.

The downside is that up top, it didn't have the same power as before, it felt flat in comparison. Basically, you're robbing Peter to pay Paul: since you need less advance the faster the motor spins up, the torque starts sooner down below since the firing event happens sooner (makes the motor think it has more compression). The extra advance makes the computer hit maximum advance sooner so the top end hit occurs earlier and thus feels flatter. If the meaty part of your powerband happened at 10k revs, it'll now hit at around 8k. (rough example).

You'll also have to run a slightly higher grade fuel or high test to avoid ping and the bike will run hotter as well. May be harder to start but mine thumbed up with no issues but it was colder out (50* or so).

Bottom line: great mod for the city but not if you like to live above 10k revs. I'm going to stick with stock.

I think since the little Bandit's compression already starts at 11.8-1 instead of it's big brother's 9.5-1, the effect isn't as effective.

[gsxr400 racer]

Just leave it stock saves on the gaskets did not make enough difference to keep on my bike

[tomacGTi]

Now you chime in, where ya been brother!

[gsxr400 racer]

Oh trying to keep my head afloat with this god for saken seasonal business and the horrible economy. All my time is spent sitting at the store trying to generate money to take care of present and very past due obligations. But im always reading on here you just wont catch me answering any carb questions LOL