my quest for more power: total loss and ignition advance?

[nz_gixxer4_racer]

Hey guys,

as me wee gixxer is dedicated race bike (for now) and as you cant have enough power, leads me to wonder whether its worth running total loss and/or advancing the ignition, and how it is done.

Total loss: So I ditch the generator? This is on the clutch side? Any thing else needed to do?

Ignition advance: is it adjustable? if not, can I modify it to adjust? This is the lefthand side/stator side isnt it? clockwise advance, anti-clockwise retard?

Thanks is advance

[M1KE]

You can file the pick up to get you a bit more advance. total loss remove the flywheel and the stator. Bike will be rev happy but lose speed quicker over hills etc.

[youroddsox]

Yeah to make the system total loss just remove the alternator and the rectifier. I warn you that you may only gain 1hp from this. If you reduce the flywheel mass as racer says then the engine will rev quicker but you may have to do a load of practice starts to get good off the start line. Its not a huge gain in my experience on engine power but does reduce the bikes weight. If your doing that you may as well get rid of the starter motor and bump start it instead. If you really want to go to town, change the battery for a lightweight ni-cad (like a heavy duty remote controlled car) charge the battery to around 16V put voltage regulators in to reduce it to 12V so it doesn't fry anything, this will ensure you are above 12V for the whole event. This is what we do in British 125's, sheds around three quarters of the battery weight.

On the ignition side of things, the advance can be changed by ovalising the holes on the pickup and filing the side of the mount to shift the crank sensor forward. I think you can get around 4 degs by doing this, after this you would have to change the electronics. I did hear from somewhere that an extra 2 degs advance yields a fair bit, didn't have mine dyno'ed so couldn't tell you. Did make it slightly harder to start.

Before you do this I would recommend that you get your fuelling fully sorted first as this is generally far more sensitive than ignition. To do this properly you would need to lay your hands on a lambda sensor and a dyno.

Hope this is of some help. Hoping when I stop being a student I will have some money to go to town on my road and race gixers. Think fuel injection will be the next step.

[nz_gixxer4_racer]

haha Im a student too which is why im interested in 'free' mods!

the idea of running total loss is growing on me. a 1hp improvement is still a 1hp improvement and is approx. a 1.6% increase in output. also the the quicker revving should add to quicker lap times (but may also punish unneccessary roll-offs - a good incentive to keep it pinned!)

question: by "shifting crank sensor forward" does that mean clockwise (to direction of stator)?

1 hp here and there may make all the difference to a 400!

youroddsox: great info there! so in place of the standard battery you can run an RC car type battery pack with a voltage reducer and it'll all run fine? do you need to swap or quick charge for every session?

I would love to throw some money at the motor: flatslides, overbore, cams, porting but once you start its hard to stop! It would be fun though!

I race against one such zxr 400: flatslides, overbore to 450cc, sp cams, total loss, avgas mix fuel, ohlins front and rear. it kicks out 80hp at the wheel! and it gives supersports a hurry up! fun but costly!

[youroddsox]

Luckily my degree is in motorsport so I still get to play with some pretty cool stuff without paying for it!

Because you want to advance the timing you need to pick up the signal from the trigger wheel earlier. So because the crank is rotating anti-clockwise if you look from the pick-up side you will need to move the trigger in an anti-clockwise direction. The engine I don't think is especially detonation sensitive so it should be alright.

On the total loss point of view. First thing you need to do is check the current draw whilst running. You probably won't be able to run rad fans as they are too high draw. At an estimate the running draw is probably between 4-5 amps with a minimal system. By knowing this and your race distance you should be able to spec an RC style battery that will last the amount of laps you need. You should be able to find the calcs on the net. In my opinion its probably easier to run a 'standard' battery and just charge it a little higher. Also the cheapest option!
You would probably have change the RC battery each session as they take a while to re-charge.

You can spend a lot of money pretty quickly on this. I am sure with the standard carbs you would be able to get good power if you could sort the fuelling. The flatsides would just make it more consistent across the range. Cheapest way to get more speed is try shedding weight out of everything.

Good luck with it, those Ohlins would be nice!

[youroddsox]

Just re-read this and noticed that I said the sensor needs to move anti-clockwise instead of clockwise, ooops.

[nz_gixxer4_racer]

Just re-read this and noticed that I said the sensor needs to move anti-clockwise instead of clockwise, ooops.

haha, yeah I figured as such.

Well. Ive been delayed by the fact that I cant get it started!!
Made a jetting change (main jet, float height, clip position) and modified the twist tube to reduce the turn and it wont fire!
new plugs and charged battery havent made a diff. plugs spark on the outside of the motor. awaiting my engine compression gauge to arrive to test compression.
feels as if fuel isnt getting through. float bowls are filling. tank is breathing. have double checked one carb and I nothing is out of place. Have reverted to previous jetting.

Just gonna test compression (to eliminate a mechanical failure) before taking it into a shop.

Any ideas oddsox?