Charging

[Al]

If you are currently getting away with no alternator, total loss and swopping batteries between passes i think there is little advantage to fitting one of these except to keep sparks bright and on time which can be an issue with total loss.
If you have the standard rotor and stator there are massive increases in output to be gained and where they claim 3to5 BHP i would argue that with regard to a track bike that it is an under estimate because of the nature of the standard generator, the falling off of revs between gear changes, the maintenance of sparks in the higher RPM's and the quality of sparks in all rev ranges.
J motors will benefit more than the early engines with their compact rotors but there is a great deal going for these race alternators despite the issues with fit and finish.
There is more than enough flywheel effect from the clutch pack to maintain a flow of revs between gear changes so no apparent issues with engine 'dropping off' too low even with high compression motors between gears.
Youre choice is simple i believe in that there is only one option for kicksatrt engines; RPK 3190.
Rob Zed1015 has all the details on his build threads about the issues with oil seal positioning etc and the 'non starter motor' version as this is does not need the oilway blanking off as far as i know because the case is flat at the oil gallery.
AL

[Steve M]

Thanks Al, running a standard alternator but also have a healtech electronic quickshifter so revs don't really drop between shifts. Sounds like something I should look into for next season.

[zed1015]

Thanks Al, running a standard alternator but also have a healtech electronic quickshifter so revs don't really drop between shifts. Sounds like something I should look into for next season.

This is the RPK3190 kickstart only version that i run on my alloy cafe.
The oil gallery issue of the starter motor version isn't present with this one and once i sorted the misalignment of the rotor and stator ( 6mm off center of the magnetic field ) which severely affected the output it's been faultless ( touch wood ) for the 10 years i've been running it.
The lighter rotor makes a noticable difference to the engine response too .

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[Steve M]

Thanks zed1050. Every day is a school day as they say. I've been looking for ways to go faster without putting anymore stress on the 1260 motor, hence the quickshifter, plus ceramic bearings, non o-ring chain, losing dust seals, etc to reduce chassis friction. The alternator mod looks like my next thing.....

[Al]

For completness there is also the self generating CDI version STK 310 which is oddly cheaper for some reason https://www.electrexworld.co.uk/acatalo ... ml#SID=942 and historically there has been this type of arrangement which you can still occassionally find https://phaseone.co.uk/for-sale/

https://phaseone801859382.files.wordpre ... G_7090.jpg
I dont see that the former would have the facility (output wiring) to run an electronic quickshifter for which you would still need a battery and the latter would need a Lucas or Wassel rotor and stator plus a Reg /Rec and a battery but both would have greater rotational inertia if that was a concern when using the quickshifter (shift interrupt).
I looked at the quickshifter for mine because i have Dyna 2000 which has the facility to dump the ignition output to earth on contact so a non electronic version would have been suffice. Thats as far as i got with it so far.
AL

[zed1015]

I would add that with the STK310 self generating ignition you can't spin the motor fast enough to produce a spark with the kickstart ( been there tried that ) and you would either need starting rollers or bump starts..

[Steve M]

Thanks both Al and zed1015, that has been a great help. One final question , I am presuming from the catalogue and the picture of zed1015's bike that the RPK3190 is designed to run with no outer cover. Is this correct?

[zed1015]

Thanks both Al and zed1015, that has been a great help. One final question , I am presuming from the catalogue and the picture of zed1015's bike that the RPK3190 is designed to run with no outer cover. Is this correct?

Yes! It bolts to the cases with the stock gasket and has an oil seal on the crank behind the rotor.
I modified a spare alt cover to act as a stone guard etc.

If you decide to buy one then read post 389 and onwards in this build thread regarding the rotor / stator misalignment , undercharging and oil seal position.
It will save you some grief further down the line..
viewtopic.php?f=7&t=14312&start=375

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[Steve M]

Brilliant, thanks. Looks like it will be my little project for the winter!

[Al]

Just had a chance to test the location of my rotor to stator situation. I replaced the rotor last year (reasons a little above this post).
It was apparent that when putting the outer casing on,.. the cover with the stator would be snatched out of my hands and slam itself shut. I took the rotor off and put three x 1.5mm washers behind it and tried again. With that extra distance the cover would resist closing fully and would spring back out just a little so i removed one of the 1.5mm washers and that made putting the cover on 'neutral'... no pull and no push required to have it seat correctly. So i have ended up with it being 3mm further out than fully home. These tiny rotors are not mass produced so i cant say if the bias of 'magnetic centring' is the same for all.
There is still plenty enough room for the crank centre bolt head not to hit the outer cover on the inside.

AL

3mm gap