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Hi, ive been told when you have removed the chargeing system from a ZXR400L1, you can remove or grind away the fly wheel so you can replace the bulky casing with a flat plate...now is this true or does it affect the engine balance, can you just grind the fly wheel down a little so it saves weight....any info on this would be great as im building a race bike for next season.

Have a look on ebay (zxr400 race flywheel) there is a modified one there, easy to turn yours into that, hope this help Stu

Jerry wrote:Hi, ive been told when you have removed the chargeing system from a ZXR400L1, you can remove or grind away the fly wheel so you can replace the bulky casing with a flat plate...now is this true or does it affect the engine balance, can you just grind the fly wheel down a little so it saves weight....any info on this would be great as im building a race bike for next season.

Could be true(about fitting flat plate), but you'd also lose the starting system.

IIRC the flywheel is rivetted onto the crank, just completely remove it, don't understand why you would want to fit the smaller one that's on ebay perhaps that's why it's for sale

Rivetted onto the crank ? not stripped mine down for a bit but isn't the starter motor gear mounted onto the small part of the flywheel, thats why you have to use it ? thats if you use a starter
Stu

stu71 wrote:Rivetted onto the crank ? not stripped mine down for a bit but isn't the starter motor gear mounted onto the small part of the flywheel, thats why you have to use it ? thats if you use a starter
Stu

Yeah, you could be right, after writing that I had second thoughts. I just can't remember and it's frustrating me. I just seem to recall the complete flywheel coming off, but, I do have the starter working, maybe old age is getting too me

I'm sure you will have it on because if my old brain works the starter flywheel goes into the spring loaded bollies on the back

The starter hub runs on one-way bearings on the hub of the Alternator flywheel. The bulk of the flywheel, i.e. the magnets and the rest of the high inertia stuff, is rivetted to this hub. these can be drilled easily. The hub is held onto a taper on the crank with a bolt. It is important to either leave this hub in place or block the oilways to the starter assembly or you'll have no oil pressure adn bloy all kinds of hell outta yer engine.

Hope this helps!
Cheers
Noel B.

I Haven't got a starter or generator on mine but i'm fairly sure the end of the crank sticks out further than the engine casing. It would be interesting to know if anyone had gone down the flat plate route because generator covers are getting expensive to source.

Hey,

the bike i have started racing has had this mod done to it, my workmate who raced it before me did it, you have to machine ( not grind ) the end off the crank and drill and tap it ( i think we used a 10mm grub screw and lots of LOCtite hyraulic sealent, we replaced the side cover witha piece of ally plate and a 10 mm piece of teflon lust incase some thing tries to hit it in a bad crash.



PS make sure you have a realy realy good seal on the crank oil gallery, or you will spit No.1 bearing

does this mean the battery wont charge,?

yes, no battery charging and only bump starting mate

bang on, we have fitted a small conector under the tail piece that after a race we wack the warmers on and a charger into the plug, the bike only ran a tiny wee batery from a scooter. this would run for a good 4 hours riding on a test day too with no charge.

does anyone have any idea of minimum weight on a zxr 400,when ya goe this extreme with the choppin!

140kg odd rmkd had his down to i think, might of been less. light tho

I'd imagine there would be a power increase gained from removing the rotor.....................less drag on the crank