Engine mod

There seems to be more and more members appearing that are racing the ZXR400 so i've created a special section just for you to show off results, discuss meets etc etc.

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Jerry
Posts: 32
Joined: Mon Dec 10, 2007 8:05 pm
My Bike: ZXR400 Race bike

Engine mod

Post by Jerry »

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.
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stu71
zxr400 oc member
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Posts: 22
Joined: Sun Jun 24, 2007 7:17 am
My Bike: ZXR400sp
Location: S.Yorks

Re: Engine mod

Post by stu71 »

Have a look on ebay (zxr400 race flywheel) there is a modified one there, easy to turn yours into that, hope this help Stu
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Ballsout Racing
L-plate hell
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Joined: Sun Nov 07, 2004 11:04 am
My Bike: tomos moped
Location: Most race circuits ;-)

Re: Engine mod

Post by Ballsout Racing »

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 :smt017 perhaps that's why it's for sale :smt017
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stu71
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My Bike: ZXR400sp
Location: S.Yorks

Re: Engine mod

Post by stu71 »

Rivetted onto the crank ? :smt017 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
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Ballsout Racing
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Re: Engine mod

Post by Ballsout Racing »

stu71 wrote:Rivetted onto the crank ? :smt017 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 :smt005
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stu71
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Joined: Sun Jun 24, 2007 7:17 am
My Bike: ZXR400sp
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Re: Engine mod

Post by stu71 »

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
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noelb
Posts: 61
Joined: Tue Oct 16, 2007 1:02 pm
My Bike: ZXR4H , H'Berg , BMW R12S
Location: Oirelannnnddd!, D'middle'o'

Re: Engine mod

Post by noelb »

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.
billy big skid
Posts: 27
Joined: Thu Jun 28, 2007 6:29 pm

Re: Engine mod

Post by billy big skid »

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.
xlr8_07
Posts: 50
Joined: Fri Feb 27, 2009 8:30 pm
My Bike: zxr400 h1
Location: Wanganui, New Zealand

Re: Engine mod

Post by xlr8_07 »

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
patlangan
Posts: 16
Joined: Thu Mar 12, 2009 11:16 pm
My Bike: tomos moped

Re: Engine mod

Post by patlangan »

does this mean the battery wont charge,?
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jake
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Re: Engine mod

Post by jake »

yes, no battery charging and only bump starting mate
xlr8_07
Posts: 50
Joined: Fri Feb 27, 2009 8:30 pm
My Bike: zxr400 h1
Location: Wanganui, New Zealand

Re: Engine mod

Post by xlr8_07 »

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.
patlangan
Posts: 16
Joined: Thu Mar 12, 2009 11:16 pm
My Bike: tomos moped

Re: Engine mod

Post by patlangan »

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

Post by jake »

140kg odd rmkd had his down to i think, might of been less. light tho :smt001
cargo
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Re: Engine mod

Post by cargo »

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