Firstly I would just like to say sorry for posting so many questions recently. I will settle down soon!

My internet searches have netted me a GK76 partsfiche but I can not find an SP one.

Has anyone got one that they could send me?

Can you put the SP's CR gear box into a standard engine? If so, are there any modifications that need to be done?

Would be good to speak to someone who had done it if someone has.

Finding the CR gearbox looks to be quite hard. The other way which would prove to be very expensive but theoretically, could you purchase each part new from suzuki (depending if you had parts numbers) and do it that way?

These are just ideas floating through my head at the moment.

Thanks for your time and thanks again for all your help so far.

If you go to 400greybike.com, there's a reference section containing the parts book for the GK76a. It has parts in it for both the standard and the SP models. There's not a great deal of difference, mainly the adjustable front forks and the close ratio gearbox.
If you like a really tall first gear (60mph plus) and lots of gear changing, go for the SP box, but I don't think there's that much in it on the road.

I don't want to seem thick but I can only find the standard GK76 parts fiche there?

I am looking in the GSXR400 manual thread.

So are the gear boxes interchangeable?

Yes, it has been done.

I belive you can match the SP bottom end, with the non-SP barrels and head.

So you get more mid-range/bottom end power.

lloydspencer wrote:I don't want to seem thick but I can only find the standard GK76 parts fiche there?

I am looking in the GSXR400 manual thread.

So are the gear boxes interchangeable?

If you look in the parts fiche, you can see all the parts for the standard bike, and if the SP uses different parts, they're usually on the next page. For example, go to page 41 & 42 of section 4 of the parts book, you will see both types of shock.
I would not waste my time hunting out an SP box unless I was racing it, and very good at keeping it in a narrow power-band.

EDIT: Actually, I might be wrong, i'll have to check. There's definitely some overlap though.

Cheers for the info Jaicen.

I am used to keeping in narrow power bands.

I own a RS250!

The SP boxes are a pain on the road and very good on the track. If you really want the SP box '4hundred' had a SP engine he was thinking of selling.

Doent the SP motors engine number start K709?