vintage 750 (now 810) racer

thanks man, that's quite a bit of reading to do....super

getting to like the thing and seeing the kind of numbers people seem to be getting, i am starting to consider building the GPZ itself as an 810 (or more?) to compete in the up to 83' open class rather than slotting the top end on the KZ650 and run it as a 750 in the 750 class.

In the open class I'll be up against 110-120 hp GS1000 and KZ100's but with a light monoshock thing with 100hp, maybe it's a better bet. We have just one top speed track where it would be at disadvantage, but on the other slower tracks, an 810 could be the hot ticket. got to think about it.

cheers

TG

Well I'm waiting for pics. So are you gonna mono shock the thing or whats your plan?

thompsonmx100 wrote:

Well I'm waiting for pics. So are you gonna mono shock the thing or whats your plan?

Battey charger found, so soon will be pics,

plans are a bit fluid/confused at the moment. initially I wanted to build a 750 racer with a KZ650 I am picking in three weeks and hop it up with parts from the GPZ I've already got.

Then, when I found out that a new open class with a cut off date of 1983 has been established this year, I am starting to consider building the GPZ as a 810 by itself.

got to decide.

nice problem to have

TG

OK, so I have taken a decision: no KZ650/750 racer, I am going to build the GPZ750 instead.

The italian federation has changed the cut-off date for the open class, so now the 1983 GPZ is allowed and I will eventually run it as open class 810.

While dismantling it I have found it to be so race ready, it will take a lot less work to get track worthy. Frame is super braced as is, gonna change the soft mounts to solid for more rigidity (unless someone has a reason why not)

Reading the gpz750 mods FAQ i tried a GSXR750 rear shock for size and its a 15 minutes job to get it to fit. Chalk one up already!

Here are some pics, in the meantime i want to sort out an adjustable length link for the suspension so I can easily change the rear height.

more info will follow

I manged to weight the bike with the original ex system and some other crap off and it came 160 kg.

Still a lot of stuff to remove but also to add back" carbs, pipe, seat. If i'll manage to keep it at 160 (350 lbs) it'll be real cool

The KZ & GPz 750 motors have a common weakness. That being valve seats

It's quite common to find the valve seats chipped very badly around the outside edge.

On a stock motor, it probablly won't show as a problem during compression or leak down testing because the 45 is usually not chipped yet. It's right on the edge of desctruction though.

If the intented use of the bike is racing with lots of high RPM, the situation will likely progress.

I only see this problem in 750 Kawasaki 4 cylinder engines.

It may not be noticable until you pull the valves and blast out the combustion chambers. Then it shows up plain as day.

What year GSXR 750 shock are you using?

Mark

That's a good choice for a bike.I am building my 85 into a cafe fighter sort of thing. I used a r6 shock to help lower the rear of the bike to match up with the lowered front better. I dont know how crazy you can get with mods but a gsxr swingarm is a pretty easy swap. Looking forward to watching you build this bike.

Thanks for the tips larry, will certainly check the valve seats now.

the shock is from a 1993 GSXR750WP. It's 312mm long compared to the 309mm stock. Had only to narrow the top eyelet bushing to make it go in, bottom clevis hole had to be opened up to 12mm + some shims added as its wider too.

dont know if i want to go too crazy with an s'arm swap, the italian vintage association is quite stiff as to waht mods are allowed, parts form bikes not belonging to the period (up to 83' in my case) are not happily accepted. 17" wheels and floating discs are a no-no.

Not complaining, I think it levels the field and maintains those bike's character.

Wil certainly keep updating.

Cheers

TG

Well damn thats no fun you need another class:P

Yeah, I know what you mean, form an american perspective it must look odd, but that's the italian way.

For good or bad, italy is a very conservative place and it is reflected also in how they approach vintage racing.

for instance, also on the street, a non approved, noisy exhaust system will get you a heavy fine, change tire sizes they will confiscate the bike for illegal changes.

The good side, the food is so good just because they stick to all the old recipes and have perfected them, and the way they keep and restore all ancient buildings is inspiring.

You just have to accept it all if you want to live here.

TG

"You just have to accept it all if you want to live here."....

Yeah sure, must be a bummer to live there... Truly, wholly freaking aye... Smoking Hot Italiano babe....