GPZ810 Engine Build

Bendix94 wrote:

To injected,

Okay, so you would go with the Mikuni RS34 flatslides?

That means it is nessercary to port the intrance of the inlets a bit? 

what range is the standard GPZ cam in? and will it still be street rideable?

thanks!
 

Personally I don't like the look of the CR inlet spigots. I do like the way the Mikuni carbs are easy to adjust.


RS34s on KZ650 with 831cc (my bike)

As for the port matching it is not needed if you don't want to do it. Just look at the ports with the rubbers on and the carbs off, if there is material to be removed it will make a slight flow improvement. If it can be done without removing the head that is good.

---

This info is from a Megacycle Cam Catalogue :

Stock GPZ-750 A1 .354" lift 250° dur

Megacycle #471-70   .380" lift 256° dur 105° LC 23 btc/53 abc .004"
                                  .380" lift 261° dur 108.5° LC 59 bbc/22 atc .004"
All around street/road performance cam. Wide smooth power band.
GPZ-750 OK with stock pistons and springs. All other models require modified pistons and springs.

Caution: GPZ 750 engines made 1983 and 1984 require special 1.070" base circle diameter in some models.
All other 750 and all KZ-650 engines have a stock base circle of 1.110". To be sure, measure your stock cams

---

The cams above will drop in and not need clearancing (according to Cam Motion) I have experience on cams above .400" lift which hit for sure.
You will also need to change shims and or tip the valves stems depending on what the stock cams measure (see caution note)

Even if you stay with the stock cams replace the valve springs with some new aftermarket units to be able to achieve a high seated spring pressure to avoid valve float. The stock springs after +35 years are probably beat and will give low seat pressure.