750 R1 Forks on a KZ650 F2 {1981}

Has anyone ever tried to fit the 1982 GPZ750 front end onto a KZ650 ? Pulled down my sons 1981 650 forks and found two different tubes, damper rods {different lengths}, different springs, and the spring on the damper rods are different lengths, also the fork bushes on one side are worn out. I have a 750 R1 i'm modifying and have the front end spare, its in good condition and it has the same 7spoke wheels and brakes . I'll be taking it all down to my friends shop tomorrow but I just wanted to throw it out there for the American guys to comment over night as there are a few differences, both are air forks but the 650 doesn't have the equalizer tube. I'm in Australia so my night is your day time... Any thoughts would be much appreciated.....

The 650-F2 wasn't sold in the USA, so you may not get a definitive answer. From the All-Balls-Racing fork conversion table the R1 uses the same steering bearings as all of the 650 usa models . The F2 is probably the same. I guess next thing would be to measure the steering head lengths. If they're the same, then you may be good to go. Sometimes the stem of the donor lower triple has to be modified to make the fit. Also & this may not really matter, but from the diagrams at Partzilla the 82 750-R1 uses the same fork seals as all of the 650 models, so the fork tubes are the same 36mm.

You may have already considered this, but the F2 meters may not be a direct fit for the R1 fork assy.

Just use the 750 forks in the 650 yokes ,the 750 R1 has a different top yoke and the handlebars on the R1 are bolted into the forks.If I remember correctly the F2 doesn't have the headlight holders on the forks,so the air tube for the 750 forks should fit,you'll just need a small clamp to hold the tube down.I'm not sure if you took the headlight holders form the R1 if they work with a round headlight.Do ask for any questions,I have a 750 R1 and a 650 F1 in the garage.

ac4 wrote: Just use the 750 forks in the 650 yokes ,the 750 R1 has a different top yoke and the handlebars on the R1 are bolted into the forks.If I remember correctly the F2 doesn't have the headlight holders on the forks,so the air tube for the 750 forks should fit,you'll just need a small clamp to hold the tube down.I'm not sure if you took the headlight holders form the R1 if they work with a round headlight.Do ask for any questions,I have a 750 R1 and a 650 F1 in the garage.

Thanks for the reply. I'll find out today how it all fits, My R1 headlight holders are a bit bent so I may cut the headlight holders off and use the tubes to hold the air tube in place. I'll also have to use the air caps off the 650 as the R1 caps are extended to hold the bars.....

The air caps are all different,forgot to mention that:)I'm not sure if there's enough space to use the R1 caps with a spacer between,otherwise you my have to cut down the R1 caps,or find another way,as the R1 forks have an internal cap,the external one is just for holding the bars.

ac4 wrote: The air caps are all different,forgot to mention that:)I'm not sure if there's enough space to use the R1 caps with a spacer between,otherwise you my have to cut down the R1 caps,or find another way,as the R1 forks have an internal cap,the external one is just for holding the bars.

Quite correct, We may cut down the R1 caps to suit, for the time being I have 2 rubber bungs in place, they actually fit well, but are only a temporary measure.
The forks fit well, they sit above the top clamp the same amount they do on the R1 with the air holes lined up, I'm using 2 clamps above the air line until I come up with a better option. One thing i hadn't thought about was the front 650 guard fitting the R1 forks, turns out they both mount exactly the same..! Another big bonus was that my R1 front end had been done up shortly before I bought the bike, it had new seals and oil and a real nice fine crosshatch on the spotless tubes, I was prepared to completely go through them but ended up bolting them straight in. A very easy swap... Thanks for your insight ac4.....