GSXR400/1135 hybrid race bike '80s

[F5 Dave]

When we did my 500 into RG250 frame which is kinda similar we plated over the inside webs around swingarm area too. It was Damon's idea, not sure if its added much rigidity but I defered to his much greater experience doing that sort of shit. Along with a few more points, like from the bottom cross diagonal closing the corner in to side frame rail.

[roogazza]

this will give some of you two stroke fans a chubby ? Made contact with an old friend last night in Waikanae. He's just completed this and is working on a second one.
Gunna zip down and catch up with him soon .He's a great bike builder and I thought he had given it all away. Good to hear he's still at it.
342599

[malcy25]

this will give some of you two stroke fans a chubby ? Made contact with an old friend last night in Waikanae. He's just completed this and is working on a second one.
342599 Nice job, still don't miss mine one bit!

[sidecar bob]

Nice job, still don't miss mine one bit!

Ok, why is that? Bit flat compared to a 750 two stroke GP bike?

[Grumph]

Ok, why is that? Bit flat compared to a 750 two stroke GP bike?

I don't know his reasons - but from observation, when they were proddy raced here, they hurt more good riders than anything else i've seen.

[roogazza]

I don't know his reasons - but from observation, when they were proddy raced here, they hurt more good riders than anything else i've seen.

They used to say that about Mach4s' too Grumph,but for me and mates we thought they were ok for the time..(Mach3s were called widow makers ). Keen for a ride on the RZ 500 tho. My mate only builds them,no interest in riding ?????? I was always his road tester lol.

[F5 Dave]

I have a mate with one in his lounge room. 17" wheels USDs, spannies. Hes changed tack and has a reverse 3MA TZR frame. Just biding my time. . . .

[Kickaha]

Keen for a ride on the RZ 500 tho.

I rode my brothers one Chch to Dargiville and back on tour one time, wasn't a bad bike for it but very hard to stay at legal speeds

[Grumph]

Back to the subject of the thread. The GSX750 engine is apart. Owner says, show what's done.

It has 69.5 ART forgings - 804cc I make it. They're heavier than the 70mm Wisecos I used in a GSX400 a couple of years ago, but they would have been state of the art at the time. Rings and bores are good. One stuck valve as can be seen in the pic. Cams have no markings as to grinder and are not buildups. If they're aftermarket as previously stated, they are done from blanks. Unusual. They are also in on standard marks - without slotted sprockets. Again, unusual.

The drive setup on the alternator end is empty. Filling the hole at the top is an oil pump. My guess looking at the two blanked off holes at the front of the sump is that it was going to be used to circulate oil through a cooler. Probably found to be not needed.

Crank bearings look quite good and reusable. Probably won't split the crank. Box looks good. Clutch appears brand new. Doubt if it had much use at all.

Other than the stuck valve the only problem is one clutch cover screw broken off - bloody single use alloy capscrews, I hate them. It'll drill out.
Head and base gaskets are reusable shim alloy. Need clutch cover and sump gaskets.

[sidecar bob]

Legendary effort, I did say very non urgent & you have had it less than a week.
The blanked off cooler lines were me. I took the cooler off & didn't want to get a yelling at from the free courier for leaking oil all through his van.
Very pleased at the minimum of work required.

[F5 Dave]

Ex valve on 4 looks pretty 2nd hand but could be picture .

[Grumph]

Legendary effort, I did say very non urgent & you have had it less than a week.
The blanked off cooler lines were me. I took the cooler off & didn't want to get a yelling at from the free courier for leaking oil all through his van.
Very pleased at the minimum of work required.

Did the lines go to and from that pump or just the sump ? Makes you wonder if the pump was ever used.

Easier to do several engines at the same time. You're always waiting for something on one of them and if bits have to go to town, better to take everything in one trip.

[sidecar bob]

Did the lines go to and from that pump or just the sump ? Makes you wonder if the pump was ever used.

Easier to do several engines at the same time. You're always waiting for something on one of them and if bits have to go to town, better to take everything in one trip.

The rear pump was blanked off, but was originally installed as an additional cooler pump, that was never used.
I'm trying to get to the bottom of it, but while the chassis is the replica, I think that's the engine out of Robbies bike & that was once the Mercury magneto drive, which was later removed.

[Grumph]

Well, this was an unexpected surprise. Stripped the head, inlets all fine, cleaned up well, but the exhaust valves...All have stem damage. Badly pitted just at the end of the valve guide area. Only seen this much pitting on vintage engines previously.

Doubt if it's from sitting. I'd pick it's a chemical reaction to this steel from whatever fuel it was on.

Sorry bout the pic quality. Very hard to get it right with my camera.