[92xjunker]

I run GSXR 1100 cams in mine with no issues.

[Molochnik]

Cool! Sounds like I needn't be concerned.

Thanks for your input!

[Molochnik]

In case anyone's interested, I've nearly gotten my bottom end together.
I took all the measurements for which there were specs in the book, and decided using the crank out of my old '90 GSXR motor seemed a reasonable path to take.
Going off the codes stamped into the crank and on the rear of the Tuna case, I ordered new babbits for the journals. Since the Tunas and GSXRs use the same part number for the babbits it seemed ok. After a check with plastigauge, everything appears to be right in the ballpark.
I also ordered new babbits for the rods...just cuz. The original ones seem to have seen enough action, so why not freshen things up.

When the cam chain first snapped and I took the chain, guide, and cams out, I performed a leakdown test and it appeared that #2 was the only one with any issues - 46% leakage and it was huffing out of the intake port. Trying to be proactive I just ordered a chain, guide and two intake valves hoping things would be that simple,
It wasn't until I got a good look at the crank that I saw some teeth were missing and realized the crank was junk.

NOTE: 90 GSXR cranks use a different type of cam chain. and because of that, you also need guides and an idler (for between the cams) from that engine too.

I was aware I was rolling the dice either using a new chain on a previously run crank a cam sprocket set, or simply using the entire rig from the 90 motor. The chain mismatch made that decision for me, so now I have Tuna cam chain for decoration.

Something else I noticed when inspecting the valves was that all of my exhaust valves checked fine - well within spec. However, all of my intakes were showing out of spec on the radial measurement. Some were right at the limit, some were over by .001 - .0015. I performed the same inspection on the brand new ones I had ordered, and they are over by almost a thousandth.
Odd, but since Suzuki is one of my favorite manufacturers, I'm going to believe that it's all OK; I'll just replace the worst of my intake valves with the two new ones.

So, anyway, the primary gears appear to mesh just fine and everything looks like a go for the top end once I get my piston circlips.

[steves]

I'd just be putting that 750 race motor in the bike and be done with it

[Molochnik]

It was a high compression motor; our gas here in California is crappy enough that standard engines can hardly put up with it.

I was never crazy about the transmission in that engine anyway. This Tuna's tranny is pretty sweet.