How to dial-in my 91 GSXR swapped Kat

[Hrutkayb]

Hi Everyone,

This is my first post on here after introducing myself in the introductions section, so I'm hoping this is in the right place.

I recently purchased a 91 Katana 600 with a 91 GSXR 750 swap. The swap was performed by the original owner, so I'm still trying to piece together exactly what parts belong to what bike. I enjoy working on bikes and this one in particular needs some tlc. I want to make sure that I won't be causing any potential damage by riding it while I save up some cash for the necessary parts.

Here's (to the best of my knowledge) my current setup:

600 kat frame
600 kat electronics?
600 exhaust (full vance&hines)
600 kat carbs (k&n pods, no airbox)
600 kat chain and sprocket (-1, +3 setup, 520 chain)
750 engine
750 oil cooler and lines

First on the list is to upgrade to stainless brake lines, the fronts are pretty spongy.

Second is to replace the chain and sprocket back to the stock settings, but do I use the settings for the 600 or the 750?

Any potential problems with my current setup, anything else that I should change for optimal performance?

Thanks!

Brad

[92xjunker]

Yeah, two issues stand out. 1) 600 KAT carbs on a GSXR 750 motor, not gonna go well. 2) pods on KAT carbs, debatable . Locate the correct GSXR carbs, it will run much better.

[Kreylyn]

If the rear wheel is OEM to the frame, then you would want the pre 600 specifications for chain length and sprockets. The tooth count is entirely up to you though. I personally would go with a 15 tooth front, then pick the rear tooth count based upon what kind of riding you do mostly. 50 for lots of spirited but lower speed (lots of curves) 45 for stock, 40 for only highway and lots of touring... or somewhere between those numbers. You will have to adjust your link count for the new sprocket counts, so keep that in mind. It's no big deal, just don't order one too short.

I'd ditch the pods and use OEM Kat airbox personally.

PO's lie... so just curious, but have you personally verified the engine truly is a 750, and it's a GSXR engine?



Krey

[GSXFJim]

PO's lie... so just curious, but have you personally verified the engine truly is a 750, and it's a GSXR engine?

True this, early GSXR's have the clutch actuator on the right hand side of the engine for cable units, some years I believe had hydraulic units as well.

Depending on the year of the GSXR engine you will either have a 14-42 (85-87) or a 15-45 (88-89) or 15-43 (90-92) all are #530 chains.

Which combo to run?, that's going to depend on your riding style. The weight of the kat is something to consider since the GSXR was lighter.

The popular combo from me for the kats lately is a 15-50, #530 chain. This will give a bit more off the line but will rev higher at freeway speeds

If your interested in a set of sprockets, shoot me a PM.

...and just an FYI, all GSXR (thru current year), Katana, Bandit, SV and TL's use the same counter shaft sprocket spline pattern.

[Hrutkayb]

Thanks for all the awesome info guys, especially the chain and sprocket specifics, really appreciate it.

Is it o.k. to run it with the 600 carbs for the time being, I'll just have poor performance and atrocious fuel economy, or will it seriously screw something up internally in the engine and I should just park it until I get the right parts?

Here's some pics:




Thanks for offering some insight on how to confirm the engine.

Cable clutch on the right side. (Check)



749 cm (check) Also looked up the engine code, looks like it's either a 90 or 91?




In regards to the clutch cable, I don't think this is any good. I've noticed that it feels like it's not engaging all the way, jumps forward when I start it in first and have a heck of a time getting it into neutral at stop lights.



And lastly, previous owner told me I had to remove the headers in order to change the oil filter, which makes me think this is the Vance&Hines exhaust for the 600 Kat engine. You can see in the pics how there's really not much room between the filter and the headers.

[Kreylyn]

600 carbs-


No damage to be done. Shouldn't cause a problem with fuel economy even. It will reduce your top end speeds/power, but at the same time give you more low end grunt. These differences will be so minor, that you probably would not notice a difference by seat of pant feel. Optimally I would suggest you go with the larger bore carbs eventually, but... no, no issue now for you to use what you got till then.


Exhaust - Nope, not a 600 exhaust. That is definitely for the 750 engine. I can see that clearly by where the collector is located. It's probably for the GSXR specifically with how the down tubes are spaced with no clearance for the oil filter. They probably needed more clearance towards the sides on that frame/fairing setup, where as on the Kat 750 exhaust you have a slight gap in the center for that oil filter to slide right out.


Clutch cable - I'd pull that off the bike entirely. With it off, check how the cable slides in the sheath. Lube it well if needed. If it won't easily slide in and out all the way by only gripping the pivot end of the cable with 2 fingers with out being really hard to pull, or it won't go in with out bending/flexing the cable, all after being lubed well... it needs to be replaced. Once you have verified the cable is good, then do a clutch adjustment.


Krey

[Hrutkayb]

That's much appreciated Krey. I was worried about running it, thanks for setting my mind at ease with all the helpful info.

Never thought I'd have to remove the headers to change the oil on a bike?

I'll give your advice a shot on the clutch cable.

Thanks again!