Few problems with my new kat.

[Big_kat]

I picked up a 94 Katana for cheap and had a few questions. It has sat for a while so it runs a little rough. I was told it has 750 carbs on it, should i rebuild them or switch back to 600 carbs? Also something is weird with 2nd gear. In goes in neutral fine, shifts into and drives in first, shifts into second fine but if you give it any gas it sounds almost like the chain skipping teeth on the sprocket although it's not, when it does this it doesnt accelerate, shift to third and beyond its fine. Any idea what this could be? Any help is greatly appreciated.

[kat600rdr]

I would put the 600 carbs on it and Clean and Sync them. I'm not sure but I think they are different. Just my $.02 As for the second gear, do a quick search on here.. I'm pretty sure that is a problem that has been talked about.. I might be all wrong, so I'll let the professionals chime in.

[Kreylyn]

If tuned right, the carbs can be used, but I would suggest using the carbs designed for the engine.

As for 2nd gear... even doing the work yourself, your probably gonna find that an engine swap is cheaper. To fix the issue, you need to replace some transmission parts, and that requires you to crack the case. A set of gaskets alone for putting it back together is going to run in the $200+ range easily, not counting the parts to fix, oil, misc stuffs, etc...

A known good engine could be had for $2-300 in the 600 and 750 range pretty easily. Invest a bit more and you could get a b12 or 1127 motor in there and really get a performance boost as well.

Krey

[Big_kat]

Do you think the transmission problem is shift forks or worn gears? I'm new to bike mechanics so be easy on me ha.

[arsenic]

It's both. It all starts with a bent shift fork. Then the gear sheers teeth off.

If tuned right, the carbs can be used, but I would suggest using the carbs designed for the engine.

I disagree with this. 600 (BST33SS) carbs on a 750 engine works fine, no problems. 750 (BST36SS) carbs on a 600 engine. That IS a problem.

[Wild-Bill]

...I disagree with this. 600 (BST33SS) carbs on a 750 engine works fine, no problems. 750 (BST36SS) carbs on a 600 engine. That IS a problem.

In other words, you agree. 750 carbs (BST36SS) don't belong on a 600.

[Big_kat]

This is starting to sound like an expensive project. Wheres the best place to start looking for an engine?

[arsenic]

In other words, you agree. 750 carbs (BST36SS) don't belong on a 600.

Yes, I AGREE 750 carbs don't belong on a 600 engine. I DISAGREE that if they are properly tuned they can be used. Because they can't be properly tuned.

This is starting to sound like an expensive project. Wheres the best place to start looking for an engine?

eBay, Craigslist

[Big_kat]

Well, I got some 600 carbs getting shipped to me from a member on here, so that takes care of that. As far as the transmission would it be ok to drive it like it is now?

[Big_kat]

Got my 600 carbs, got the tank cleaned up inside, filled it with gas. Bike cranked up fine. When I blipped the throttle and then let off the rpms would keep climbing. Or if i adjusted the idle it would be fine for about 15 seconds then rpms would increase on there own. Cut it off, looked at the carbs and fuel was dripping from the bottom of carbs 3&4, mostly carb 3. Started to drain the fuel from the tank into a gas jug, couldnt get the pet cock to cut off completely, realized Id forgotten to connect the petcock vac line as well. Once i got the gas all drained and took the tank off I started the bike up assuming the petcock was just overloading everything with fuel. Ran fine, no drips, no hanging/increasing rmps. Thoughts on where i should go from here?

[Wild-Bill]

1. You're going to need to rebuild the petcock. Kits are available for about $25.
2. Your float valves aren't sealing. Hopefully running a little fuel through them will clear that up. Try filling the carbs again and then try to blow into the fuel lines. If you can get air through there then you'll need to track down which carb is leaking and figure out why.
3. The issue with idle speed is probably related to vacuum. The disconnected vacuum line is a huge leak. It's also common to get leaks from the boots going to the airbox. It's tricky enough to get those things sealed up that a lot of us recommend installing the airbox to the carbs before installing the carbs onto the bike. Plug off that vacuum line and see if the problem goes away. If not then start looking for more leaks.

[Kreylyn]

It would surprise the heck out of me if the float leak resolved it's self with cleaner. I would strongly suggest you remove the carbs, pull the bowls, do a simple cleaning of the float needles and seats, make sure the float heights are right, and test them on the bench to make sure they are sealing off correctly with the right fuel level.

Krey

[Big_kat]

Put the tank back on with a little bit if gas in connected the petcock vac line, idles fine, great throttle response. Fuel was barely wetting the bottom of carb 3. I know its a good idea to check the floats and float needles but does that sound like the petcock is just dumping too much fuel in?

[Kreylyn]

Put the tank back on with a little bit if gas in connected the petcock vac line, idles fine, great throttle response. Fuel was barely wetting the bottom of carb 3. I know its a good idea to check the floats and float needles but does that sound like the petcock is just dumping too much fuel in?

If the flaots and float needles are working right, you can't "dump" too much fuel in.

The petcock does not regulate fuel flow at all. It's just set up to turn the fuel off if the bike is not running (vacuum operated) otherwise it's full flow.

The carbs regulates how much they let in.

Krey

[Big_kat]

Sorry if I'm asking dumb questions, I'm not too savvy on carbs and their workings. I'll dig into them tomorrow i guess. Thankyou.