Running Rough

[Da_Pipe]

First, Thanks to everyone who takes the time to post their problems and solutions and how-tos. It has made things a lot easier for me.

Now then, a little background. I bought a 2004 Katana 600 a few weeks ago with ~7500 miles on it. Guy I was buying it from (second owner) said all he had done was change the oil when he got the bike and that it had been sitting for around a year, maybe a year and a half. I had a mechanic at a local Suzuki dealership give it a look over and make sure there was nothing major wrong that I was overlooking before I bought it. He pointed out some general maintenance stuff and said I might have to get the carb rebuilt because it was running rough and was a little sluggish. He said I could run a few tanks of gas through it and that might solve the problem.

So I bought it, changed the oil, put new spark plugs in, cleaned the air filter, ran a tank of gas with sea foam through it, got new tires, put new brakes on the back wheel, lubed/tightened the chain and ran another tank of gas through it. It seemed to run a little better after the seafoam and fresh tank of gas, but it still was rough and would hang for 10 - 15 seconds when you gave it a little throttle and let off. So I checked the compression, just on the off chance, and it was within a few lbs across all four. Figured it was the carbs since it had been sitting for so long without stabilizer. I pulled them off and cleaned them, I read Carb 101 and followed it as best as I could, only I didn't touch the a/f screws because the plugs were still in. The pilot jet on carb #1 looked clogged and there was a little crap in the bottom of the bowls but other than that it looked pretty clean. Put new viton o-rings in the bowls, checked the float height and put on new bowl gaskets with rtv.

Put everything back on, hooked up a temp gas tank and it fired right up with no problems, but it was still running rough. Tried to do a synch with a homemade manometer, but I never could get the readings to stay stable. I would get them the same then after 15 - 20 seconds it would slowly swing one way or the other for a little bit then swing back. I got them as close as I could. Then I started fiddling to see if I could find anything obvious. I noticed that the tach bounces around about 100 - 200 rpm no matter how many rpms it's turning. So I'm thinking vacuum leak? But I read someones post saying that the valves could cause problems that seem like vacuum problems. So my next steps in order are: check the valve clearances, check the boots for leaks, clean the carbs again.

Note: The idle screw is turned all the way on and has to be for the bike to idle sort of ok around 1200rpm. Incase that's a flashing neon sign to anyone.

On to my questions.

1) Do you HAVE to replace the rotor cover gasket when you pull it off or can you get by with the old one and some rtv if it's in ok shape?

2) Do you have to replace the bowl gaskets on the carb everytime you pull the bowls off?

Any comments, suggestions, or maybe brilliant insight that would solve my problem in 5 mins would be greatly appreciated.

And sorry it's so long but I figured it was best to give as much info as possible.

[brentwoodkris]

I had a really rough idle on my 97 for the longest time. First thing KR members suggested was a vacuum leak from one of the many seals. My problem ended up being a float height and synch issue though as my local mechanic got it tuned up for me. I'd check to make sure that all of your vacuum hoses, gaskets, and seals are in working order first.

[Kreylyn]

Now then, a little background. I bought a 2004 Katana 600 a few weeks ago with ~7500 miles on it.

... I pulled them off and cleaned them, I read Carb 101 and followed it as best as I could, only I didn't touch the a/f screws because the plugs were still in.

....So my next steps in order are: check the valve clearances, check the boots for leaks, clean the carbs again.

Note: The idle screw is turned all the way on and has to be for the bike to idle sort of ok around 1200rpm. Incase that's a flashing neon sign to anyone.

On to my questions.

1) Do you HAVE to replace the rotor cover gasket when you pull it off or can you get by with the old one and some rtv if it's in ok shape?

2) Do you have to replace the bowl gaskets on the carb everytime you pull the bowls off?

Any comments, suggestions, or maybe brilliant insight that would solve my problem in 5 mins would be greatly appreciated.

And sorry it's so long but I figured it was best to give as much info as possible.

Might be a typo, but there is a "carbs 102" that is for your carbs. Use that, as there are minor differences.

Next steps look good, and sounds like a logical process to resolve the issues.

It's possible to get by with out replacing it, but... that's alot of work to chance it's not gonna work and have a leak/need to replace it. Up to you, which is more worth the cost of the gasket. Piece of mind it's right to start with, or ... a few more hours of work & still having to replace it on a 50/50 chance.

I've never had an issue with needing to replace the bowl gaskets due to taking the bowls off alone. Only need to replace them if they are showing signs of wear, cracks, dry rotting, etc... They should be soft, pliable, and still retain some of their round cross sectional shape. If they are very squarish on the cross section, then it's probably a good time to consider replacements.

No idle below 1200 rpms tells me dirty idle circuit still. Since you did not pull the air/fuel screws out and clean that circuit, it could be as simple as that is where the issue is.

Krey

[Da_Pipe]

Thanks Kreylyn, I'll look that up.

I would like to replace the gasket, the problem is how long it takes for it to be shipped. I was hoping to do the valves this weekend. Guess I'll have to order it and do them next weekend.

Looks like I'll start with the vacuum first then, as brent suggests. Thanks.