engine is....weak?? or something

[eak0703]

bike: 1996 Kat 600, stock exhaust. not stock airfilter, but its shaped like a stock one and goes into the stock airbox. carbs are from a 1991 600.
carbs have stage 3 jet kit.

the issue:
bike starts, bike warms up and runs...idles just fine. revs just fine...all the way up..no stutter, no hesitation..no problems. Once in a while after reving really high it may drop RMPs too low and stall, but this doesnt happen all the time.

As soon as i put it into first and try to ride...the engine just gives out..drops rpms and stalls. i can get the bike to ride by holding in the clutch putting into first, then revving up to 5k and riding the clutch...bike starts to go...acceleration = crap...barely anything at all. can shift just fine but always the same issue..if im not 1/2 way on the trottle the thing stalls. not only that, but after it stalls sometimes it has a hard time starting.

anyone seen anything like that before?
thanks appreciate it.

[Sasquatch]

hmm..shot in the dark....carb issue's

Shot in the pitch black...bad rings (poor compression...I had a moped that did that)

[Tmod]

How long has this been happening?

Tmod

[eak0703]

The bike wasn't working at all. I was fixing it up.

After getting some new carbs on it, it appeared to work just fine (the guy i bought them from said that he had cleaned them prior to taking them off his bike...which he sold for parts after the CDI died and he got a GSXR 750)

I had tried starting an running the bike and it was fine. I had even ridden it a little with just the fuel left in the carb bowls...it was weird, but i had attributed that to there being no gas.

Now was the first time that i got the tank on it and tried to go for a little longer ride. I can "ride" it, but if im not very careful with giving it waaaay loads of gas then itll simply die.

it almost feels like the spark plugs became fouled and there is weak spark..coupled with the fact there is a stage 3 jet kit, but a stock air filter and exhaust....maybe it isnt getting enough air??

no blue smoke or any smoke at all out of the exhaust....when i put my hand to the end of the pipe when the bike is running i feel good force of air coming out.

oh...when i put the bike into gear it almost feels like its running on just one cylinder.

i just cant understand how it can idle fine and rev up fine through whole RPM range, but as soon as the engine has to do some actual work it dies.

[Sasquatch]

ok, pull the plugs, and see how they look (and make sure they are all getting good spark. A stage 3 jet kit with a stock air cleaner and stock exhaust is not a good combo.

[Sumo514]

Did you try to run it without the air cleaner?

[eak0703]

ok, pull the plugs, and see how they look (and make sure they are all getting good spark. A stage 3 jet kit with a stock air cleaner and stock exhaust is not a good combo.

Yep, that's what i was thinking. My current thinking is that this is somehow related to the larger jets and less air.

I will pull the plugs like you suggest. I am pretty sure that they will be kinda black. does that mean that its too much fuel and not enough air?

What i dont understand is why it idles and runs and revs through all the RPMs just fine. only when i try riding. Its not the sidestand switch..the engine is not just cutting out. If the spark plugs were fouled...then it would die and then not restart no?? yet it always re-starts just fine....baahhhhh

I don't think its the piston rings...if there was a problem there i assume that i would be seeing blue smoke out of the exhaust? there is no smoke of any color.

any other thoughts?

Did you try to run it without the air cleaner?

yep, I've tried that. I ran the bike with no exhaust or air filter. it appeared to run just fine. The only catch is that i didn't get a chance to ride it like that. So i've no idea if it would bog down and die with no air filter/pipes.

[Slofuze]

I had an experience recently with mine where I actually "dropped" two cylinders. It sounded fine until you put it under load........max speed was 50-55m/phr til I got it home. I had issues with the battery the week before and tried over and over to start it....to no avail. I bought a new battery, instaled the plugs and I was doing ok (smoked like crazy for a bit in the driveway) for about an hour...maybe less.....and then it basically went "limp"....top speed was like 55m/hr.
Apparently I found out I "dropped" two cylinders due to fouled plugs....changed the plugs again and rode it hard for about an hour to clean all the crap out. It's been fine since.

[arsenic]

of course it weak, it's a stock Katana engine

[Newbie2it]

Pull the bowls on the carbs and check your float heights. I'm betting they are off. Which could explain why after a high rev the idle drops and the loading of the spark plugs.

Since you'd have the carbs apart, clean them agian. Wont hurt anything.

[eak0703]

Ok, i've played around with the bike some more: here's what i've found

bike would start rough..run ok..when i tried to ride the engine would die even when i was giving it gas....

initial thoughs: stage 3 jetkit with regular air filter and stock exhaust = cause of problem...incorrect.

started her up, took the air filter off..sprayed a little carb cleaner in each carb..problem went away. rode 4-5 miles...same crap. At this point my assumption was---> spark plugs must be gunked.

Took the carbs apart, they look quite clean on the inside..took the 120 jets out, put in the 112.5---> question: do the needles need to change too?

sprayed a little more carb cleaner into the carbs---this re-set me for another 5 miles of test riding.

rode with the 112.5 jets..5 miles later..same thing.

took plugs out: 1, 2, and 4 are covered in black soot...3 was clean.

i soaked the ends of the plugs in carb cleaner, then took a wire brush to the ends and now they look brand new. i checked each plug and it had good, blue spark...it would spark even at 6-7mm like the manual says. gaps on the plugs are within acceptable range: per the manual. I also made sure that each of the plug wires worked..and they all did.

this is where i'm at now..i have 4 clean sparkplugs, and i'm thinking the issue is with carbs...

what should my next step be?

started

[steves]

Air bubble in the fuel lines? Did you replace them?
Petcock problem. Does it show the symptoms on "PRI" setting?

Best thing with problem carbs sometimes is to return to stock jetting. If you have no issues with the stock jetting... that's your problem. If you do, time to look elsewhere....