PCV & Blowby

[Temple 5.0]

History of bike - I'm new to katanas but getting to know them really well... My buddy picked up a 99' 600 for under $500 so naturally it needed a little work. After a tank cleaning, starter, battery, & oil change it fired up & we put about 60 miles on it. The bike wouldn't idle & it didn't run the best but we figured it was leftover rust from the tank clogging the carbs. After taking them apart & not seeing much of anything in there I sprayed the ports with carb cleaner & put them back on.

The problem - after putting the carbs back on it was just bogging down & would die. We took the PCV hose off & something that smelled like gas & looked like oil came out for a little bit but would idle & run fine, if we connected the hose back to the intake it would bog down & die. I'm guessing this means the rings are shot & that is blowby going into the intake choking the oxygen to the motor. Is there an actual PCV valve I can change? Can we just put a filter on the end of the pcv hose & cap it off on the intake & ride this thing?

[Kreylyn]

History of bike - I'm new to katanas but getting to know them really well... My buddy picked up a 99' 600 for under $500 so naturally it needed a little work. After a tank cleaning, starter, battery, & oil change it fired up & we put about 60 miles on it. The bike wouldn't idle & it didn't run the best but we figured it was leftover rust from the tank clogging the carbs. After taking them apart & not seeing much of anything in there I sprayed the ports with carb cleaner & put them back on.

The problem - after putting the carbs back on it was just bogging down & would die. We took the PCV hose off & something that smelled like gas & looked like oil came out for a little bit but would idle & run fine, if we connected the hose back to the intake it would bog down & die. I'm guessing this means the rings are shot & that is blowby going into the intake choking the oxygen to the motor. Is there an actual PCV valve I can change? Can we just put a filter on the end of the pcv hose & cap it off on the intake & ride this thing?

Actually, nothing like that at all...

Pretty simple resolution.

Your carbs are not sealing off fuel flow. The float needles are bad, dirty, or improperly adjusted allowing fuel to continue flowing and overflow the carb bowls. The fuel will trickle down into the cylinder and wash down the walls filling the crank case and mix with the oil.

The oil and fuel mix now has over filled the crank case. The engine also sprays this fuel enriched mixture on the lower side of the pistons to cool them... and that richens your running a/f mix.

The result is a poorly running bike that gets worse as it warms up.

The fix... pull the carbs, clean them, test the float needles and properly adjust the floats.

Drain the oil and put in new.

(as a side note, it's not part of the problem but... check the petcock is working right and don't leave it on prime).

Krey

[Temple 5.0]

I questioned that as well but after it stopped blowing the fuel out it was still blowing a lot of air & when I connected it back to the intake the bike would sputter & die.. I will check the bowls because that is likely a large part of the problem. I'm really hoping i can pull a few off without removing the carbs but I doubt it. Which direction does the arrow point for on/res/prime? I don't see any indicators on the body, i think it has been repainted.

[Slofuze]

9 O'CLOCK..........Reserve
6 O'CLOCK..........Run
3 O'CLOCK..........Prime

[phantasm]

Going to HAVE to pull the carbs to clean them correctly. Check out the wiki (top left of page) and look up carbs 102 for a step by step on doing it right. Untill they are done, it'll be hard to diagnose any other problems, if there are any.

[Nut-Nut]

Are you disconnecting the vent hose? if that is the case, this sounds like a clogged air filter...

[Temple 5.0]

With the pcv vent hose disconnected it idles around 900 & seems to run pretty well. when we connect the hose it dies. The filter looks good but that may not be the case. Odometer shows 18k miles. I'm feeling more confident that the floats aren't adjusted correctly according to yalls vapor recovery system details. I'm going to set them to 1/2" over the lip & see how she runs after that. Maybe I can find/remove the good ol' restrictor plate while i'm at it. Thanks for the help, I will update when I find something.

[05RedKat600]

Don't remove the restrictor plate in the valve cover. That will create more problems.

[scottynoface]

You cant just "set them to 1/2" over the lip" and see how it runs. If you look in your factory service manual there is a specific height the floats need to be set at, something like 14.X mm.

[Kreylyn]

13mm for the post... converted is really really close... 13mm -.51"...

And while checking that is good, it's probably more so an issue with the needle seats being dirty. Cleaning is nessasary. Use a q-tip to get in there and clean the seat well with.

Krey

[Temple 5.0]

Q-tip would have been good... I re-set the floats to just over 1/2" closer to 14mm & still flooding, fuel economy on these things is looking terrible. Pulled the carbs again & changed out the o-rings on the needle seat & the emulsion tubes, I used a Buna 008 on the emulsion & 010 on the needle seats. I think its holding fuel now. It was idling really high, like 3k with the choke out & I believe everything closed up. I haven't double checked the work but it sounded much better. Would have saved some $$ if I had changed the o-rings right away.

Don't remove the restrictor plate in the valve cover. That will create more problems.

I was just quoting Will Farrel as a joke but I do believe I need to adjust the valves a little. Do these have hydraulic lifters? I think it has a tapping noise.

[05RedKat600]

Q-tip would have been good... I re-set the floats to just over 1/2" closer to 14mm & still flooding, fuel economy on these things is looking terrible. Pulled the carbs again & changed out the o-rings on the needle seat & the emulsion tubes, I used a Buna 008 on the emulsion & 010 on the needle seats. I think its holding fuel now. It was idling really high, like 3k with the choke out & I believe everything closed up. I haven't double checked the work but it sounded much better. Would have saved some $$ if I had changed the o-rings right away.



I was just quoting Will Farrel as a joke but I do believe I need to adjust the valves a little. Do these have hydraulic lifters? I think it has a tapping noise.

No overhead cam motor has hydraulic lifters. The Post 600's have tappets. Valve adjustment will take longer to get the fairings and valve cover off than to adjust the valves. You will also need a signal generator cover gasket.

[Temple 5.0]

Didn't do the valve adjustment. Its not my bike & i have other stuff to do (65' mustang restoration). Since cleaning carbs, changing the o-rings, & setting the floats correctly the bike has been running pretty good. It probably needs new plugs & maybe another oil change but this kat has been resurrected & is pretty fun to cruise around.

Thank you everyone for the help, there's nothing better for a project than a good educated forum!

total cost $590, not bad for a good 2-wheeler