Troubleshooting smoke

[jacer]

Last week I traded my 04 gs500 for an 02 kat 750. In the week I've owned the Kat I've noticed a few problems and I'm hoping you can point me in the right direction for fixing them.

First, the bike smokes. Sometimes a lot, sometimes a little. I get a bit of blue and a quite a bit of white smoke.

Secondly, the fuel economy sucks. The bike is getting around 12-15mpg, when it should get 60+

Third, the bike is idling around 2500, often jumping up to 4500.

My theory is that it needs either a new air filter, or needs the fuel to air mixture adjusted. It isn't burning the all of the gas in the cylinder so the gas is washing out the cylinder and the oil is burning off. I'm worried this will damage my rings.

I guess my question is, how likely is it that it's just fuel to air, either from a bad air filter, or from having the screws too lose?

Any input would be appreciated.

[Kreylyn]

Check your oil level... and if it has fuel in it.

If you do, then it's a whole different issue you need to fix.

Krey

[clasage]

Sounds like the fuel problem is your float needle sticking. The idle could be the air/fuel setting.

I would suggest checking out carbs 102, do a good cleaning and inspect the float needles. and as most advise start out at 2.5 turns out on the a/f screws and work from there.

[cintidude04]

Even after getting in working order don't expect 60+ mpg, who ever told you it gets that lied to your face.

Welcome to KR

[jacer]

Even after getting in working order don't expect 60+ mpg, who ever told you it gets that lied to your face.

Welcome to KR

Thanks! 60may have been a pipe dream, but I would like to get more than 12. Honestly, I'm just frustrated because the summer is passing by and I don't want to ride until I get stuff fixed. The person I bought it from is a motorcycle mechanic, but he's either really bad at his job of a very shady businessman.

If it isn't too serious I'd like to fix it myself and start learning how to handle the small engine repairs, I'm just worried I got shafted and sold my old bike which was running great for a piece of garbage that hasn't been maintained.

[steves]

Blue smoke is oil. White smoke is water vapor.

Some white smoke at start up is normal. but it should not continue to make white smoke when warm.

[Badfaerie]

Thanks! 60may have been a pipe dream, but I would like to get more than 12. Honestly, I'm just frustrated because the summer is passing by and I don't want to ride until I get stuff fixed. The person I bought it from is a motorcycle mechanic, but he's either really bad at his job of a very shady businessman.

If it isn't too serious I'd like to fix it myself and start learning how to handle the small engine repairs, I'm just worried I got shafted and sold my old bike which was running great for a piece of garbage that hasn't been maintained.

It's my experience that the majority of motorcycle mechanics are shady business men AND very bad at their jobs. I raised an eyebrow at the 60 mpg as well, especially from a 750. Closer to 40-45 mpg seems more in line.

I would start with your basic new-to-you bike maintenance. Pull and thoroughly clean your carbs, check/adjust the valves. Put in new plugs. Change the oil Put carbs back on correctly, replacing rubber bits as needed. Sync the carbs.

If that doesn't take care of you problems, it's time to start considering deeper issues.

[Mojoe]

well jaser, not knowing the mileage on the bike leaves me limited in my ideas about what could be your problem, but if you are blowing blue smoke, bad rings jump to my mind. if that bikes has over 40-50k miles on it, I hope you at least took a compression test before trading. at minimum I will start a bike up, then repeatedly open-close the throttle at least 8-10 times and look for blue smoke. if I see any more than I would expect, out comes my compression tester. any bike that age, with a fair amount of miles on it, always has me considering the shape of the rings. aside from something outright "blowing up" or "flying apart", rings are usually the first thing to wear out in an engine.

my suggestion would be to check for gas in your oil, and do a compression test. first a dry one, then a wet one. that means take one reading across all cylinders, then add a good tablespoon of oil to each cylinder and take another reading of all cylinders. if you see a significant jump in compression, your rings are shot.

[jacer]

well jaser, not knowing the mileage on the bike leaves me limited in my ideas about what could be your problem, but if you are blowing blue smoke, bad rings jump to my mind. if that bikes has over 40-50k miles on it, I hope you at least took a compression test before trading. at minimum I will start a bike up, then repeatedly open-close the throttle at least 8-10 times and look for blue smoke. if I see any more than I would expect, out comes my compression tester. any bike that age, with a fair amount of miles on it, always has me considering the shape of the rings. aside from something outright "blowing up" or "flying apart", rings are usually the first thing to wear out in an engine.

my suggestion would be to check for gas in your oil, and do a compression test. first a dry one, then a wet one. that means take one reading across all cylinders, then add a good tablespoon of oil to each cylinder and take another reading of all cylinders. if you see a significant jump in compression, your rings are shot.

I really should have included this as it's pretty important. The bike has 6,800 miles and has been stored for two winters in Iowa.

The more I look at things the more I realize the guy I bought it from was pretty sketchy, but actually made quite a bit more by selling my gs500 and buying the katana 750, so I'm hoping the cost to fix isn't too much more than what I made in the sale.

edit: I appreciate everyone's input. I'll have some free time this weekend where I will check the floats, resync the carbs, and replace the airbox. Looks like I'll add a compression test and an oil change. Thanks again! I'll keep you posted.

[05RedKat600]

I really should have included this as it's pretty important. The bike has 6,800 miles and has been stored for two winters in Iowa.

The more I look at things the more I realize the guy I bought it from was pretty sketchy, but actually made quite a bit more by selling my gs500 and buying the katana 750, so I'm hoping the cost to fix isn't too much more than what I made in the sale.

edit: I appreciate everyone's input. I'll have some free time this weekend where I will check the floats, resync the carbs, and replace the airbox. Looks like I'll add a compression test and an oil change. Thanks again! I'll keep you posted.

Your float needles are sticking, your carbs need cleaned, and I'm willing to bet that your oil smells like gasoline. If it does, change it out ASAP. Pull the oil fill cap and sniff, that will tell you straight away. No need to replace the airbox, just do a leak test with some starting fluid (ether).

If the bike is idling high, be sure that the choke plungers are returning all the way. Check for vacuum leaks, and while you have the carbs off drill the plugs over the A/F screws and set them at 2.5 turns out. Air cleaner replacement is 8K according to the factory, IIRC, so it may be time.

[Mojoe]

I really should have included this as it's pretty important. The bike has 6,800 miles and has been stored for two winters in Iowa.

ahh..ok. definitely not bad rings, unless one flat out broke or someone did some major beating on the engine.

[jacer]

I want to thank everyone. Especially 05Kat600. I drained the oil put a new oil and air filter on, reset the a/f to 2.5 and had the carbs refurbed and synced at a local shop. The mechanic took it for a ride and said it was running like brand new and I can pick it up this afternoon.

[05RedKat600]

I want to thank everyone. Especially 05Kat600. I drained the oil put a new oil and air filter on, reset the a/f to 2.5 and had the carbs refurbed and synced at a local shop. The mechanic took it for a ride and said it was running like brand new and I can pick it up this afternoon.

Don't thank me too much. I was just referencing everything that had already been said into one post, lol.