Is my engine running lean or rich?

[in_denial]

Hello,

I just purchased a 2000 v star 650 (first bike). The bike has 16k miles on it. It is very clean, has good power and I got a great deal. I just ordered the Clymer manual (3-5 days delivery) so I am posting here to see if you folks have any quick suggestions. I noticed that the engine has a slight backfire/sputtering on deceleration and would take a while to warm up, so I was thinking that it was running a little on the lean side. There was also some minor bluing on the exhaust. I took the plugs out last night and they appeared to be fouled. They were coated with carbon (not wet oil). Now I was thinking that it might be running a little rich. I cleaned the plugs and re-gapped at .0035. The engine seemed to warm up quickly, but the it was still sputtering a little when downshifting and decelerating. What do you think this is?

Thanks,

[niterider]

I don't know the answer to that; however, my previous bike and the one that I own now both back fire at decelleration. since they both run great under accelleration I never thought that was something to worry about. Both were twin cylinder type engines. I thought it sounded great as I was comming into town and slowing down for the speed limit. I may be wronge, there may be something wronge, but chances are it is okay.

[kar_the_terrible]

yeah backfiring while decelerating or downshifting can mean that you are running a little rich. I adjusted the idle screws on my bike to make that problem go away. Makes sense since as you slow down you normally release the throttle to virtually closed anyway...

I havent had that problem since. Except now I get backfiring while riding at highway speeds... methinks my carbs are being flooded and the float levels need to be adjusted.

[in_denial]

Would a motor running too rich contribute to the engine taking a long time to warm up? I have to wait about about 5 minutes until I can fully open the choke without the motor stalling at idle. I would think this would be a sign of the motor running too lean. Any thoughts??

Thanks,

[ZooTech]

Backfiring is a lean condition, not a rich one. Being too lean would explain your excessive need for the choke. My bike backfires by design through the use of emmisions controls that actually introduce outside air into the exhaust during deceleration, but you'd never hear any of it thanks to the catalytic converter and over-zealous muffler baffles. Is it possible your jets are clogged with tarnish? Have you tried running some SeaFoam or similar product throught the engine to help clean up deposits?

[in_denial]

Zootech,

I was thinking the same thing. I think that since it was running too lean, the previous owner would run the choke closed for a long time to warm the engine up. This probably caused the plugs to foul up.

On a different issue, I notice small oil specks on the right side of the bike. The specks are on the right side of the gas tank as well as the engine. It is all clear oil. I am wondering if it's coming from the right front shock. I checked the boot and it looks clean, but there is a dirt ring on the fork. It rubs off really easy. This is not present on the left fork. I may have to look into this more.

Thanks,

[in_denial]

Zootech,

I was thinking the same thing. I think that since it was running too lean, the previous owner would run the choke closed for a long time to warm the engine up. This probably caused the plugs to foul up.

On a different issue, I notice small oil specks on the right side of the bike. The specks are on the right side of the gas tank as well as the engine. It is all clear oil. I am wondering if it's coming from the right front shock. I checked the boot and it looks clean, but there is a dirt ring on the fork. It rubs off really easy. This is not present on the left fork. I may have to look into this more.

Thanks,

[ZooTech]

I notice small oil specks on the right side of the bike. The specks are on the right side of the gas tank as well as the engine. It is all clear oil. I am wondering if it's coming from the right front shock.

I think you're right on the money. Sounds like you need new fork seals. I haven't torn into a set of forks yet, but I'm confident it isn't too complex. You could even take the opportunity to swap out the front springs for something better if you want to.

[in_denial]

Thanks Zootech,

I can't wait for my Clymer manual to arrive! I'm going to rip into the fork, replace the seals and hopefully get a set of stiffer springs. I also thinking about adjusting the rear shock for stiffer ride. My bike seems to dive in the corners probably because of my weight (285)

I am also going to give that Seamfoam a try. Do you follow the directions or do you use a more concentrated treatment in the gas? I read somewhere about a person filling up the carb bowl with the stuff and letting it sit overnight. If this stuff doesn't work, I may need to take the carb apart and check the jets. For some reason, that scares me.

Thanks,

[ZooTech]

I am also going to give that Seamfoam a try. Do you follow the directions or do you use a more concentrated treatment in the gas?

If you can get some directly into the carbs it wouldn't be a bad idea. As far as adding it to the gas, just follow the directions. I think one can of it can be used in as little as four gallons, so maybe use 2/3 of it in the fuel tank after a fill-up and use the remaining 1/3 for pouring directly into the carbs. I used it in a '91 Nissan Stanza that I bought off eBay to cure a rough idle and an initial stumble upon acceleration. It did wonders for both symptoms. All I did was disconnect the vacuum line running to the brake booster and allow it to suck in an entire can of the stuff until the engine died. I let that sit and soak inside the intake tract and against the intake valves for five minutes, then fired it back up. The engine smoked like a chimney for about five minutes as all the dirt and carbon burned off, but afterward the engine idled smooth as silk and was a lot more responsive. I also use it in my bike as a fuel stabilizer during storage.