Slight bucking under light throttle

[J. Kidd]

She seems to be running strong other than that.

Under light throttle, cruising with minimal load (level ground) at about 45 mph, I'm starting to get a slight bucking. My first thought was a vacuum issue but the lines from the tank seemed fine. Didn't really want to go crawling through the carbs unless I have to.

The problem seems to most prevalent when the bike isn't working - either not working to go faster or not working to slow down - just in that lazy area of "enough throttle to maintain speed" (and at that slow, there isn't much wind resistance to overcome).

My next thought was throwing some fuel cleaner through but I did this in the spring when she came out.

Next thing I'll check will be spark plugs. I have to check the mileage but I just changed them last year (probable 7-10k miles). They're probably due but would worn plugs cause the symptoms described? If not, does anyone else have any suggestions on where to look?

Thanks.

[katana bob]

how long since the carbs were synched? I doubt it's plugs or it would be more consistent.

[Court93kat]

What RPM range are we looking at when the bucking occurs? You might just need to downshift and get the rpms up a little. If it is running strong in all other situations, there might not be anything wrong with the bike. Running 1/3 bottle of techron with your next fill up will definately not hurt anything.

[The CyberPoet]

What RPM range are we looking at when the bucking occurs? You might just need to downshift and get the rpms up a little.

+1

If you're in top gear at 45, it'll lug simply because the bangs are happening too far apart. Generally, you want to keep the engine at a minimum of 4500 RPM while cruising...

The other possibility is that your chain has seen better days or is way out of adjustment, and is jerking as it goes from a good section to a stretched-out section.

Cheers,
=-= The CyberPoet

[slayergsxf1]

Yep,,,what cyber said....

[Ghir]

Really? I cruise at 3000ish rpm.. no bucking for me, but I do have to downshift If I want to get going..

[The CyberPoet]

Really? I cruise at 3000ish rpm.. no bucking for me, but I do have to downshift If I want to get going..

Stop doing that!

Actually, it can have long term carbon-build-up consequences (ever hear the phrase "blowing the carbon out" about some old ladies car because she never got on it? Same concept). 4500 is a good rule of thumb, although you can lug it down around 4k. 3k is really too low, IMHO.

Cheers,
=-= The CyberPoet

[Court93kat]

Yep,,,what cyber said....

Man... I feel like MD86 now.....

[The CyberPoet]

Yep,,,what cyber said....

Man... I feel like MD86 now.....

Sorry, Sarg! Really, it isn't my doing...


Cheers,
=-= The CyberPoet

[md86]

Well now , from what I'VE read , surging at cruise indicates a lean condition in the pilot circuit . But that's just what I've read in MANY online articles and tech articles in magazines ....

[BIG BILL]

I had the same problem with mine.
The bike had stood in a Dealer for a year.
The carbs were filthy and needed tuned.
Once done the bike ran like a dream.
I only wish the dealer had done this first.

BIG BILL

[J. Kidd]

Thanks to all.

After reading the responses and knowing my bike, I'm betting on the chain. I've got 20,500 miles on the original (stock) chain that was put on the bike 10+ years ago. I knew it was on its last legs and was just trying to get through fall so I could replace it as a winter project (I've never replaced the chain and sprockets before).

I'm going to initiate a search now to research what the stock chain and sprocket sizes are for my '95 600 but would like some input if anyone has the time (and patience - in case it's fresh in your head) as far as:
1) improving acceleration slightly - don't want to go too extreme but a nice bump would be cool (ie. dropping a tooth, adding a tooth, whatever).
2) recommendation for a good quality chain and sprocket set
3) place to get said chain and sprocket set at a good price