Took It In For A Tune, Now It Runs Worse

[wantahertzdonut]

I posted a number of times last year about some nasty vibration coming from my engine during midrange rpm's, and the general concensus was to sync the carbs which I'm sure had never been done.  I took it to the shop and while it was there I asked them to change the air filter to a high flow unit and check the tuning on the carbs since my mileage was dropping down to around 40mpg, down from 45-48.  I asked them to tune it to stock specs.  This was back right around New Year's.

Fast forward to now and I'm just starting the season, and discover the bike has 'holes' in the rev range and no power down low.  Worse yet is my mileage absolutely sucks.  I went to reserve at 133 miles this morning, which is absolutely pitiful!  Graned, we may still be using the "spring blend" gas, but this is mid 30's mpg.  I'm losing faith in my shop and I'm not too interested in waiting several weeks for another shop to do an adjustment, so does anyone know where I can find out about adjusting the carbs to run right?  Or should I wait until we get back into summer gas?

[pmackie]

Check that wizz bang new "high flow" air filter...

If it's a K&N, maybe it's been overoilled, or needs cleaning again. If it's an off brand, then maybe it has too much restriction.

But my guess is the air filter. If you want to check, take it out and go for a quick ride. As for adjusing the carb, they can only change the air screws without taking them apart and changing jets and/or shimming needles. The air screw adjustment WILL make some difference off idle, to about 1/4 throttle.

[wantahertzdonut]

I'll try pulling the air filter.  If it runs better, would you recommend a K&N or just a stock unit? 

Is there a good shop manual for the B6?  I'd like to get one because I'm doing a lot of my work blind, and I'd prefer to have some day-to-day guidance since I prefer to do my own maintenance.

[StangMATA]

Any exhaust mods? I'm curious if you are running lean.

[Red01]

Besides what's already been posted, let me mention that a free flowing air filter and the jetting to match is not likely to improve fuel economy.  Done right, it shouldn't make ridability worse though.

[wantahertzdonut]

Stock exhaust.  No other mods on the bike either.

I only asked them to do a stock tune, they shouldn't have changed any of the jetting.

[pmackie]

Hey wantahertzdonut:

If it runs better, would you recommend a K&N or just a stock unit?

I only asked them to do a stock tune, they shouldn't have changed any of the jetting

Yea, I agree, it is not likely they changed any of the jetting, but it IS possible that they tweaked the pilot air screws.

That's whey I suggest looking at the air filter first, and look around in the air box, because your symtoms sound a lot like a clogged air filter, causing the bike to run rich. I'm not fully familiar with the 1G 600, but on the 2G, you can get the air filter clogged with oil coming up from the engine vents, so look at the filter and in the air box. As for filter type, the K&N is usually a recommended upgrade for the 1G's (Not the 2G's), but it needs to be clean and not overoilled.

If your still having issues, look at the spark plugs to see if the colour is good (light brown) and that all plugs look similar. If you have some very dark or carbon looking ones, you may be up for a carb removal, cleaning, etc.

As for a manual, search the site, there used to be some links to downloadable manuals here.

Let us know what you find...

[wantahertzdonut]

Got some promising news.  I dropped the bike off last night at the same shop and they were able to get to it first thing this morning.  As it turns out, the guy who worked on it really didn't know what he was doing and the carbs were way out of adjustment.  They thought this guy was better than he really was, and is no longer employed there.  They took the carbs out, re-cleaned them, and went through and tuned everything from the beginning.  I won't be able to pick it up tonight since I'm meeting my dad to go car shopping, but I'll get it tomorrow morning.  I'm going to put some miles on it and see how it goes.  I'm crossing my fingers, but I'll also believe it when I see it. 

In the meantime I'm going to pick up a service manual since from here on out I want to be doing my own work, then I don't have to worry about someone else screwing something up.

[wantahertzdonut]

Picked up the bike on Saturday and so far so good.  I topped off the tank and so far it runs very smooth, and my idle is exactly where it should be.  I'll find out how good a job they did when my main tank runs out.