After the discussion last week from various people about max speed, high end stumbling, and back firing I got to thinking.  My bike (2000 LS650) does indeed like to backfire (not always the loud cracking type) between gears if you are slow on the shift.  SO I was suspecting that I am running lean (the carb srew has never been drilled out).  On the way home I had a situation where while going about 55 I needed to pass.  When I rolled on the accel (in 5th) it started stumbling at about 65.  I let off (I didn't need to go any faster to get around the guy anyway) and the problem went away.  This left me w/ a huh??? whas up in my mind.  So when I got to a long staight away I decided to see either what the max speed of the bike was or where the stumbling begins.  At a little above 70 the stumbling starts no mater how gently I apply accell.  
Also note that the muffler that I have is the stock muffler but it is blown (a little better than a strait pipe).

What I need to know is:  Am I just running lean and if so is this a problem that I can leave to fix the next time I tear the bike down.  I put roughly 100 miles every day on my bike but it is all below 60 mph.  I want to wait due to cash flow.  I need a new muffler but i want to put a supertrapp on and that will lead likely to rejetting and such.  I do not have a crap load of cash to blow but will due what is necessary to keep the bike healthy.

And could someone out there take a photo of thir carb so I can see exactly where the proper spot is to drill access to the adjustment screw.

sounds like the centrifugal force of acceleration caused your float to stick a little and the bike leaned out.  Stock it should be capable of doing that without a stumble...I think?

If your stock muffler has baffles removed, you're probably running way too lean now. If your jetting is stock, you need to rejet.

If you like the sound of the exhaust as it is set up, you need to jet (tune) to it. Otherwise go ahead and get a muffler or whole exhaust system that you DO like the sound of and tune to it. There is no sense in tuning to a pipe if you don't like it.

Personally, I find the Stock H-D Dyna I put on my 87 to be too wimpy sounding. I don't know how the baffles were modified in the Dyna muffler on my 99, but it sounds much deeper, and a bit louder without being obnoxiously loud. I do wonder why it has turned blue in only one spot about 2/3 the way down the muffler's length.

However, since the 99 is chopped, I'm considering putting on a really loud turnout style muffler I've got.  People kind of expect "obnoxious" loud from a chopper, and I wouldn't want to disappoint anyone! After all, somebody has to live up to that "menace to society" reputation.

skatnbnc wrote on 12/31/69 at 16:00:06:


i dont think carbon build up is big issue with these bikes, because they are running so lean(as a rule). HOWEVER, in your case, you should take the bike out and give it a good warm high speed run, to warm the oil up and heat the moisture out of it, to prevent sludging and corrosing from aluminum/water. perhaps once a week, or what ever is convenient. jmo

I just put on a supertrapp, 6 disks, no tuning required.

In fact, I'd say it's a little more restrictive than stock, yet louder.  The sound reminds me of the Gold star my dad raced.  Good rich tones, only not as loud.

After having this for a few weeks my opinion of loud pipes has changed... I still beleave loud pipes don't save lives, but quiet pipes are a liability.  If you are hard to be seen, it's good to be heard.