Firefighter wrote on 12/31/69 at 16:00:10:


Ha, ha.  I asked you about rider error.  Ha.  You know, it should be mandatory for all bikes to be sold with the original owners manual.  I think that people keep them as a souvenir when they sell the bike, but that would have helped you to know about the interlocks.

The problem with trouble shooting via the internet is a lack of the senses.  I can't hear your "pops" and compare them to those that I've actually heard.  When we bought our bikes new, at first we joked about the backfires which on a stock bike can be pretty substantial.  They are a "boom" sometimes, and not a little "pop".  However, after a while they became annoying to me and I decided to fix it.

When this started, you called them a backfire, so I immediately assumed (what else can you do on the WWW?) that your bike was stock inside the carb.  Well, we do know what "assume" means don't we?  And that is what happened...

Anyway, the pops are minor and quite common but can still be tuned out a bit better.  The way to go about it is to make sure that you have no air leaks and to make it a bit richer.

You siad you turned the screw in to 1 turn?  Why?  Does it run better that way?

Okay, here's my update...

First, the DJ needle is ever so slightly longer than the stock needle but the added length is on the top end so it makes no difference.  The tapers appear identical.

Second, I misread the DJ instructions.  They DO say to reuse all stock washers and spacers.  They also say to set the clip at the 4th notch down.  This is the effective equivalent to using a stock needle and shaving about 1/3 of the white spacer off.  With this arrangement, I had quite a few backfires (on just about every throttle release and on shutdown).  It was pretty much like stock (except that I have the MAC muffler installed now).

Third, I changed my clip to the 5th notch down and kept the white spacer in and she seems to be running pretty well.  I have the occasional backfire/pop on throttle release when shifting but never the final fart on shutdown.  I have no visible smoke and no smell of gas, so I'm feeling okay about it so far.

I think she's pretty close to the way I want her with my current parts.  She still has the DJ 146 main jet installed (the largest in the kit) - at least until I get my larger Mikuni mains delivered.  I have a 152.5, 155, 157.5 and 160 ordered.  I'll play with those and see what works best.

Savage_Rob wrote on 12/31/69 at 16:00:10:


This sounds like progress.  No black smoke.  Good.  Did you readjust the idle mixture?

Quote:


Firefighter had a 144 DJ main installed in his.  So a 146 is the biggest DJ main?  I wonder if a 155 is bigger than that.

Darn  

That is a plus.  Is there a face value on the coupon?  Maybe they can adjust your carb too.

I'm expecting my new Mikuni mains any day now but I did get a chance to ride in to work this morning and noticed after I arrived that I have a very brief puff of black smoke visible at the start of any throttling (from idle).  I also noticed some exhaust leakage (small amount of soot) at the juncture of the header pipe and muffler.

Any suggestions on what should be used to help seal the exhaust leak?

What would be the first thing you'd play with regarding the black smoke... the needle valve adjustment or the idle mixture screw?  I'm thinking the needle valve but would like some opinions.

Can do.  I just didn't know if there was some sort of heat-resistant tape or some sort of gasket material folks usually use between the two to enhance the seal.

Whew!  This thread sat dormant for a while.  I had some difficulty procuring new mains to play with but finaly got a few (some from my local HD dealer).  Overall now, I have the DJ needle with the clip on the 4th notch and the white spacer installed - also using a Mikuni 155 main jet.  I am using a K&N direct replacement air filter and a MAC muffler.

Now I just have to record the MAC.