Getting mufflers to seal

woodman · Full Member Joined: Oct 12, 2008 Posts: 256

I have a 78 Xs650E I recently bought. My problem is a popping at idle and backing off the gas in gear which I think is cause by the left muffler, a Dunstall replica, not sealing. The right one seems Ok. Do you think a new reducer would help or is this just something they do? I tried some Hi-Temp Silicone but it didnt help. It drives me nuts. Sure would appreciate any advise. Cant afford a new exhaust system right now after all the money Ive spent on it.

xsjohn · Posted: February 8, 2009, 8:19 pm Post subject: Re: Getting mufflers to seal

Sounds more like carb problems to me........xsjohn

jayel · Posted: February 8, 2009, 8:48 pm Post subject: Re: Getting mufflers to seal

popping on decel. is lean on that side, (carb sync) back the air/fuel screw on that side out a 1/4 turn and see what it does

woodman · Full Member Joined: Oct 12, 2008 Posts: 256

Got the front wheel off to change tire right now but will try that weather permitting when I get it back together. Just put new points in, set timing, adjusted cam chain, adjusted valves, set carb mixture screw to specs 2 1/4 out & balanced carbs with mercury balancers, & put 2 new plugs in. The muffler reducer sleeves are kind of shot, Ill order new ones anyway

xsjohn · Posted: February 8, 2009, 9:57 pm Post subject: Re: Getting mufflers to seal

With 2 carbs one could have a plugged or mis-adjusted pilot circuit.....cleaning is never any fun.....clean the rough side again and leave the good running side alone....... a small guitar string gently in the 3 pin holes from the pilot circuit in the throat.....spraying carb cleaner to check....storage leaves a tough mess to clear.....once cleared it seldom comes back unless the tank is not clean......

xsjohn

woodman · Full Member Joined: Oct 12, 2008 Posts: 256

Its getting a new fuel tank when it goes back together. I was syncing the carbs with a little snowblower tank I have rigged up for that purpose

xsjohn · Posted: February 8, 2009, 11:27 pm Post subject: Re: Getting mufflers to seal

Geting the sync correct requires that both sides be running just right on with the mix screws....screw the 42.5 pilots with the BS34's........some easy throttle on the back roads checking the plugs for proper color and adjusting the mix screws gently till this happens is good..each side independently...(engine has to be a full operating temperature 10 miles at least on a warm day)....no more than half the way up the side of the electrode with the black (that's pushing it) and watching the round portion of the plug for just a "trace" of soot on the end of your finger..no new plugs for this...on the express the same thing but with the correct needles and main jets.....won't get into that since the right runs 25 degrees hotter than the left.....no on believes that or cares so tought s*** for them..........lately I connected the carb barbs like pamcopete said with 3/16 tubing.........won't fix a carb mess but will help hot starting and help smooth out a near perfect idol.......live and learn....thanks pete.....

screw 8-7cr ......love 8-0cr........only 11 years to come to that definate conclusion for me.....tuning problems are over.....screw the rattiness and heat...........on the express with 18/29 is amazing now.....sorry for the rant.....spent to many years on this I guess........3500 at 65mph ...no vibes........go anywhere and when I get there it's just as cool as when I started.......and no engine noise.....and idols right out at 1100 just where it was set whe I started out.....done

xsjohn

woodman · Full Member Joined: Oct 12, 2008 Posts: 256

Its a 78 John with the 38mm carbs, but I get what youre saying on the plugs. I have another problem with it over advancing too. Guess I need an ATU also. When I set the idle timing on the mark it advances about 1/4 inch past the total mark. Im afraid if I set the total where it goes it will be too retarded at idle

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