Blown off exhaust can causes lean idle after repair??

[Detman101]

Perhaps you all can help me understand this.

My carbs were set and running perfectly. I adjusted my MAC exhaust canister and forgot to mount the rear flange to the mounting bolt.

Taking off down the street at 60 mph and the canister blew off the header.
The bike lurched, lost power temporarily and I skidded to a stop at the next light. I noticed that it was substantially louder
than normal and looked down to see my muffler missing!!

So I turned around and went back for it. I think a car had run over the end of it so I picked it up and strapped it to the bike.




With the bike louder than the 4th of july I rode to a muffler shop and got it bent back into shape to fit onto the header.

Once I got the canister back on I noticed that the bike now runs lean in the idle range even though the mixture screws have not been touched.

My question is what could cause the leanness even though the muffler is intact and back on the header? I can adjust the mix screws
easily but I'm baffled as to how the can coming off can
throw the mixture screws out of whack?

Thanks,
Dm of mD

[first timer]

my guess is that there is still some leak going on, what do your plugs look like? if the plugs are lean it could be that you have now *improved the performance* of the muffler by adding extra spaces for exhaust gas to escape ( the canister is not giving as much back pressure as it did because its bent up. ) you could try cloging any of the holes where exhaust is escaping and see if that helps. other then that you may have to rejet but i would hold off for now.

-ryan

[Detman101]

Kewl, thanks Ryan.

I haven't checked the plugs yet cause it's been pizzling here for the past few days. The bike runs pretty good but it lean pops from 2500 rpm to about 3500 rpm.
I'll check the plugs and then richen up the mixture screws a 1/4 turn.

Thanks bud.


Dm of mD

[Detman101]

On the first day of repairs my GS gave to me...
Turned the mixture screws out a 1/4 turn, easily.

On the second day of repairs my GS gave to me...
Fouling rich plugs cause I opened the mixture screws 1/4 turn easily.

On the third day of repairs my GS gave to me...
Three stalls at stoplights and Fouling rich plugs,
Cause I opened the mixture screws 1/4 turn easily.

On the fourth day of repairs my GS gave to me...
Stupid Barend mirrors that won't stay in place cause the engine isn't smooth, three stalls at stoplights and Fouling rich plugs,
Cause I opened the mixture screws 1/4 turn easily.

On the fifth day of repairs my GS gave to me...
A TRIP TO THE HOSPITAL!!!
Stupid Barend mirrors that won't stay in place cause the engine isn't smooth, three stalls at stoplights and Fouling rich plugs,
Cause I opened the mixture screws 1/4 turn easily.


Um...that's it. I'm dead.

Dm of mD

[KGB]

Did a baffle escape when the pipe.......left the bike?

If some of the packing came out, creating less pressure, this could cause the problem.

Or you may have bent a valve......doubtful but possible

[Detman101]

Well, the baffle definitely didn't come out. Everything was intact when I got back to it. If I bent a valve wouldn't there be other signs present. Like that self-destructive sound of the piston hitting the valve?


Dm of mD

[KGB]

Not always.
A bent valve may not seat correctly, enough to seal.
It may not be bent to hit the piston, just enough to loose power.

If you can try a compression test or a leak down test.
Leak down usually indicates rings, but will tell you if something is wrong

[Detman101]

Okay, I will have them try that this saturday.

I feel so thwarted because when I finally got the carbs set perfectly and decided to just ride it and not tinker with it. This crap had to happen.
Now I've gotta tinker with this bitchass bike again and can't ride it.


Dm of mD

[Detman101]

Why can't I just have something simple like the stator dies or I need a new tire or I have to replace turn signals or something?

It always has to be the most utterly complicated $#!+ on the damned bike.

:x
Dm of mD

[Detman101]

Checked the plugs. Fouled beyond foul.
I believe that richening the mixture screws is not the answer.
I will try raising the needles half a clip this evening if it doesn't keep raining outside.
If it does I can go to thelocal garage and do the work.
Something has to give.
God wouldn't give me more than I can handle.

First things first I've gotta re-lean out the mixture screws.


Dm of mD

[Detman101]

Found the problem.

Exhaust headers somehow loosened up at the cylinder and also exhaust canister was not on tight enough again!
I got it on there good this time with a hammer and a block of wood. Then I retightened the header onto the cylinder head. No more popping.

Now to check my timing...

Dm of mD