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1493 Views 7 Replies 6 Participants Last post by  Kenny4
Ever since I put the Yoshi duals on, it's been backfiring on decel under load in all ranges---Have played with a/f screw changed jetting up and down---Have never been able to fix it---It starts good and runs strong---I did find some leaks in the exhaust connections but way back by muffler.

Can't get to the leaks so I just pulled off the whole system and put on another brand new set of duals---Pro Circuits---And crap---It backfires worse with them on and there is no exhaust leak anywhere.

The only 2 things I haven't looked at is the pilots to see if they are dirty or clogged or checked valve clearance---I've held off on the valves as so many have posted up what a bucket of worms they opened---Actually R&R'ing the the air filter box is for some reason more intimidating to me than the valves.

If you guys have any other suggestions please post up---I'm sure if I mess with the valves I'll be back on here whining about something:p:p

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How many turns out are your fuel screws?
How many turns out are your fuel screws?
They are 3 turns out
I'd check the valves anyway if you feel you can just to eliminate one more thing.
I had the same issue I got 42 pilots and was able to tune it out now I never have any popping.
Had same issue when I put my HMF's on changed out the pilots to 42's fixed the issue
It's probably lean and needs bigger pilots as others have pointed out, but check the valve clearance anyway. It's part of scheduled maintenance and needs to be done.
Appreciate the posts---If I change out the pilots from #40's to #42's, (most of the threads recommend this when UPP's are added but not for stock), if it's too much/too rich how will I know in the seat---What should be a good indicator that it needs to go back to #40's.

Today is Wedn. and I might be leaving tomorrow nite to do about 150 miles of riding---I don't want to do anything that will screw it up---As it starts fine and runs well except for constantly backing off on decel---I love the rumbling sound of it but can't be any good for it to run this way---Also the rear exhaust has been showing black carbon/soot lately, (at 182/185)--I don't have any other jets, but was thinking of trying to change the front to the rear, (185/182), just to see if it does anything noticable.

When I get back will definitely look at valve clearance too---Thanks

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