SuzukiSavage.com - backfiring on roll-off

Steddy58 Full Member Offline Ooops I did it again Posts: 240 Liverpool UK Gender:	backfiring on roll-off 01/18/22 at 08:30:11 Hi all, the bike has suddenly decided to start major backfiring when I close the throttle I haven't done anything to it lately also the airscrew on the mikuni vm36 doesn't seem to have an effect anymore, just wondering if anyone else has had this and what's the problem/solution I did do a search but it keeps timing out on me,cheers
Back to top	« Last Edit: 01/19/22 at 05:50:27 by Steddy58 » 1988 sav, mikuni vm36 carb (lancer),high comp piston, racing cam, raptor petcock, self-made exhaust, delkevic silencer (ryca header), K&N air filter, 48,000 miles IP Logged

Dave YaBB Moderator ModSquad Offline SuzukiSavage.com Rocks! Posts: 17820 Camp Springs, Kentucky Gender:	Re: backing on roll-off Reply #1 - 01/18/22 at 08:33:23 You likely have something plugging up the Pilot Jet.
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Serowbot YaBB Moderator ModSquad Offline OK.... so what's the speed of dark? Posts: 28375 Tucson Az Gender:	Re: backing on roll-off Reply #2 - 01/18/22 at 08:37:02 ... or you've developed an exhaust leak
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Steddy58 Full Member Offline Ooops I did it again Posts: 240 Liverpool UK Gender:	Re: backing on roll-off Reply #3 - 01/18/22 at 09:34:50 Ok thanks for that I'm about to take carb off and give it a clean and a jolly good sorting out : I'll let you know what occurs if anything, cheers
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Gary_in_NJ Serious Thumper Offline LS650 Cafe Racer Posts: 2625 Amongst the Twisty Roads	Re: backing on roll-off Reply #4 - 01/18/22 at 11:49:13 Check the two nuts on the exhaust flange at the head. If come loose (and they do) you will get significant popping on throttle roll-off.
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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28764 L.A. California Gender:	Re: backing on roll-off Reply #5 - 01/18/22 at 11:54:09 I would check for air leaks 1st. wave a lit candle around the joints on the header and muffler.
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justin_o_guy2

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What happened?

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East Texas, 1/2 dallas/la.

Re: backing on roll-off
Reply #6 - 01/18/22 at 13:09:52

Serowbot wrote on 01/18/22 at 08:37:02:

... or you've developed an exhaust leak

That would be my first step. While it's cool,snug the bolts that clamp the exhaust to the head. BE Gentle. It's better to need to snug it occasionally than try to get it tight enough to not ever work loose. It's either going to strip out,or twist off
You'll never get it tight enough to not get loose again.

If that isn't It,look at the muffler to header connection.

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Steddy58

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Ooops I did it again

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Liverpool UK
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Re: back-firing on roll-off
Reply #7 - 01/18/22 at 21:03:41

After taking the carb off, cleaning, checking jets etc. I put it back on, started it up and it started poppin' like before it was only when I bent down to see if there was something I was missing and I leant on the exhaust that I noticed it was wobbling, on further inspection the pipe was loose in the head ( a bit like meself ) it felt like the exhaust gasket had vanished, I tried to tighten the nuts but they were as tight as. I'll buy a gasket take the pipe off tighten it all up and hopefully Robert will be your mothers brother - so take a bow one and all for being blob on with the correct problem you cant beat experience, cheers

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1988 sav, mikuni vm36 carb (lancer),high comp piston, racing cam, raptor petcock, self-made exhaust, delkevic silencer (ryca header), K&N air filter, 48,000 miles

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Serowbot YaBB Moderator ModSquad Offline OK.... so what's the speed of dark? Posts: 28375 Tucson Az Gender:	Re: backfiring on roll-off Reply #8 - 01/19/22 at 08:32:51 PS.. I always use a dab of anti-sieze on those header bolts.
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ckahleer

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Re: backfiring on roll-off
Reply #9 - 01/19/22 at 10:25:45

I too had that problem. Header was loose, the material between between the gasket's outer crush rings was gone, the header bolts were torqued to spec. Using a tap and die, I cleaned up the threads and with a new gasket was able to get the header tightened up. I do question whether the bolts are coming to their torque spec due to clamping force or if the bolts are bottoming out.

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Serowbot

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OK.... so what's the
speed of dark?

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Re: backfiring on roll-off
Reply #10 - 01/19/22 at 12:52:41

...and another thing... Grin

I wondered the same thing on my 20 year old bike,.. so when I put a new crush gasket in, I installed it over the old one. One crushed, one fresh, adding to the thickness overall. Haven't had leak since and it's been a couple years so I guess that worked out.

ckahleer wrote on 01/19/22 at 10:25:45:

I too had that problem. Header was loose, the material between between the gasket's outer crush rings was gone, the header bolts were torqued to spec. Using a tap and die, I cleaned up the threads and with a new gasket was able to get the header tightened up. I do question whether the bolts are coming to their torque spec due to clamping force or if the bolts are bottoming out.

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Hiko Senior Member Offline SuzukiSavage.com Rocks! Posts: 250 Tauranga New Zealand Gender:	Re: backfiring on roll-off Reply #11 - 01/20/22 at 01:30:02 I replaced my bolts with studs and dome nuts The full thread into the aluminium can then be used
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Eegore

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Re: backfiring on roll-off
Reply #12 - 01/20/22 at 07:08:54

"I wondered the same thing on my 20 year old bike,.. so when I put a new crush gasket in, I installed it over the old one. One crushed, one fresh, adding to the thickness overall. Haven't had leak since and it's been a couple years so I guess that worked out."

I've done the same thing and have gotten the same results. Just leave that old one in there.

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