Suzuki Marauder VZ800 Surge, Pop, Backfire, and Die.

[shawsown]

THE BIKE: So, I have a beautiful blue Suzuki Marauder VZ800. 2001. About 268k miles. It has Vance and Hines debaffled exhaust with proper jetting as well, done by the previous owners mechanic. The pipes are wrapped and the bike does still have the PAIR valve still on (this may be important). I recently had the starter switch replaced by my mechanic and the previous owner had done a bunch of tweeker wiring in the back, he had the brake and turn signal wires stripped and crossing (which was blowing the turn, brake, and starter fuses, as well as killing the neutral and turn signal heads up lights). It was bad but I seperated them with electrical tape and now no more blown fuses and the neautral and turn lights work again.

THE PROBLEM: Day 1 of problem: Bike came off the freeway running fine, got to the city and started to surge, but not revving any higher. Started backfiring like crazy, loud and most often in third but also in second. Bike didn't backfire too much before, just occasionally but to be expected with PAIR Valve and Aftermarket Exhaust. Then bike started to die when letting off of throttle and once at a red light. Started back up fine, except for once when I had to turn the key off/on to restart.

Day 2: Bike started just fine. Didn't take it out for a run but thought the problem may have been changing weather.

Day 3: Taking bike to commute, started very rough. Applied a bit of choke and idle jumped up. Then ran 1 block with surges and a popping/hissing sound coming from the gas tank area. Surged and then a half a block later died. Key turned off/on to start again. Turned around and headed home with surging, backfiring, hissing/popping sound and stalls. Also noticed what felt like a puff of air hitting my right leg right where the Pair Valve is housed.

Day 4: Tried to start, started rough, idle sounded uneven, hissing/popping sound from tank area, possible "ticking" sound under tank, would die on it's own about 1 minute after starting. Checked hoses, noticed rear turn and brake wires had frayed again due to where the previous owner had them routed, near the wheel! Fixed that, separated wires, replaced turn signal fuses. Put a bit of SeaFoam into the gas tank and let sit overnight.

Day 5: After Seafoam went to refuel with Chevron (A US gas station that ads cleaners to fuel) gas (previous fillup was at a shady gas station, so maybe bad fuel?) bike started okay but after 2 blocks started to surge with no RPM rev's and backfire loudly. Traveled about 2 miles to Chevron with surges and backfires galore. Also that odd popping/hissing sound from around gas tank. Filled up and on the way back bike died twice as I let off throttle, restarted fine. Died again while sitting at red light, wouldnt restart until I turned key off/on twice and started up. Before key pressing starter did nothing. Also noticed on my way back another jet of air against my right leg near where the Pair Valve is housed.

So, what do we think? I love this bike but she's been a fussy bad a$$ b!^ch. Did I put crap fuel in? Wouldn't the seafoam have helped? Is my pair Valve the culprit? Or something worse? I'm mechanically inclined but not trained but I'm also broke.

Thanks in advance for the ideas and I'll try and post a video of the sounds if I can tomorrow. This is also my daily commuter and I hope to have her well by Monday.
*SOLVED!*

So, first off, thank you for all of the suggestions. Based on a few of the suggestions and a lot of YouTube I bought some Carb Cleaner and sprayed it around a few connections with the engine running. The reason is that for a vacuum leak the idle would abruptly change when the flammable carb cleaner was sprayed on/near the leak. I had no results at the carb connections, but just underneath the tank, between the heads, right behind the PAIR Valve, *bum bum bum* abrupt idle change! I sprayed the carb cleaner again, followed by compressed air to dry the cleaner, both times got sharp changes in the idle.

I look around the spot and just see the giant radiator hose leading down, no cracks or wear there, hmm, what could it be? No other hoses there.....waitaminute...no other hoses, but an outlet?

Turns out the tweeker that owned the bike before me has connected the Radiator Conduction Hose (The little house that runs from the radiator hose to the Pair Valve) WITH A ZIPTIE! A ziptie that came undone and the hose had completely disconnected and hid itself behind the PAIR Valve housing.

So I went and bought some actual hose clamps, took the PAIR Valve housing off, reconnected the house, pulled the broken ziptie and used a proper clamp and Kali (the name for my beautiful bike) lives again!
Took her for a test drive to the coast line to celebrate.

This was all made possible by the carb cleaner vacuum seal check trick, and remember zipties are not for a running motor!

Thanks again everbody.

[Nobby the Bastard]

Air leak between carb/fi and manifold
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[Johnnythefox]

Leaking header pipes/gasket? Pair valve can be removed.

[Robby]

Running out of electricity feels just like running out of petrol. Someone has been cocking around with the electrics, and you've had problems there.

So I would be looking at the electrics. Two things:
1. Easy thing. Check that it's charging. Put a multimeter across the battery, hold the revs at 4k, see what voltage you get. Around 14.5v is good. 12v means it isn't charging, 40v means it's overcharging. In either case, the reg/rec is most common culprit.
2. Hard/tedious thing. Look for dodgy wiring and corrosion on the earthing points. Pay particular attention to the wiring on the ignition side.

A problem with the exhausts or PAIR valve could cause a bit of popping and noise, but I wouldn't expect this amount of trouble. Enough of us have ridden bikes with exhausts totally rusted through and the biggest problem has been the noise, not the performance.