Spluttering / Backfiring etc...

[Method]

Right ive had my GS500 for a while now and about 2 months ago i broke down. I was riding along the A1 at around 90mph / 7-8k revs... then it started to pop a little and splutter, loosing power, like it does when you run out of fuel and you have to switch to the reserve. Well i got off the A1 and it completely died on me. I pulled over but couldnt get it started.

Well the same thing happened again this morning, twice. Doing about 90mph at about 8k revs, and it started spluttering again and backfiring, then just cut out. Well i managed to get it started again by cranking it over with the throttle wide open. and thought nothing of it, rode on a bit and on the way home about 15mins later, the same thing happened. This time it took slightly longer to sort it out. But got it going again by turning the fuel tap upwards and cranking it over. When i bought the bike i was told, Up = Off, side = reserve, down = on. But aparently Up is actually a purge valve for the diaphragm carbs...?

Basically just wondering if anyone has any ideas on whats causing this, and how to sort it out...

My theorys are:

Fuel Blockage - Take off float bowls and clean out
Fuel Blockage somewhere else in the system - Wash out tank / fuel lines, everything...

ALthough the problem with the second theory is that im planning to go on a 100+mile trip tomorow as i have errands to run...so dont realy have time to wash the whole thing out lol
____________________
CBT Aug '03 ... Gilera GSM 50 ... Honda NSR 125 Aug '04 ...
Full Test Dec 04... Suzuki GS500 Jan 05... Suzuki SV650 Mar 07... Gixxer 6 K5 May 08... Oh and my 'Rado
My Bikepics.com - No Brakes, No Gears... No Fear.

[DanceLikeAMon...]

My GS had the same problem when I first got it. It didn't backfire, but after a few minutes riding it stared to ride like it was out of fuel, then it would just die. It would start again if I left it for a few minutes, but then would die again if I put any strain on the motor.

Mine went to the garage to be fixed (it was booked for a service anyway), and apparently it was being caused by (in equal measures) dirty as buggery carbs, shoite spark plugs and a filthy as fook air filter.

Might be worth checking those first since they're easy fixes.

Snip: Oh yeah, and you are right about the fuel tap, there isn't an "off" on the GS because of the diaphragm thingymabob. If you run out of fuel or the bike has been standing for a while you turn it to the prime setting to trickle fuel into the carbs (apparently)

[Method]

Yeah, im just going to brave the heat now, take off the tank, clean the plug, clean the carbs a bit, wash them out, check the plugs aswell actually because i havent done that since ive had the bike

Yeah it must have been a blockage somewhere along the line, as using the purge valve to trickle fuel into the carbs definately seemed to do the trick.

Cheers mate! Im off to do those things now
____________________
CBT Aug '03 ... Gilera GSM 50 ... Honda NSR 125 Aug '04 ...
Full Test Dec 04... Suzuki GS500 Jan 05... Suzuki SV650 Mar 07... Gixxer 6 K5 May 08... Oh and my 'Rado
My Bikepics.com - No Brakes, No Gears... No Fear.

[Method]

Ok ive just taken the plugs out = fine, taken the air box off = fine, the only thing i cannot get to is the fucking float bowls, i removed everything to get to them but couldnt undo the screws to remove the bowls, which is a bitch, i need to. UGH!

Well i just started it up and its popping still and not running right, stupid backfires ffs
____________________
CBT Aug '03 ... Gilera GSM 50 ... Honda NSR 125 Aug '04 ...
Full Test Dec 04... Suzuki GS500 Jan 05... Suzuki SV650 Mar 07... Gixxer 6 K5 May 08... Oh and my 'Rado
My Bikepics.com - No Brakes, No Gears... No Fear.

[cqueen]

you still not got yourself a new bike method? tut tut

[Method]

No The amount of times ive wanted to chuck this bike in the bin, someone comes along and tells me i have to stick with it, i have to keep it, i cant get a new bike... then i think "mmm its not that bad realy...", Then something like this happens again and its back to wanting to get rid of it.

I take it your VFR is long gone???
____________________
CBT Aug '03 ... Gilera GSM 50 ... Honda NSR 125 Aug '04 ...
Full Test Dec 04... Suzuki GS500 Jan 05... Suzuki SV650 Mar 07... Gixxer 6 K5 May 08... Oh and my 'Rado
My Bikepics.com - No Brakes, No Gears... No Fear.

[cqueen]

long gone! on sale in a local garage i would estimate for about £1200 lol (he bought it for £770 but i dont care really)

[pipnet11]

Just to be sure, is it actually backfiring? or is it actually after/latefiring (ie in the exhaust) which everyone always seems to call backfiring. Backfiring is where it fires back through the carbs. If it is doing this then it is because of a weak mixture (usually). When I had this problem I found it was because of a nearly blocked pilot jet due to a large amount of brown sludge in the bottom of the carb
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I love the girls that do, I hate the girls that dont, I hate the girls who say they will and then they say they wont, but the girl I like most of all and I think youll say Im right, is the girl who says she never has but looks as though she might. - Max Bygraves

[mchaggis]

A knackered spark plug and low oil made mine horrible and spluttery and produced copious popping in the exhaust. I think the burning oil fouled the plug and was the cause of the seizure.

DLAM covered everything it could really be, bar a dodgy ignition system. It could be a problem with the plug cap, CDI unit, HT lead etc I suppose.
____________________
I must not be a troll...
Mmmm, Guinness
Discovering the delights of Hammerite and a 3/4" brush.

[Method]

Ok right ive done a few miles on it now, i took off the airbox, cleaned the plugs, and removed the carbs. cleaned a whole shed load of orangey red rubbish from the bottom of the float bowls, but now there is a new problem... or the original problem has taken on a new form...

It now seems to mis-fire (popping through the exhaust) and jump, at anywhere below 4k revs... above that it is fine. Then when you close the throttle, it seems to rev on its own at around 3-4k revs, but it fluctuates up and down, around that range... then after about 15seconds, it drops down to like 1k and then dies...
____________________
CBT Aug '03 ... Gilera GSM 50 ... Honda NSR 125 Aug '04 ...
Full Test Dec 04... Suzuki GS500 Jan 05... Suzuki SV650 Mar 07... Gixxer 6 K5 May 08... Oh and my 'Rado
My Bikepics.com - No Brakes, No Gears... No Fear.

[imadoofus]

[Method]

[F1reblade]

I had a GSX with a vacumn fuel tap, on the fuel tap should be 2 pipes one to take the fuel to the carbs the other sucks from the inlet manifold & causes a vacumn in the tap which allows the fuel to flow. If there is a hole in that pipe it could be starving your engine of fuel. You can take it off the inlet manifold & suck on it, you shouldn't be able to. If you can it's foorbar'd.

[Method]

Thanks for that F1reblade!

Right, ive just been out there and had a mess about with it, stripped it all down again, and i seem to have cured the backfire through the carbs and the rough idling... now there is just a crackle / popping in the exhaust when i closed the throttle...?
____________________
CBT Aug '03 ... Gilera GSM 50 ... Honda NSR 125 Aug '04 ...
Full Test Dec 04... Suzuki GS500 Jan 05... Suzuki SV650 Mar 07... Gixxer 6 K5 May 08... Oh and my 'Rado
My Bikepics.com - No Brakes, No Gears... No Fear.

[LustyLew]

Could be rice crispies in the fuel tank?

They seem to go 'snap, crackle and pop'...

I'm sorry, I couldn't resist, the heat has got to me...
____________________
Like a Yorkie - I'm not for the girls

[Method]

..................
____________________
CBT Aug '03 ... Gilera GSM 50 ... Honda NSR 125 Aug '04 ...
Full Test Dec 04... Suzuki GS500 Jan 05... Suzuki SV650 Mar 07... Gixxer 6 K5 May 08... Oh and my 'Rado
My Bikepics.com - No Brakes, No Gears... No Fear.

[R4nger]

Check your tap is working. Clean it out and put back together. Get new fuel hoses and mix Redex with the fuel in the tank. Also clean out the carbs and replace the air filter. This will solve your problem of dying. It only dies at 90mph because there is a partial blockage somewhere between the tank and the engine... simple?

See if it does it on the prime (UP) position on the petrol tap. If it still does it then, replace the hoses and clean the carbs. If you can not do your carbs then I could LEND you some.

Up = Prime - Petrol is free flowing (Does not rely on the pressure (sucking) on the tap to open the diafram up to let petrol through)

Forward = Reserve

Down = Main/Standard etc.

Can't be arsed to spell check on Google.

[imadoofus]

so what did you end up doing in the end?
cos i might need to do similar stuff.
and i havent cleaned the carbs ever, so not too crazy about doing that. but i might have to

[Method]

Basically i removed the tank / seat / air box / air filter / plugs / carbs.

Removed the air filter and gave it a quick clean, cleaned the plugs / caps, drained the tank and washed it out, dropped the float bowls off the carbs and cleaned them out, checked the floats were moving freely and had no splits / holes, removed the top of the carbs and checked the diaphragms for holes / slits, and made sure the slides were moving freely, had about a 40min fight trying to get the carbs and airbox back in with the stupid rubbers and that was pretty much it. Its going in for a service sometime soon just for an all over check and a much needed service + front tyre.

Just got a few things left to do on it today now, including;

N/S/F Indicator not flashing
O/S/F&R + N/S/R Indicators flashing at double speed ( which makes the bike look like a rolling night club at night )
Front light flashing with the left indicators instead of the N/S/F Indicator

All Good Fun
____________________
CBT Aug '03 ... Gilera GSM 50 ... Honda NSR 125 Aug '04 ...
Full Test Dec 04... Suzuki GS500 Jan 05... Suzuki SV650 Mar 07... Gixxer 6 K5 May 08... Oh and my 'Rado
My Bikepics.com - No Brakes, No Gears... No Fear.

[imadoofus]

[Method]

What bike you got? If its a GS500 like mine then it is just a pain when your trying to get the rubbers connected properly, because they are a bit fiddly to reach.

If your just going to clean the float bowls then you shouldnt need to remove anything, just stick a screw driver under the bowls and take off the screws, and no it wont affect the float height. If your taking the whole thing off and checking for air leaks etc and cleaning the air box etc like i did, then the hardest bit is getting the airbox to fit back into the frame without either getting stuck, or trapping pipes on the way

The first time i did it, i had no problems at all, then the next day i almost through a big hissy fit, throwing tools on the floor etc Its a straight forward enough job to do, i think the heat just got to me and therefore i didnt have the concentration / patience to replace them in the correct way.

I have a few pics that i took with my phone of it in peices if you want to see?
____________________
CBT Aug '03 ... Gilera GSM 50 ... Honda NSR 125 Aug '04 ...
Full Test Dec 04... Suzuki GS500 Jan 05... Suzuki SV650 Mar 07... Gixxer 6 K5 May 08... Oh and my 'Rado
My Bikepics.com - No Brakes, No Gears... No Fear.

[imadoofus]

[Method]

Ok heres the pics anyway, the rubbers are between the air box and the carburettors, and then between the carburettors and the engine. They are called "Manifolds"
And in the pictures they are positioned where the red lines point to, (the bit marked 1)...
____________________
CBT Aug '03 ... Gilera GSM 50 ... Honda NSR 125 Aug '04 ...
Full Test Dec 04... Suzuki GS500 Jan 05... Suzuki SV650 Mar 07... Gixxer 6 K5 May 08... Oh and my 'Rado
My Bikepics.com - No Brakes, No Gears... No Fear.

[imadoofus]

oh i fixed the loss of power in mine.. It was a leak in the airbox rubbers, thus fouling the plugs and loss of power.
The revs I havent got to yet.. possibly idle speed adjustment should fix it.

[R4nger]

I gave up putting the rubbers back on my carbs. I'm just going to buy K&N pods soon with a dynojet kit.