strange engine problem - SV650.org

25-01-05, 05:34 PM

My SV has been doing this strange thing for a while now. Occasionally when I come to start my bike it will go onto one cylinder, and backfire quite a lot, but just riding it down the road about half a mile causes the second cylinder to start kicking in, before it then comes in fully and problem solved! The weird thing is that my bike will be fine for ages then one day it will just do this strange thing then the next day its fine again. I dont think its related to rain cos it has happened in the dry a lot of times after bein in my garage. My SV has done a lot of miles, 32,000. Someone suggested it could be the coils wearing out, would that be possible? Just seems strange that simply riding it down the road fixes it. Anyone got any ideas what it might be?

25-01-05, 08:14 PM

Methodical checking of everything has to be the name of the game. However, does it perhaps fire up OK on both pots when you start with the choke on and then start playing up as the engine warms up and the choke is released? A slightly sticking choke slide or cable might be giving problems.

OTOH, backfiring suggests ignition probs.

Heck, what do I know.

25-01-05, 08:16 PM

I thought it was choke cable too so I replaced it and replaced the springs and
plungers and all related parts but that made no difference so dont think its the choke, thanks for the ideas tho

25-01-05, 10:03 PM

So basically the engine becomes hot and it starts working?

MrMessy · 26-01-05, 12:19 AM

Does this happen if it has been stood unused for days? If you start it, does the second cylinder start up without blipping the throttle. Does it mis when you open the throttle. If it does these it is possibly just fuel evapoating out of 1 carb. Coils normally breakdown when they get warm. ie starts O/K then misfires/ cutouts when been run for a while.

26-01-05, 09:38 AM

yeah it does usually do this if its been left standing for a few days. And yeah, it usually ticksover on both cylinders, then as soon as the throttle is opened it goes onto one cylinder. And yeah I assume it is just the engine getting hot that starts the second cylinder firing again

Sid Squid · 26-01-05, 11:26 AM

Could this be the wet fuel strikes again?

It's that time of year, I suspect it is.

26-01-05, 11:52 AM

I think you might be right sid squid, i thought it was this too so I added some "dry fuel" additive from halfords and the bike runs a lot better with this in the tank. Doesnt totally cure it tho. Would I need to maybe drain the fuel tank and carbs to sort it properly?

Sid Squid · 26-01-05, 04:32 PM

Drain the carbs first, see if that works, if it does but the trouble comes back after a while, then perhaps you'll have to do the tank too.

26-01-05, 09:55 PM

Thanks mate, I shall do just that

25-01-05, 05:34 PM	#1
mattyL Guest Posts: n/a	strange engine problem My SV has been doing this strange thing for a while now. Occasionally when I come to start my bike it will go onto one cylinder, and backfire quite a lot, but just riding it down the road about half a mile causes the second cylinder to start kicking in, before it then comes in fully and problem solved! The weird thing is that my bike will be fine for ages then one day it will just do this strange thing then the next day its fine again. I dont think its related to rain cos it has happened in the dry a lot of times after bein in my garage. My SV has done a lot of miles, 32,000. Someone suggested it could be the coils wearing out, would that be possible? Just seems strange that simply riding it down the road fixes it. Anyone got any ideas what it might be?

26-01-05, 11:26 AM	#7
Sid Squid No, I don't lend tools. Mega Poster Join Date: Jul 2003 Location: Skunk Works, Nth London Posts: 8,680	Could this be the wet fuel strikes again? It's that time of year, I suspect it is. __________________ If an SV650 has a flat tyre in the forest and no-one is there to blow it up, how long will it be 'til someone posts that the reg/rec is duff and the world will end unless a CBR unit is fitted? A little bit of knowledge = a dangerous thing. "a deathless anthem of nuclear-strength romantic angst"

26-01-05, 04:32 PM	#9
Sid Squid No, I don't lend tools. Mega Poster Join Date: Jul 2003 Location: Skunk Works, Nth London Posts: 8,680	Drain the carbs first, see if that works, if it does but the trouble comes back after a while, then perhaps you'll have to do the tank too. __________________ If an SV650 has a flat tyre in the forest and no-one is there to blow it up, how long will it be 'til someone posts that the reg/rec is duff and the world will end unless a CBR unit is fitted? A little bit of knowledge = a dangerous thing. "a deathless anthem of nuclear-strength romantic angst"

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25-01-05, 08:14 PM	#2
chazzyb Guest Posts: n/a	Methodical checking of everything has to be the name of the game. However, does it perhaps fire up OK on both pots when you start with the choke on and then start playing up as the engine warms up and the choke is released? A slightly sticking choke slide or cable might be giving problems. OTOH, backfiring suggests ignition probs. Heck, what do I know.

25-01-05, 08:16 PM	#3
mattyL Guest Posts: n/a	I thought it was choke cable too so I replaced it and replaced the springs and plungers and all related parts but that made no difference so dont think its the choke, thanks for the ideas tho

25-01-05, 10:03 PM	#4
snoopy Guest Posts: n/a	So basically the engine becomes hot and it starts working?

26-01-05, 12:19 AM	#5
MrMessy Member Join Date: Sep 2004 Posts: 557	Does this happen if it has been stood unused for days? If you start it, does the second cylinder start up without blipping the throttle. Does it mis when you open the throttle. If it does these it is possibly just fuel evapoating out of 1 carb. Coils normally breakdown when they get warm. ie starts O/K then misfires/ cutouts when been run for a while.

26-01-05, 09:38 AM	#6
mattyL Guest Posts: n/a	yeah it does usually do this if its been left standing for a few days. And yeah, it usually ticksover on both cylinders, then as soon as the throttle is opened it goes onto one cylinder. And yeah I assume it is just the engine getting hot that starts the second cylinder firing again

26-01-05, 11:52 AM	#8
mattyL Guest Posts: n/a	I think you might be right sid squid, i thought it was this too so I added some "dry fuel" additive from halfords and the bike runs a lot better with this in the tank. Doesnt totally cure it tho. Would I need to maybe drain the fuel tank and carbs to sort it properly?

26-01-05, 09:55 PM	#10
mattyL Guest Posts: n/a	Thanks mate, I shall do just that