View Full Version : SV650 choking when hot
Today i had unpleasant experience...i had around 80km trip ,driving arround 80-90kmh, and when i reached my destination....i noticed that my bike started choking on low rpm...if i drive it under 3.5k rpm, it chokes. Above 3.5k it runs smooth. After that, i left the bike for like 45min and when i started it...it was running smooth. Same thing happened on my way back home.
Any ideas about what`s wrong?
Sid Squid
25-05-14, 05:16 PM
Curvy, Pointy?
...forgive me, but i have no idea what u just said xD
DarrenSV650S
25-05-14, 05:43 PM
He means are you male or female
Geodude
25-05-14, 05:43 PM
What model of sv have you got? if you have an sv ;)
Geodude
25-05-14, 05:44 PM
He means are you male or female
:p
So far with my research on web, i found that if the bike runs good when cold, and acts weird on low rpm when hot, it`s probably electrical problem...spark plug or something. Is there any truth in that?
Paul the 6th
26-05-14, 10:15 AM
my mechanical experience is doing oil changes (badly, forgetting to tighten sump plug fully) but I'd hazard a guess at the mass air flow sensor maybe? Sounds like it's running super rich, so when cold that's fine but once it warms up it's still getting too much fuel through/not enough air hence choking (check the air box to see if there's any obstruction in there).. Dead or dying MAF sensors can cause all sorts of weird and wonderful issues on modern cars, so I've carried the same logic across to your bike..
My ex's fiesta had assorts of nightmare running problems - one of which was as if the car was restricted to 60mph - it literally wouldn't go above 60 like it had a hard limiter on it. Research indicated MAF, disconnected it and went for a spin, ran perfectly and went far, far beyond 60 without a problem. Ran it without a MAF for a few days while replacement item came, we had terrible mpg and the revs were up and down at tick over but the new part solved all this.
Maybe have a look at the state of your spark plugs, they can indicate whether it's running rich or lean
http://motogymkhana.pl/katana/wp-content/uploads/2013/04/spark-plugs-guide.jpg
Me and a friend of mine just chwcked the spark plugs, and it trns out that the bike is running rich(rich means more fuel...right?) . Also the air filter needs cleaning
Can the tps sensor be making this kind of troubble?
TPS is set up ok, i replaced the spark plug(it was CR9E instead of CR8E), but...i still don`t have the chance to test it on a longer ride due to the rainy weather. I`ve noticed that something has changed in the bike tho...i used to get backfire from the exhaust, but now i get it on specific RPM, If i ride it on around 4500 rpm, and i release the throttle i get backfire..every time.
Is it possible for me to have this problem cuz of the clutch switch? The previous owner dropped the bike and the switch is gone, so they just connected the 2 wires together for the bike to run. I saw this video and it seems like it makes sense. I ordered a new switch from ebay and i`m waiting for it to get to me.
Any advice would be apreciated
This is the video that got me thinking that the switch might be the problem http://www.youtube.com/watch?v=4_qnGJihHvM
backfire as in like a gun going off or a pop like a balloon bursting?
Hmmm more like a balloon burst, it usually pops once or twice.
Sid Squid
05-07-14, 03:23 PM
If it runs OK when cold I'd have a look at the coolant temperature sensor.
are you saying that the bike now runs fine but you get a 'pop' from the exhaust?
I haven`t had the chance to test the bike on a longer run with the new spark plugs and the improvised clutch switch yet. I`ve been running it around town and it runs good, just like it was running before the changes. The only difference is the rpm on which i get the pop from the exhaust. I used to get it on higher rpm, and now i get it around 4.5k
so its not 'choking' any more?
Sid Squid (http://forums.sv650.org/member.php?u=188) any idea how to test the coolant temperature sensor?
And Bibio, either on monday or tuesday i`ll take the bike out of town for a longer run, and let you know if it`s choking or not.
Do u think the exhaust has something to do with the backfire i get? I have after market exhaust, Sebring Twister
Paul the 6th
06-07-14, 09:52 PM
I've heard of maps on high performance audi's (s4 b5 2.7 bi-turbo modified to high hell) being mapped to throw extra fuel through the engine on the over run (coming back down from high revs) or during gear changes (when the clutch is in) so that the extra fuel/running rich cools the piston crowns... I'm guessing it's a similar thing as shown in the video, so if you absolutely rev the ass off the bike and then pull the clutch in, it will run a little rich to deal with extra heat..
I've also read/heard that if an engine is going to have rich or lean issues, it's far kinder for the engine to run rich.. Running lean can lead to burning and scorching of the internals.. Running rich, at the very worst may wash the oil off the bores but generally just means a fouled spark plug (sooty) and affects mpg..
I'd go with the clutch switch on this occasion.
As for the backfire at 4,500rpm, if you have an aftermarket can this is pretty normal. My 05 sv used to pop coming back down the revs from 5 to 4 thousand (beowulf can), and the zx9r I've just picked up pops repetitively coming back down the revs between 6 to 5 thousand..
I just put the stock exhaust back on, and i still get backfire but it`s rare unlike with the aftermarket one...and usually at the same rpm
I have to admit..riding with the stock exhaust made the ride much smoother and quiet. I kinda like it. Too bad the exhaust is all scratched
The clutch switch did not solve the problem. Now i`m waiting for both of my mechanics to be available to work. I can`t fix this on my own xD
wideguy
25-07-14, 08:49 PM
Did you ever clean the air filter? Did that make the plugs look good and the engine run cleanly?
If you haven't done that yet, why not? The hotter plugs were probably in the engine to keep them from fuel fouling with the rich mixture. Does it use oil?
Yeah, i cleaned the air filter like a month ago. I did not notice any change in performance. As for the spark plugs...last time i checked they were as if the engine was running rich.
is the bike otherwise running ok apart from the 'backfire'?
On shorter rides , everything is ok. But if i take it to a bit longer ride(and by longer i mean 30ish min ride with overall speed of 120-150kmh, it starts to act weird on low rpm(below 3k or 3.5k), it chokes and if i let go of the throttle, it`ll stall. Above 3k or 3.5k rpm, it runs ok.
i think we need a bit more information.
was the bike ok then suddenly started not running right?
did you do anything to the bike before the problem started e.g. lift the tank or mess with the throttle bodies?
ok here we go...i got the bike in february, and because it was pretty cold, i could not take the bike on a long run. So everything was ok. I noticed the problem when i first took the bike on a longer run. Yes, i did remove the tank, i had it repaint. I made sure i reconect everything and i think i did a good job cuz i`m not getting any FI codes. Even if i did mess up something back than(not connect something), i`ve lifted the tank 4-5 times since than so i pretty much know where everything needs to go.
Throttle bodies...up untill a week ago(when i was at a local mechanic), i had no idea what throttle bodies are. (while we are on the throttle bodies subject...do the plates need to fully close at some point while the bike is running? I started the bike with airbox open so i can see, and they don`t fully close when the bike is running on iddle).
the plates at the top will 'flutter' as you rev the bike.
in your other thread you say that there is a strong smell of gasoline (petrol here in the UK) how strong is the smell, can you smell it standing next to the bike?
well...i do have a smelling problem, so i have to get realy close to the engine to sense it, but when my local mechanic saw the bike, he instantly said that he smells gas. So i can say ye...u can feel it.
with that i would say that you have a fuel leak under low pressure. double check that you have interlocked the fuel connector from the tank to the throttle bodies correctly, possibly a bit of grit or something in there. check the surrounding area around the connector for signs of petrol leaking.
when you had the tank sprayed did you remove the fuel pump?
No petrol leak anywhere, that was the first thing i checked.
And yes, i did remove the fuel pump.
You think i messed up somethig wth the pump?
its starting to sound like it. i have read that the fuel pressure regulator can come loose, maybe yours has been knocked and is on the verge. or the strainer is blocked.
Hmm it's worth to be checked. I'll work on that first thing tomorow.
Ok..what exactly do i need to pay attention to here? Last time i opened the fuel pump i thought it`s just 1 big piece(tho i didn`t actualy pay attention if it can be disassembled)
http://youtu.be/Ru6Dva560_I
I found a vacum leak near the air pressure sensor. I cut the hose so it'll be tighter but it still leaks.
http://rs1279.pbsrc.com/albums/y532/Marusi_Stevo/Mobile%20Uploads/20140818_223929_zps87b6f53a.jpg~320x480?t=14083974 91
This was the part if the hose i cut off
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