running on one
 

Went a run the other day. Bike running on one cylinder (rear) most of the time. But it ticks over without stalling. Thought I would swap ignition coils over to prove but I cannot locate them. Took airbox off and tried to follow Ht lead without success. Anyone know their location? Looks like the coils come with the Ht lead attached are they interchangeable anyway. Any words of wisdom greatly appreciated I do not consider myself a spanner man!

Sv650X

Re: running on one
 

ts amazing what a bit of sun through the window can do. located the coils but swapping them over does not look easy. Still welcome an words of wisdom on my way forward

Re: running on one
 

https://forums.sv650.org/images/ca_m...s/viewpost.gif
Its amazing what a bit of sun through the window can do. located the coils but swapping them over does not look easy. Still welcome an words of wisdom on my way forward
by SEEKER



You ought to have started a new thread. :rolleyes:

Are you saying that it is running on one cylinder occasionally but will idle normally? My AL7 is reluctant to idle on one but occasionally at a petrol stop will have a hiccough and try (badly).

How old are your plugs (mileage and age)? Has the bike been in heavy rain/wet roads? The SV's front cylinder has always been prone to suffer especially if the plug drain holes are blocked. Is the petrol "fresh"?
__________________

Re: running on one
 

Thanks Seeker for the reply - Please delete your post in suspension and brakes. I have corrected my error!!


It is running mainly on one cylinder. Pretty certain it starts on one only . It did clear for a very short distance on the run for about a couple of hundred yards. It does not backfire at all. Its not water related I only ride it in the dry and its in need of a wash!. I did fit new plugs not so long ago but have ordered a new set in case one is duff. Bike has only done 8.5k in 23 years . Petrol fresh and has been Redex and fuel stabilizer treated.

My thinking is that if its on one cylinder at tickover and also at 4k revs + it is more likely to be electrical than a

carburetion problem. Any suggestions greatly appreciated

Re: running on one
 

So, it's not an SV650X which you put in your first post? It's a curvy - a carb model?
One problem that can afflict curvy's is sticking choke plungers.

I haven't owned a curvy in a while but one problem I encountered was a failing fwd cylinder plug - the bike started ok and would run for bit then start misfiring. It's the only bike I've owned that has a plug malfunction (other than a 2 stroke oil fouling - but that went with the territory).

Make sure you buy your NGK plugs from a reputable source - there are a lot of counterfeits.

Re: running on one
 

first thing you need to do is check/swap the plugs. take the plugs out and check the spark by putting it in the plug cap and holding the plug cap against the outside of the cylinder (try to hold it against an unpainted part like a nut or bare part of the frame) with a plastic/wooden spoon or insulated pliers. it should be a nice crisp blue/white colour, if not then either the plug is duff or the plug cap/HT lead/coil or igniter (curvy) is duff. do this with both plugs. or just swap the front and rear plugs if the rear stops firing then its the plugs.

with all models the RR connectors get furred up causing bad running problems due to not letting the battery charge properly. the pointy connector is a nightmare.

with curvy as seeker said its sometimes the choke plunger getting stuck.

bad card/TB balance wont cause running on one cylinder but its always a good idea to have them balanced once every 3 or so years. later twin spark bikes need an electronic tool to balance the TB's.

with pointys its sometimes the TPS out of tune but this does not let the bike only run on one cylinder.

Re: running on one
 

I believe SV650X is the correct official designation for the first year of curvy models ;) (It never helps when manufacturers re-use designations does it?!)

Anyway, back to trying to help OP, a few thoughts:

• Swapping coils is a bit fiddly if you have larger hands, but not impossible. Getting the small wiring connections re-attached was what I found most awkward due to the limited length out of the loom.

• From memory, I think the front coil low-tension wiring is what pulses the tacho, so if the rev-counter works but the front cylinder not then that narrows electrical gremlins to coil, HT lead or plug. Bibio's suggestion of plug swap first will help narrow further.

• I seem to recall the HT leads are different length front and rear so that may impede a check by swapping. I can't remember if HT leads can be changed out from stock coils.

• Is it possible the front carb float or plunger has stuck, causing fuel supply randomness? Does the exhaust have a stronger smell of petrol than usual? If not, the fuel is possibly not getting through, and this may also be why it's not backfiring at all? A few gentle taps of the float bowl may free it (though impossible to know for sure, or how permanent a fix it will be), otherwise I fear it's a carb off and stripdown required to check.

redtrummy, I know I'm not very far away from you but unfortunately I have a car in pieces that I need to dedicate most of my spare daylight time to, so sadly I can't offer much right now to come and get hands' on. I could probably plan in something for Feb/Mar if you want a second pair of eyes and can wait a bit?

Re: running on one
 

If it turns out to be the ignitor (CDI?) then drop me a message as I have a spare one gathering dust.

Re: running on one
 

Thank you all for the replies, and a special thanks to Ruffy and Dak for their respective offers.
I have had a bit of a domestic re the Brother in Law which needed resolving so have been somewhat preoccupied of late, plus I am waiting for the plugs to arrive and due to the poor light in the garage I need a mildish day, when its dry and can get the doors open to move things forward. I have a poor sense of smell but I did think there was a petrol smell when pulling up to a stop, will get the wife to verify.
Will keep you informed and thanks once again.


Does any one know do the Ht leads disconnect at the coil end?



And one final point, I have dug out the service record and it is designated a 650X in there.

Re: running on one
 

The coils leads are fixed at the coil IIRC.

Check the plug caps and drain holes as well.

Click here,

https://halnico.com/SV650/PlugCaps/S...PlugsCaps.html

Or,

http://straticus.epizy.com/SV650SparkPlugsCaps.html

Re: running on one
 

Thank you R1ff - reckon I have a lot to check!

Re: running on one
 

Any progress on this RT?

Re: running on one
 

Thanks for asking Gary - Too cold for me in the garage! New plugs and JIS screwdriver arrived (Bibs choice) Midway in renewing the lads bathroom as well - Granddaughter arrival expected anytime soon. Been on at him for 3years to get it done now its panic stations! so I may end up Sorning it at the end of the month until I have more free time. The Cub is/was running well but roads wet/salt no way.

I wonder what it is but I really miss not being out on two wheels, suffering withdrawal symptoms I think!

Re: running on one
 

On the black side of life! The lads bathroom is not yet finished! (Only limited access now, cannot disturb the newborn. However, in the meantime I mulled Suzy's problems over, surely if it was electrical then fuel would be dumped into the exhaust which would cause popping and banging which just didn't happen? So I started the bike to recheck and promptly burnt my hand touching the front exhaust pipe, ran it through the rev band and above 6k it was obviously running fine. (I doubt in my local area I have reason to hit 5 -6 k when riding her, so back to carburation. The bike had very little fuel in it so gave it another good shot of Redex (Bow down to the powers of Redex) ran the bike for a few minutes, left it for a couple of weeks, tried it again with a short run and it was running pretty well with the odd misfire! Hopefully I will be taking it on a bit of a run tomorrow to check its current status. If the outcome is good I will own an unused JIS screwdriver and a couple of spare sparkplugs, time and test will tell! Or on the black side of life I have an intermittent problem

Re: running on one
 

Fingers crossed! Hopefully it was a bit of dirt in the carb innards somewhere that's now been dislodged, dissolved or burnt away.

Pretty sure you'll find a use for that JIS screwdriver eventually - good tools are never a waste for practical hands, it's just a matter of timing!;) And the plugs will be ready for next routine service time.

Re: running on one
 

Did you ever take the choke plungers out and make sure they are free and working? The front one is awkward to get at and they are very often the source of running issues on the carb model.

Re: running on one
 

No but I figured out where they are and if problems continue I will thanks for the reminder! First it needs an oil change so does the Cub, both lawnmowers and the motorhome and the car , garage full of oil ready. Just need the weather to warm up first, plus got the garden to set, ground too cold here yet. Better than being bored I guess.

Re: running on one
 

Progress! After a short run on Sunday Suzy started spluttering so Monday I decided I would have the front choke plunger out if I could get it out (thanks for the reminder again Biker Biggles) so full of trepidation I removed tank and air box when I heard something fall - it was a tank retaining washer, luckily it missed falling into a carb! Thought must be my lucky day things usually go wrong for me, so rags bunged into the carb mouths and onto the plunger. It WAS my lucky day the retaining plate screw was a good 8 mill out, loose! So carefully removed the screw, plate and plunger, every thing clean as a whistle! Bunged a little grease on the plunger and spring and carefully replaced the items back into position then took it for a spin. A lot better but still seemed to misfire now and again but I did the long overdue oil change. Ran it up for its MOT today and it seemed fine so hopefully the end of this saga! That plunger and associated bits has not been touched in 24 years of ownership.
Must say it was a lot easier job than what I was expecting. Thanks all

Re: running on one
 

Decided to give the bikes engine a turnover in the hope of perhaps having a run on it now its finally stopped raining! Noticed a pool under the bike- on tracing its source it appears to be diluted petrol/oil and the petrol component is coming from the rear carb. Have read previous threads I think the petrol tap may be the favorite cause allowing fuel down the vacuum pipe . It seems to still run fuel after I have switched the bike off so I propose that is my starting point tomorrow,
then sticking float/needle?


Does anyone have any other suggestions what may be the culprit?



Thanks

Re: running on one
 

Yes. Failing or failed Petcock and float heights incorrect/stuck. Has happened to me on one of my old Hondas with CV carbs when the bike was left on the side-stand. The fuel also got past the inlet valves and contaminated the oil. You could smell the petrol in the oil from the filler hole and caused a vapour-lock/hard turn-over.

I drained the oil and replaced it with some cheap 20w50 and ran that for a few mins and then dumped it. I repeated this again and the put proper oil in with new filter . I did not want any bottom-end shell contamination that could ruin the engine.

You may be lucky and no fuel in the oil but if not see above.

Re: running on one
 

Thanks RiF, Went out this morning to have a play but it was just too cold. will give it ago on a slightly warmer day!

Re: running on one
 

Don't blame you. I hate working on me bike in the cold :smt026

Re: running on one
 

Well today was nice and warm so I had a quick look. I took what I think is the vacuum pipe from the bottom of the tank. No petrol came out and the bike did start with it disconnected. That did surprise me. I did notice that the rear carb was expelling atomized petrol out of the carb mouth, and when I killed the engine, petrol dripped from the carb. I therefore perceive I have a fault with the rear carb. Is there anything else I should consider? And if not, anyone any idea what could be the likely fault?

Re: running on one
 

I'd check the float height in that carb and reset it if required.

I would replace the float needle valve/s as well and the base and filter that are included in these kits. A lot of the stuff in the kits won't get used,

SV650 Carb Kit eBay


https://i.imgur.com/vWzjm9y.jpg

https://i.ebayimg.com/images/g/KLYAA...zM/s-l1600.jpg

Re: running on one
 

Thanks again R1ff, I have removed the carbs ready to take a look. I thought it would be a sod of a job, they have never been stripped down since new but all the screws came undone A1 ok. Has anyone any info on checking the float height? I did have the manual downloaded on an earlier computer but that went kuput. I found where it said standard was 7mm but that was all. Think the obvious and likely cause is a float needle with gunge stopping it sealing. Ashamed to say the bike has still less than 9k on the clock - never really get much time to ride it but when I do I always come back brighter than when I set off (assuming its running ok)

Re: running on one
 

Please send for the service kit. There's no point in putting the old Float Needle Valve back in. The base-filter unit can be cleaned but they come with the kit so put the new one in. The Float Needle Valve is not the innocent little thing it looks like. The little plunger on top is part of a micro-spring loaded system with an ultra tiny spring inside it. With constant daily use they last decades but if left unused for say a couple of years the springs can become corroded and stick adding to fuel delivery problems.

As for float settings:

Using a steel ruler with a bit of masking tape wrapped at 7.5mm mark use this video but you only need to make sure
that at the furthest point from the axle the float-corner is 7.5mm +/-10% to the carb body when held close the the angle the carb will be when in-situ. Float adjustments are best done with the float off to prevent damage to the Float Needle Valve.

https://www.youtube.com/watch?v=g6y32Gw5HK4


Tip: Keep a magnet handy and stick the axle to it when stripped out :)



When all done and happy the icing-on-the-cake is to balance the carbs as per,

http://straticus.epizy.com/SV650CarbBalance.html

Re: running on one
 

Thanks again R1ff. I watched loads of y tube last night but non as good as that. I fully intend getting a kit . The wife is due to have her knee replacement next week and the weather is supposed to be turning colder( heard that one before) so it will give me a job to do in the warmish utility room
Better than the cold garage! Cheers once again

Re: running on one
 

Well I have made a start. Checked the diaphragm on the suspect card looks fine. I then tried to unscrew the float bowl and cannot shift any of the 3 screws using a JIS impact driver. If I drill the heads off am I likely to have any problems removing the threaded part, or any tips to get them undone? You never see these problems on Ytube!

Re: running on one
 

I had to drill out a couple. I ended up using a left hand drill bit. Don't use easi-outs. I had to replace one with a small nut and bolt.

A cheap kit like this did the job fine,

Left hand drill kit eBay



Before you try this leave the carb/s soaking in some diesel fuel for a day or so and then if you can get some Mole/Vise grips on the screws see if you can turn them out.

Also I always keep one of these around for focused heat and useful for several jobs,

Butane Blow Torch eBay

Re: running on one
 

Thanks Riff - I did look at Easi outs but was not convinced. I do have access to a culinary torch, the wife's! Found it great for soldering 15 mill pipes as well much better than a blow torch. I did try it on one screw but failed. The front carb (mucky one) all undid ok. A friend is bringing another impact driver I will try that, then the diesel if I still have some, then the LHB if all before fails

Re: running on one
 

Progress made! A 5inch set of mole grips undid the two screws opposite each other, the third was removed by tapping the float bowl until the seal gave, then the screwdriver undid it.
You were crack on with the diagnoses R1FF (I hope) the float was stuck in the up position, on touching it, it dropped. Checking the needle its internal spring seemed weak compered to the new one. All changed plus a going over with carb cleaner and a blast out with compressed air. Carbs back together with vacuum hose extended on the front carb ready for balancing if the bike runs ok after carb refitted
Once again thank you R1FF

Re: running on one
 

Great news :)

I've been servicing CV carbs for around 20 years now 1st on my old Hondas and now my SV. Icing on the cake when all good is the ,"Carb Balance",

http://straticus.epizy.com/SV650CarbBalance.html?i=1

I suffer from Industrial VWF ( Vibration White Finger) plus a damaged right shoulder/neck that took best part of 3 years Physio and Cortisone injections to get back to useful so I have to keep my SV smooth.

Considering my SV is now 25 years old it rides as smooth as if it was only a few years out of the Show-Room and always gives great MPG :D

Re: running on one
 

carbs refitted, and it started! - had to tweak to get the tickover down to 1.5ishk. Cannot fully test as its sorned, but MOT possible on the 24th and if all is well, then a balance. Probably end up doing a 2 bottle DIY job.
Got a friend that suffers from white finger after a lifetimes work in the mines. His first job was looking after the Pit ponies!

Re: running on one
 

Once you can get the carbs balanced it does no harm to run some fuel/petrol cleaner. I put a couple of egg-cup fulls in every few tanks. I always keep my eyes out in ASDA as they sometimes have a good double bottle deal on Redex but the best stuff I've used is this,

Carlube fuel cleaner eBay

It seems to give a bit of pep to the engine but I also believe it negates any side-effects of E10 fuel. I've used fuel additives for decades and never yet had a stale fuel problem when I used to ,"Winterize" my Motorcycles :)

Re: running on one
 

Finally! Weather forecast on bbc and on the met seemed to indicate a dry day, managed to book the MOT for today (after countless no answers from the test station). Got it out of the garage and immediately it started to rain! However bike seems to run fine and it has passed. Good to go from the first of May although I hope the weather warms up, it was pretty cold out there

Re: running on one
 

Great :) You can at least start to fine tune and shake out the cobwebs :D