BUGGER....

[backfire]

Was riding the old 650 into work tonight and lost power from one side...just did not fire, so rode to work with the accelerator hard out and could only do 80kph. Riff Raff was suitably unimpressed as she was riding behind and kept getting a blue blast from the exhaust. My question, is this a case of a fowled plug or something much more sinister??

Be good to hear what you guys think.

[Riff Raff]

:Riff Raff was suitably unimpressed as she was riding behind and kept getting a blue blast from the exhaust.

Not at all, I think everyone should inhale large quantities of exhaust fumes, especially when sitting behind you at traffic lights

:My question, is this a case of a fowled plug or something much more sinister??

Not unless you ran over a chicken!

[Artifice]

you'd expect a cloud of blue smoke every time a fouled plug fired. so check the plug for good spark and maybe she's running rich on that cylinder. mind you what would i know im a take it to the shop cos it costs more when i fix it type of guy.
otherwise maybe rings? bad gasket, ahhmaybe its been sitting in the gargre too long without a good stroking.

oh yeah welcome to ze forumns

[Posh Tourer :P]

Take the plug out and earth it and check spark. Check the HT leads are connected properly if there is none. If there is still no spark, replace the plug and try again. Still no joy, then you have more problems than I can diagnose... If spark is weak (compare to the other side if you arent sure) just replace the plug, and you should be all go again.

[Paul in NZ]

Pretty rare for a plug to fail on it's own these days, there is usually a reason.

Still, they are quite cheap so whack in a fresh one and see how you go, could get lucky and you can do it faster than logging onto the net.

For combustion to occur you only need fuel, air, ignition and compression to be there all at the right time. Just figure out which one is missing!

Paul N

[White trash]

Me Dads 650 Special went out on one once. Fouled plug thinks them.

Holed piston sez bike. So they welded a nut into the hole in the pistoan and sold the bike quick smart.

i hope you didn't get that one.

[Motu]

An XS650 running on one cyl? that's par for the course mate,check all the XS650 sites,there will be a thread about ''my Special cuts out on one side''.Mine did it for years,I think I fixed one cause,but then had another similar fault.Does it do it when hot?

One cyl could be running lean,or it could be running rich and fouling a plug.I take it has points? Go over the ign system,I've had them seize on the pivot - gotta be old to do that! Condensers (I have 2 sets on my XS1 so I can swap on the side of the road),and the coils are renowned for being weak.I'd go for the carbs first,pull one lead off and see how it runs,do the other side - it should run almost the same on both sides.The side running crappy will be the one to look at....well possibly,these things have taken on the British persona,curved balls a plenty.

[scumdog]

One of the coils bad - or one end of the coil if it is a double-ended one?
Also if one lung is out it often seems to smoke more than when it's running.

Go the cheap route first, try a new plug then new lead (swap leads to see if it is a bad lead) then coil etc!!

Is the fuel on individual lines to each carb? could be one clogged or similar.

[Jackrat]

This happens on my bike sometimes.
So far it's always been crap in the Carb.
Put a filter in the fuel line.
If it ain't that I would check the Plug then coil.
Go here for lots of info'
www.650motorcycles.com

[Riff Raff]

I'm really sorry I overtook you on the way home from work yesterday Orpy - I had good intentions of following you all the way to ensure you made it home, but I couldn't stand the fumes you kept blasting my way (and having to do 70kph down the motorway). I figured since you got all the way to the Papakura offramp you would get all the way home. Oh well, I'm sure the exercise of pushing your bike home would have done you some good!!! Hope the 650's stay in hospital isn't too costly!

[Bonez]

I'd go with SDs theory. IIRC the Yamaha coils of that era wheren't the best.