Spark Plug Colour - Spark Plug Color

Seems like a good article, but I like to keep it a little more simple.
If your plugs look like the plug in the centre, you have good combustion.
Spark Plugs.jpg
 
Thank you for the feedback RTG, simple is good! After two 60 mile runs this week my plugs are staying the same colour and correspond well with your perfect example, so I am pleased with that. No more fiddling with the carbs for me for a while???

In the article I referenced I liked how they observe the Ground Strap/Ground Electrode to see how long or short the zone is where the crap is kept burnt off. They also look at some more subtle features regarding the porcelain and overheating. According to the line on the Ground strap my plug is a little bit cold - Better to be there than too hot! I run too hot on my RD years ago and cracked a piston.

I felt the article filled in some of the gaps in my knowledge were actual hands on experience was close to zero.
 
Yes, 2 stroke engines can run hot. I had a Yamaha 305 cc scrambler that ran very hot when I bought it used. It was due to the crankshaft oil seals being worn out. The vacuum in the crankcase was drawing in extra air and making a very lean mixture.
New oil seals and no more hot engine.
 
IMG_4327.JPG IMG_4328.JPG IMG_4329.JPG Gentlemen, while on the subject of plugs... check my left one out:/
Right side one is perfect. Left is super clean and shiny. Bike losing power bc of this...
1980 xs650
Bs34 carbs
 
If you want to know how to read spark plugs without the distraction of urban myth, amateur speculation, oversimplification, and suchlike distractions, go to www.strappe.com, click the tech button, then click the spark plug icon. That will take you to Gordon Jennings' classic article on plug reading. It's the only really sensible thing I've read on the subject. Jennings was unique--a master tuner who was also a master wordsmith.
 
Thanks G1, will do. I read some other threads where it seems the issue with my left plug is constant fuel washing (at least is how I understood it). Still reading up on it so I can find a solution. Nothing I do with the fuel settings changes the outcome of this left plug and it just started doing this.
I may need to open up my carbs again. But before I do I want to know exactly what to look for and what I'll be doing. I just cleaned them not long ago, rebuilt them, synced them, adjusted the floats and replaced a bunch of stuff. I didn't ride it for a while and when I wanted to today was hit with this issue.
 
Skubik, pull your dipstick and sniff. If you smell fuel you've found at least part of the problem--petcock and/or float valve defect. I can see the plug is shiny, but it's a long way from clean, can't tell if it's fuel fouled or oil fouled. The problem may not be in the carburetor at all.
 
Skubik said:
View attachment 105451 View attachment 105450 View attachment 105448 Gentlemen, while on the subject of plugs... check my left one out:/
Right side one is perfect. Left is super clean and shiny. Bike losing power bc of this...
1980 xs650
Bs34 carbs
Click to expand...
looks to me like that cylinder is simply not firing at all. If you had a spark and compression and fuel in the left cyclinder you'd expect to see some carbon residue at least (sooty coating)
My first step would be to do a comparison compression test on both cylinders to make sure that your engine has compression on the left cylinder and your valves are not too tight . Then do a simple spark test or try swopping the plug leads between cylinders and see if the problem transfers to the other cylinder.

NOTE If you have electronic ignition make sure that both plugs are grounded when doing any spark tests
 
Thanks Peanut I think you're right, I did notice the left exhaust was cold yesterday also, it did get warmer but not like the right side. About to start messing with it again. I appreciate the help.
 
Skubik said:
Thanks Peanut I think you're right, I did notice the left exhaust was cold yesterday also, it did get warmer but not like the right side. About to start messing with it again. I appreciate the help.
Click to expand...
no worries ...hopefully its something simple.
What is your ignition system ... stock ? or something exotic
 
Stock electronic ignition. I do have new NGK plug wires and bought the ignition coil from MikeXS. Running 7's for spark plug heat range.
 
Switched plug wires around and left exhaust cold right exhaust hot. Gonna check my valve adjustment on that left side, hopefully that will be the problem.
 
good test ....confirmed its not an ignition problem to the left spark plug at least.
Did you swop your spark plug yet ?
Try adjusting your valves a little looser to make sure they are seating properly . Present thinking is to use the XS-1 and XS-2 valve lash adjustment and let the exhaust valves seat a little longer.
Have a read under 'XS650 Cams' http://www.smedspeed.co.uk/tech.html
 
Seems this left side not firing is an issue from when the bike was built........... http://www.xs650.com/threads/float-bowl-extremely-slow-flow.48762/ Reading back over the thread/link you mention carb kits, new adjustable needles from 650 central, coil from mikesXS.

Seems you had success playing with the fuel T........seems a bit odd..................maybe revisit some of the suggestions and and add some of the thoughts into this thread..........Needle valve was leaking......was the seat for the valve checked..........Just rambling thoughts.

When you replaced the needle was the needle jet replaced as well ???
 
Hi All: I'll grant that it is a very rare thing but I have seen a case of a brand new plug that was simply defective and no amount of f@rting around would get it to fire.

I suggest swapping the plugs themselves to confirm that you haven't stumbled upon another rare bad plug.
 
MaxPete said:
Hi All: I'll grant that it is a very rare thing but I have seen a case of a brand new plug that was simply defective and no amount of f@rting around would get it to fire.
Click to expand...

already suggested that pete but I wasn't thinking clearly either. that cannot be the case can it!

If swopping the leads between cylinders transfers the problem to the other cylinder and the non working cylinder starts working normally then it can't be the spark plug
 
Thanks for all the replies fellas. My son came over and needed help with his car so I didn't get a chance to check anything on my bike. I'll check the valves in the morning and also try some new plugs, I have a new set in the garage I can throw in. Seems like either of those two things would solve my issue, bikenwas running good before and has no leaks of any sort. The main problem is I don't ride enough and this bike doesn't like to sit for very long lol, every time I get it running right and then sit for a month it's like I have to start over with something or other. Guess I'll just have to ride more!
 

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