YAMAHA21 Posted January 30, 2016 Share Posted January 30, 2016 I've just done a proper plug chop with a brand new plug. I did one pull through the gears up to 5th WOT and held it for about 10 seconds, then killed it and coasted to the side of the road where I put the old plug back in. Here's what the test plug looks like: *EDIT* I chopped slightly more thread off: There is no brown ring at the base at all, the electrode is all white, does this mean the bike is running lean and that I should swap the 240 jet for the 250? Cheers Link to comment Share on other sites More sharing options...
Moderator Cynic Posted January 30, 2016 Moderator Share Posted January 30, 2016 I am assuming your taking the piss here, least I hope so. 2 Link to comment Share on other sites More sharing options...
neversaydie Posted January 30, 2016 Share Posted January 30, 2016 Hmmmmm What with the "Ive put too much oil in" posts, one may be excused for thinking indeed someone is taking the piss Link to comment Share on other sites More sharing options...
YAMAHA21 Posted January 30, 2016 Author Share Posted January 30, 2016 47 minutes ago, Cynic said: I am assuming your taking the piss here, least I hope so. I'm not taking the piss, what's wrong? Link to comment Share on other sites More sharing options...
Moderator Cynic Posted January 30, 2016 Moderator Share Posted January 30, 2016 Ok i'll bite. A plug chop is running the engine at a constant throttle, rpm in the area the engine is running badly for a sustained period of minutes then cutting the engine. Once stopped safely you swap plugs, (chop one for another). ie a plug chop and look at the electrodes to show how the motor is running. Black and sooty, oily, tan colour, even showing red spots in the ceramic. These are all good indicators of engine/carb conditions. Hacksaw not required..... Link to comment Share on other sites More sharing options...
YAMAHA21 Posted January 30, 2016 Author Share Posted January 30, 2016 There's lots of people referring to chopping the threads of a plug to have a look at the mixture band as a 'plug chop'. http://www.mopedarmy.com/wiki/Plug_chop - " Pay special attention to the area deep in the plug around the base of the ceramic center insulator (it helps to cut the plugs threads off with a hacksaw or use a plug scope, especially if it is a hot plug with a long insulator); A thin ring of black soot should develop around the bottom of the insulator. If it is too tall it is too rich, specially if it's approaching or covering the tip, if there is no soot ring it is too lean." http://www.thequadconnection.com/walkthroughs/how-to-plug-chop!/ - " Now for the plug chopping part, first make sure the quad is FULLY warmed up, then you will want to ride or drive to the spot you plan to do the plug chop at (dont forget the socket and ratchet), and install a new plug. start up the quad and immediatly start going gears 1st through 6th its ok if you can only make it to 5th gear, now while you are in 5th or 6th gear hold it W.O.T. for at least 10 seconds or as long as you safely can , the point is to get the engine really pulling hard. now while you are still holding it WOT pull in the clutch and shut it off immediatly and roll to a stop. now pull out the spark plug and put the old one back in for the ride back. now with the plug you just did WOT on cut the threads off the end of the spark plug to expose the insulator and there should be a smoke ring that is cardboard colored at the bottom of the insulator, if there isint then you are running lean, if you are running lean increase the main jet 1 size and plug chop again until perfection! " http://kawtriple.com/mraxl/carb/plugchop.htm Link to comment Share on other sites More sharing options...
Moderator Cynic Posted January 30, 2016 Moderator Share Posted January 30, 2016 Sorry but I'm looking to see if the date is 1st April. Internet gags to trip the unwary methinks.. Link to comment Share on other sites More sharing options...
YAMAHA21 Posted January 30, 2016 Author Share Posted January 30, 2016 You've lost me mate, are you saying that all the links I posted are trolling or something? Link to comment Share on other sites More sharing options...
Moderator Cynic Posted January 30, 2016 Moderator Share Posted January 30, 2016 Well I'm no bike expert as far as qualifications go but I have had the better part of 25years of riding and fixing my bikes and maintaining 2 competitive v8 engine land rover trials vehicles as well as helping my dad who was a mechanic man and boy, this is the first time I've heard it done this way. Always willing to learn and happy to be proven wrong but any tuning shop will tell you it could take 20 or 30 road or dyno runs to tune in a carb (my Suzuki took 28 runs to set up), can't see anybody trashing 20 or 30 plugs (more on a multi) for a carb tune at 5 or 6 quid a pop can you? Link to comment Share on other sites More sharing options...
YAMAHA21 Posted January 30, 2016 Author Share Posted January 30, 2016 So do you never look at the mixture band to see how the jetting is? There must be some truth behind it if that's what everybody seems to be doing. I just wanted to know if my plug indicated the bike was running lean. After doing some researching, it does seem to be running lean as there is no visible mixture band at the base of the plug. I think people just cut the threads because it makes it alot easier to see the mixture band and judge how big it is. I've installed the 250 jet so I'll go for a run tomorrow and see if 6th gear feels any better (6th had no power with the 240 jet). Link to comment Share on other sites More sharing options...
Moderator Cynic Posted January 30, 2016 Moderator Share Posted January 30, 2016 How I have done it, like I said earlier. Fit the plug then go for a trip of a couple of miles and run the bike in the problem area then take the plug out and shock horror, look at the end. Basic and reliable with some experience, if its black its bad, if its clean its bad, light dusting will do. Not to mention the old plug can tell you as well doesn't necessarily need a new plug. If the old plug comes out jet black covered with wet oily residue its bad or a lot of short slow runs. The plugs in my TDR (which runs sweet as) are actually a light brown for the most part, near perfect. Although she does only get used for proper rides not commuting in traffic. The better guide in the modern age is getting a thermocouple to tell you the actual plug temperature. There is a sweet spot, the exact details escape me but Airhead has one on his DT and thinks it is really useful to keep the engine sweet. I'm tempted myself. Link to comment Share on other sites More sharing options...
neversaydie Posted January 31, 2016 Share Posted January 31, 2016 First time Ive heard that one, physical plug chop eh 1 Link to comment Share on other sites More sharing options...
YAMAHA21 Posted January 31, 2016 Author Share Posted January 31, 2016 Maybe one person got confused, thought a plug chop was chopping the threads and then the idea spread from there... You can see why you would think there was physical chopping involved though. Link to comment Share on other sites More sharing options...
Moderator drewpy Posted January 31, 2016 Moderator Share Posted January 31, 2016 well if you don't know, you don't know! plug chop is running the bike at WOT and cutting the engine with the throttle shut off at the same time. unscrew the plug and check the colour of the white ceramic 1 Link to comment Share on other sites More sharing options...
blackhat250 Posted January 31, 2016 Share Posted January 31, 2016 Actually " Stan stephens says its the colour on the threaded part, , in Motorcyle Mechanics mag, But fkn ell " that's a plug chop ,,,,, some ones takin the piss , Link to comment Share on other sites More sharing options...
YAMAHA21 Posted February 1, 2016 Author Share Posted February 1, 2016 Does it really matter what it's called lol, it basically the same as what your saying anyway except the point is to look at the base of the plug instead of the top and you are only testing the main jet. Link to comment Share on other sites More sharing options...
YAMAHA21 Posted February 1, 2016 Author Share Posted February 1, 2016 Just saw this, Gordon Jennings talking about reading plugs in 1977: "A lot of amateur tuners, some of whom are fairly successful, will look at some plug freshly removed from a two-stroke engine and offer advice based on the color of the oil deposited on the insulator nose. In fact, if the plug is hot enough there won't be any color, and if there is that still has nothing much to do with air/fuel mixture. If you think about it you'll realize that the only color you can get from an air/fuel mixture is the color of soot. When the mixture trapped in an engine's combustion chamber has more fuel than can be burned with the available air, then combustion will be incomplete and the excess fuel will remain as soot, which is not brown or tan or magenta or any color other than black. And if your engine's mixture is too rich, the sooty evidence will be present on the spark plug's insulator, in a very particular area." "You won't find any soot out near the insulator nose, on a plug that's running hot enough to keep itself from fouling, because temperatures there are too high to let soot collect. But the insulator is much cooler deep inside the plug body, and coolest where it contacts the metal shell, which is precisely where you "read" mixture strength. Look far inside a plug, where its insulator joins its shell, and what you'll see there if your engine's mixture is too rich is a ring of soot. If this ring continues outward along the insulator to a width of even a millimeter you can be sure the mixture is rich enough to be safe, and too rich for maximum output. In most engines best performance is achieved when the mixture contains only enough excess fuel to make just a wisp of a "mixture ring" on the plug insulator." http://www.strappe.com/plugs.html 1 Link to comment Share on other sites More sharing options...
Moderator Cynic Posted February 1, 2016 Moderator Share Posted February 1, 2016 Struth. Giv3 a dog a bone. I can show you the plugs from my tdr to spoil that theory. In 77 oil was far removed from the oils of today and mixing it was giesswork so all 2strokes were run rich to stop the mixture going lean because of the oil. The engines were also lower in compression running poorer fuel which left a considerable amount of crap behind in the cylinder. Modern bike engines run much leaner and cleaner. The very pinacle of 2strokes are cleaner than 4strokes (thx for killing the 2stroke because you couldnt make a good one Honda) but thats another story. Because they are much cleaner the plug tips are a valid guide. Black and oily is obvious, but they can have a dry sooty appearance if rich and if running nice the residue will be minimal leaving just bare remnants of combustion which give a brown tan colour. I know so cos ive seen it. Link to comment Share on other sites More sharing options...
YAMAHA21 Posted February 1, 2016 Author Share Posted February 1, 2016 What would you say about this plug then, it's the one I've been using for the last 1000 miles or so. Also I tested the 250 jet today and the bike decelerates in 6th gear and it feels like it wants to stall a bit easier when pulling away, I need to be more generous with the throttle. Does this have anything to do with removing the snorkel from the airbox? Link to comment Share on other sites More sharing options...
neversaydie Posted February 1, 2016 Share Posted February 1, 2016 I'm out Link to comment Share on other sites More sharing options...
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