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[Peter 53]

Ladies/gentlemen!


Can anyone explain why my 1999 500 runs better with the plug gapped to .63? I tried it at .50 but hesitation/splutters/coughs told me to open it up.


A little background: recently I replaced the header pipe with a free-flowing one, then I stuck a Velocette fishtail on it. I haven't changed the jetting at all yet, but I can confirm that with the standard header pipe and horrific 'torpedo' silencer it was running rich... to the point where the coldest days were ideal.


Just curious to know why the bigger gap works better...

[Paul M H]

It should be 0.46 to 0.50 try closing it a bit if its still the same try a fresh plug and check all cable connections on coil ETC before going any further.

[Craig]

Sorry to go slightly off Topic,


But on My 500 & 350 I have all ways used them as is out the Box & with a Slight Viz adjustment after Cleaning for over 20 years (gasp horror)..


All did Run slightly rich / oily But Good Starters & No Long Term Problems.On Any Bike.


( A Mechanic Once Said to me ,Why Bother Re Setting a New Plug ,Thats Been set at the Factory)??


I Should added that on all My Bikes I have Messed around with Carb,Breathers,& Exhursts with No Plug Problem.. Though I Try & Keep My INDIA 350 as Close To Standerd (Home Mkt,Free Flow) as I can.


So Was I Lucky or??  ..Mainly Us NGK, Indian WICO, Odd Champion!


My Last 500 though suffered with Some NGK lating weeks Only some 6 months Pluss.. Some Blame Un leaded or ethanol... But My 350 NGK was Fine???


More Puzzels than answers, "But Do whats Best for The Individul Bike"


Cheers...

[PeteF]

Well, .63 (mm I presume) is 0.0248 inch


My Enfield has always been set at 25thou with no problem.


I tend to set all plugs at 25thou as I happen to have a 25thou thumbnail and can never find the feelers


If you engine is happy with that I wouldn't worry.

[Peter 53]

PeteF


That's actually the best reply I could have hoped for... although not exactly a technical explanation I think the thumbnail gauge is actually a brilliant idea!


I wonder if my little toenail would be about right to set the points gap - where did I put that vernier gauge?

[Craig]

 


Peter & peter, I agree..


Sorry I did not want to sound too silly, but when I Ever I clean the Plug I Use the thumbnail Guide as well....


Must be a Lodgic to it some where, Perhaps as with Most things India Enfield, due to slight Manufacting differences ,Everything is a Guide Only till Proven Wrong!?


Toe Nail For Points..Nah I use me Pen knife Blade..(hang on I am on me 5th Knife)............


 

[Peter 53]

Paul


The thing was it was a brand new plug that I started with the .50 gap, until it all went wrong. 


If it's a mystery why it runs better at .63 then so be it! 


Just wondered if any of you clever people had any idea of why the small difference in gap makes such a big difference in how she runs... maybe it's true and size does matter? 


Anyway, cheer for all your comments as usual - and thanks for reminding me that these are idiosyncratic and enigmatic animals! 

[John N]

I can vouch for the thumbnail gauge, I've been using it for 45 years - never failed!