Odd situation, thoughts?

[Mannix]

So my bike, 83 maxim, didn't start the other day. I had a few problems starting previous and now it just quit. Might need to charge the battery, but I noticed a curious thing while checking her over: both of my spark plugs are cracked in half. Don't know how or where the other halves may have gone.

So I figure I'll start there. I can still read the plug serial number, Champions RA6HC so I buy two yesterday. But, right now (posting from my phone) I got one plug in but the boot/cap won't click in place (head of the plug seems to big) and it seems like it's not the right plug for my bike, but it is the same as the cracked one I pulled out?! What is going on? Could the P.O. have hooked it up like that on purpose? How have I been running this whole time? I found the factory issue plug serial number inn the 82's manual I'll try that? Confused newbie in San Francisco.

 

[Lou Ranger]

When I got mine, I saw on here:

A DOHC that doesn't run? That's unpossible! Probably the carbs...

especially if it's an '83.

I know that the manual calls for NGK plugs, and that when my mechanic friend saw my previous bike (Ysr250), the first thing he said was "we have to lose that Champion plug right away".
In all seriousness, is it possible the PO installed the wrong plugs, but it still ran for a while until finally the plugs got over-stressed from being wrong and simply shattered from fatigue? Since you have an '83 SOHC, what else could it be?

 

[Ironhead]

your new plugs probably have the little terminal tips screwed on. they're only finger tight so just unscrew 'em and press the boot onto the bare threads. that's how i roll. literally.

 

[Mannix]

Yes to terminal tips still on! So after getting NGK plugs and returning one of the Champions I bought, I discovered to unscrew the terminal tips, BUT the NGKs wouldn't screw in at all! Too big! So back to Oreilly Auto parts for the third time to get the Champion I just returned.

But once I put the right ones in, I got her to push start, and button start afterwards; we'll see what happens tomorrow.

Seems like I'm running rich though. And she idles really high after about 15min going 50-60mph if you guys have links handy to threads on here that might help those

 

[Lou Ranger]

But once I put the right ones in, I got her to push start, and button start afterwards...

Our old Honda CRV manual recommended 2 kinds of plugs, one for mostly city driving and one for mostly long distance driving. Honda's description was that one was hotter than the other and the only difference was the number in the code. As I recall the 8 was hotter than the 7.

I found a conversion table which says the Champion RA6HC is compatible with the DR8ES-L which Yamaha calls for. But the table also says that the Champion RA8HC in compatible with DR8ES-L. And, it says that the RA6HC is compatible with the D8EV, DR7ES and a bunch of others.

http://www.gadgetjq.com/spark_plug_cross_reference_motorcycle.htm
​

This second site, on the other hand, converts the DR8ES-L into a Champion RA4HC, not a 6 or an 8.

http://www.sparkplugcrossreference.co.uk/​

This confusion, without an adequate explanation from an expert and not just a plug salesperson, would be enough to send this Luddite fleeing to the NGK store and sticking with what Yamaha had intended - especially if the engine didn't run perfectly. It is, after-all an '83 DOHC - right B-W?