NGK Iridium IX BR8EIX - Maybe they suck?

[CCRider]

Ever since I rebuilt the top end on my 450, I've dealt with some minor tuning problems. Hard starting sometimes and a rough spot just above idle. I've always blamed carburation, because I upgraded the ignition to Dyna coils and NGK Iridium IX BR8EIX plugs (+ new points, condenser and timed with a timing light) when I did the rebuild.

Yesterday, I was going to go for a ride but couldn't get the bike to start. I figured the plugs might be fouled from sitting in the traffic on the way into Barber so I pulled them and they looked a little carboned up but not too bad. I grounded the plugs to the head and turned it over but no spark from either side. To make sure there wasn't a bigger problem with the ignition I put a screwdriver in the plug cap and got a nice arc between the screwdriver and head. I cleaned the plugs up a little and tried again and then I was getting an intermittent spark - sometimes at the electrode but sometimes down in the plug near the insulator. So I pulled the cheap Champion plugs from my 350 and tried them out - nice fat spark. I installed them, kicked it over and she was running before I hit the bottom of the stroke. Went for my ride and she ran great. The rough spot above idle was gone.

So, anybody have experience with these plugs? Dr.J has posted that he liked them, but I just reread him post and he ended up going with a hotter than recommended plug. Maybe they're not so good with our low powered point ignitions. Maybe they're just really intollerent of any fouling. Maybe they need to be gapped differently from a standard plug.

I may play around with the gap latter, but for now I'm sticking with the std plugs.

Thanks, CC

 

[teazer]

Iridium plugs are probably the best at firing when partially fouled. We use them on street bikes that need a good spark and on some of our race bikes. I love them.

They have a built in resistor so you should probably change plug caps to not resistor if they aren't already. If they fouled, it's either oil or too much fuel. maybe jetting is slightly too rich at the bottom end.

 

[crazypj]

I prefer non-resistor plugs with points ignitions and 5K/ohm plug caps (even though they should be 10K/ohm ;D )
Use EGV suffix.
I put B8EGV in 360

 

[DrJ]

Yes I did use Iridiums with my Dyna 3 ohm coils for a short period. Although they didn't perform badly, the hotter rated BR7 NGK plugs were better. Perfect tan colour around the contacts. Ran with those for thousands of miles no problems.

 

[djelliott]

Yes I did use Iridiums with my Dyna 3 ohm coils for a short period. Although they didn't perform badly, the hotter rated BR7 NGK plugs were better. Perfect tan colour around the contacts. Ran with those for thousands of miles no problems.

Agreed. I've had great luck with the BR7's.


Sent from my iPad using Tapatalk, bitches.

 

[crazypj]

BR7's are resistor plugs, the iridium's should perform better as they have fine wire electrodes
Check voltage to coils, if it's low you may be 'blowing out' the spark kernel.
Shrouding from standard type plugs may be an advantage with the old combustion chamber design?

 

[Garage_guy_chris]

ive played with my 450 all summer and been chasing fuelling issues all summer. after alot of trial and error and probably a dozen sets of plugs;
-b8es - nothing wrong with them they are the "proper" plugs, i was finding they would wet out easily and foul easily, kinda hard to find..
-b8egv - seemed to make the bike run harder and stronger?!?!? also had a tendancy to wet out and foul easily also pricy, at $20 for 2 plugs (i had 2 sets laying around)
-br8es - out of the bunch these seem to resist wetting out also seem to take more to foul. there cheap and plentiful at $7 for 2.

Im running stock coils and 5k ngk cap, never bothered trying different heat ranges.

 

[teazer]

Yes I did use Iridiums with my Dyna 3 ohm coils for a short period. Although they didn't perform badly, the hotter rated BR7 NGK plugs were better. Perfect tan colour around the contacts. Ran with those for thousands of miles no problems.

Glad you mentioned that. I hear people say that they changed plugs or timing to lean out teh mixture and of course the only think that changes mixture is jetting and related things like filters etc.

What happens is that if plugs are hotter, they burn off more of the carbon and fuel and oil so that they look as if the mixture is leaner. Of course it isn't but we see similar results ie the plug tips are getting hotter and therefore cleaner.

That's why reading a plug is so hard - was the timing correct, was the plug too hot? etc. We have to get the right plug at the right ignition timing before we can start to understand what the plug is really telling us.

For example:
Plug reads black and wet, so I advance teh timing and change from say a B9 to B7. The result is that the plug looks much cleaner at whatever revs I was reading it, but in reality I now have a very hot plug and too much advance. When I run that bike hard, it's probable that the excess ignition advance will cause the bike to detonate and overheat and I'd be trying to understand what went wrong.

It's easy to misunderstand plugs and to come up with a "solution " that masks the underlying problem and causes other problems later on.

 

[CCRider]

Thanks for the input guys. Looks like I may have been a bit premature in my excitement. Still had a hard time starting the bike the next day. Lots of black smoke after she started but it did still run better than before. I've been through the carbs multiple times, cleaning, checking float height, etc. Maybe I'm just overchoking it when starting.

CC