Topic: Shorter plugs with ported head?

[MattFreeman]

I've been showing my plugs around to a some folk trying to learn what they are telling me and a friend with a lot of motor, but not sohc experience, pointed out that they look like they may be intruding into the ported head too far.

Here's a couple of pics of my plugs. It would seem that I'm running lean and I'm addressing that but should I look for shorter ones?

[70CB750]

What engine and what plugs?

[TurboD]

Those look to be the correct plugs, ported or not. If the plugs are too long the engine will not turn over.

[MattFreeman]

What engine and what plugs?

F1 engine, the plugs are marked DR8ES-L

It was pointed out that the first 3 threads are sooty suggesting that the are protruding that far in. And that in a HiPro automotive situation they are shimmed to fit flush in the head...

[TurboD]

I read your other thread, It appears as though you are fighting a power problem (bike will not go over 65mph). I think in the end you will find a actual problem. If your plugs are all firing and without missing or popping, although they may not be optimal, the bike should run faster than 65mph.

it is completely normal for the first few threads to be colored or sooty, the actual combustion sealing does not occur until the sealing washer.

 

[70CB750]

Everybody and his brother is using these in CB750s, I would not worry about the protrussion. 

[TurboD]

Generally speaking in any engine. Additional spark plug length, as long as it does not imped intake or exhaust flow, will only add to compression.

I think your time would be better spent looking else where for the problem.

[MattFreeman]

Cool. I hoped for that answer.

I was just throwing it out there out of respect for the person who mentioned it.

Thanks for the imput.

[Jerry Rxman Griffin aka MuthaF'er]

Doesn't the -L stand for long??

Doesn't look like the piston hit it though.

[KickOnly849]

Doesn't the -L stand for long??

Doesn't look like the piston hit it though.

-L is a half heat range, 8.5

[PeWe]

DR8ES-L lenght of the tip ..... http://forums.sohc4.net/index.php/topic,77832.msg869100.html#msg869100
I have used DR8ES-L back in the 80 and last year too.
Important to compare how engine run with color of the plugs. Intermittent function/failure of an ignition wire will foul plug. I have seen that last year until beginning of this month.

[MattFreeman]

DR8ES-L lenght of the tip ..... http://forums.sohc4.net/index.php/topic,77832.msg869100.html#msg869100
I have used DR8ES-L back in the 80 and last year too.
Important to compare how engine run with color of the plugs. Intermittent function/failure of an ignition wire will foul plug. I have seen that last year until beginning of this month.

Thanks for the link. If they're good enough for Hondaman....