SPARK PLUG GAP

[brip]

I am new to the forum and have recently purchased 2 Roketa Sicily 50cc 4 stroke scooters... I noticed they both have the Torch sparkplugs and I'm putting in NGK CR7HSA plugs,,, question is, I have read thru all of the scootdawg info and am somewhat confused at what the gap should be,,, one thread says .22-.24, one .24-.28 and up to .35 gap..

[Jacine]

What does your manual say about the gap? There should be some information in there.

[brip]

my manual says .22 - .24 but also states to use an NGK BR8HSA plug which is a 14 mm plug and mine clearly is a 10mm plug..

[Jacine]

The gap is would be most likely .22.-.24. You can check the gap on your old plug. The only plugs that generally are not gapped manually are the iridium.

[brip]

the original ones are gapped at .25". I'll set them at that... I'm just curious why some are setting the same plug at .35"... didn't know if the performance improved because of it... thanks.

[Jacine]

Depending on the plug one unit hotter or one unit cooler, DREPRA-8, DREPRA-7 DREPRA-6 the gap can be adjusted for a hotter or cooler spark. The bigger the gap the cooler the spark, but on a hotter plug would make the larger spark (normal) and therefore ignite (theoretically) more fuel. Spark gaps can also be adjusted for altitude. You can file the electrode to a V which increases the spark surface area and creates a larger and hotter spark. You can also do spark alignment so that the plug faces into the chamber and not against the wall. These are generally racing and larger bike techniques that don't generally do much for small engines.

[ashdump]

Well you sure know your plugs, Jacine!

BTW, keep the pics a'comin!

[domc]

Ok I'm game...what do you do to the spark plug for high altitude since I live in Denver, Colorado. I've never hear of this?

[griff10]

Don't do anything for altitude, as far as the ignition system is concerned doesn't matter a bit what the altitude is.

Jetting though is another issue.

Bill H.

[motomech]

Unless dropped on the floor , Japanese plugs should not be gapped.

The gap is perfect from the factory

The gap is called for in the plug size.

Spark plugs with a suffix of -8 or -10 or whatever is indicating the gap in thousands of millimeters.

I repete, there is absolutly no reason to mess with the gap of Japanese spark plugs and it will create more problems than solve percieved ones.

[brip]

If that is the case, then back to my original question: what should the gap be on an NGK CR7HSA plug

[motomech]

I don't know, never dropped one.
Probably .024", buy a another one and ckeck it.
That is a very common small engine plug(including the Honda Elite 80).
I have installed hundreads, if not thousands, without ever touching the gap.

[90GTVert]

I do like to at least check the gap on everything but Iridium plugs, regardless of being factory preset. I may not have dropped them, but I don't know if they were dropped at my local auto parts store etc... I would just gap them at .026" (don't gap them 1/4 inch .25"). While I'm at it, the "spark alignemnt" technique that Jacine referred to is commonly called "indexing." Don't bother indexing your plug for this application. I've never felt any gain or saw a mph increase on a 50 from it.

[brip]

thanks everyone....

[Jacine]

May 23, 2008 16:59:39 GMT -5 domc said:

Ok I'm game...what do you do to the spark plug for high altitude since I live in Denver, Colorado. I've never hear of this?

For high altitude you use the hotter plug and gap at the higher end of the range. This tends to give you a larger hotter spark that can compensate for lower 02. Or you can get the hotter iridium which are not gapped.

Note NGK I believe reverse their numbers so the lower numbers are hotter.

I was right the first time.

[bob]

You might like to read this.
NGK Technical

Bob

[Jacine]

I am going to start a new thread and discuss American spark plugs first. You'll be able to compare it to the NGK.

[firstscoot]

May 24, 2008 6:08:54 GMT -5 90GTVert said:

I do like to at least check the gap on everything but Iridium plugs, regardless of being factory preset. I may not have dropped them, but I don't know if they were dropped at my local auto parts store etc... I would just gap them at .026" (don't gap them 1/4 inch .25"). While I'm at it, the "spark alignemnt" technique that Jacine referred to is commonly called "indexing." Don't bother indexing your plug for this application. I've never felt any gain or saw a mph increase on a 50 from it.

Are you not supposed to gap the iridium plugs? I just bought one and checked the gap. It was too big so I adjusted it. Was I not supposed to do that?

[scooterollie]

Yes, you can change the gap on Iridium plugs! You do have to be careful not to hit the center electrode or it's porcelain cover. Same thing goes for the Platinum version. I use a tool that touches and bends only the grounding electrode.

[firstscoot]

May 25, 2008 7:14:16 GMT -5 scooterollie said:

Yes, you can change the gap on Iridium plugs! You do have to be careful not to hit the center electrode or it's porcelain cover. Same thing goes for the Platinum version. I use a tool that touches and bends only the grounding electrode.

cool. I also have the spark plug tool to bend the electrode.

[scooterollie]

Just be careful. Some of the tools have a thick end that will contact the center electrode cover causing it to crack and ruin the plug. If your tool has a thin end, it usually allows enough clearance but you still need to exercise caution.