Spark Plug?s and more...

OK I will start this post by listing the mods on my ski
94 701 superjet
milled heads
bored carbs
lightweight flywheel
b pipe
skat trak impeller
and some handling mods

The other day my ski quit running on me and I pulled the plugs when I got home and they are fouled. I went up to the store today to get some new plugs and now I got some questions. First of all, what would have caused my plugs to foul? They were replaced by the previous owner last summer. Are they just old and worn out possibly? I am mixing my gas and oil at 50:1 with yamalube oil just as reccommended. I was running NGK B8HS plugs. The guy at the auto parts store (a nicer/more knowledgeable auto parts store) started talking spark plugs with me (im a newbie to wrenching so a lot of it confused me). They did not have NGK's so I ended up getting Denso W24FS-U. He said these were the same as the NGK's and the visual inspection makes me think they are the equivalent plugs. He said that these Densos will actually have a better spark then the NGKs. Anyways will I be fine running these or should I find some NGK's and take these back? Now, back to the spark plug conversation... he started talking about how my plugs got fouled and then recommended that I run a temperature range higher plug and that it would burn my fuel better, keeping me from fouling my plugs and providing me with a better spark and more power. He gave me Denso W22FS-U plugs and told me to test them out. I figured I would just buy them since they were cheap. Now, should I be running these plugs or the W24FS-U plugs? Or should I just skip the Denso's and get the NGK's (will my superjet like me better if I use NGK's?). Also, what should I gap my plugs at?

On a side note, the guy at the parts store started asking me about gas, etc. He said with my mods I don't really need to be running 93 octane. I thought this was bull as he was telling me to run 89 or possibly even 87. I attributed this to the fact that he probably knows very little about jetskis. I have seen everything here saying I need to run high octane and 93 is what the previous owner ran. Should I stick with my 93 or am I pissing some extra money down the drain every time I run 93?

Sorry about the long post but I would like to be more knowledgeable about this so I dont screw my ski up now or in the future.
 

a/cman74

the want to bee
Location
suckville ,texas
I will replace my plugs every two or three weeks on my super jet on two stokes they will foul out pretty often but it don't always mean somethings wrong if they been in cents last summer the where due to be replaced
 

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
Length. For a stock head, you use HS. Aftermarket heads (thicker) use the ES plugs (Or vice versa?) The longer plugs for the thicker heads.

Oh, and I run my plugs for an entire season without a problem, no fouling. Not sure what the deal is.
 

keefer

T1
Location
Tennessee
If you have the stock Yamaha head then run the B8HS plugs like Matt said. The B8ES will stick down too far into the combustion chamber. If you are running the stock Yamaha plug caps you should really be running the BR8HS plugs. These are short reach resistor plugs which will cut down on the RFI generated by the ignition. If you have the aftermarket NGK resistor caps then run the non resistor plugs.
 
my thoughts

I would run 93 octane, it isnt going to cost you that much more and come on treat your baby good. About the plugs, I always run NGK in my Kawi but it is just personal preference. I have no knowledge with those other plugs sorry. Have you been idling a lot or anything out of the norm? I wouldnt worry about fouling a plug here and there but if it you begin doing it a lot you may want to look in to that further.

Off topic but do you go to GVSU?? I go there and am always looking for someone to ride with. I am home right now in Traverse City but come early to mid August I will be back and looking to do some riding. Where do you ride around there? For a couple years the only place I have found is the Grand River which is ok at best.

MATT
 
miller said:
I would run 93 octane, it isnt going to cost you that much more and come on treat your baby good. About the plugs, I always run NGK in my Kawi but it is just personal preference. I have no knowledge with those other plugs sorry. Have you been idling a lot or anything out of the norm? I wouldnt worry about fouling a plug here and there but if it you begin doing it a lot you may want to look in to that further.

Off topic but do you go to GVSU?? I go there and am always looking for someone to ride with. I am home right now in Traverse City but come early to mid August I will be back and looking to do some riding. Where do you ride around there? For a couple years the only place I have found is the Grand River which is ok at best.

MATT


I do go to GVSU. I have two friends that will be here in the fall that ride superjets also. I live in Hillcrest off of 48th street. I would definately be down for riding in the fall. I ride mostly at this little spot off of Warner. It is a gravel pit that is connected to the grand river and it is awesome for riding. It is secluded, no DNR, and not a whole lot of boat traffic. Otherwise I ride at some local lakes and will soon be doing some riding at lake michigan (especially in the fall with the bigger waves :woot: . Hit me up when you get back to school
 
stick with the plugs that are recommended for your ski. only use ngk's!

easy way to remember the diff between ES and HS?

ES = extended size
HS = half size

the R at the end means resistor. i dont get the R plugs, even though the manufacturer recommends it. kind of a double standard, i know. but why would you want a resistor? im not worried about rf interference on my SJ!

i gap @ .030"
 

2002zxi

Got old, bought another ski
Location
MO/OK
keefer said:
If you have the stock Yamaha head then run the B8HS plugs like Matt said. The B8ES will stick down too far into the combustion chamber. If you are running the stock Yamaha plug caps you should really be running the BR8HS plugs. These are short reach resistor plugs which will cut down on the RFI generated by the ignition. If you have the aftermarket NGK resistor caps then run the non resistor plugs.


I think I'm going to take some pictures and have you all look at the heads and wires.
 

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
I have my MSD total loss brain 6 inches from the coils and about 10 inches from the plugs. I run non-resistor plugs and have ZERO issues.
You said you have a shaved (stock?) head. Measure your compression.
I don't think you need to run anything other than pump gas. Whatever the highest is (92?)
 
So basically I just need to replace my plugs with some NGKs like I had and keep doing what I have been doing. Sounds good to me. Does anyone know if I could keep these densos (the equivalents to the b8hs) as a backup plug? Or should I just take them back when I take back the higher temp plugs. Also, does everyone agree on the .030 plug gap? Now I just gotta find somewhere that has some NGK's. I was running the non resistor plugs. This wont hurt my ski if I continue to run non resistor plugs will it?
 
White99z said:
So basically I just need to replace my plugs with some NGKs like I had and keep doing what I have been doing. Sounds good to me. Does anyone know if I could keep these densos (the equivalents to the b8hs) as a backup plug? Or should I just take them back when I take back the higher temp plugs. Also, does everyone agree on the .030 plug gap? Now I just gotta find somewhere that has some NGK's. I was running the non resistor plugs. This wont hurt my ski if I continue to run non resistor plugs will it?

Team alpine has them. I just got some on saturday. First time changing my plugs since i bought the ski..
 
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