is valve additive fouling my plugs

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machten
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Post by machten » Mon Nov 20, 2006 10:39 am

Hi Peter,

Had a quick look. LRP disappearing, use ULP, PULP, UPULP plus additives. My point was that LRP was a pretty ordinary product. I'm happy to disagree on the fuel density thing!!!

Kev

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Steve Foster
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Post by Steve Foster » Sat Aug 28, 2010 3:08 am

I'm interested in the "density" side of fuels such as Shell V-Power and am tending to agree with Kev's comments about fuel density (having corrected his reference to octane/density) rather than the opinion expressed that:
Im sorry, but I don't agree, "higher octane density" is just BS, the so called premium fuels have the same ingredients as plain 98 fuel, but they have more cleaning additives, no Dellorto or other carburetor will "notice" this, but the entire engine, including plugs, will stay cleaner.
When fouling plugs, there's something else wrong, like weak ignition, bad leads, or just worn or wrong heatrange(!) plugs.
.

Re density, I quote from the Shell Australia web site http://www.shell.com.au/home/content/au ... /overview/ :
Although Shell V-Power is compatible with most bikes there may be a requirement to make slight adjustments to the engine such as changing spark plugs, and reducing the size of carburettor jets, or a combination of both.

.... as a result of the high density of Shell V-Power, it tends to enrich the air-fuel mixture.
Since I began using it (with Valvemaster) I have been fouling plugs (the same experience as Craig in France and Vince). The plugs seem to indicate that the engine is running rich but I don't necessarily think that that is the whole story. I'm finding lots of black sooty deposits even after relatively short "spirited" rides of 50 kms or so and am wondering whether comments elsewhere on this site about V-Power being an "oily" fuel indicate that the composition of the fuel as well as its higher density may come into play.

Other factors? Have gone to a one grade hotter plug, have good plug leads and a strong spark (upgraded coils some time ago), have clean air filters.

I am going to try reverting to a normal 95 octane fuel and will post the outcome. I am also going to try Nulon Lead replacement as well as the Valvemaster to see if the lead replacement+fuel combination is a factor, but I will be careful to change only one variable at a time.

Steve.
1974 Ducati 750 GT

machten
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Post by machten » Sun Aug 29, 2010 4:35 am

Steve,

Re density, I quote from the Shell Australia web site http://www.shell.com.au/home/content/au ... /overview/
Although Shell V-Power is compatible with most bikes there may be a requirement to make slight adjustments to the engine such as changing spark plugs, and reducing the size of carburettor jets, or a combination of both. .... as a result of the high density of Shell V-Power, it tends to enrich the air-fuel mixture.
Yep. That's what I was saying. I subsequently spoke to a few guys ( at the time of this thread ) in the refinery laboratory where they design, produce, test and certify fuels, who confirmed the view you quote.

It might be BS, but the guys that make the fuel didn't seem to think so.

The statement that:
The quality of the new, modern premium fuels is so good, every engine will run good (or better) on it, without any adjustment whatsoever.
...is not supported by the techs that I talk to that make the product. On the contrary, they suggest you select fuel according to suitability for your engine.


Kev

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Steve Foster
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Post by Steve Foster » Sat Nov 13, 2010 3:11 pm

An update from my previous post in which I mentioned the problems that I experienced after switching from standard 95 unleaded to Shell V-Power.

Since reverting to 95 unleaded the symptoms of oily and sooty plugs, black smoky exhaust, etc have disappeared. I didn't re-jet the carbs or make any other changes such as plug heat range (I'm running slightly hotter plugs anyway) - just a back-to-back comparison in order to control variables. Some may be of the opinion that the jetting should have been adjusted for the different fuel but I didn't think it worthwhile to make that change because it didn't seem to me to be simply a matter of running rich - there was the oilyness as well (e.g. if I put one hand over the end of the exhaust while revving the engine it was covered in oily spots, not just the sootiness that would be evident from a rich mixture.)

I have tried both Valvemaster and Nulon lead replacement products and there was no perceptible difference in engine operation, unlike the effects of changing fuel which were immediately apparent.

I'm sure that V-Power is great for modern Ferraris and also for Peter's '85 Mille but the 750 GT has been running beautifully on standard 95 + LR additive so that's what I'll continue to use.
Cheers, Steve.
1974 Ducati 750 GT

bobnorton
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Post by bobnorton » Wed Nov 17, 2010 2:12 am

After a fill up with Shell Optmax my 250 sooted up its plug and became a fussy beast. Standard unleaded has restored nomal performance.

lloydmarine
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Re: is valve additive fouling my plugs

Post by lloydmarine » Mon May 14, 2012 7:45 pm

I too had this exact problem,
I started running a 98 octane fuel and began fouling plugs...to the point that they were fouling every 50km. ('75 squarecase)
I read the comments in this post and dropped back to a 91 octane and occasionally used a 95 octane and have NEVER fouled a plug since. And I reckon I have done at least 1500km since changing to a lower octane fuel.
As for the valve saver lubricant I have not noticed any difference whether it is used or not in relation to plug fouling.
Every bit of info helps.
Cheers
Mike
'75 860 GT
'78 900 GTS

wdietz186
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Re: is valve additive fouling my plugs

Post by wdietz186 » Tue May 15, 2012 7:36 pm

I would try running without any additives at all. The lead replacement stuff is there to protect old cast iron valve seats and fairly soft steel valves. Our Ducatis use a silicon/bronze valve seat and pretty good quality steel in the valves. What the lead in the fuel did other than raise the octane of the fuel was provide an expendable coating/lubricant to the valve seating faces. This was mostly to prevent the valve face and seat forming micro welds when they were very,very hot. These microscopic welds would be broken when the valve opened again leaving a rough surface that burned away,slowly letting the valve sink further into the head. This doesn't happen on our bikes and as lead is pretty much banned in available fuels who knows what compounds are being used in these additives? I've run unleaded in my 750 GT for years and haven't had any problems with my clearances closing up or any evidence of detonation visible on the plugs or piston.

radecal
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Re: is valve additive fouling my plugs

Post by radecal » Wed Jun 06, 2012 6:47 am

Have had similar issues with my 82SS (warmed engine). Chased plug fouling issues for ages and found that the fine print on Shell 98 octane is right. Very rich running on the 40s. I changed to another brand and got a better response but have dropped the idle jets back a bit and she seems to have settled down. Never an issue when the throttle is wide open, only just around town/idling. I suspect the electrical system may play a big part as well as the weaker systems in the older bevels don't handle the new fuels (or what they sell us here in Queensland) as well as my later ones. Had to go hotter on the plugs depending on the time of year.
I notice the Shell 98 doesn't run well in any of my bevels or belts (plugs seem to have a black scum on them) but the injected are no problem.
It is my understanding that due to government restrictions on hydrocarbon emissions being released into the environment, modern fuels are less "volatile" than the older leaded fuels. Kev may be able to confirm that with the techs.
Never used an additive but I have hardened valve seats in my runners so can't comment on their effect on plugs. Only thing I use is StaBil to keep the fuel fresh for extended periods if I can't use it in time.
I do know the fuel goes off bloody quick if left for more than a couple of months due to the way it is made now. 5 year old tin of unleaded looks and smells like paint varnish while another drum of old Super I still have looks like the day it was made and still runs in my AJS.
Even in my cars, I notice a big difference in mileages depending on when we get fuel delivered to town.
Often hear people complain about the swill we sometimes get.
Regards,
RAD
RAD

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abmartin
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Re: is valve additive fouling my plugs

Post by abmartin » Thu Jun 07, 2012 5:18 am

I'll second what Rad says about fuel going off quickly. I use StaBil for all gasoline-powered motors that need to be laid up for more than a couple of months, which happens pretty frequently here in Canada. No more problems with gummed up carbs and difficult spring starting. My car, a Ford Probe GT, would turn on the check engine light if it sat for any length of time. It would extinguish after running a tank of fuel through it.

Bruce
1979 900SS
Fredericton, NB
Canada

JasonBav
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Re: is valve additive fouling my plugs

Post by JasonBav » Sat Feb 07, 2015 12:13 pm

Hi, I have just come across this forum post, I know its a bit old.
I live in Sydney, and have been having allot of trouble with fouling plugs, I have recently purchased a 1974 GT with 32mm dellorto's. The previous owner had a bevel mechanic replace the valves and guides and as well as new rings and a hone (so I have good as can get compression). I have a Dyna s ignition, a rely to power the dyna coils, a st2 rotor to up my charging.
My question is, with todays modern fuels and me playing around with the jets and setup of the carb I can't seem to get a good looking plug, if I go for a good hard run (run off the main jets and needle etc) and take a plug out they look o.k but the running around in the city, my plugs look sooty black and fluffy, is this is as good as I can expect. I mainly use 91 and sometimes 95, I read somewhere that they were going to bring a colour dye to identify what ron was what, but all the fuel I have seen looks like a yellowish to almost clear.
I was told by a bevel mechanic to go up to a het range ( NGK refrence a BP5HS) as he reckons todays plugs and what they use to be I am thinking heat ranges.

Vince
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Re: is valve additive fouling my plugs

Post by Vince » Mon Feb 09, 2015 12:44 am

Bit of a waste of time reading plugs these days.Other than the seat of your pants there is only one good way and thats a Dino.
Give Mick a ring at Motocycle Weaponery at Mona Vale.He is there Dino bloke,very helpful and the best bit is he owns a Bevel.

machten
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Re: is valve additive fouling my plugs

Post by machten » Tue Feb 10, 2015 2:56 am

Dunno about that Vince. I've tuned Dellortos more than good enough for street use for 30 years without access to a dyno. Reading plugs is still relevant too. The fuel has changed but the combustion engine and the signals it leaves hasn't.

Kev

Vince
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Re: is valve additive fouling my plugs

Post by Vince » Fri Feb 13, 2015 9:26 pm

Maybe if you are are doing the strong light and magnifying glass stuff up the plug inner but thats beyond me.The black sooty or white or tan thing seems not so easy for me these days,they usually come out black and yes I am going to say it MODERN FUELS.Just fitted a set of brand new Mikunis to my Leverda and the plugs came out after 200ks looking like they should or did back in the day eg not black at all,nice and honeyed so maybe new tight non leaking carbs are whats needed.

machten
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Re: is valve additive fouling my plugs

Post by machten » Sun Feb 15, 2015 2:11 am

[quote]....so maybe new tight non leaking carbs are whats needed.[/quote]

Yeah Vince, I suspect you're right that that helps...certainly for trying to get the old damn things to idle and synch evenly. Over the years I've accumulated about 6 sets of PHF 32's and a mate of mine used to work in an engine development company. He had them all laser measured down the slide paths for me. The printouts made for interesting reading!

Kev

machten
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Re: is valve additive fouling my plugs

Post by machten » Sun Feb 15, 2015 8:24 am

All that being said, you can tune Dellorto's pretty well and you can read the plugs. This one of my mine from my 900 is a little lean for my liking, but close to right...

It's actually a little darker than you see in this photo...

Image

Kev

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