HPDI 200 - how smooth should it run at low RPM?

I was just thinking of some other item that could possibly cause a difference in the carbon buildup. Regarding spark plugs.
I have been seeing some videos where folks just replace the plugs with factory gap setting and don't check them. I have always checked them and found them to be off per my feeler gauge.
Dennis, do you just install the plugs as-is from factory or do you readjust them? I wonder if this might have something to do with why I have a carbon buildup more than others...... What say you?

ROBERTH said:

I was just thinking of some other item that could possibly cause a difference in the carbon buildup. Regarding spark plugs.
I have been seeing some videos where folks just replace the plugs with factory gap setting and don't check them. I have always checked them and found them to be off per my feeler gauge.
Dennis, do you just install the plugs as-is from factory or do you readjust them? I wonder if this might have something to do with why I have a carbon buildup more than others...... What say you?

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Yes, I always check the gap, first. If you're questioning them, go ahead and pull them out and check. You can "read" the plugs, too. Make note of which cylinder they come out of.

Thanks Dennis, I am not actually questioning them as I am OCD on plug gap so know they are right per my feeler gauge. Just wonder the difference in those motors that have the narrower gap vs the wider gap when I have to add more gap to them which seems is always the case.
Do you find the same? They always need more gap?
Each season, usually just under <100 hours I replace the plugs. They always look clean and good per the manual expectations. Never any are in a fouled or wet condition. Even my O2 sensor is clean, just the carbon in the chamber and sniffer tube.

My experience over the years with NKG plugs is that they were gapped in spec for my SX150 right out of the box. I do randomly check the gap on used plugs and occasionally, I will re gap.
Note that when you check gap, you should use a wire feeler gauge not the flat metal blade type. For new plugs it doesn't make that much of a difference but for used it can give a false reading ( may read less than the actual gap)
I can get three seasons out of plugs and like a few other parts, I change them out of guilt, not hours.

Good point Seasick, I always wonder about the feeler gauge not reading right, but I always negotiate with my brain waves that if I can slide between the electode and tip with some resistance, I am good. However, angle is important.
I haven't been able to find a wire gauge with the 1.5mm -1.6mm or so size.

I wonder if I am adding just enough gap where it might cause less combustion and therefore more carbon buildup....dunno....but might be one thing I can try, replace with new with no gap check, just factory and see what happens.

ROBERTH said:

Thanks Dennis, I am not actually questioning them as I am OCD on plug gap so know they are right per my feeler gauge. Just wonder the difference in those motors that have the narrower gap vs the wider gap when I have to add more gap to them which seems is always the case.
Do you find the same? They always need more gap?
Each season, usually just under <100 hours I replace the plugs. They always look clean and good per the manual expectations. Never any are in a fouled or wet condition. Even my O2 sensor is clean, just the carbon in the chamber and sniffer tube.

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For my motor, I haven't found the need to alter the factory gap spec. I also don't change them every year - I check them - and give them a quick brushing/cleaning/gap checking - but I put them right back in unless there's an obvious issue.

Thanks Dennis, maybe I am on to something. Reason I change them is due to the corrosion on the plugs. I even coat them when replacing with corrosion sprays, but guess they get hot enough to burn it off and still corrode/rust.
The plugs always have looked good and even burn on all cylinders. I always thought they could go another season.

y corrosion do you mean rust on the bases? If you get rust frequently on the plugs, you may have a water leak under the cowling, I have seen that on some motors. It can be a very small leak or even possible a disconnected pitot tube hose. If there is enough salty mist, you may see more green on power lugs than normal. I am interested in input from others on there experience with rusty plugs.

Hi seasick, actually, at times water does come in the cowl when waves come over the motors. Most likely that is where the saltwater dribbles down on the plugs. Unlike the OMC Seadrive I used to have, the Yamaha's don't have a baffle to keep water from dropping on the motors when it can come in the intake.
I run the motors with the covers off even recently and nothing is leaking anywhere, it just comes in the intake area. My shroud seals seem to still be in good shape.
Nothing is green, I keep the motors sprayed down with protectant. Usually only a couple of plugs are the worst which I think are in the path I mentioned where that water comes in and drops down on that area.

Seasick, you got me thinking a bit deeper. Got in a new set of plugs. I found a wire type gauge and checking the plugs, I discovered something I had not caught onto.....
The side electrodes are not flat, the edge is curved so it aligns with the center electrode being in the shape of a cylinder. When sliding in a flat feeler gauge, it is making the gap way too wide. Using the wire gauge, inserting vertically between the center and side electrodes is the right way to check the gap. I never have seen this before and realized the design. My eyes are failing or I was just not paying close attention.
I am wondering if the gap being so wide was not hot enough of a spark allowing the extra carbon buildup. I will check this weekend, weather permitting if it runs better or not with the new plugs with factory gap.
Thanks guys for the feedback. I hope this might be something that benefits these motors and my carbon headaches!

DennisG01 said:

I originally started with Yamalube because it was a safe bet, but then switched to synthetic for less smoke. I use Evinrude's XD100 full synthetic, now. It runs about $45/$50 per gallon.

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Hi Dennis, sorry to resurrect this old thread, but doing so as at the time of the conversation, I was convinced to move over to Yamalube 2m oil and see if their claimed lower ash content would resolve my carbon buildup issue especially in the O2 sensors. Well, it didn't help and might have been worse. Also, and I forget where I posted about it, I had a season I did not fish as much due to moving, etc. and the 2M oil sat in garage for the season, only to find out is went bad, so lost 2 cases of it.
So, as I was again starting to research, I have not found much about the XD100 oil, but the very few folks mentioning it swear by it for reduced carbon build up and then I found your comment about it as well. My next purchase for this upcoming season will be the XD100 once I burn off the new Amsoil I just refilled the remote tanks with after cleaning them out from the bad Yamalube oil.
Just mostly checking in with you if you are still using it and still having good results?

Yes, I am still using the XD100 with happy results - I use it in my mother's GW, too - she has a 150OX66. I also use Startron and RingFree religiously. I would LOVE to find an alternative to RF - I'm convinced of it being a good product... I just think it's excessively expensive. I'd read about Chevron Techron - but haven't found enough definitive info... and I don't want to be the guinea pig... how 'bout you - want to take one for the team?

Dennis, you can run Techron Marine with confidence and ditch the ring free and startron. Techron/Chevron makes PEA, the detergent in ring free. It works and it works very well. I scoped my old ox66 before and after a season of use of Techron. Night and day difference from Startron.
If you want another opinion, look up Project Farm on YouTube. He tested Techron, Startron and others. Techron outperformed them all.

I may have said this before but I am lazy and don't want to reread all the posts

Carbon buildup on the plugs can have more to do with the precision oiling system on Yami 2 strokes and less on the brand of oil. First easy step is to check the oil linkage for proper adjustment.

Buildup may be caused by too rich a mixture. Possible cause include a leaky fuel injection nozzle or a bad/dirty O2 sensor ( testing should include the heater circuit) The port into cylinder one that the O2 sensor is connected to can also be plugged. That can cause the motor to run rich

Hi Dennis, yeah, I had mentioned I was switching over to the Techron Marine, but it is still sitting on the shelf since I have not run out of the Startron and Ring Free+ yet. Maybe I will switch over during upcoming season just to see if it helps or not.
The hesitation there would be the protection that Startron has done in using Ethanol Fuel. No corrosion issues, No rubber hose deterioration, no issues at all regarding fuel. I need to read up again on the Techron Marine again and see if it can replace both the Startron and Ring Free as mentioned by family affair. I forget what I had learned since it was so long ago....

family affair said:

Dennis, you can run Techron Marine with confidence and ditch the ring free and startron. Techron/Chevron makes PEA, the detergent in ring free. It works and it works very well. I scoped my old ox66 before and after a season of use of Techron. Night and day difference from Startron.
If you want another opinion, look up Project Farm on YouTube. He tested Techron, Startron and others. Techron outperformed them all.

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Very intersting, Fam! Thanks! I will definitley put more thought into Tech vs RF. My experience (about 7 or 8 years now with the Star/RF) has been nothing short of "very happy"- fuel is alway super clean when I check it by draining the VST and the O2 sensor is nice and clean, too... so much so, that when I went to get a replacement gasket, I had my "barbell" with me and the Yamaha tech said "What the hell do you do to keep this so clean?"

I use Startron for different reasons, though. I attribute the lack of carbon to the RF, not the Startron. Although Startron to should help with cleanliness, I use that primarily for the stabilizer aspect and also to fight ethanol issues.

If I remember correctly, Project Farm compared the anti-carbon effects of the various additives - which I would never expect to see Startron compete with RF or Techron.

It's nice to hear what you found by looking at the pistons with the Techron. That might just the push I need to take the leap

Ok, I went back to Project Farm and also some other references. I feel like I have been reschooled. Pretty sure I have watched these videos before, but didn't catch on about the corrosion protection differences between different additives. The only one he tested that did absolutely no corrosion was the Stabil! I have not had great experience with Stabil in the past, but maybe I had some old Stabil sitting in the shed for years and it had gone bad. So, from a corrosion perspective, I now would consider Stabil. I refer though to the newer version of the Stabil Marine 360 which defines corrosion protection among also ability to help with any water if we had any in Ethanol.
Folks also mentioned that the amount of PEA in the Techron Marine was very high and thus we all know Techron has been a miracle worker on a car engine running rough, so it must do something very well in that area. Not sure what it does, but have had results in less than 50 miles to improve running of a rough car engine. Not mine of course...lol.

I feel like I want to follow Dennis's magic to get my HPDI's running cleaner. So I will be placing an order for XD100 from Domo as the season approaches. Will run out the Amsoil first, then switch over.

Like Dennis though, I have had no issues showing any fuel problems with the Startron and Ring Free+, but Project Farm has scared me now on the corrosion and durometer reading on the hoses hardening with the Startron....

Now, with all the confusion, if I switch from Startron and Ring Free+, what to use?
The Techron Marine is said to be a replacement for Ring Free and fights both corrosion and water. So seems it is a single product to do not only what Startron and Ring Free was doing, but also adds the corrosion protection that Stabil does.
Here is what AI says about Techron Marine replacing Ring Free:
Techron Marine (Chevron Techron Protection Plus Marine) is widely considered a suitable and effective replacement for Yamaha Ring Free Plus, as both use powerful PEA (Polyetheramine) chemistry to clean carbon deposits from fuel injectors, carburetors, and combustion chambers

Then I found this in AI about the Stabil Marine 360:
No, STA-BIL 360 Marine isn't a direct replacement for Yamaha Ring Free Plus because they do different primary jobs, though both are fuel additives for marine engines; Ring Free focuses on carbon removal and lubrication (like Techron), while STA-BIL 360 primarily stabilizes fuel, prevents corrosion, and handles ethanol, but some users find STA-BIL's cleaning properties sufficient, while others swear by Ring Free for specific carbon issues, especially with older 2-stroke Yamahas.

So where I am now parked is to use the Techron Marine as the replacement for Startron and Ring Free+ and see how it goes with the XD100 oil over the next season, then check the O2 sensors and hope they are pretty like Dennis's...

Isn't this fun?

RF+ doesn't stablize fuel - which is the main reason I also use Startron.

I'm not sure about the Startron vs hose tests PF did and their actual accuracy. I've been using Startron in ALL my gas stuff for proably 20 years with no issues. I use it in chainsaws, weedwackers, lawnmowers, a plethora of small and medium OB's and a few larger OB's.

On the other hand, ethanol CAN harden hoses - especially the kind used in small engines (chainsaws, weedwackers, etc).

FWIW, I also ran Pennzoil from Walmart in the before mentioned ox66. It seemed to like it. With Techron Marine, the engine ran incredibly well and stayed clean like Dennis's experience with Startron and Ringfree.
I bought Stabil Marine 360 2 years ago for the Zukes. It looks similar to the Techron, but the viscosity of the Techron Marine was like oil. The Stabil is water like. It claims to prevent corrosion and has PEA, but the % of PEA is unknown.
The only reason I bought the Stabil 360 was because I could buy it in a gallon container and made the same claims as Techron. Found out after it arrived that it only had a 2 year shelf life!
I'll likely go back to Techron Marine, unless I see something to suggest the performance is similar to Techron. I can't remember if PF tested it specifically.
While the PF testing was good, there seemed to be some holes in the test methods. Regardless it did provide some good information to see how some products compared to others.

I always enjoy PF's stuff... moreso if he would stop yelling

From "what I know" (which is sometimes not that much), 360 is more like Startron and less similar to RF+. Many years ago, Startron was the first company (Star Brite) to come out with a stabilizer that also fights ethanol. Soon other companies followed suit. Stabil did, as well - adding the bluish 360* to their lineup in addition to the standard red stuff. Essentially, 360* is the red stuff along with ethanol fighting stuff added in.

I used to use the Pennzoil synth oil as well - and liked it - but it got hard to find and that's when I found XD100

Edit: I meant I used the full synth Pennzoil - and that was the one that was then hard to find