I have been doing a little reading and have got questions about that generation of Yamahas. If I understood it all there is an 0X66 that is carbureted, another that is fuel injected at the throttle body and called Saltwater series II, another that is direct injection to the cylinders individually. I don't know if that is some other series designation. Now how do those fit in with one I see labeled HPDI? They are all two stroke. Can someone dumb it down for me ? Which one is the one I hear people rave about being "the best motor Yamaha ever built?
Which 0X66 is the good 0X66?
- Thread starter Halfhitch
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All OX66's are fuel injected at the throttle body. HPDI was the next gen with direct injection (high pressure direct injection). But, yes, the simplicity and reliability of the OX66 series is well deserved. Keep the oil injection system working, your fuel clean, and use something like Ring Free and it's nearly bulletproof. They're a beast of an engine.
Oh... don't use the Yamaha Yamalube oil. It smokes more than most (which means it can also foul internals faster, too). Mercury makes good stuff - but I've been using Evinrude XD100 and have Been very happy with it (good price, too).
Oh... don't use the Yamaha Yamalube oil. It smokes more than most (which means it can also foul internals faster, too). Mercury makes good stuff - but I've been using Evinrude XD100 and have Been very happy with it (good price, too).
So does the Saltwater II series that has throttle body injection idle and run at a slow troll ok? Does the later HPDI run cheaper or smoke less? The reason I'm asking is I am looking at boats to buy and there are some nice boats for sale at reasonable prices with the two strokes. As soon as it says 4 stroke in the ad the price jumps 8 to 12 grand. Seems to be a lot more of the Saltwater II series for sale than the HPDI. Is there any particular point in the developement years where there was an important improvement that should be watched for?
I don't really know what the SWII designation has to do with things - maybe it was a further development of the OX66 along the way? But it's always been referred to as an OX66 as the primary identifier.
Yes, an HPDI will smoke a bit less (negligible) and be better on GPH - but again, it's only going to be by a small amount. On my Offshore, as an example, I run 27MPH to 29MPH in the upper 3,000RPM band and consistently get 9 to 11 GPH. That really ain't all that bad!
I couldn't tell you about the trolling "difference". But there's no issues with the OX66 at idle or low RPM's.
The OX66 has a cylinder deactivation system where it runs on 5 cylinders till about 1,700 and then 4 cylinders till about 2,300. Or thereabouts, anyways. I don't know is the HPDI has that or not.
I don't notice only missing one cylinder - but it's noticeable when 2 are missing. But, in my opinion, it's more of an aesthetic thing as the prop is still spinning consistently. But, truthfully, the only time I'm at 1,800 to 2,300 is on my way to the 3,000 range
Yes, an HPDI will smoke a bit less (negligible) and be better on GPH - but again, it's only going to be by a small amount. On my Offshore, as an example, I run 27MPH to 29MPH in the upper 3,000RPM band and consistently get 9 to 11 GPH. That really ain't all that bad!
I couldn't tell you about the trolling "difference". But there's no issues with the OX66 at idle or low RPM's.
The OX66 has a cylinder deactivation system where it runs on 5 cylinders till about 1,700 and then 4 cylinders till about 2,300. Or thereabouts, anyways. I don't know is the HPDI has that or not.
I don't notice only missing one cylinder - but it's noticeable when 2 are missing. But, in my opinion, it's more of an aesthetic thing as the prop is still spinning consistently. But, truthfully, the only time I'm at 1,800 to 2,300 is on my way to the 3,000 range
The 150-200 hpdi engines were very good. They were a 2.7 liter. Most of the big displacement hpdi engines (over 3 liters) had major issues.
Ox66s generally don't like to run for sustained periods under 2200 rpm. We did it with ours, but had the engine really well dialed in and ran Techron marine religiously.
The hpdi was a cleaner version of the ox66s using direct injection. Unfortunately they all did not have the reliability reputation of the ox66s.
All ox66s were Salt Water Series II.
Ox66s generally don't like to run for sustained periods under 2200 rpm. We did it with ours, but had the engine really well dialed in and ran Techron marine religiously.
The hpdi was a cleaner version of the ox66s using direct injection. Unfortunately they all did not have the reliability reputation of the ox66s.
All ox66s were Salt Water Series II.
I also heard not so stellar feedback on the 300 HPDI. Maybe the 250 also. I fish on a 25 Sailfish pushed by twin 200 HPDI. Those motors have over 2000 hours and run very well
No. Our 1999 225 did not. I tracked hours with self powered hour meter under the cowling.
As for ox66 oil, Penzoil marine 2 cycle was low cost, low smoke, low carbon deposits and readily available from Wally World.
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Are you referring to the full synthetic Pennzoil? I used to use that but then could no longer find it. I thought they stopped producing it? I like the full synth stuff because of the "less deposits" thing. Although Ring Free really does seem to help with that... I just wish I could find a "known good" replacement for it since it's awful expensive. I've heard some say that Techron is the same - but I've yet to find out any definitive info/proof on that.
The original 150s as I recall reading about were fresh water models. At some point in their development a model line geared towards brackish and salt water applications was introduced and named the Saltwater Series.
As with all engines, maintenance is important and relatively simple. In addition the motors handle 'neglect' better than other models and manufactures. I would change impellers Avery 4 seasons or so, plugs every year or two depending on usage. T-Stats last a long time, 4 or 5 seasons. The SX series are loud, gas guzzlers, smoke more than others and have primitive diagnostic capabilities ( and NO, there are no hours maintained in the engine controller). Like most 2 strokes, carbon buildup on the rings can be a major issue and lead to failures. Using an additive like RingFree can extend the motor's life significantly. So as is usually the case, the maintenance history is one of the more important factors in assessing how good or bad a particular motor might be. Consistent fresh water flushing after use is also very important to motor life. The HDPIs are somewhat more complicated but also great motors ( the 300 may be an exception but I have no hands on with a 300 and can't remember even seeing one)
As with all engines, maintenance is important and relatively simple. In addition the motors handle 'neglect' better than other models and manufactures. I would change impellers Avery 4 seasons or so, plugs every year or two depending on usage. T-Stats last a long time, 4 or 5 seasons. The SX series are loud, gas guzzlers, smoke more than others and have primitive diagnostic capabilities ( and NO, there are no hours maintained in the engine controller). Like most 2 strokes, carbon buildup on the rings can be a major issue and lead to failures. Using an additive like RingFree can extend the motor's life significantly. So as is usually the case, the maintenance history is one of the more important factors in assessing how good or bad a particular motor might be. Consistent fresh water flushing after use is also very important to motor life. The HDPIs are somewhat more complicated but also great motors ( the 300 may be an exception but I have no hands on with a 300 and can't remember even seeing one)
Sardinia306Canyon
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Just my own experience
1999 twin carburated 150 = stinky, smoky, thirsty, continuously plug fouling when trolling, sold them after 4 years and replaced them
2003 twin HDPI 150 = less stinky, smoky, thirsty, not fouling plugs, 1 exploded after 3 years and 1 mont at 5000 rpm as probably piston ting got stuck at inline or exit hole. Yamaha refused any warranty and i could sell it for parts to get a few 1000 back.
2006 F150 flawless 800 hours without any of the above problems, Yamaha did not informed about harmonic balancer issues however no problems till i sold boat and outboards in 2020
The HDPI series was a rather big disaster for Yamaha and the best way to avoid problems is to not buy them or in case use religiously Yamaha Ring-Free and the best, low ash 2 stroke oil (and crossing fingers)
Chris
1999 twin carburated 150 = stinky, smoky, thirsty, continuously plug fouling when trolling, sold them after 4 years and replaced them
2003 twin HDPI 150 = less stinky, smoky, thirsty, not fouling plugs, 1 exploded after 3 years and 1 mont at 5000 rpm as probably piston ting got stuck at inline or exit hole. Yamaha refused any warranty and i could sell it for parts to get a few 1000 back.
2006 F150 flawless 800 hours without any of the above problems, Yamaha did not informed about harmonic balancer issues however no problems till i sold boat and outboards in 2020
The HDPI series was a rather big disaster for Yamaha and the best way to avoid problems is to not buy them or in case use religiously Yamaha Ring-Free and the best, low ash 2 stroke oil (and crossing fingers)
Chris
It has been a few years, but I think I bought the blend. Prior to using Techron, I used Startron. After 2 seasons plugs were consistently carboned and gooie. Once I changed to Techron marine, the difference was remarkable. Despite trolling, I could run plugs indefinitely. When I pulled them, they looked almost as clean as a 4 stroke. Even the inside of my prop was clean. I'm a believer in Techron marine. It also sells for a fraction of the cost of Ring Free. My cars get an annual dose as well.
Oh, also stuck a scope in a couple cylinders. Zero carbon deposits and looked more like a 4 stroke.
You have to be diligent checking and adjusting if needed the precision oiling system linkage. Sometimes a linkage part breaks and the oil pump goes to the most oil position which is OK at speed but not at trolling or idle.
About the oil; Is there synthetic 2 stroke oil? Just use a good brand of 2 stroke oil. I had the best results with Pennzoil XLF
When I first got my OX66, it occasionally fouled plugs with Yamalube. Switched to Pennzoil XLF with good results, and less smoke. About $17/gal.
Startron is simply a stabilizer/ethanol fighter - it probably helps to keep the injectors clean, though - and it certainly helps to keep the injectors from gumming up. I didn't "think" Ring Free or Techron stabilizes? Maybe they do. But I'm happy to use both! My fuel, whenever I drain the VST, is always crystal clear (well, with a blue tint!).
Like your experience with Techron, mine has been the same with Ring Free. For example, the O2 sensor and "barbell" have stayed amazingly clean by using Ring Free.
That's good news to hear that you are having the same results with Techron... I may just switch over!
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Yes, the Evinrude and Penn I mentioned were/are. I "think" Penn only has the blend (XLF) anymore - but that's good to hear you had good results with the blend, as well.
Sardinia306Canyon
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There are many synthetic two stroke oils
Lucas Marine 2 cycle oil (Synthetic blend)
Lucas Semi-Synthetic Land and Sea
Quicksilver DFI Oil (synthetic Blend)
Motul Outboard Synt 2T
Most low ash oils state also low smoke or similar
Amsoil Saber (not marine)
Motul for motorcycles
Castrol for motorcycles
The use of non TCW-3 oils for outboard use is a personal view
After the experience with my HDPI i rather would use a motorcycle full synthetic oil than rely on Ring-Free or similar products to clean carbon deposits from low quality non synthetic oil.
Chris
If I feel the need to do a compression test on an 0X66 I'm going to look at, will it harm the electronics if all the spark plug wires are left unconnected while cranking?
If I need to do a compression test without warming the engine and it has been sitting for a while, what might I expect to see psi wise?
If I need to do a compression test without warming the engine and it has been sitting for a while, what might I expect to see psi wise?
I won't go into detail, but there were a number of things I did to get my ox66 dialed in. The linkage rod was one of them.
Sold the boat to my Dad's buddy. Still going strong!
Dennis, Techron Marine is a different product than Techron. If I had to guess it is likely more concentrated than regular Techron and it is a fuel stabilizer - including for ethanol. The active detergent is PEA. Same stuff as ring-free.