OS HYPER or YS 50ST for Trex 600n......???

[Adrenaline]

:DOHHi Freaks,
I amtrying to make my mind on what engine to buy for my Trex 600 nitro pro.....
I was wondering if you could advise between the OS and the YS.
Which one is the most pwerful?
which one is the most reliable?
Which one is the most user friendly?
Thanks a Million for helping me.
Regards,
Brian.

[archiebald]

Adrenailine,
since it was me that suggested you post here I had better answer - and in more detail than before.

Power - from what I understand, under equal conditions and with the right muffler these engines are pretty much equal on power.

Reliability - Main problems I've seen with the OS are main bearings breaking up and holes in pistons. The bearing problem seems not only to be with the original bearings. For some reason aftermarket bearings also seem to have a shorter life in the hyper. This is just based on what I've read in the last couple of years on various forums. I've also heard a few people report that they eat glow plugs but this may be down to individual tuning.
The YS is not as common so it is difficult to get a feel for the reliability. I have heard of one or two having broken crankshafts but that seems to be an isolated problem so it might have been a single bad batch. At my club we have three YS50ST's in Raptors (including mine) and nobody has yet had any mechanical problems.

User Friendly - The OS is conventional in that it uses muffler pressure to pressurize the tank. The result is that even with a header tank the mixture will vary between a full tank and 1/4 tank. It will lean off as the tank empties. It also means that your tank receives exhaust gases which will speed up the decomposition of the clunk line.
With reragd to your mixture changing, you could opt for a carbsmart from CSM that will help to keep the settings optimized automatically but that adds to the cost and complexity.

I would rate the YS better here. As I am sure you know the YS uses pressure from the crankcase to pressurize the tank through a check valve. This means that the only vapors returning to the tank are from clean unburnt fuel so in theory clunk hoses should last longer. Since the pressure is maintained in the tank by the check valve, it also means that the pressure is virtually constant throughout the entire tank. Added to this, the YS carb uses its own pressure regulator so you can be sure the mixture will not be unexpectedly changing. Once set up, the YS should therefore require less tweaking.

Most people state that the OS can be more powerful but it requires fiddling to get it there. The YS seems to have a broader range of power and is easier to keep in tune.

Installation - The YS takes a little more figuring out due to the plumbing, but it is really not so difficult. The YS does not need a pressure nipple in the muffler so you can simply remove it and replace with a screw. You may want to confirm that your tank fittings are tight and nothing can chafe the tank. Since it is pressurized it will bulge slightly.

My Personal Experience - I had problems getting my YS50ST transitioning well through the mid range and after some testing I returned it to YS and they found the regulator was sticking so they repaired it FOC, all done by freight collect. After that, the engine has been wonderful and I have so far not needed to adjust the needles at all. I run it with the Hatori #522 and it has excellent power and consistent running.

Starting - Only real difference is that the YS should be cranked for 10~15 seconds on WOT with no booster in order to pressurize the tank. After that, operation is no different.

Fuel consumption - difficult to state but I think it is better than an OS because the engine can be tuned for a consistent run.

If I was in the market for another engine right now it would be a toss up between the YS and the TT RL53H. I personally wouldn't want a hyper.

[Adrenaline]

Dear Archiebald,
I would like to thank you for all your details.
I think that you have convinced me to go for the YS.....
Will have to get used to all its goodies...
Regards,
Brian.

[Wrench]

Hint,

On the YS, first start of the day, After you fill the tank and block off the vent, give the tank a short shot of fuel from the fuel pump. This will slightly pressurize the tank and get fuel to the engine easily. I use this method on my YS1.60's and it works slick. No more cranking for 30 seconds to get fuel to the pump.