88 na, i don't want to take it off, i just want to disable it and run premix. i've checked the forum search feature and all i get are post about removal.
just so you'll know the scca says it must stay. but most racers i talked to disable it.
just none would tell me how.................
thanks
robert

 

I haven't delt with S4 but I'm asuming you could just remove the metal rod between the intake and OMP. I'm not sure if that would close it compleatly or if it would still be part way open though.

 

If its working properly don't remove it. Run pre-mix as a supplement. Running pre-mix will NOT give you more power in ANY way shape or form. It is only a supperior(to some not to others) way to lubricate and a substitue to those who have had an OMP fail on them or other components of the system. Please read my thread it should be near the top of the search for MOP or OMP, pre-mix etc whatever. There are two definate sides to the argument of whats best for lubbing the internals of your engine but its your call in the end. I would just supplement the MOP system if I was in your position.

Again for those that are missled about pre-mixing.


REMOVING THE MOP/OMP or any of its parts WILL NOT ADD POWER OR MAKE YOU FASTER IN ANY WAY SHAPE OR FORM.

Santiago

 

Gonna have to side with Santiago on this one.

Leave the OMP on, and if premixing is your gig, then run it as a supplement.

 

ok, i understand that it doesn't add power. i knew that before i asked.
heres what happens.
after each 20 minute race session on track i use 1 qt. of oil. that means your losing that much ablitiy to cool the engine. so i want to run an aftermarket radiator with a second inline oil cooler. right now i couldn't even run a longer race without fear of screwing up my motor. so if i disable the omp i won't burn off all my oil and by premixing i'll still lube the rotors.
i don't want to argue over this but all the racers i talked to disable theres and run premix. 30 years of racing 2 strokes tell me that it will burn cleaner and lube better than 20 - 50 motor oil.
whenever i shift i get huge puffs of smoke out the back. and have been questioned about it from the stewards.
so i don't want to be black flaged.
thanks
robert

 

No argument there...But a normally running rotary should only use a quart of oil every 3000 miles. You have other issues.

Jarrett

 

runing premix won't solve your problem, your problem is that your oil control rings are giving up! You need rebuild!

 

runing premix won't solve your problem, your problem is that your oil control ring are giving up! You need rebuild!

 

Not necessarily.

MOP Injectors can default open (dumps too much oil in).

From looking at the whole MOP under my S4 NA's UIM, If one of the vac lines gets plugged for the MOP injectors, they will be dumping too much oil in.

At least that what I make of it with everything torn apart.

Comments anyone?

 

it'll still only suck as much as the OMP is giving it, though if you're going through a quart every race, i'd say that's a bit more than the OMP is going to be giving

 

Can the MOP fail?

 

Indeed! More-so on the s5's where it fails in the open position, I'm not too sure if the s4 can fail open though.

 

I would imagine Mazda would design them all to fail open.. But that's just my imagination..

How can we test the S4s for proper working order?

Still if air is inteded to be drawn into the housing as well as oil via the oil injector, and the air side of it is plugged, it' still going to draw more oil than it should, correct? Maybe not MUCH more..

That's just what I can see with everything torn apart. I may have the design mixed up.. But it seems logical..

 

I am going to have to disagree. One of the main benefits of running premix is that it does not allow the engine to develop as much carbon and ash from the engine oil being burnt. Premix lubricates better, and doesn't create near as many deposits, so your seals are much less likely to stick.

 

Nobody is debating the merits of pre-mixing. But if a standard rotary is using 1qt for every 20 miles, that might be indicative of a bigger problem.

If disabling the OMP curbs the oil consumption, then I would like to read about it in future posts...

Jarrett

 

Why's that? Seems pointless, there's no advantage to removing it.

I agree about the oil consumption. That's way to high. I doubt the OMP is completely resonsible for this, but make sure its actuating rod isn't stuck in the WOT position.

 

I've actually driven around with my MOP actuating rod stuck at WOT (on purpose) and I saw no change in oil consumption than with it's natural setup.

Uh oh?

 

That doesn't sound right...

 

Trust me I am one of the biggest supporters of two stroke oil rather than the engine oil BUT you have other problems if your eating that much oil. I beleive these gents that are mentioning the oil control rings being dead or dying are correct. I would pre-mix for a race with the MOP arm disconnected and see if the oil consumption lessens if it goes away completly then that IS indeed the problem but if it does not then you have serious internal problems that may require a rebuild to resolve.

Santiago

PS- wow I got Jarret on my side

 

Dude, do you have smoke on start-up and/or deceleration coming out of your pipes? YES? THAN BE 100% SURE THAT YOUR OIL CONTROL RINGS ARE FAILING!!! THAT HAS NOTHING TO DO WITH OMP! Your car can still run strong and it can take months (maybe year, depends have many miles you drive) until it fails and will smoke constantly.

 

Proof?

 

Guys - My MOP failed, Mazda said frozen. Can I leave the pump on and premix or must is be removed? Not sure what to do here.

 

Yes

 

JRAT - yes to remove or yes to leave the MOP on?

 

Leave it on.