OMCs; low speed ??

[bh/]

Re; 49ci OMC triples, 1-3/8, or 1-1/2" carbs.
If I run the high speed jet up so that it starts to 4 stroke at mid range,
can I bring it back in by cutting down some on the low speed jets?
-or do I risk sticking it coming off the throttle?
Is any one running #70s+, high speed jets?

[Dave M]

Not Sure...

Brian,

If I am understanding you correctly, not sure if I am, but if you lower the low speeds you will risk stalling getting on plane. The loopers like a lot of fuel when you give it gas to get on plane, and I sometimes run into the hassele of stalling just as it planes off.

Does this help your questions ?

[Abbott Racing]

Dave, I'm driving the rig so here is what we are facing. Got past the getting the boat to not stall on takeoff, however as she approaches top speed the motor feels like it hits flat spots, then picks up RPM's again. To me it feels like she is missing fuel. It's got lots of snot coming out of the corners, but it's getting that hesitation as it winds out that is the dilema.

[Dan M]

Don' know if this would apply to the tripples or not, but some of the carbs on the Pro motors don't like the ram air effect that you get at speed. Spray shields and fairings can have a lot to do with the way that the air reaches the carbs. At speed, you might be going a litte lean if the carbs are "open to the air". As rpm's drop, speed also drops, and the motor becomes happy again until the cycle starts again. Some spray shields can create a vortex at speed that can screw up the airflow. Even saw that when a carb left the protection of a fixed boat mounted shroud in a turn that the motor would go off key. Just another thing to take a look at.

Dan

[Dave M]

I have found the Ram air does not affect the 3 holer to much. It might help or hurt depending on some other things done.

But if you lower your low speeds to compensate as Brian was asking, it would probably stick. Work out the top speed jets. Lower down until the plugs look right. Don't go out for more than a straightaway when you are testing this, those people that go two or three laps are asking for trouble when setting your jets.

[bh/]

"jets"??

Dave;-I was not able to get on this site the last two days, but the 'surging' at WOT that Bob [and Rossman] experienced was a run lean condition that we cured by screwing in much bigger jets. I was getting 'rich' plug readings,
IMHO, but its hard to accurately read them if one does not get a good ignition chop at WOT. The guys like to idle back to the beach, and thats understandable, as charging the pits at 80mph does not make friends!!
My concern before last weekend, was that with the jets we had, we could make either a small or large change, and I opted fore the large, hoping we would not 4-stroke at mid range. Hard to really tell on the short course we ran at Almonte, but with the small prop we used, it ran clean thru to 8000.
Daltons #67 triple runs the 'modern' carbs with the air screens on the side, and experienced bad 4-stroking at mid range, causing big problems on a short course. I think I best buy some 'numbered' drills and make up some jets,
as my local Bombardier dealer is quoting me $45/ set of three.

[Dave M]

You got it

Buy a real good set of numbered drills, and put them on the shelf and label them, JET DRILLS ONLY. Otherwise you get them all mixed up like i did once !!