OMC Tech: Crossflow Jets

**FMP** · 05-24-2020, 11:12 AM

Call Bob's https://bobsmachine.com/product/reve...dges-5-degree/

Or Skeeter and ask what they have on file.

Maybe a smaller four blade to help stern lift.

If you think the motor is as good as it's going to get.

**DieselDood** · 05-24-2020, 11:31 AM

I'm not sure if the motor is as good as it gets, I don't have much to compare to. I was looking around at other guys fishing yesterday no one has anything similar for me to try and judge off of.

I did happens to see my same boat on CL locally with a Suzuki 150, so I just sent him a message to see if we can compare notes.

I was thinking about the smaller blade say a 13" diameter VS all the 14" I've been running. Maybe a 23P 4 blade but a 13" would work better?

I talked to my "local" Skeeter dealer last fall. They don't know CRAP about this hull. LOL I told him the model and he transferred me to the old guy in the parts department and he vaguely remembers them but didn't know any details.

I did find out of a prop shop not far from me. I'm going to reach out to him this week and see what I can find out. It sounds like he's been doing this quite a while. Maybe he remembers this old hull

**DieselDood** · 05-24-2020, 12:27 PM

I'm not sure if the motor is as good as it gets, I don't have much to compare to.  I was looking around at other guys fishing yesterday no one has anything similar for me to try and judge off of.

I did happens to see my same boat on CL locally with a Suzuki 150, so I just sent him a message to see if we can compare notes.

I was thinking about the smaller blade say a 13" diameter VS all the 14" I've been running. Maybe a 23P 4 blade but a 13" would work better
I talked to my "local" Skeeter dealer last fall. They don't know CRAP about this hull.

LOL I told him the model and he transferred me to the old guy in the parts department and he vaguely remembers them but didn't know any details
I did find out of a prop shop not far from me.

I'm going to reach out to him this week and see what I can find out.
It sounds like he's been doing this quite a while. Maybe he remembers this old hull

**racer** · 05-25-2020, 08:38 AM

In your latest video I can hear a surge in the engine so its still now running right. What jets are in it? If that is with a 19 inch pitch and not turning Higher than it shows/sounds its not right. Ran a 18 Hydro sport with a 93 150 on friday it turned a 24 Raker 5800 and had no issue planning. Be interesting to run on a load wheel

**FMP** · 05-25-2020, 09:55 AM

Page 24, jets what jets

**DieselDood** · 05-25-2020, 01:57 PM

Originally Posted by racer

In your latest video I can hear a surge in the engine so its still now running right. What jets are in it? If that is with a 19 inch pitch and not turning Higher than it shows/sounds its not right. Ran a 18 Hydro sport with a 93 150 on friday it turned a 24 Raker 5800 and had no issue planning. Be interesting to run on a load wheel

The surge is when I trimmed up. It makes a DRASTIC difference when I trim up to even up 1/4 from all the way down. Right now the motor is mounted at the highest hole as well.

Well it must not be running right then if you are able to spin that prop on that Hydra-Sport.

Jets are... Jets:
Main 64C
in the bowl (Orifice as noted in the parts film): 31
top of the throat, I've seen called the air bleed: 28

I did switch over the 64C/D so the C is in the carbs now because you had noted that the D was not the proper jet (and larger) for these carbs with the metal bowls.

There is a gentleman from this board that isn't far from me and has a dyno, and I'd be happy to take it to him if he was willing, but he hasn't answered my messages, so I'm not going to keep bugging him.

I'm going to pull the plugs and take a look. I know it's not a chop test, but I figured out today we put on close to 20 miles on Saturday for that tourney.

**FMP** · 06-04-2020, 04:55 PM

Fixed it or nixed it?

**DieselDood** · 06-04-2020, 05:54 PM

Been busy. I met up with RJ, a member here.

He had me install my 36 air jets into the 5/16 carbs (had 28) and that made a huge difference.

He has some jets we are going to try, but since it's running better than it has been he had me check the plugs and found one whole bank running pretty good, the other whole bank running really rich. So... we talked and the only difference is one is the 5850 (proper burn) CDI pack and the other is the 8500 (rich). I tried swapping CDI packs, but that gave me some issues and I had to switch back right before the tourney last night.

I'm going to reinstall that and give it another try when I'm not so pressed for time.

Don't worry, I'll keep you updated.

The 36 Air jets made enough of a difference that I was able to step up to the 21P prop with 2 people and full livewells. I was really surprised!

**FMP** · 06-04-2020, 06:34 PM

Sounds like you'll still find more

**DieselDood** · 06-04-2020, 06:40 PM

Originally Posted by FMP

Sounds like you'll still find more

For sure. I just need life to slow down a little and stop raining. I had everything set to test for tuesday, but we had a storm come through and I had to return everything back for Wednesday... except I thought I was safe with that CDI pack.

I must have mixed up 2 wires or something cause it was sneezing back. I didnt have my timing light to do a real diagnosis on it, so I just switched back and it ran good for the night.

**FMP** · 06-04-2020, 09:50 PM

Like too fast neutral idle sneeze that needs a little bit richer but then doesn't idle in gear until the other issue is fixed?

**DieselDood** · 06-05-2020, 07:40 AM

I'm not sure. That part is new to me.

If I came off idle it was ok, but I could tell it wasn't right. I did try to drop it in gear and I was unable to get it into gear without it dying. And that was a sudden "off" situation

I'd come down to idle and it would either sneeze back, or instantly stop.

I switched CDI packs and it didn't do that and ran good for the tourney. Including idle for... 10ish min before blast off

**DieselDood** · 09-04-2020, 02:22 PM

Ok... So update:

End of June I totaled the Skeeter this motor was on. I hit a rogue wave while testing (looked back to verify water pressure after lifting the motor to the top notch) and cracked the hull 8' long. Scary ride to say the least. I was almost ejected. It wrecked my trolling motor (slammed the head into the deck) and one of my graphs as well.

I picked up an 85 Champion with a blown 150hp Crossflow. So... I threw together some junk parts and let the Skeeter go away.

Same motor, different boat. Which... seems to be a much better hull design!
Anyway... the motor.....
Considerably better, but still tweaking.
Since this post... I've installed 2 of the same CDI packs. (actually just picked up another 8500rpm pack, I want to see if somehow things go rich again, and if they will pull that mid range stumble out)
Then played with about every jet combination I have access to, thanks to rjdubiel. It started with Idle 36, Mid 31, Main 64. Now I'm at a 33 Idle, 31 Mid, and 61 main. By all the information I can find on the 3.5 bore motors this should still be rich, but the plugs tell me to stop. I don't have any 60 mains, or I'd probably give them a try. 58.5 is the next step down I have.

With a 23P 4 blade, it stumbles coming out of the hole. With a 23P 3 blade it spins up and gets on plane nicely.... but both Props are low on the top end RPM. The 23P 4 blade I only see 4500rpm at 53mph and with the 23P 3 blade I see 5200rpm but only 46mph. I did try a 24P 3 blade and it does not get out of the hole very well at all, and actually when the motor gets to 3100ish RPM it will blow the prop out if I'm not careful. Which honestly doesn't make any sense to me.

I'm going to see if what we found before holds true, and the timing profile changes with the 8500rpm packs and it starts showing rich on the plugs. Early with my testing on the Skeeter before I had one of those packs fail, the 23P 4 blade was great for one trip around the lake. Then I hit a wake and it wouldn't get on plane again. LOL So... I suspect that the timer base that is on it, may be more compatible with the 8500 packs, instead of the 5850 packs that are on it now.

Theories... I can't find any information telling me how they set the timing profile on the CDI packs. I do know that the 8500 RPM packs do have a different firing order, so the top and bottom cylinders get switched when they are hooked up as compared to the regular packs. Does it ramp up the same as the timing arm, is there a delay, etc.

I may swap those tonight and give the boat a run on Sunday and see. I'm hoping to be out fishing on monday....

Anyway... I know a few folks are following this, so I wanted to give an update.

I'm also trying to find a 21P 4 blade. My 21 3 blade is beat pretty bad (it was $30, I wasn't expecting much) but it gets out of the hole Really nice with that, but has the same 46mph top speed. (need to try this one again with the tach working)

It's slowly coming along though. I think I may try and track down some intake stuffers to gain that small extra as well.

**keefallan** · 09-04-2020, 06:00 PM

Great read. Sorry I didnt see it till today. I had been away from S and F for awhile.......when you posted this . Check with Chris Carson for his intake stuffers(that go behind the cages). I actually used them and the factory black rubber stuffers in my 175 build last spring. But unfortunately, its still sitting and awaiting to be installed on a boat. I am curious to see compression numbers for it, because of the intake stuffed and the 2.6 heads also.

**Revenge22** · 09-04-2020, 10:22 PM

good to see you back, but not good that it's still got issues! Now we know a few things:
a) no combo of orifices are getting you were you need to be so fuel is probably not an issue
b) the power packs you've tried are good.
So that leaves the only other 2 things since the coils and plugs/wires are good: stator and timer base. Did you test the stator for a ground condition? Voltage output? same for the timer base? you should use a digital shop tach to make sure your dash tach is accurate. I had a queer situation with a 70hp 56 cube motor last week. mid-range it was surging, but only noticed from the drivers seat. very subtle. did a test and sure enough it was grounding out, but all other tests were good. it was getting hot blue spark on all 3, so i was stumped. did the carbs so trusted my work and ruled out a fuel issue. these ignition components can really do weird things!
the timer base: i've had them register such low voltage i thought my gauge was broken, yet the motor still ran. only a semi-bad idle made me look further. if i remember correctly you did all of this earlier, but it's got to be timing/ignition related. are you sure you are up around 28 degrees at WOT? The dwell function set to 0 on your timing light? sorry just trying to see if anything jars your memory. it's also very possible the motor has great compression, but leakdown reveals bad skirts, but sounds like its idling buttery-smooth as they are supposed to? no lean sneezing? did you try those gt-150 heads i sent you?
one tiny thing about fuel: i do have a service bulletin from the mid 1980's that mentions the duel traditional fuel pump setup and how fuel starvation was an issue on some of these, and gave a warning to use the new pumps with different part #'s if issues cropped up. does this have 2 pumps or vro/oms blocked off/working?