Newb questions on 1990 Merc 200 Racing on Hydrostream Valero YT

[DangerNewb]

Hello all, pretty new here. I just bought a 1986 Hydrostream Valero YT with a 1990 200 Merc Racing (at least that's what the cowl says).

I bought the boat locally in NC and found where it had been listed on S&F a few years ago up in Illinois.

Old ad: http://www.screamandfly.com/showthre...ight=valero+yt

Really don't want to blow this thing up. Prefer to run it 4-5 times per year and just keep it for awhile. I've not driven it yet, just a test ride with the previous owner. I'm not interested in getting every possible mph, just some good fun. I tried posting to the old for sale ad here to see if that previous owner might chime in. No response as of yet. The guy I bought it from passed along a handwritten page of notes from a previous owner.

-16amp chargiing system, no voltage regulator
-timing set to 24 degrees
-30cc heads
-compression 130-135 each cylinder
-WH-46 carbs with .080 jets in 1,3,4,6 and .082 in 2 and 5
-New rings
-Ported and lapped reed cages
-Chris Carson fiber reeds
-BU8H plugs
-Electric fuel pump
-Automotive fuel regulator 4-5 psi
-All new gaskets and seals
-New water pump
-D-ported pistons with enlarged boost ports
-Light cut in exhaust chest
-Solid motor mounts
-Titus gear case nose cone
-25 inch Predator 4 blade prop
-Dual EGT probes
-Stay away from 5,000 rpms, EGT too hot (1250 degree max)
-Mercury high perf gear lube each year
-Penzoil Premium Plus oil at 40:1



Lots of questions:

1) 30cc heads -does that mean they have been cut down for higher compression? Need higher octane fuel? I have convenient access to 90 octane non-ethanol fuel and use it in my motorcycles, other boat, yard tools etc. I'd like to continue to use that if feasible.

2) I went ahead and found a used Fluke temp guage to plug into the leads that run up to the drivers seat. Any thoughts on this 5,000 rpm too hot deal? I won't have the gauge until next week and would like to run it some this weekend. Seems like 5,000 may be a good fast cruising speed on this set up? Hard to say until I get the tach working.

3) From reading around, it seems the 25 inch prop might be sort of low pitch for this set up. Any thoughts appreciated - yes, the tach will be helpful again.

4) I don't know a lot about these motors, but I've read the Bridgeport motors needs lots of love and rebuilds. I don't think this engine is one of those. Any thoughts on how high strung / high maintenance this engine might be?


The hull is claimed to have been re-cored. Everything feels solid so far. The transom seems stiff. Very small (less than one inch) surface cracks at each back corner of the splash well.

Anyhow sorry for the book, but I wanted to share all the info I have. I appreciate any and all thoughts and advice from those who know a whole lot more about this than me.

[DangerNewb]

Another question: The guy who had it before me said he installed an intake plate with a plastic cover to see if it would quiet it down some. He gave me three dual bore tapered intake pieces (sort of like very short velocity stacks) that were on it before. Would swapping back and forth between these impact air intake enough to require any jetting adjustment?

[90 5.0]

30cc heads and 130psi cranking compression doesn't jive.

Do a comp check first will tell you where compression is. 30cc should be at least 150psi on a 2.4

[bullet123]

Atleast 150.

[DangerNewb]

OK. I'll check out the compression. Any thoughts on octane if it has 150 psi compression or if it only has 130-135? At what point do you need more than 90, 93 octane?

And any hints to where the rectifier is on this thing? Trying to sort out the tach. Thanks for any help.

[bullet123]

150 psi I would run 93. Looks like someone did some kind of mods on the wiring. That square box beside your starter solenoid looks like a regulator. That is where my rectifier is.

[90 5.0]

OK. I'll check out the compression. Any thoughts on octane if it has 150 psi compression or if it only has 130-135? At what point do you need more than 90, 93 octane?

And any hints to where the rectifier is on this thing? Trying to sort out the tach. Thanks for any help.

93 if it's 150-155 at 30cc I'm guessing it's at least 155 if healthy depending on port work.

Mine is 148-150 across all 6 @ 31cc

the box that says Cdi is a rectifier/regulator combo. A lot of people have been going to that with 16amp vs the straight old school un regulated rectifier.

[bullet123]

Interesting. Not to hijack his thread, but sometimes I get over 15 volts when running hard. That little guy would eliminate that problem. 90 5.0, happen to know part# for that regulator/rectifier?

[DangerNewb]

So my tach is wired into the CDI box then? I'll look again to see if I can find a switch on the tach to set it for 6 cylinder and see if that helps any. I was told you have to set the switch to the number of cylinders for aftermarket tachs. If not, I'm sort of lost on what to do about the tach. The CDI box looks fairly new so hopefully that is good.

Bullet123, mine says 194-8825K 1 on it if that helps.

[90 5.0]

Interesting. Not to hijack his thread, but sometimes I get over 15 volts when running hard. That little guy would eliminate that problem. 90 5.0, happen to know part# for that regulator/rectifier?

I do not know the part numbers for the cdi one it's a replacement for the Mercury one that comes on a promax etc. I would rather run the Merc unit. Lots of guys take one of the Merc regs(they are 20 amp each so 40 amp has two) and run that. I've been meaning to try myself, Mine spikes over 16v at times just running the old school rectifier.

[90 5.0]

So my tach is wired into the CDI box then? I'll look again to see if I can find a switch on the tach to set it for 6 cylinder and see if that helps any. I was told you have to set the switch to the number of cylinders for aftermarket tachs. If not, I'm sort of lost on what to do about the tach. The CDI box looks fairly new so hopefully that is good.

Bullet123, mine says 194-8825K 1 on it if that helps.

yes it would be wired into that. If someone stuck an automotive tach on it it will read crazy.

I have autometers but they were modified at autometer for two stroke v6(I have heard they won't do that any longer).

They do sell a marine tach now but not like the recall and playback ones I have now.

[DangerNewb]

Few updates. I know some of this is more appropriate for other forum areas, but didn't want to have 5 threads going.

Was able to run the boat and it seems to run strong. It needs pretty much full throttle to get on plane and doesn't like to run under about 35 mph, porpoises pretty bad. Trim change doesn't seem to make much difference. I did have 3 people and full to 1/2 tank of fuel. Is this normal for these types of boats? Rough water is hard to deal with because if you slow down for the waves it starts bouncing. Local lakes have a good amount of traffic. I've read some people add a whale tail type device to the lower unit to help with low speed planing. Any thoughts?

Found the switch on back of the Medallion tach after I ran it so I'll have to check that out next time out. I found a label on the back of tach. 1-5 setting. 1 = 4pole, 2=6P, 3=10P, 4=12P and 5=20P. Any thoughts on what setting is correct for v-6 2 stroke? I went with 4 for now.

Any recs on a good shop for props to get some advice and get something possibly used that has been checked out. Ran across BBlades.com. Any place else? Thanks for any advice.