Noise from new motor...

[cmb1998]

I have a rebuilt 2.5L sportjet. It's more or less the same as a 200HP outboard. Rebuilt top to bottom, new pistons, crank balanced and polished, block bored (1 hole got a sleeve the rest were bored and honed), heads were cut to run 90, Chris Carson Reeds. Carbs are stock and pulled off the motor that came out (still running, but my winter project was to rebuild another one with a little more HP and better balanced) and were rebuilt a year ago. I did a link and sync. Timing is set at 0 at idle (spec for the SportJet) and 22 BTDC at max.

I did the break in per manual. It's got about 4 hrs on it now. It runs perfect at Idle up to ~3000 RPM, then 3000-3800 i get a funny rattle (more apparent on deceleration), then at 3800 it smooths out and run great to 4500 (highest i have taken it). I tried clean fuel, cooler plugs, no change. I really only hear rattle, I can't feel it in the motor. With the motor cover on, i can't hear it all. I don't know if the old motor did this because I never ran with the motor cover open.

Should I be worried? Where to start trouble shooting?

I've got a video file if it helps, but looks like i can't post those types of files.

Maybe this work? -> https://1drv.ms/v/s!Al6bDnQY16DdiFsrH--pJlUTkAPW

Note: it's not as loud as what's in the video...

Thanks,

Chris

[cmb1998]

I have a rebuilt 2.5L sportjet. It's more or less the same as a 200HP outboard. Rebuilt top to bottom, new pistons, crank balanced and polished, block bored (1 hole got a sleeve the rest were bored and honed), heads were cut to run 90, Chris Carson Reeds. Carbs are stock and pulled off the motor that came out (still running, but my winter project was to rebuild another one with a little more HP and better balanced) and were rebuilt a year ago. I did a link and sync. Timing is set at 0 at idle (spec for the SportJet) and 22 BTDC at max.

I did the break in per manual. It's got about 4 hrs on it now. It runs perfect at Idle up to ~3000 RPM, then 3000-3800 i get a funny rattle (more apparent on deceleration), then at 3800 it smooths out and run great to 4500 (highest i have taken it). I tried clean fuel, cooler plugs, no change. I really only hear rattle, I can't feel it in the motor. With the motor cover on, i can't hear it all. I don't know if the old motor did this because I never ran with the motor cover open.

Should I be worried? Where to start trouble shooting?

I've got a video file if it helps, but looks like i can't post those types of files.

Maybe this work? -> https://1drv.ms/v/s!Al6bDnQY16DdiFsrH--pJlUTkAPW

Note: it's not as loud as what's in the video...

Thanks,

Chris

any suggestions on where to start with troubleshooting?

[roadkill636]

Arnt thoes cylinders coated and cant be bored?
Or is it a steel sleve block?

Nothing comes on when i click your link

[cmb1998]

Arnt thoes cylinders coated and cant be bored?
Or is it a steel sleve block?

Nothing comes on when i click your link

I don't believe so. The motor is a 2002 2.5L. This is the second one i have built, the first was was same year / model and i bored that one too.

If you PM me your email addy I can email video. Any help would be great.

I was talking to a guy at the dock that said he thought the noise sounded like "reed noise", but it seems far too loud...

Thanks,

Chris

[cmb1998]

Should have said I had it bored. Precision Sleeve in Portland OR did the boring. He does many 2.5L blocks, he had a half dozen in process when i droped mine off. Guessing he would have called it out if it was coated.

[cmb1998]

Cold Compression #'s -
1 - 119
2 - 118
3 - 120
4 - 121
5 - 122
6 - 120

Spark plugs below have about 1.5 hrs on them

Trying video again - might take a min. Big file. https://1drv.ms/v/s!Al6bDnQY16DdiFsrH--pJlUTkAPW


Any ideas where to go next? Motor runs smooth as butter, it's just the mid range rattle.

[Capt.Insane-o]

That's normal.under decel.

[cmb1998]

That's normal.under decel.

Although much less, I get the same noise when accelerating or just cruising at ~3600 RPM's. Is that normal.

[Capt.Insane-o]

What's the backlash in the pump like?

[Motv18]

The odd one is , check your shift link and synch. The clutch could be rattling.

Look for lose things.

[cmb1998]

What's the backlash in the pump like?

How do you measure the backlash? As part of my rebuild, I had the pump stator (very different than the one on the engine , impeller, and wear ring rebuilt. The wear ring is a UMHW unit cut to match the impeller.

I didn't replace any of the bearings in the pump. Thought about it, but... I was actually thinking there was a chance the noise was coming from the pump, but hard to tell.

Any advice on what to check on the pump?

[cmb1998]

No clutch, the sportjet is a direct drive out of the crank to the impeller. "Shifting" is a bucket that drops down in front of the nozzle to direct the flow of water forward or aft.

Thanks though.

[capteliminator]

When i rebuilt my first 2 stroke I heard the same noises. I t bothered me so much I tore it down with about 20 hrs on it to find nothing wrong. Its more than likely normal.

[Capt.Insane-o]

I can't tell if it's in an aluminum boat or not but the exhaust on a SJ is very noisy, all kinds of weird sh1t noises come out of it. One of my customers has one in a Jon boat type thing and you'd swear the whole boat is going to fall apart going down the river.

[Motv18]

Ahh you have one of them if it’s running it’s pumping. Always fun at the dock.

Possible traped object.

Anyone else think the plugs are a bit to clean. Do your pistons read good.

We we all hope for something else, but sometimes it really is what we think it is.

Fuel and time