Idle power problem

[Tom Brown]

I have a problem that has crawled up my butt and would appreciate some help.
The engine is an XR-4. It won't idle.
The slowest I can get it to run is 900 RPM in the water (1000 RPM on the hose). It will sound OK for about 25 seconds, miss the odd time for the next 10 seconds, and then just die.
When I put it in gear, it will die. It doesn't struggle for a couple of rotations and then sputter and die... it dies instantly. I'm pretty sure if I threw a rag on the flywheel while it's idling, it would kill the engine.
It's idling fast enough to really hammer the gear case when I engage forward gear. Basically, I can't shift it at this time. That's OK because it won't drag itself. If I start it in gear and can manage to get it up to 1500 RPM, it hits like crazy. All of the power is still there on the middle and top end.
I'll mention that it's not over-propped, to say the least. It's definitely not dieing because I'm trying to swing a huge wheel.
The carb bowls will still have fuel when it dies but it does seem like it's running out of fuel. The plugs don't look very wet after it dies.
Here's what I've done:
Timing - I've timed this thing about 30 times, indexed the flywheel, and it is within a degree at high speed.
Compression - All cylinders test between 127 & 131 lbs.
Idle Stabalizer - It wouldn't run with it on so I removed the box and now it will idle, after a fashion.
Carbs - I've rebuilt them a few times... new gaskets... cleaned the hell out of them and inspected the tiny idle holes and passages with a magnifier... they look like brand new. I also tried a set of carbs from another engine. It seemed like it would idle a tiny bit slower with the other carbs but still no power and won't idle for long.
Reeds - I had a new set of Boyesens kicking around so I installed them. I lapped the cages to 1000 grit. Those cages so smooth they are shiny. It made a noticeable improvement to the midrange but no change at idle.
Spark - I can pull 3/8 ~ 1/2" of spark from each plug wire and they all look blue and strong.
Carb jets - It seems like it's running out of gas so I bumped the idle jets up a bit. The original jets were 0.052. I've tried 0.046, 0.052, 0.056, 0.058, and 0.060. It seems to idle smoothest with 0.056 jets... but not for long.
Idle bleeds - I've checked these things against the manual. They are routed correctly to the right places. I'm thinking about freshening the tygon. These seem OK but it will give me something to do now that I've freshened so many other things under the cowl.
Block leaks - Now, I'm not saying my block doesn't leak somewhere but I've soaked the hell out of it with a few cans of WD40 and I can't tell that it's leaking anywhere.
I think at this point, it's pretty clear something I've already looked at is not right.... but what?
I would really appreciate any ideas.
Thank you,
Tom

[MAXIMUS]

I have a problem that has crawled up my butt and would appreciate some help.
The engine is an XR-4. It won't idle.
The slowest I can get it to run is 900 RPM in the water (1000 RPM on the hose). It will sound OK for about 25 seconds, miss the odd time for the next 10 seconds, and then just die.
When I put it in gear, it will die. It doesn't struggle for a couple of rotations and then sputter and die... it dies instantly. I'm pretty sure if I threw a rag on the flywheel while it's idling, it would kill the engine.
It's idling fast enough to really hammer the gear case when I engage forward gear. Basically, I can't shift it at this time. That's OK because it won't drag itself. If I start it in gear and can manage to get it up to 1500 RPM, it hits like crazy. All of the power is still there on the middle and top end.
I'll mention that it's not over-propped, to say the least. It's definitely not dieing because I'm trying to swing a huge wheel.
The carb bowls will still have fuel when it dies but it does seem like it's running out of fuel. The plugs don't look very wet after it dies.
Here's what I've done:
Timing - I've timed this thing about 30 times, indexed the flywheel, and it is within a degree at high speed.
Compression - All cylinders test between 127 & 131 lbs.
Idle Stabalizer - It wouldn't run with it on so I removed the box and now it will idle, after a fashion.
Carbs - I've rebuilt them a few times... new gaskets... cleaned the hell out of them and inspected the tiny idle holes and passages with a magnifier... they look like brand new. I also tried a set of carbs from another engine. It seemed like it would idle a tiny bit slower with the other carbs but still no power and won't idle for long.
Reeds - I had a new set of Boyesens kicking around so I installed them. I lapped the cages to 1000 grit. Those cages so smooth they are shiny. It made a noticeable improvement to the midrange but no change at idle.
Spark - I can pull 3/8 ~ 1/2" of spark from each plug wire and they all look blue and strong.
Carb jets - It seems like it's running out of gas so I bumped the idle jets up a bit. The original jets were 0.052. I've tried 0.046, 0.052, 0.056, 0.058, and 0.060. It seems to idle smoothest with 0.056 jets... but not for long.
Idle bleeds - I've checked these things against the manual. They are routed correctly to the right places. I'm thinking about freshening the tygon. These seem OK but it will give me something to do now that I've freshened so many other things under the cowl.
Block leaks - Now, I'm not saying my block doesn't leak somewhere but I've soaked the hell out of it with a few cans of WD40 and I can't tell that it's leaking anywhere.
I think at this point, it's pretty clear something I've already looked at is not right.... but what?
I would really appreciate any ideas.
Thank you,
Tom
Tom if you take a moment to loosen the clamps, disconnect the fuel line, I believe you should be able to lift the motor off the transom & if you have a trash can close by try to gently set it in there.... In America you can actually scrap those things out for about 50 bucks! Next get a car motor with a squiter on it & strap that on the back... It will take a lot more than a rag to stop it from rotating! Problem solved & good times ahead! Look at that... I still have time for a round of golf! :idea:

[timebomb1]

Tom what jets are you changing? The main, idle or the vent? I had my floats sticking and it caused it to die from to much fuel. Got rid off the carb motor and put an efi with a Brucato pcu and no more troubles.
Switch to efi and press on. Gary.
I got an efi front half and air horn ready to ship up north.
It will match that cowl.

[sorry dog]

Take an old Windex bottle and filler up with mix and start squirting when it starts hiccuping to see if that helps.
At least that is my redneck way of diagnosing fuel issues.
Actually I had to start my last Zuki that way since I was too cheap to replace the primer valve.
BTW - is this an electric pump or mechanical?
I had a 50 Zuki that acted like that once. It had a pin hole in the diaphram that would leak enough at idle to not pump enough, but acted fine at higher rpm's.
Come to think of it... I had another diaphram with a pinhole in it but that led to another problem.

[Tom Brown]

Thanks, guys.
Even you, Maxi.
Dog, I just push the key in to activate the idle enricher. With 0.046 jets, I could keep it running after a fashion by pushing the key in every 10 seconds. With fatter jets, pushing the key in is an instant kill.
Tom what jets are you changing? The main, idle or the vent? I had my floats sticking and it caused it to die from to much fuel. Got rid off the carb motor and put an efi with a Brucato pcu and no more troubles.
Thanks, Gary.
I'm changing the idle jets. The floats are fine. It's not flooding, I think it's starving.
I'd be for EFI, but not with a Brucato PCU. I'd only consider it with a MAD EFI system or, if I had to, a curved Motorola box. Anyway, that would cost way more than an XR-4 is worth.

[sorry dog]

So...is it a electric pump or not?
A cheap experiment might be to hook the fuel line up to a 1 gal can and hang the can above the motor. 2.4 feet = 1 psi
BTW...there are cheaper ways to EFI than SDS.

[Towndrunk]

Tom if you take a moment to loosen the clamps, disconnect the fuel line, I believe you should be able to lift the motor off the transom & if you have a trash can close by try to gently set it in there.... In America you can actually scrap those things out for about 50 bucks! Next get a car motor with a squiter on it & strap that on the back... It will take a lot more than a rag to stop it from rotating! Problem solved & good times ahead! Look at that... I still have time for a round of golf! :idea:
Tom, you have a fuel delivery problem. Leak, bad diaphram,bad bulb or collapsed line.
Maxi, I actually did this once back in 74-75. My jon boat was being towed in
for the 3rd time in a week and I had enough. I unscrewed the 2 clamps and shoved that old johnson 35 sea horse right in the Illinois river. Next day I went and bought my very first new outboard, a 40 ho Merc. It was a whopping $875 new!!

[MAXIMUS]

Tom, you have a fuel delivery problem. Leak, bad diaphram,bad bulb or collapsed line.
Maxi, I actually did this once back in 74-75. My jon boat was being towed in
for the 3rd time in a week and I had enough. I unscrewed the 2 clamps and shoved that old johnson 35 sea horse right in the Illinois river. Next day I went and bought my very first new outboard, a 40 ho Merc. It was a whopping $875 new!!
Its amazing the prices of shit today... My buddy jacked up his 9 hp motor on his zodiac... I think to replace it was like 1800 bucks...

[rrrr]

Tom if you take a moment to loosen the clamps, disconnect the fuel line, I believe you should be able to lift the motor off the transom & if you have a trash can close by try to gently set it in there.... In America you can actually scrap those things out for about 50 bucks! Next get a car motor with a squiter on it & strap that on the back... It will take a lot more than a rag to stop it from rotating! Problem solved & good times ahead! Look at that... I still have time for a round of golf! :idea:
This is the first post I've ever seen you make that made any sense......

[73kona455]

Tried feeding it some bran muffins???