Picco .26 - Nothing But Idle

[billkalicious]

Hey Guys (and Gals) I took a minute to "Introduce Myself", go check it out! I know you're dying to know me. :jk: I feel like I know most of you after so much time around this board.

Sorry for the long post, but I'm totally stumped on this Picco and I want to get everything I've tried in here to help troubleshoot my issue. Here's the short version. I have a Savage SS, broke the stock mill and bought the Picco and broke it in. It was running great. As mentioned in another thread, I had a crash in which the truck ended up in two pieces. When I bought the parts to put the truck back together, I bought a motor-saver filter and new fuel lines. I put on the motor-saver and new fuel lines. I checked the mill over and see no cracks anywhere in the case or head.

When I start the truck, it will idle. Blip on the gas and it dies. With or without the ignitor. I've let it idle until it's around 190 and get the same results. I've reset the needles to factory, I think. I've been all over this board and other boards and found the most common setting for factory is HSN Flush and LSN one turn in from flush. The LSN is about 7 turns out, the book says to go 10.5 to 11. With that, the needle is almost falling out. If any of you have a different setting for factory, please lemme know and I'll give it a shot. I have played with both the HSN and LSN going 1/8th turns on the HSN and hourly on the LSN and get the same results. I've also tried the HSN at 3.5 turns out, this is from the book.

Since I was using the same glow plug that I used during break-in, I bought a new one. I couldn't remember what I had in there before and couldn't find a particular one in my searches. My LHS (not HT!) didn't have the ofna 51007 but he recommended a DYN2521 O'Donnell racing glow plug. Have any of you had good/bad luck with this plug? Any recommendations?

I took the carb apart and found some crap in the high side. Got that all cleaned out. It appeared to be pinhead sized balls of grease. I imagine these came in when I switched the fuel lines. On the LSN, I noticed what looked like a piece of the top o-ring (closet to the head of the needle) that had come off. The o-ring itself looked good, I'm not sure how this got there.

I have checked the clutch shoes/springs and flywheel. All good there. The crank turns with the expected amount of resistance. I read about having too long of fuel lines can cause flooding, so I shorted them to what I had before. I'm using a header tank (which has been in place since I got the truck). I still have the crappy stock tank with primer, but the header tank takes care of the leaning as the tank empties. I have a clunk in the header tank for a filter, but not one inline. The clunk looks clean.

That's all I can think of as far as things I've done. I won't have any time to mess with this until Friday afternoon, so if I don't respond before then, that's why. I'm trying to get as many ideas as I can before I spend another 6 hours on this. The first thing I'm going to try is a new glow plug. I'm trying to avoid tearing down the mill, it's scary the first time. I'll take apart my BMW 325is engine, but haven't done anything with one of these. If any of you guys have any ideas, I'd love to hear it!

Thanks for any and all help!

 

[Rolex]

A lot of usefull info, but still missing some.
First, you say it will start and idle, right? What happens next, when you pull the trigger? Does it just continue at idle RPM, or does it stall?

I just re-read your post, and I see that if you blip the throttle it dies.
Okay, lets start with that. Once it's running and up to temp, start to lean the LSN in very small increments, while blipping the throttle in very short throws. Just little twitches, not enough to make the truck start to pull. If, while leaning it, and twitching the trigger, it's able to get to higher RPMs, then continue to do this till it wants to pull out without stalling. Put the nose of it against something, and when you can give it some trigger and feel the clutch engaging, and the engine not stalling, you're pretty close to where it should be. The LSN is only for idle and low end, and you will most likely have to re-adjust the idle screw as you improve the LSN settings.
By the way, if leaning it does not improve anything, return to the setting it was at, but then use the same procedure, except this time, richen the LSN a little at a time.
Since I can't see it or hear it, I have no way of knowing exactly which way it should go. If, at the present idle it's spitting a lot of oil out of the exhaust, it will need to be leaned. If you don't get any, it will need to be richened.
When it runs up to half throttle, don't change the LSN settings, but instead start making your adjustments on the HSN. That one is for WOT settings.
Keep us posted on what it does.

 

[rossb]

The proper plug is a medium cold plug. I've used the Ofna 51007 and an HPI R4 Medium Cold. The McCoy MC-8 would also be a good choice.

The motor sounds lean. Could be an airleak or improper needle settings. Check the tank for leaks. Go to a quiet room, remove both lines, plug one with your finger, and blow into the other. You should not be able to blow at all. Could be an airleak at the carb or the backplate. Richen the HSN up 1/2 a turn and see if it changes.

 

[jon2]

billkalicious, Ok I had that same problem orginally with my Picco 26 and I found that with the needle settings at break in , A MC-59 and the semi Hot as hell weather I found the plug to be thr wrong heat range. I found the temps going too high fast. I broke the engine in with a MC-59 but when I ran it for speed it would die. I sealed it with RTV prior to running so I counted the air leaks out. This is from my experience. I went to a MC-8 and it was happy with a few more needle adjustments.

 

[jmarzilli]

the lsn from the factory is 10.5 - 11 half turns or about 5.5 full rotations. i had the same problem with my engine when i was trying to tune it.

 

[billkalicious]

I stole a couple of seconds from the evening to come check out the thread. Thanks to everyone for the suggestions! To give a bit more info, currently there is a significant amount of oil coming out of the exhaust, but I've had the LSN too lean, the engine sounds really creepy. Hard to describe, but the RPMs go up and it sounds like it's stuttering. I got real familiar with that sound with my stock mill.

Rolex: It seems that it runs up to about half throttle before dying. From what you said, that leads me to the HSN. If I have the LSN set to just rich enough to keep it from sounding lean, and it runs to at least half before dying, I think it's pretty close. Am I right there? Also, when I richen/lean out the HSN, will I need to make a counter adjustment to the LSN or should I leave it alone once the afore mentioned is true?

rossb and jon2: I've got two recommendations for the MC-8, so I'll pick one up on Friday and throw it in. I've read a lot of posts talking about RTV, but have never took the time to figure out what that is. So, what's that stuff? When you say you sealed it with RTV, I'm assuming you sealed the back plate. I've also heard of ppl sealing the carb with RTV too. Do you think it'd be a good idea to do that?

jmarzilli: Very weird on the adjustment for the LSN. I just checked the paper that came with the engine again and it says 10.5 to 11.5 turns. It doesn't mention half turns anywhere. Doesn't matter to me tho, I'll run the LSN in a couple of turns and see how it sounds. I'll try just about anything at this point.

Gettin' off early at noon tomorrow, the company said we did well last year, so we all get a half day off. More time to figure out this puzzle. Hopefully I'll be able to post a happy post on Friday afternoon...early afternoon would be better. Thanks to everyone for your replies!

 

[rossb]

To answer your question about RTV, I have sealed both the backplate and the carb neck in all of my Nitro Motors. I also remove the needles to inspect the o-rings before putting the motor into service.

The LSN on my Picco 26 is currently set at about 9 turns (don't remember for sure) and mine runs incredibly strong. Keep in mind that it is possible to set one needle too rich and another too lean. The HSN can affect the entire RPM range and the LSN affects low to mid range RPM. If your LSN is too rich you can load the crankcase up with fuel and when you start to take off the motor will run rich even if your HSN is too lean. Both needles need to be configured properly.

An aggressive motor like the Picco does require more accurate tuning than your stock mill. Your initial description sounds lean to me. If the tuning is off the motor will run like crap. If the tuning is off on a stock motor (like an S-25) the motor will still run ok.

As I said before, I would start by richening up the HSN 1/4 - 1/2 a turn and see what happens. Leave the LSN for now, we can worry about that after you get to the point where you can accelerate without killing the motor.

 

[billkalicious]

Well, I'm a bit closer now. I actually got it to run around the driveway for a short bit. I can't seem to keep it running very long. I decided to pull the head and have a look. I found that fuel had been coming out from under the head! I think I found my air leak. Next question, when I put the head back on, should I use red, blue or no thread lock? To be safe, I didn't use any. It's starting to get a lot more stable now. I got to run it for a couple of minutes before dying. I'm getting real close.

Thanks again to all who offered suggestions!

 

[Rolex]

No locktite needed on the head. Press the head firmly against the block till you know it's seated squarely. Drop in the bolts, and spin them all in finger tight. No work your way around in a criss cross star pattern snugging each one a little bit at a time. Go around about 5 or 6 times till you tighten them down good. That system makes sure the head seats flat and puts even pressure on the shim all the way around.

 

[billkalicious]

It's a beautiful day in sunny KC today... Took Rolex's advice, loosened the head and made sure it was square and tightened in a star pattern. Finally got the needles where they needed to be. It was running REAL lean. I got it to idle, then waited for it to warm up a bit. Once it was warm, I would punch it and let off. It kept dying. I kept opening the high end. Finally got to where it wanted to take off. After a bit more tweaking, I was able to run about 20 mins! I'm a bit excited to be back in the world of working savages again. Thanks for the tip Rolex.