Here we go again.... I was over at my friend Chris' house yesterday and saw his beautiful Summit 3 sitting sadly on the garage floor with cobwebs between the gear legs and flatspotted Tettra wheels.

I've got to get this beauty in the air so I need some help.

Some of you may remember Chris asking for help with his RF-P not running correctly. Just to re-cap, the idle is inconsistant and surging and high RPM varies. Some times you can throttle up and its good (11500) and sometimes it struggles. It also dumps a ton of fuel out of the carb after you shut it down.

http://www.rcuniverse.com/forum/fwd....ageID=10057583

We have swapped the 86 carb for a known good 86 carb with no change. Since he obtained this engine used, the previous owner may have messed with the pump (there's no paint on the screws).

First of all, is the SF-P and RF-P pump the same? I'd like to swap the pump from my known good running SF-P and see what happens.
Second, does anyone have experience adjusting the pump to help get this thing back on track?

If all else fails, I'm pulling it and installing a brand new YS .61 AR.

All the 4 nipple pumps are the same. Sounds like the pump pressure has been increased. The screw should be flush with the housing surrounding it. Compare your 'good' pump screw settings with the messed up one. Unfortunately, the other possibility is the pump diaphragm is no good. If your pump corrects the problem then you've isolated the culprit. I don't know if you can even get pump parts any more (probably not). You can try soaking the pump (assembled) in methanol - be sure the pump gets loaded with methanol. Lastly, you can disassemble the pump and clean the parts. Take the pump apart carefully I believe there is a spring in there. I've never seen an exploded view diagram of the pump internals (maybe somebody here... Bax?) can help; so you need to be sure you can assemble it correctly. I probably have a used one (or more), but can't guarantee the condition.
Good Luck,
Will B.

I can't imagine that each pump was tuned, so the pump settings must be X number of turns out?

Jeff,

according to OS they are. Each engine is run and the pump is tuned to the engine and then "sealed" prior to sale. But I have no clue if this is in fact true.

I disassembled my used Hanno's pump because the previous owner decided to use some gunk instead of gaskets to seal the engine backplate... Unfortunately, as we know, the Hanno 2 nipple pump is different from the SF-P's and RF-P's. As far as I know there is no difference between these two engines other than the crankcase and piston sleeve. Maybe the pistons are different due to the skirts. The pumps should be identical as Will points out.

David.

We've never peformed repairs on the pump/regulators. They were all factory-sealed. They used a glue-like sealant, and there were gaskets between layers. The basic mantra was "take it apart and it's ruined". Unfortunately, even the factory doesn't service them anymore. We don't have any blown-up diagrams of the pump.

Setting the pump was performed at full throttle with the high-speed needle set to one turn out from closed. The upper screw was turned to adjust for just rich of peak RPM. The lower screw was the screw that determined when the return line opened, and was used to help adjust the idle. Turn either one too far and you damaged the regulator portion of the pump. They were basically set to be either just flush or just below the rim...we're not sure at this point, and we cannot locate the two pages of small, closely-typed directions we once had about setting the pumps.

Thanks Bax. I compared my un-touched pump off an SF-P to the one off this RF-P. The upper screws were similar in depth, but the bottom screw in the malfunctioning RF-P is set at least an 1/8" deeper. I may play with adjusting the bottom screw with it mounted to my SF on a test stand. But for now, I just want to get that Summit 3 in the air!

I had the plane on a stand inverted so the engine was up-right, full tank of PowerMaster 10% 22%oil, new K&B 1L, APC 12x9, full length header and some carbon fiber tuned pipe.

Once the engine was primed, it took forever to start (as it did with the original pump and carb), spraying a lot of fuel out of the carb. Once it finally lit, I went to full throttle to set the high end needle. I didn't tach it because I could not get a consistant rpm. I could adjust the needle and set it a bit below peek (about 1 turn out), but after 10-15 seconds it would start surging and sometimes just quit. Low end was a mixed bag of just quitting - couldn't tell if it was loading up or leaning out.

I noticed the carbon pipe was comming apart at the "muffled" section so I removed it and installed a Macs muffled pipe off my SunFli. Same odd running condition. I even ran it without the pipe and header. Wow was that loud and messy! Still running odd...and inconsistant.

I decided to pull the engine and take it apart.

Looks like the previous owner did some grinding on the intake and transfer ports. Can someone take a look at this work and tell me if these "modifications" have ruined the liner?

Also should the knotch in the piston face front or back?

Hey Jeff,

I think it's about time you put that OS asside for a paper weight and do what you said in your original post. Put your YS in the Summit and go fly the crap out of it..........

David

Jeff, to the front, opens the intake port.

David, It's already installed... Just waiting on a header and prop adapter.

That's what I thought. At least that was correct. What about the "Modifications"??? [&:]

There's also a 0.0150" / .38mm head shim installed.

They were trying to do some port flow work, crude though.

Hi Jeff, good decision to go with the YS!!!!
Your OS seems pretty 'F' ed-up to me []. If you want to keep playing with the OS, I would try running it with a stock 7L (non-pump carb) to determine if the performance modifications are working or just ruined the engine. If the engine won't run reliably/consistently with the non-pump carb then it has become a paperweight [:@] - sorry. If the engine runs well on the 7L carb then you need to replace the pump or pump and carb. I've never been a big fan of the 4-nipple pump/2-nipple carb - too much plumbing and I don't think that much fuel gets returned anyway. The Hanno pump/carb works great if you can find one. The OS pump assemblies will last for a very long time if kept clean and no 'adjustments' are performed. There can be wear in the carburetor, though most commonly it is the needle that wears.
Have fun with the Summit!!
-Will B.

Looks like someone has messed with the porting [&o]

I took these photos some time ago

Left SF Ring Side engine

Mid V Rear Nelson Liner (Modified porting)

Right Standard OS V RE

I think the best bet also is to Run it on a standard 7D, or 7F carb no pump and see if it does runs stable.

If not sell it as a parts engine.

Question : I have a NIB OS61SF-P Ringed, front carb, never been touched. I have heard of gasket problem's, with these older engine's, and now I am hearing more. Do I have a future paperweight here?
I have zero experience with pumped engine's.

Crank

Vince,
If you are going by the original poster's experience here, he had a special POS engine to start with! I'd think a NIB virgin like yours would run perfectly. The gaskets and diaphrams are not natural components so shouldn't start to break down until exposed to fuel. My buddy runs his and has for 20 years so it'll be fine until we're too old to care.
Chris...<br type="_moz"/>

Thanks Chris, good to hear. Are you going to the Reno Air Race's ? I'll be there for one day, also family visiting, etc.

Vince

Chris,
My buddy got that engine/pipe for free so I guess he got what he paid for!

Hey Vince. What day are you going to be at the Reno Air Race? My wife and I will be attending (Friday, Saturday, and Sunday) - staying at the Nugget.

Jeff - Lv here 9/14, return to FL, 9/21. Sending you a PM of Reno plan's.

Vince

Hi Jeff,
Good to hear!

Hi Vince,
Taking the wife to Gay Paris. She stood by me when I raced up there and years of spectating, so I've decided to take her somewhere else. She speaks 7 languages so I'll know more than ever about the place!
I want to go to Goodwood next year. Proper dress in the paddock is lacking at Reno!
Chris...

Chris - Have a good time there. My daughter will be there Monday. She is int'l. flight nurse, bring's patient's back to USA and other place's in the world. She only speak's English & Spainish, get's by with German. Sending you a PM.
Vince

Here is modding done right,
except for the liner work see the groves made on the piston,
helps to keep a little oil against the cyl wall especially at TDC.

Crankpin,
If you think you might have a problem engine, let me give you my addr and I'll run him for you[sm=wink_smile.gif].