I've found out the hard way that Sullivan tanks are problematic almost all the time. The same for the blue silicon fuel lines. I've had more leaks and pin holes in new line than I care to remember. There is a thread around here about using the pink Prather medium fuel tubing. I've used that and never had a leak. It is tough and about the same price. It's worth changing when you consider that it will last a long time. I changed all of my Sullivan tanks to the Dubro tanks with the notched front. Those seem to be much better and better made. The Sullivan stoppers will leak and turn brittle. The hardware fit on the Dubro parts are better.

I'm having a difficult time with my .72 and I think it is an air leak somewhere. I just put the carb back together today with new O rings and a new velocity stack. It began to spit fuel. The engine seems to run fine with excellent power on the first fllight. The second flight is usually good too. But, the third flight is where problems begin. It seems to sag in the air and it sounds lean. Richening it on the third flight seems to make it run okay. The fourth flight is where it just won't run right. I can go either 1/4 turn lean or 1/4 turn rich and the engine sags, RPMs are all over the place without reason, and won't tune at all. Nothing works at this point and it's time to pack up for the day. I put RTV around the manifold at the cylinder and that seemed to cure everything for about 5-6 trips to the field. Then, the problem came back with the fuel spitting added in to make things more interesting. I'm flying it tomorrow, so I'll know if the carb O ring did the job. The low speed needle valve seems easier to turn now. I also stretched the spring out some as it began to die every time I adjusted the LS NV about the same time my problems began.

I almost forgot. Blowing on the fuel lines to check them for leaks sometimes won't show them. I found that out too.

Jim:


Looking for a response on the question regarding the FA 72 Intake Manifold and suspected o-ring issues. Any one else experiencing o-ring problems and how did they fix them?

Thanks!

Bob

After installing the O-ring in the head and placing the intake tube just inside the O-ring, I take a tooth pick and place RTV in front of the aluminum washer. Seems to work for a while? Maybe some high temp silicone would be better?

Seems as though the 72 has more trouble with this than the others. But all Saito's I've taken apart back there seem to have nicked O-rings.

Also the O-ring that belongs at the head joint is a harder "Viton" O-ring whereas the one in the carb is a regular O-ring. If you buy a gasket set for a saito, it will have one O-ring in a seperate package inside that says "Viton" on it. The carb O-ring will be loose in the bag.

Enjoy,

Jim

See my post [link=http://www.rcuniverse.com/forum/m_3207723/anchors_3207723/mpage_1/key_/anchor/tm.htm#3207723]here[/link]

Bill.

I just found a ton of power in my 72. I opened up the the baffles in the muffler one drill size at a time untill I got to 5/32. That alone was good for 500 rpm and the rich mid-range went away and it ran perfect from idle to WOT. I also picked up some Cool Power 30% heli mix and that was good for a few hundred more rpm and a great low idle. I've heard guys talking about the Saitos on 30% are much happier engines and mine seems to be.

Was that better range after the baffle drillling measured before you upped the nitro?

The mig-range was much better after I drilled the baffles and before I went from 10% to 30% nitro. It ran way to rich at part throttle and the high end just didnt seem right to the ear if you know what I mean. Once the 72 lost all that back pressure it really came alive and as much as it improved then, adding nitro just made great things even better. Now the 72 swinging a Zinger Pro 12-6 can just about hover my 6Lb 10oz GP CAP 580, almost.

OK. I just got some hard numbers this morning. The 72 with wild cat 10%nitro and 18%oil(80/20 blend) I was getting 10,400 rpm with a Zinger pro 12-6. After opening up the baffles the rpm jumped up about 500 rpm and the idle and midrange were much smother and the high end was just singing. Put the tach to it this morning at the field running Cool Power 30% heli mix which is all synthetic and, acording to their web site, 22% oil low viscosity, I was getting 11,300rpm! Now we're fly'n! Before, I flew around at half throttle, anything less and the plane wouldn't hold altitude well, and WOT was needed to bang it around. Now I can stay in the air at 1/4 throttle , take off and fly aerobatics at 1/2 and go hog wild at WOT and it really cooks now. Thought about up'ing the prop to a 12-7 because the Cap 580 loves it fast and I've got the power now. Thought about the open header deal with the Formost tube and might try it to see if there is any more gain. If there is the 12-6 will then be too small anyway and the 13-6 or 13-8 looks to be the next option. Anyway these are just my own observations any anyone who has "been there, done that" please jump in here. Mike

That sounds about right. I measured 9800 RPM with an APC 12x8.