saito .82 losing power/ surging
 

i've had my saito .82 for about 2-3 months and it's been the BEST glow engine i've ever owned. since last week though, i've noticed a little less power. i tried fiddling with the needles, but no improvement. i decided to adjust the valves since i havnt done that and thinking that that might help a bit. i also wanted to see how many turns out my low speed needle was set at but miscounted so i basically had to start from scratch in retuning it.

at the field today, it was WAY down on power (even less than before i messed with it). i played with the both needles and got it to run a bit better, but power is still way way down and it seems to surge (rpm's keep on fluctuating at full throttle, mid-range, and idling).

before the problems, my max rpm's on apc 13x7 was about 10,400. now it's barely turning 9,800, but the main thing is the rpms keep on fluctuating wildly (one second, it'll be at 9,800, then it'll drop all the way to 9,200, then maybe back up to 9,500). it seems to be running very hot but if i back out the hs needle anymore, it's so low on power, it barely wants to fly! (hs needle at 1 3/4 out).

i tried looking for leaks but cannot find any. the engine runs very "messy" though, with lots of fuel build up on the backplate. i think it's just fuel spraying out from the intake vs. a leak, but not sure.

does anyone have any suggestions?

before these problems, the engine ran flawlessly. in fact, i NEVER had a dead stick with it, it hand starts every time, made lots of power and tuning was a breeze. this is my first 4 stroke and i think i may have done something wrong while adjusting the valves??

thanks,
brian

RE: saito .82 losing power/ surging
 

I'm interested in the answer as I have a Saito .82 also, having not run it yet.

Thx.

RE: saito .82 losing power/ surging
 

Hi...........I was having the same problem, but I found out just why it was happening. I was getting the dreaded "fuel tank foaming" problem. I have two Saito 82's in two different planes with only one of them doing the surging thing. I switched engines & the good one started surging & the problem engine was OK. I stopped the awful surging by installing a Dubro # 161 sintered tank clunk, (the sintered brass clunk broke down the foam) & installing a inline fuel filter. (further breaking down the foam). This is installed on a Goldberg 330 Extreme profile, so foaming can be a problem anyway. The problem is now gone. .....................Just a thought..............

A lot of different things can cause your problem...........unbalanced prop, air leak, contaminated fuel, loose backplate screws, debris in carb, also you might check for carbon buildup under the exhaust valve. Just had this problem on a OS 52 FS, where the valve was not seating properly due to the buildup. Again, just a few thoughts........good luck :D

RE: saito .82 losing power/ surging
 

Also a bad pressure line from the muffler. The inner portion gets soft and starts to collapse, restricting pressure to the tank.

RE: saito .82 losing power/ surging
 

i replaced all the lines, including the one in the tank attached to the clunk. the prop is balanced. not a foaming problem. i also put some rtv silicone in the intake tube attached to the carb (just to make sure it wasnt leaking from there, which is more of a problem with .72's anyway).

i also check all the bolts including the ones on the backplate. i also opened up the valve cover and checked the clearences again. the intake seemed a tiny bit loose so i tighted that up, but i dont think valve clearance was the cause of my problems.

will fly again tomorrow. hopefully it'll run better. i HATE having to drive 35 minutes to the flying field only to be messing with the engine instead of flying!

brian

RE: saito .82 losing power/ surging
 

Best bet: You have a restriction somewhere. if you have replaced your tank system try removing the HS needle and pump some fuel BACKWARD from the needle opening up through the fuel inlet. Watch your eyes! I have seen this work several times.

Good luck.

RE: saito .82 losing power/ surging
 

i replaced all my fuel lines, including the in-tank clunk line. i readjusted my valve clearance and put some rtv silicone gasket maker in the intake tube/ carb interface, tightened up all the bolts, reset my low speed needle to factory and started tuning from there.

it flew much much better. the rpm's a still a bit low, but power pretty much back to normal levels. hopefully tweaking the needles a bit more would help get back the few hundred rpm's. it probably was a pin hole leak in one of the lines or my low speed needle set too lean.

RE: saito .82 losing power/ surging
 

Could it be that you damaged the Piston or Cylender from running lean, and may never get the RPM's back [:@]

RE: saito .82 losing power/ surging
 

what does it take to damage the piston/ cylinder? if i did indeed run it lean, how many times would i have had to do that to cause damage?

when an engine runs lean, how exactly does it get damaged?

RE: saito .82 losing power/ surging
 

Hard to damage a Saito with a lean run.

Bill.

RE: saito .82 losing power/ surging
 

How are you tuning the high speed and low speed needle valves?

RE: saito .82 losing power/ surging
 

i was at the field today and it ran worse than ever before!

first flight: very unreliable idle. after idling for about 2 minutes, it will just quit (while i'm taxiing out to the runway). while i'm on the throttle. problem only while idling. the interesting thing is that after flying for about 7-8 minutes, it acts like it gets real lean by itself. when i land, i literally have to trim the throttle down about 15-20 clicks just to get it to slow down enough to land! but while i'm taxiing out to the runway, it'd have to have the idle trimmed all the way up otherwise, it'll quit!

2nd flight: i went back to the pits and went really rich on the low end until it's so rich it'll hardly even hold an idle. from there i very gradually leaned it to the point where it'd idle ok. but again, after 2 minutes of idling, it'll want to quit and i'd have to trim the throttle all the way up to prevent it from quitting. it flew ok, but again, towards the end of the 7-8 minutes it feels like it gets real lean (hesitates real bad on transitions, surges, and just loses power and sounds like it wants to quit). i land and touch the engine and ouch!! it's super hot!

3rd flight: i tried playing with the high speed needle (although i'm almost certain that i'm not too lean). but i richen it up even more (now at about 2 turns out), pulling only 8,700 rpm. when i have it set "normally", it peaks at about 10,000 and i turn it back down to about 9,500 which is about 1.5 turns out. again, it had problems holding an idle for more than 2 minutes. but i flew it anayway and after 3 minutes it would just slow down and speed up erratically when i'm at anything above 1/2 throttle. it was definitely overheating but i'm POSITIVE i'm not running too lean on either end. if i richened up the top end anymore, it would not even have power to fly. the low end is backed out so much that it's even richer than the setting it came with from the factory. i didnt count how many turns out, but the screw is flush with the throttle arm. this is my second saito, and typically the factory low speed is set about 3 turns too rich (and the screw is flush with the throttle arm).

anyway, i give up. any suggestions, anyone??

i'll probalby just send it in and see what horizon says.

the weird thing is that for the first 3 months, it ran absolutely flawlessly and i have not touched anything since...... one day it just started surging a little and then things got worse and worse despite my replacing fuel lines, adjust the needles, sealing any possible leaks i can think of (rtv on the intake tube/ carb, threadlock on all the bolts on the backplate, muffler, etc.....)

brian

RE: saito .82 losing power/ surging
 

Boosted 180,

Take Scratchonly's advice and back flush the spray bar after removing the high speed needle valve. Position a paper towel to catch any debris that gets flushed out.

JC

RE: saito .82 losing power/ surging
 

Just to be sure everything is in order, I suggest going to www.saito-engines.info and tune the engine just like it says. It takes time, but is well worth it. There is another good way to tune it, but this is a good way to learn how to tune the Saitos. This is assuming that you don't know all of this. If you do already, sorry 'bout that.

Are you using something like 10 or 15% nitro fuel with around 17% oil? It is highly recommended that castor is used with the lube. Are you using the original glow plug that you broke the engine in with? If so, it is definately time to change it to another Saito or OS F plug.

Surging like you posted in your first message is sometimes due to the low speed needle valve being too lean. The link I gave will explain that. Also, you mention that the engine ran well for the first 3 months you had it. Down here, the weather has really turned hot and humid. That will make your spring or winter settings too lean due to increased oxygen. Therefore, the engine needs more fuel to mix. You didn't mention how many tanks of fuel the engine has thru it, but it may still be breaking in.

By the way, once you tune it just right ,especially the low speed settings, fuel economy will be the best you can get from it.

Did you set your valves like the manual says? That should be done right away if you haven't. It's easy once you do it once.

RE: saito .82 losing power/ surging
 

blw, i'm familiar with the saito home page. it provides a lot of useful information. i'm fairly confident that i've set the needles exactly as the instructions specify. although i wouldnt call myself an engine "expert", i know enough and have had enough experience with them that i'm pretty sure it's not something so "simple" as wrong needle settings causing my problems.

i'm running 15% powermaster (which has about 18-20% castor). the plug actually is the stock plug that came with the engine. i'm planning on changing out to an o.s. #f, but the engine ran so incredibly poorly today that it's hard to imagine a plug can cause such seemingly serious problems (esp. the overheating).

i'll take apart the fuel tank tomorrow and look very closely to rule out a problem with my fuel system. i'll again set the needles back to stock and tune from there again and see what happens. but it doesnt look good from teh way it was acting today. i think there may be something more serious going on like some type of a mechanical problem inside the engine or some air leak in the engine itself....

i'll let you all know how things go.

RE: saito .82 losing power/ surging
 

The .82 has the plastic backplate doesn't it ?... Your discription sounds a lot like the way my .72 runs when the Oring at the intake manifold to head junction is leaking... On my .72 all it takes is a backfire (good pop) to blow that seal..

RE: saito .82 losing power/ surging
 

My .72 has only backfired once, so I'm lucky with it. All that I've heard is that the .82 does not have the backplate problem. Most of mine was the screws backing out after one run. I use epoxy in the threads now.

Boosted- I certainly didn't mean to sound like you didn't know how to tune the engine. I just know that it can be tricky, especially with the low speed settings. A lot of times, break ins will ruin or damage the original glow plug. I always take mine out and put in a new one after it has run on the bench.

RE: saito .82 losing power/ surging
 

so i've done everything i could think of. flushed the spray bar, set things back to factory and tuned it EXACTLY like the instructions on the saito webpage, replacing all the fuel lines, making sure there's no leaks, making sure all the bolts are tight on the engine, i'm now sure it's something with the engine itself.

i went out a few hours ago to try one last time before sending it in. here's what i noticed: while priming the engine (finger over the muffler, open throttle and turning the prop over to get fuel into the carb), i noticed that fuel was leaking out of the carb right at the area of the low speed screw. i was not able to tell for sure if the carb was just flooded and it came out through the intake or the low speed screw itself. but at this point, i really starting to think that there's a leak somewhere in the carb (maybe a bad oring in the low speed needle?) this would definitely explain all my symptoms.

but despite seeing this apparent leak, i fired up the engine anyway and same problems. after just 2 minutes of running on the ground, the engine got really hot and started surging (not as bad as last time, but still noticable). i'm POSITIVE i'm running rich, both on the low end and high end.

i didnt feel like messing with it any longer so will pull the engine out of the plane tomorrow and send it to horizon.

i hate down time, but this will give me a chance to finish up my foamy from charger rc. i generally dont like foamies all that much but am looking forward to this one just as something to practice some "on the deck" torque rolls and harriers with. in my edge (the plane with the saito), i dont have enough confidence to do it at anything less than 30 feet up.

i'll let you guys know what happens with the engine.....

RE: saito .82 losing power/ surging
 

Before sending out I would mount it on a test stand and run it. That would eliminate the fuel delivery system on the plane and isolate the engine so it can be tested alone. I believe its a good idea to run problem engines on a test stand to simplify loacating problems.

RE: saito .82 losing power/ surging
 

Are you sure both valves are sealing good you may have a piece of carbon holding on open
My son-laws 82 is doing the same thing right now if we find the problem I'll post back with what we find

RE: saito .82 losing power/ surging
 

install a new tank in your plane by rubberbanding it to the outside. test run the engine on that with all new fuel lines. 90% of problems on engines are tank related.

RE: saito .82 losing power/ surging
 

it is not a fuel tank/ fuel system problem. i've replaced the tank as well as the lines, twice. i've mounted it outside the plane to see exactly what's going on while the engine is running. no leaks, no foaming, no restrictions in the lines.....

skiman762, please let me know what you find out in your case.

i was going to take the carb apart b/c i think there's a bad o-ring or something of that nature in there causing a leak but dont have any time and also i'm just tired of messing with this engine. i'll let horizon find the problem for me. that's what warranties are for......

brian

RE: saito .82 losing power/ surging
 

It sounds like the possibility is that one or both of the valves are sticking. This will happen occasionally when a very high Castor Oil content is used and the varnish from the burned castor oil adheres to the valves and guides. From our instruction manual:

1. Fuel. For maximum protection and
loogevity of Saito engines, Saito
recommends a fuel containing 20% oil
and 10-15% nitro methane. If this blend is
not readily available, the next best
selection is a high quality 2-cycle glow
fuel, such as Hangar 9 Aero-Blend,
Omega, Cool Power, K&B, Power
Master, etc. Use of fuels composed
entirely of castor oil is not recommended.
A mix of synthetic-castor oil is acceptable
and can be found in the various fuels
described above.

As a rule, the lower the castor content the better.

Pete
Category manager
Horizon Hobby inc.

RE: saito .82 losing power/ surging
 

hi pete, if the problem in fact is the valves sticking, what's the fix?

i'm using powermaster 15% with 18% castor oil. almost everyone at my field uses this fuel with their saitos and no problems. some people say that using synthetic oils instead of castor is better at preventing varnish build-up, but castor supposedly has better protective properties. some of the saito "guru's" on the forums are very adamant about using castor instead of synthetic. this is my first 4 stroke so i have no opinions on this.....

brian

RE: saito .82 losing power/ surging
 

Synthetic oils will probably not varnish an engine. Some castor varnish is good for the moving parts. Synthetic oils won't survive the heat ranges these engines run at, but castor will without burning away. A case can be made for castor protecting some parts that are susceptable to heavy wear, like cam lobes. If you run your engine too lean, be prepared for some damage as synthetic oils will be burned, whereas castor won't. Oil that burns away won't provide much protection against friction, and won't carry heat out of the engine with some excess, unburned oil.