ccrebidoux

My Feedback: (3)

I've been a Saito user for 10+ years. Great engines, powerful, reasonable priced. But for the last 4 or 5 years, I've gone through 4 or 5 mufflers on a Saito 56 and I'm now onto my 3rd muffler on my Saito 120. They keep shaking loose and stripping the threads out on the mufflers, or the exhaust pipe or at the cylinder head.

I've tried just about everything to keep the exhaust system tight, I've torqued the heck out of it, even shock torqued it, used Loctite 620 ( a high temp, gap filling thread locker) supported the muffler with a stand off so the threads aren't stressed by the weight of the muffler so much, I've even changed the crank bearings on the 56, and I've balanced my props too. I can't find the source of my vibration and I'm tired of ordering mufflers and exhaust pipes.

I was planning on doing a Vancouver Vanguard Fairey Firefly this winter with a Saito 180 but I think I'll shell out the extra $100 for a Laser 180.

Just for the record, I'm a licensed aircraft mechanic so I'm somewhat familiar with torques and stresses, but this one's got me beat. If ANYONE has any insight, I'd love to hear it.

Chris

w8ye

My Feedback: (16)

After they have vibrated around loose for a while it is hard to do anything with them

If you can catch them new and tighten when hot, they seem to stay. You have to re-snug them two or three times while hot.

jaka

Hi!
Do you balance your APC props?

GaGeeBees

My Feedback: (23)

Had that problem once on a Saito 1.50. Once I got the new muffler, I did what w8ye recommends and retightened while still hot after the first run and it's been solid ever since (through three flying seasons).

For the Fairey Firefly, how about going with the 2.00 V-Twin (yes, it's expensive) and flex exhaust. It should still fit nicely inside the cowl you'll get less vibration than with the 1.80 and it'll sound great

Kmot

My Feedback: (24)

Hey Chris, if it were me I would drill the muffler nut and then just safety wire it.

daveopam

My Feedback: (9)

I use teflon tape and have no problems. The tape seams to fill the void more than lock the thread. If the pipe can't ever start to move it will stay tight. After 5 years of Saito flying I have had two loose mufflers. I use 3-4 wraps with the thread of course, and tighten best I can.

David

ccrebidoux

My Feedback: (3)

I don't use APC's. I'm into scale, so I usually use Zingers. But they are balanced before I put them on.

I have also resnugged them while they are hot. Could be the fact that they've already damaged the threads [:@] cause they've loosened off afterwards.

The 200 would be nice, but I think I might have to remortgage the house for the fuel that puppy'd go through!

I'll give teflon tape a shot. Thanks guys!

Chris

RGN01

Get some liquid gasket - I use an orange version from Halfords in the UK - smear it onto the threads and the problem will go away!

Richard

ajcoholic

My Feedback: (10)

SOme regular clear silicone smeared onto the threads of any 4 stroke muffler will effectivley hold the exhaust from vibrating loose (orange RTV would also work but isnt necessary).

AJC

liquid_TR

Use teflon plumbers tape - you wont regret it. (and you dont have to tighten the h*ll out the nuts either)

flipstart

Several flyers at the field have experienced your same frustration with Saito muffler systems. Most have switched to OS for that reason. I don't use the muffler on a Saito-just a straight pipe brased to the bent pipe that comes with the engine-forget muffler pressure-mine seem to run fine w/o pressure. Teflon tape seems to be the best fix-if you catch the problem soon enough. Even the straight pipe will work loose without the tape on the threads.

XJet

I use teflon tape, snug the manifold down so that it bottoms in the head, tighten the lock-nut, run the engine up until it's good and hot then re-tighten.

No problems after that!

blw

My Feedback: (3)

The mufflers seem to work pretty well if you tighten them like Jim said. You do have to check them the first few times and snug them up.

w8ye

My Feedback: (16)

Saito mufflers seem to be a non event for me personally? I have just not ever had any trouble with them.

But I have seen Saito engines where people have used pliers on the pipes and mufflers. Where they had all kinds of strange material on the the threads. Where the pressure nipple has come out. And a Saito 125 that the back half of the muffler was missing.

ccrebidoux

My Feedback: (3)

As I said, I've been using saitos for close to 10 years +. I've only recently started having issues. Maybe the engines are getting "looser" with more run time and shaking a bit more?? Am I getting older and need more Wheaties?? I don't know.

Haven't gotten to putting the tape on yet, work keeps getting in the way of my fun.

Chris

iflyfisher

I also vote for the teflon tape. I had a .91 in my Citabria that gave me identical problems. Horizon replaced the muffler at no charge after the threads got too buggered up to grip. When I installed the new muffler, it also came loose. Then someone on the forum recommended the teflon tape. Used it and have had zero problems since.

Ken

pilotpete2

Ditto[8D]
Pete

lucien

I would caution against doing any torquing while the motor is still hot..... that aluminum is a lot softer at operating temp than when cold and the risk of galling and stripping the threads is a lot higher when hot..... Only torque anything on the motor when it's COLD never when hot......

On my old saito 1.50, the muffler was just part of the preflight - I'd check the jam nut and the pipe with a wrench each time and go fly. It was loose more often than not, but never came off or gave problems in flight because I always tightened it before then...

LS

onewasp

Sorry, I have to disagree. Do it once hot (I use an 8" wrench).

The only way you could screw up the threads in the cylinder/head is to have too few turns into the head with the manifold pipe. (If you do that then frankly you are asking for problems!)

The hot "tighten the hell out of it" works------so also does the teflon tape (which I now use).
My experience covers the 180 all the way down to the 82a. Same procedure!!!!

Before the cast mufflers made their appearance I had numerous spun aluminum muffler$ dis*****emble themselves in any where from one to three flights -- this on the 150and 180 but only once did I ever have the manifold (header) come loose-------on any of the engines----even then it was 'snug' but movable.

I prefer the teflon tape but trust me even King Kong isn't going to screw up the threads on the cylinder with a properly inserted manifold pipe.
PROVISO: this assumes you haven't screwed up the threads by letting the manifold pipe flail about!

AKFireMedic

My Feedback: (2)

I do it exactly the same as XJet. Seems to work great for me.

Hobbsy

My Feedback: (102)

This is what an 8 inch wrench can do when you get a little HamFisted FarmBoy syndrome. This is the cylinder off of my old Saito 1.50. This is of course the intake, on the exhaust I screw the pipe in until it's bottomed out, I never hurt on of those.


Picture won't load.

Hobbsy

My Feedback: (102)

Finally

flipstart

It seems strange to me, from an Engineering viewpoint, that a company producing only 4 strokes, couldn't come up with a better design for attaching a simple muffler system. Especially considering the number of complaints and/or fixes that surface on this problem.

w8ye

My Feedback: (16)

I doubt if the factory teams have trouble with them?

But they have made changes in the past from the machined muffler to the cast muffler with the break away all thread pipe.

Then they started machining a groove on the outlet to retain a silicone diverter.

More recently they changed to the 15 degree pipe with the cast muffler for cowl clearance considerations.

onewasp

Hobbsy, #1 my comment was directed only to the exhaust side. #2 I assumed some sort of reasonable intelligence #3 you may have confirmed some thoughts I've had in] the past