Saito r33

[John Lucas 4]

I thought I would post these photo's to show what the thick end of a £1000 looks like after 3 or 4 10 minute flights excluding running in.

Photo damage to rear of crankcase

Photo con rod pin wedged up inside piston

Photo before engine was dismantled

The "C" clips decided to let go allowing the pin to come out into the crankcase . One "C" clip was undamaged and the second clip only found bits.

Oil used was, Belray 2 stroke racing oil and Deluxe Materials 2 stroke oil. The reason for the two types of oil used were because the vertical cylinder was getting a lot hotter then cylinders 2&3.

[Ron Gray]

That’s not good. Have you had a chat to the shop you got it from?

[John Lucas 4]

Answering your question no I haven't because of the time I have had the engine the manufactures warranty is long past. Besides this engine managed to blow three spark plugs during running in and in this case I spoke to the importers who weren't interested offering me a couple of percent reduction in the next product I buy from them.

[Robert Welford]

Saito should be interested in why a new R33 engine has failed so catastrophically. I would contact Saito in Japan.

[John Lucas 4]

I could give them a go just to see what response I get, but I won't hold my breath.

[flight1]

Two different oils were use, were they mixed or did you swap from using one to another? The oils might not have been compatable so reducing there ability to cool and lube.

I use valvoline Synpower 2t this works better on the four strokes than the other oils as it gets past the cylinder better. I had problems using other oils untill i swaped, they were fine in the 2 strokes, we need a oil expert to tell us why it's so.

[John Lucas 4]

No they weren't mixed , the tank was drained and refilled with fresh petrol. It will be interesting once I get my engine back as I am having a fuel intake manifold modification plate fitted.

[Ron Gray]

I would certainly go back to Saito about this, they are a high profile manufacturer so one of their higher end motors going pop so soon should be of interest. I know Laser would be

[John Stainforth]

You could try Horizon Hobby, the distributors in the US in Champagne Illinois. They have provided me with excellent service of Saito engines on several occasions.

[Paul Marsh]

I know Richard who flies at the Greenacres fly-ins, has had 2 Saito 3 cylinder radials blow up, with one cylinder giving up. Seems a common problem with Saito petrol radials, where the glow, far as i know not heard of any problems.

maybe not enough lubrication getting into that one cylinder..?

[Engine Doctor]

Could it be that the petrol versions suffer from ignition timing problems causing the bottom end to fail ? If as is suggested the glow version doesn't suffer any bottom end problems then my bet would be on the ignition setting/ module fault causing knocking and eventual big end failure.

Looking at the pics again there is a lot of black sludge probably caused by the crankpin moving about in con rod.....not good. Did it not knock or show an symptoms ?

Back in the 1960s the Triumph Tiger cubs and BSA C15 s occasionally broke crank pins  and was almost invariably found to be caused by  poor ignition setting causing engine knock. Even poor fuel could damage engines back in the good old days . Pinking or ignition knock could and often did blow holes in piston crowns but f pistons survived damage could be done to the bottom end.

 

Edited By Engine Doctor on 17/03/2019 17:57:02

[John Lucas 4]

Yes the ignition timing is wrong it's to far advanced, this is something that is going to be addressed with a magnet and sensor ring conversion kit

[Jon H]

This is not uncommon im afraid. And before i get yelled at for slagging off a competitors product just take a look around the web. Its not an isolated incident and its the weekend so i have my modeler hat on today.

One thing i would ask is what prop you are running and how you fly the engine. By 'how you fly' i mean do you bring the throttle back when the model has its nose below the horizon or do you leave it where it was? Im not trying to be critical, but many pilots leave their throttle open in dives and this can cause significant rpm rise and could lead to over revving. If you used a small prop on the engine and went into a dive of say 30 degrees at 70-80% throttle it would not be hard to over rev an engine like this. With all those moving parts you really want to keep the revs as low as possible and its very important to come off throttle, perhaps down as low as 1/4 throttle, when in dives.

The only other thing i cant quite see in your first photo is if the holes in the master rod have egged where the link pin for the slave rod goes through. If they have egged or broken, and are damaged equally then it is likely the master rod failed first and the slop in the link pin levered the E clip off the end.

Advanced ignition is not ideal for sure but i would not expect it to cause this type of failure in such a short time.

Mismatching of the cylinders is also not uncommon. I had the same issue with a saito 450r3 due to the poor design of the intake system. This caused even more issues with the FG84. Just do a search for the details of that.

Either way, i wouldnt mess about when it comes to the repair. New bearings throughout, new master and slave rod, new link pin and probably new pistons. Costly i know, but if there is any metallic debris left in the engine at all you risk a further failure

Edited By Jon - Laser Engines on 17/03/2019 19:57:07

[Paul Marsh]

The guy who flew the models at Greenacres, Richard Ginger is a very good scale flyer, and flew the models how they should - anyone who knows him can vouch for that.

Still, he had two engines fail. You're probably right, it is not the fuel, but the ignition system causing a backfire in one cylinder, think it was the 2nd cylinder that failed twice in a row.

[Jon H]

Yea Richard is a big Laser fan so i have heard the story from him.

The first failure was a straight casting fail causing a cylinder to depart the engine. The engine was repaired but failed again, at Greenacres. This was (i suspect from his description of the damage) a failure of a link rod big end. The crank counterbalance then whacked the stub end of the rod and pushed it into the top of the cylinder, shattered the piston and levered the whole cylinder off the engine. This was a different cylinder to the first one that tried to escape.

Again, i didnt see the engine myself but its the most likely explanation for the damage it sustained based upon his description to me.

In any case, Richard did everything right as far as i could tell. my comments earlier relate to a great number of the radials flown on youtube being flown in warbirds and they do a great many powered dives and fast beatup's of the runway. Looks great, sounds great, but then deathly silence

[cymaz]

I had the same thing happen on my Evo 7-77. I was very , very lucky. One of the slave rods came off as I was turning it over by hand in getting it ready to fire up. One of the C clips broke. An engineer club mate made a backplate that bolted into the web. The engine is about 6 years old.

Edited By cymaz on 18/03/2019 06:23:10

[Jon H]

Its relatively common on the ASP radial as well. There is a thread on RCU about it as most guys strip and rebuild their engines before they even run them.

[Ron Gray]

Rather puts you off these smaller radials. Oh well, there’s always Moki I suppose, just means bigger ‘planes!

[Frank Skilbeck]

Posted by Ron Gray on 18/03/2019 09:34:34:

Rather puts you off these smaller radials. Oh well, there’s always Moki I suppose, just means bigger ‘planes!

But no issues with V twins, apart from availability.........................

[Jon H]

Posted by Ron Gray on 18/03/2019 09:34:34:

Rather puts you off these smaller radials. Oh well, there’s always Moki I suppose, just means bigger ‘planes!

if you push a moki too hard the cylinder may crack. They will also throw conrods and pushrods if over revved.

There is nothing wrong with the moki engines, its just that engines of this size and complexity take no prisoners when it comes to abuse.

[Jon H]

Posted by Frank Skilbeck on 18/03/2019 12:16:55:

Posted by Ron Gray on 18/03/2019 09:34:34:

Rather puts you off these smaller radials. Oh well, there’s always Moki I suppose, just means bigger ‘planes!

But no issues with V twins, apart from availability.........................

yea

[Jonathan W]

Thing is, if the engines are spark ignition, it's a simple fix for the manufacturer to have a rev limit built into the electronic ignition module.

[John Lucas 4]

Good afternoon all,

Firstly thank you all who have responded on this thread. I spent a good hour yesterday trying to locate an email address for Saito and failed miserably .

Jon, the engine is turning a 18x6 wooden prop, the engine is installed in a DB Sopwith Pup so the engine is not abused and only uses full power when required ie entry into loops etc and spends it's time just tootling around the sky at half power. Different to some of the displays I see at the shows where there is only one place for the throttle and that's wide open. By the way the petrol I am using is ethanol free at £20 for 4L. Looking back I suppose I should have put a Laser 150 in but at the time Lasers were in the middle of moving so that hit that on the head so Jon when are the V's coming back as I would like a 40cc for my P47.

Moki's are a nice engine for people with deep pockets and after all the trouble I have had I don't think I will buy another radial. I don't think Saito have really got it together regards petrol engines I also have an FG21 petrol which was in a P51 and it never ran right especially around half throttle so I put a Saito 82 glow engine in and it runs perfect through the rev range, perhaps they should sort their carbs out or install Walbro carbs.

I picking up my rebuilt engine up this coming Thursday together with a nice bill, but in the Pup on a lovely afternoon ticking over on the end of the strip all the trouble I have had will disappear.Hopefully

John

[Frank Skilbeck]

You can see John's pup in flight here in the 2nd video (clue it has biplanes in the title), it's the green one, the other one (Daves) has an OS120.

[Jon H]

Hi John

Nice to see the two pups up together but does the engine always sound that rough? Perhaps its the recording but it really didnt sound very happy all the way through. Also is the model nose heavy?

Your model certainly isnt likely to over rev the thing but cooling could be a problem with the low airspeed. My stampe was marginal on cooling with a 180 glow and fell over using the petrol on one of those really hot days last a summer. A small mod to the baffle had it fixed. I can see in the video you have a nice baffle there but you might want to open it up a little as it seems only about half of the cylinder is exposed? its hard to really see it in the video.

To me 18x6 seems really small but i see its the biggest saito recommend. From the specs its clear the engine has a very short stroke so that is probably why they dont recommend larger props. That said, petrol engines dont load up like glow engines as the ignition point is fixed. Perhaps retard the ignition slightly and fit something like a 20x6 prop to keep the revs down. Its the prop i recommend on our 180's but you would have to try it out and see if the engine sounded very unhappy. I wouldnt load it below 7000 on the ground with 7500 being a good place to be. As a side note, i dont know what prop the other chap is running but i think he should go bigger. 16x6 at least and perhaps 17x6. Get the revs down and thrust up

As for walbro carbs, they dont work on engines this small. Your radial is effectively a 70 size engine, there just so happens to be 3 of them in the same cowling. As only one cylinder is drawing fuel at a time the carb only needs to handle the fuel draw of a 70. To put that in context, my 180 petrol at 6500rpm draws approximately 0.0018ml of fuel per induction stroke and its more than twice the size of your cylinder. Metering fuel at that level is beyond a walbro carb, at least it was on my 180 when compared to my performance expectation.

I will pm you about the V twins to keep the thread on track.