Saito 82b vibration

[Chris Wareing]

Hi

I have a Saito 82b in a hangar 9 Katana 50. It has had plenty of air time, starts very easily, has plenty of power but produces a lot of vibration. I'm using an OS F plug and 10% fuel. Has anyone else had this problem and if so have you any suggestions to cure/reduce it. I have thought of changing to a Saito plug. Has anyone any experience of these and could changing the plug help?

Chris

[Jon H]

Saito engines are known for this but to be sure double check prop and spinner balance and integrity of engine mounts etc

[Colin Leighfield]

Mine is in an Fw190D and I can't say I've noticed any significant vibration. Props are balanced though. I don't see how the plug would affect this, unless maybe it was causing pre-ignition.

[Stevo]

None of my Saitos really vibrate that much,well no more than any other. If pre-ignition were a factor it may throw a prop and of course the head may be need to be shimmed. Not really possible on a Saito I'm afraid. All mine are OS 'F' with 10% nitro.

Is the vibration at the engine frequency - (prop out of balance, crankshaft bent...) or at half of that which is an ignition related issue...

As Jon says, check out the spinner... prop... mount etc.

[Mr.B.]

At what power throttle position / rpm does in vibrate? Low throttle? High? all the time?

[YakMad]

Try a higher percentage nitro fuel, I use 20% in all my smaller Saito's and no Castor oil as it causes sticky valves in Saito's, you don't say what prop you are using but I found my 82 is happiest on a 14x6 prop as I found it ran rough on a smaller prop (13x8). Don't bother with the Saito plug as its too cold unless you run 30% nitro, the OS 'F' is the right plug for it. I know this site has been mentioned before but its a good source for Saito engine info. **LINK**

[Cuban8]

Check the integrity of the fire wall - cracked glue joints can give vibration problems, particularly with four-stroke engines.

[..]

I have an 82b & I haven't found it any more prone to vibration than my OS and SC four strokes.

One thing tho is that they do vibrate a lot when they are rich on the low end , you say it's had lots of airtime but maybe a retune would help?

[Charles Smitheman]

I have two FA82b. they are quite harsh running engines. I think they are tuned for power rather than smooth running.

Leaning out the idle helps a lot. The mixture is set very rich out of the box, and can be leaned out when properly run in.

And resetting the valves might help.

Also a solid airframe absorbs the vibration better.

I tried putting two washers under the glowplug to reduce the compression slightly, it might have made a slight difference, and it still ran perfectly. A shim under the cylinder might also help, but this is a bit of a fiddle to do.

The smoothest running Saitos I have are the old FA30 open rocker. But then they cannot pull the skin off a rice pudding!

[Colin Leighfield]

It's interesting to hear how we have different experiences with the same motor. I've never noticed harshness or vibration with my FA82B, it's pretty much the same as the other four strokes I've had, OS91, TT54, ASP70 and 120. I had an ASP180FS for a while and it was more marked with that one, not a big issue but screws could shake loose if you didn't keep an eye on them. The Saito is a lovely motor, the only other comment I would make is that it seems to chuck more oil out than the others, but that's something else of course. I do take the point about getting the mixture right though.

[Chris Wareing]

Hi all

Thanks for all the advice. I have tuned the engine to be as lean as possible at the low end without it cutting when the throttle is advanced and have balanced the prop etc. Pre -ignition sounds a possibility as it runs hot and will throw the prop on starting at any other than a very low throttle setting. Would a "colder" plug help with this or is more nitro a better bet? I had thought about shimming to lower the compression ratio (litho plate under the cylinder) has anyone had any experience of this?

Chris Wareing

[Colin Leighfield]

Hi again Chris. I've been thinking about this and I might be able to relate to where you are coming from. I bought my FA82B new to go in the MR Fw190d9, here. When I first ran it up, it wasn't far off the right settings, so I spent a little time getting it "perfect". However, as I was doing this, it seemed to be going off and getting rough, so I continued to alter the settings. In the end I spent about 20 minutes on the ground and just seemed to be making it worse. During this time, it was getting pretty hot. I left it to cool right down, then set it back to where it had been originally. I then re-started it, fined the needle off a little, did the "hold it upright" test and just flew it. It was perfect and has been in each flight since. My conclusion was simply that the engine overheats quite easily if held on the ground for too long, even if the cooling provision looks adequate, it needs to be in the air. I think there's a fair chance you're experiencing the same thing, have a think about it. Prolonged ground running for setting up purposes doesn't seem to be a good idea and can make you think that you've got problems when really, you probably don't.

[Chris Wareing]

Thanks Colin.

It is possible that the problem may be due to overheating though I don't usually do prolonged ground runs. I'll try flying with the cowl off and see if this helps. Nice model by the way, I'm close to completing a FW 190 A8 from The Brian Taylor plan for the Saito. I have another 82B in a Tony Nijhuis Harvard this seems to be much smoother but has a much more rigid mounting than that in the Katana. Does your 190 fly well, it certainly looks good in the air.

Chris

[Engine Doctor]

I assume you have balanced all the usual suspects ,prop and spinner ?I fitted a Saito 82B into an acrowot that I was asked to build for a club mate. I was asked to get it flying an did the test flight .It proved to be very powerful and smooth. Only criticism was the oil from the exhaust but that's was obviously down to the fuel used,bekra I think. We later changed to southern model craft 20% with 17% synthetic oil which was much better. You may have a badly balanced engine as they do occasionally escape the factory. I have two supposedly identical YS 140 FZ's one is so smoooooth and the other one vibrates into a blur? So bad in fact that I won't use it until I have stripped and checked why (it was unfortunately out of warranty before I used it and found the problem) .Do let us know if you cure the problem.

[Colin Leighfield]

Yes Chris, it's a dream, flies like a trainer. Mick hasn't done these for years and I found it part built on EBay. Since then I've found another one partly built, also on EBay! Although simple to build, the outline is scale, so there's got to be scope for putting in the detail and I might do that with number 2!

The FA82 has got more than enough power for it, even though it's 1/6 scale, 69" span and about as long. Good luck with your motor, Personally I'd leave the compression alone, it's probably to do with engine mounting or something basic. I'm sure you'll sort it out.

[Chris Wareing]

Thanks Engine Doctor.

I would be interested to know the results of your YS investigation. Perhaps my Saito has a similar problem.

[Jon H]

many artf's supply engine mounts that are made from some type of soft cheese. it might look like glass nylon, it might feel like glass nylon, but its integrity leads me to believe it is actually a type of cheese. this could be a contributory factor!

[John Lee]

Had the same problem in a Hangar 9 Toledo Special. Changed the H9 supplied spinner to an aluminum one, problem solved.

[Stevo]

Jon,

Blue cheese apparently...!

The following is based upon a conversation with Engine Doctor... along with a Saito spin on things.

If you wish to shim it. get a piece of Litho plate, around 3" square. This will give you enough to hold when working with it. Take off the cylinder, and press the base of it against the plate on a bench, and scribe round it.(round the bit that inserts into the crankcase!)

Now cut the hole out with a sharp scalpel blade. Make sure it sits over the bottom of the cylinder. Now scribe around the square bit... Don't cut it out yet. press the engine bolts into the plate. Then drill the plate, then cut out the shim with sharp scissors.

Then anneal the aluminum; first rub some soap all over the shim; then play a blowtorch over it CAREFULLY until the soap goes black - then move the torch away immediately. Leave to cool.

Clean it up and fit - I usually put some blue Hylomar around this bit but not essential. That should do it!

It is not something that I have done, but one day may have to!

Edited By Stevo on 30/10/2014 17:37:26

[Chris Wareing]

Hi all

Thanks again for all the advice. The H9 mounts were somewhat cheesy. I am in the process of rebuilding the katana after a crash which broke one of the mounts, among other things! I have bought some much more substantial mounts and will try these first. I will leave shimming as a last resort following Stevo's method.

Chris