Merlin Man

Hi,

I have a friend who has a new Saito 82 in a BT MKII Spitfire. He has asked me to test fly it for him but I am concerned about the engine .

I have had no direct experience of this size Saito but it has significant vibration at peak RPM ( 9,800 ). The engine was purchased new and this is it's first time of operation.

We have balanced the prop and spinner and double checked the engine mount security. We have checked the tappet clearance ( just as a precaution ?willing to try anything ? )

This motor has had only 6 x 12 oz. tanks of fuel so far, and so it is not really run in.

The vibration is such that that it is difficult to touch/ hold the needle valve for tuning at full revs and yet the vibration does not seem to affect the performance ? I am concerned that , apart from possible engine damage, the vibrations will damage the airframe over time.

I am hoping that someone might be able to shed some light on this problem. This amount of vibration is surely not normal for one of these engines is it ? Thanks in advance.

Cheers,
Merlin Man.

Warbird Man

My Feedback: (95)

Have you tried some different props and or run it without the spinner? If that doesn't solve the problem, most likely you got a bent crank shaft. It shouldn't vibrate that bad as you are stating.

Johnnie Red

Hey Merlin man

Did you screw the engine directly on the mount or you use any shock absorbing material?

Has your engine mount the capability of hosting a four stroke of that displacement or it is the stock one provided by the kit? (It maybe provided for use with a smaller size 2cycle...)

Keep us posted
Kind regards
J.R.

deatonbt

I had a problem where a 2 stroke engine would vibrate. It seemed to balance, but the prop was reamed slightly off center.

TFF

Find a test plane and mount it the same way and fly it for a month and work the bugs out; a warbird is the worst place to break in an engine. You might even cowl it to get use to that change. Sags and dead sticks are not fun.

smithcreek

My Feedback: (25)

A few months back I was looking at the Saito 72 and 82 engines for a kit I'm building. I found a lot of threads complaining that the 82 had vibration problems. The plane didn't really need the 82 so I played it safe and went with the 72. Do a search, you should easily find others with the same complaint.

maukaonyx

Now I am worried, since I have a new used 82 for my BH T-28. Maybe I will switch to the OS 71 or 91 that I have on the shelf. That 82 is so purdy...I will do a search too, to learn more about this potential vibration problem. RCU is great for these heads up threads, but everyone has different experiences too, so I'll do some research and go from there. Jon

TedMo

I have 2 82's and have been running them for over a year or more ,on and off. No vibration problem. I would say you do not have them tuned well and or mount is insecure. What are you useing for fuel? I use 10% for both my 4 strokes as well as 2 strokes with total success. One of mine is side mounted the other inverted both run great in idle and wot.

Merlin Man

Hi All,

Thanks for your replies and apologies for the delay .

I have just spoken with Mike , whose engine is the one at issue here, and he tells me that the problem is solved. !

Apparently, the Saito manual states to start tuning at 5 turns out on the top needle. !! He did this but didn't progress very far from this position by the time I saw the engine. (I didn't check the tuning since it was pulling 9.800. ) However , he has now tuned it at about 2 turns out and the vibration has gone. . I have also suggested he use a larger prop to "slow" it down a bit. He is now getting 10,000 and I think he also adjusted the lower adjustment to the factory 1.5 turns ( I don't know what is was, but the transition was ok before ? ) and is as pleased as a dog with 5 tails! So , it seems tuning was the culpret as some of you suggested.

Again, thanks for your help and happy flying.
Cheers,
Merlin Man