William Robison

My Feedback: (3)

Sport_Pilot:

Being "Up front" about it, I've never owned a TT four stroke. I've flown the TT two stroke and was happy with it, and I don't recall hearing anything bad about the TT engines of either type.

But I just sent my last OS four stroke, a good running 0.80 engine, off in trade for another Saito. And the fellow I'm trading with says he's never gotten the Saito to run properly. The Saito is an 0.80 also.

This should give you a good idea of which brand I prefer. And the trade will leave me all my 4c singles being Saito brand.

Bill.

Sport_Pilot

Will Robison,
The best deals I have mader were usually from someone who couldn't get it to run right. Usually a few tanks of fuel and the engine was broken in. So doesn't say a thing to me.

Hobbsy

My Feedback: (102)

In being up front I too had a TT .42 GP for a short time for the sole purpose of testing the Teo Diesel head, that being done I passed it on to a friend. It was a fine engine but I just won't go there. I have Saitos, Enyas and YSs all top quality engines that leave no need to go elsewhere.

JimTrainor

Is this a good place to ask why Saito uses a spur gear for the cam, and everybody else that I'm aware of uses a helical gear?

In the all the posts I've read here (rcuniverse) I seem to recall accounts of gear teeth breaking in Saito engines, but I can't recall any reports of OS style helical gear teeth breaking.

Did they choose the spur gear to lower manufacturing costs, boost power (less friction than helical), to differentiate themselves?

Hobbsy

My Feedback: (102)

Enyas, HiMax and others also have spur cut gears. Since the cam is 90 degrees to the crankshaft in the OS and others, helical is about the only way to do it.

JimTrainor

Of course, I understand the helical is the only choice if the cam is 90 degrees to the crankshaft. But, is this the basis of the their decision to use a helical hear, or is their decision to use helical gear the reason the cam is at 90 degrees?

I'll check out Enya. Thanks.

William Robison

My Feedback: (3)

JimTrainor:

This is not to say it has not happened for other reasons, but all the Saito cam gear failures I've heard about were caused by improper gear lash adjustment on re-assembly by a user - never an engine that had not been taken down, or one returned from from "Factory" service.

The lateast Saito design has fixed gear mesh, the user can't mess it up.

The OS 4c engines with the rear cam had a moderately complex spur gear set to drive the cam. When they went to the front cam I would suppose Ogawa and company did not want to be accused of copying Saito so they opted for the more expensive helical gear set.

And with OS being one of the most copied model engine manufacturers in the world, almost everybody else used helical gears also.

Enya being Enya, they will probably stay with the rear cam.

Many other methods of cam drive are possible, including rubber band (Gilmer belt) driven DOHC, a shaft driven disc valve, and the currently popular sleeve valve design RCV engines. But these last two don't really have a camshaft at all.

Bill.

JimTrainor

William, Is the gear lash problem caused by failing to put the correct gasket under the cam housing? I think I read a post by you about that?

How does one identify if their engine is of the latest design?

I have a used Saito 80 that I plan to disassemble for cleaning, bearing change, and maybe a new ring. Hence my curiosity.

Thanks for all the info.

Sport_Pilot

and the currently popular sleeve valve design RCV engines

How can this be popular when you can't find any on the field? Yeah some have bought it for scale and what not, but not popular.

William Robison

My Feedback: (3)

JimTrainor:

Yes, on the early model Saito the gear lash was set by the gasket thickness. On the later design the cam cover comes off with the camshaft staying in the block. The cover is much thinner, and doesn't have the large round area for the driven gear.

Sport_Pilot:

"Popular" was a poor choice of words, I should have said "Well known." And I've not seen any glowing user reports on them either. Magazine reviews have all been positive, naturally. I have seen complaints about their high vibration levels, RCV says "Use a heavier plane."

That's not my idea of a correct solution. I'll not buy one until they smooth them out.

Bill.

Hobbsy

My Feedback: (102)

I don't know where people get that RCV engines vibrate, I have a .90 SP and a .58CD both are very smooth.

William Robison

My Feedback: (3)

Dave:

The report and response I saw were on the RCV 1.20 engine.

Bill.

Hobbsy

My Feedback: (102)

I guess I'll just have to get one and see if it is really vibration or just huge tortional impulses like big Saitos have.

William Robison

My Feedback: (3)

Dave:

Check post #8 in this thread:

http://www.rcuniverse.com/showthread...=RCV+vibration

And then go to this thread for an extra cost cure:

http://www.rcuniverse.com/showthread...=RCV+vibration

There are others, but these will do for now.

Bill..

bgi

My Feedback: (7)

Sport_Pilot, my initial experience with the TT 91 FS was very positive.

Problem 1: of the two, one arrived with the cam gear one or two teeth off. This caused the engine to run poorly at throttle positions past 1/2. I fixed that problem.

Next problem: Valve cover screws strip very easily.

Next problem: One of the engines still runs very poorly. I can't remember if this is the one with the timing problem. Repeated calls and emails to Ace has resulted in no response.

Price comparison: I can spend $40-$50 more and get a Saito 90. I have 4 Saitos and have had no problems with them except the back-plate breaking on a 72 resulting in a carb falling out (no airplane damage). Horizon offered to send a new backplate and gasket set. Comments here on Horizon are generally good. Why waste hours of my time on a TT when I can get a Saito 90 for such a little bit more cash? If Ace isn't going to support their products, I will not waste my time and money on them.

I also have a couple TT 46 Pros. While I'm generally happy with them, for a little more cash I can get an MVVS 49 or Webra 50. Either is vastly superior. So I'll be buying no more TT's.

Sport_Pilot

Well I have had two also, the first one had a loose screw on the cradle which broke, ACE replaced it, no problem. It ran like ball busters until it started to make a squeaking sound. Couldn't duplicate it by turning it over by hand. Sent it to ACE but unknown to me they were moving to California! My engine apparently was on their moving van to California. Took a couple of months but they came through. They admitted the bearings were bad, not rusted, and replaced the entire engine because the retainer had let go causing further damage to the internals. Maybe you have a point. But I am still breaking this one in, it is starting to pick up that extra power they have, and starting to behave in the inverted position. If it does the same as the last one or ACE gives me poor service I will be in your camp.