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Old Nov 18, 2012, 01:47 PM
Ala Flying Dude is offline
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Need 4 stroke identified? tks


Hi, I have been in to electrics for 2 years.
So I am not up to speed on 4 stroke motors.

Refer to 2 pictures This is a t-4 90 overhead cam 4 stroke, the seller doesnt know the manufacturer,
One factor is the drive belt off the motor that turns the prop. Obviouslly one would need spares

Any one know manufatuurer as well as a parts source.

Tks Dude
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Old Nov 18, 2012, 02:42 PM
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Those images don't open up ... so they remain too small to be seen.
Old Nov 18, 2012, 03:12 PM
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Well I can't see the pics they are too tiny. But if you say it is a T4-90 that means it is a Webra engine. They used to make the rotary valve four stroke engines for quite a few years a long time ago.
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Old Nov 18, 2012, 07:10 PM
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Tks


Tks for the help so far, I took those pics fro a ad the fellow had, its on ebay on used rc airplanes a japanese zero,

Appreciate it
Dude
Old Nov 18, 2012, 07:33 PM
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Originally Posted by earlwb View Post
Well I can't see the pics they are too tiny. But if you say it is a T4-90 that means it is a Webra engine. They used to make the rotary valve four stroke engines for quite a few years a long time ago.
100% correct Earl.

Bill
Old Nov 19, 2012, 04:25 PM
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Originally Posted by Ala Flying Dude View Post
Tks for the help so far, I took those pics fro a ad the fellow had, its on ebay on used rc airplanes a japanese zero,

Appreciate it
Dude
A"T4-90." is a Webra engine.

http://www.ebay.com/itm/63in-Japanes...item2ec393369a

The belt drives the rotary valve in the cylinder head, not the crankshaft.

IMO, forget it unless you like to tinker. Webra is gone and parts for these have gone to the collector status and are getting pricey.
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Old Nov 20, 2012, 01:16 AM
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Originally Posted by Ala Flying Dude View Post
Tks for the help so far, I took those pics fro a ad the fellow had, its on ebay on used rc airplanes a japanese zero,

Appreciate it
Dude
This is the engine in question. It is very heavy. I used to make boat-anchor remarks when talking about it in the past. In short : I would not suggest starting with this one, espescially when it has been fiddled with by some previous owner. The correct setting of that headvalve is a nightmare. A clubmate of mine at RBWings club did make considerable changes to his at the time with good results. This is an engine from that period when every manufacturer was jumping on the 4-stroke horse.
Old Nov 20, 2012, 04:03 AM
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These engines have the benefit of being quiet and easy to handle.

Quite collectible, I believe.

Modest performance.

If it were mine, I'd keep it for its novelty-value. I reckon it would be a pleasure to see it running.... perhaps in some big vintage model.
Old Nov 20, 2012, 04:07 AM
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A fella from a previous club of mine had one and for its capacity it was huge . Not that that means anything , just saying is all ,Cheers the pope
Old Nov 20, 2012, 06:36 AM
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I bought and used a Webra T4-80 for a long time on a P51 Mustang many years ago. The engine wasn't all that powerful, but it had a distinctive sound that was different from the Saito or OS four stroke engines. So it sort of sounded a little better and more scale like. in comparison to the other model engines of that time period.

Nowadays, the belt for the top end are next to impossible to get. Fortunately the belt doesn't wear out for a long time. But since there aren't any replacement belts, it does make it a problem should you ever need one. Setting up the timing on the rotary valve can be tricky. But I forget what one does to get it set anymore. Thus I agree with Reginald in that I would not want to run the engine.
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Old Nov 20, 2012, 07:33 AM
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The one Reg has pictured is the super charged one, it has crankcase supercharging like a YS, but uses one way valves instead of a rotary valve. This is the un supercharged version, note plates where one way valves go. Mine is a T-4-.87. Picture #2 is another one, note plastic idler pulley bracket, mine was broken so I made an aluminum one like in Reg's picture
Last edited by I TOBOR; Nov 20, 2012 at 07:43 AM.
Old Nov 20, 2012, 10:50 AM
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Quote:
Originally Posted by earlwb View Post
I bought and used a Webra T4-80 for a long time on a P51 Mustang many years ago. The engine wasn't all that powerful, but it had a distinctive sound that was different from the Saito or OS four stroke engines. So it sort of sounded a little better and more scale like. in comparison to the other model engines of that time period.

Nowadays, the belt for the top end are next to impossible to get. Fortunately the belt doesn't wear out for a long time. But since there aren't any replacement belts, it does make it a problem should you ever need one. Setting up the timing on the rotary valve can be tricky. But I forget what one does to get it set anymore. Thus I agree with Reginald in that I would not want to run the engine.
I do have an original spare Webra belt for the 90 but seem to remember I did order a replacement version at our local Industrial Parts shop for someone and there was no problem with the size, even made from the same material. I can find out if you like. Beeing Webra thus German it is likely that they bought off the shelf belts on the market. The main problem with the T-90 was the shims for adjusting the vertical conical valve, inspired by the full-size Aspin valve. Leading the mixture trough the crankcase was to make use of crankcase pressure. This happens twice during every cycle. This kind of supercharging did not lead to great results with the T-90 and was abandoned in later versions, a set of close-off plates and gaskets could be bought separately from webra for owners of the first version. If someone is interested I can ask my clubmate what he did change on the valve. I flew the one in the pictures on a large Telemaster but was never happy with the running of the engine. The first version used a reed valve under the carburettor.
Old Nov 20, 2012, 11:47 AM
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Reginald, thanks for the offer, but I sold the engine and plane years ago. I doubt I'll get another one, unless the price was really good. But if you knew the part numbers or specs of the belt, it would be really useful information to have out here on the internet.
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Old Nov 20, 2012, 06:44 PM
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Here's mine NIB never run. I would like to have one to run in a big oldtimer.

Bill
Old Nov 21, 2012, 04:14 PM
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Here's the photos out of the ad, ones that are that badly discolored I find it works better to just convert them to black and white.

As for identity of the engine, its right in the title of the sale page:
63in. Japanese Zero rc airplane with webra T4-90 4 stroke


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