HP VT 21 The Frustration Continues

[@dmrcflyr2]

****UPDATE**** I appreciate all of the comments and suggestions. I just did a few of the suggestions. 1. Increased the tank height by about 3/4" - 1". 2. I found an APC 10x4 prop in my stash, heavier flywheel action. 3. Angled the muffler downward. 4. Set timing so larger opening is seen on the inlet side, so one tooth more. I just did a very brief run in my closed garage and did not see much, if any of an improvement. I will try to run it a bit more after work plus add some fuel to the tank to provide better head pressure.

[@rcdieselrc]

How is compression when it quits? I believe it's a sealing problem with the ring or valve.

[@capt998]

Can I suggest you put the Bottom of the tank level with the carb center line. I know this is not supposed to be how to run it, but lets see if it even get flooded with fuel and will smoke more when it runs. It ran at full throttle but tweaking the needles seem to do so little difference. Also, may be keep the plug power on till it gets better tuned throughout the throttle range.

[@DjayLSD]

cool, but with 5 of these of experience. the best plug to work on them was the Os Type F. it still being a 4 stroke engine, most enya and hs plugs would work but not properly. the 21 are also a bit more finiky on the break-in than 49s , but it has to do with moving mass and rotating mass. My reccomendation would be to run it on a full tank of 0% nitro 20% castor 80% methanol at 3/4 throttle on an almost lean setting at full. once the tank is empty, run normal 10% for 2-3 tanks. the two first not over 3/4 rpm, and if the engine stalls, let it 5 min before another start. on the 3rd, start to tune it for high end and idle. It will respond like clock and sing like a bird. Even if this is kind of a "break-in" procedure. it has to be done EVERY time the engine get dissambled/cleaned and put back together. i emphase on the EVERY. It is most likely due to the way those are made compared to most nitro engine, very intricate design, care needed, but very good engines. Also, Type F plug being longer(wont be an issue of contact because of plug seat hole desing, you need to add 2 extra cooper shim/gasket on it, but it does the job like charms.

[@dmrcflyr2]

This is a very long video, try to watch it all as there is loads of comments throughout while I troubleshoot this engine. Viewer discretion is advised as my language gets somewhat colorful as the frustration increases. To recap: 1. I have had this engine apart about 5 times in the last year and a half. 2. It has been timed correctly each time. 3. I have checked it for air leaks at the carb and intake and even used gasket sealer on both to eliminate that possibility. 4. I am running the specified 10% nitro and 22% oil content fuel each time. 5. I have run several different plugs in it to include the K&B 7311 as specified by MECOA. 6. I have an HP VT 49 that runs flawlessly with the same fuel and setup.

[@chrkmb]

Yup ...I watched the whole thing . I'll never get that 2 hours back..Lol.... But hey I share your pain , I have VT 21 doing the same thing. I'm not going to give up on it any easier than you have . I was an automotive Master Technician for 30 years and love a good challenge . I'm retired now so I have plenty of time to cuss , drink beer and fiddle with small agrivating engines . I'll let you know how it goes ... hehehe..

[@tempest411]

I have an HP 49VT that behaves this way. I've noticed the compression disappears once it heats up. I'm going to disassemble it, replace the ring, and carefully measure everything with micrometers and see if any of the clearances are more than they should be. I do suspect the problems stem from the rotary valve leaking compression, as another person here mentioned. That would definitely explain the inability for to idle very low.

[@stevebarr9604]

Yeah I think I'm going to put mine on the stand tomorrow and see how it runs cause I haven't started it in years!

[@valic000]

Hi David,.. I watch most of it..as its a long video..but the symptoms are clear... If I had the engine in my hand,I would do maybe this ? ...my intuition says me, that it is a carb/ fuel issue...As you say,even with out markings check, the valves are balancing symetrical...So should be good... Maybe a previous owner had a " great idea,to modify" the carb??? ..like bigger bleed holes or jets??..Maybe try to alter there something (by close a bit a bleed hole?) ..if possible,to see,how the idel RPM behave.... Or in the factory made a mistake?? there is a channel blocked..or leaking, bad casting?..something like this.. maybe a other test carb??...just to be sure, the rest is ok.... than you can lock your energy on the carb...as the rest is good ! Try maybe to make a flow restrictor on the front of the carb..so you get better suction.. just to see, if its better...or worse...to rich...to lean?...and go on from that further. a....maybe one other thing! You can take a look, if there is no leak in the head..the valve...that some exhaust pressure gas leaks to the intake side..and prevent good flow at low speed?? Maybe some manufacturing issue,.... Do try a pressure/ seal test .. I hope you find it..and I am sure,you dont give up so easy mate!.. I am sure, you are always there..just open your eyes and rethink! You are good enough to find the issue.! Many best engine regards from Holland to the USA mate!! and dont forget.. I v been watching !!! ;-D Peter

[@dmrcflyr2]

Thank you Peter. The last time I timed it I did it with the head off, obviously and observed TDC of the piston, I never rely on the mark on the drive hub. I have disassembled the carb completely and I did not see any noticeable signs of user alteration. Right now the engine is oiled up and ready to sit for another year or be sold. i am not spending any more time with this engine this year, if ever. It just isn't worth it to me.

[@OlliKarhun]

I liked the colourful language! Sometimes it just is like that with these engines :)

[@valic000]

@@dmrcflyr2 Hi David. I understand the frustration...I had also some engines,that drove me crazy..But I can understand it mate. But one thing you can try..its easy! You have so many engines..just pop a another carb to it..even its provisory...and maybe it runs like a swiss watch?? from there,you you can close in the problems..thats the way to go.... but give it a break for now... many well-meant regards David!!

[@mikemac8434]

Hello David, Mike McIntyre here. I watched all of your videos and the problems you have had with this motor. 1st -- you have an older HP VT21 4 stroke made before 1990. How I know is on the mounting lug it says "Made in Austria" another is the rotary valve. The old rotary valve is brass (alloy) in color, which wears out and leaks. When MECOA started manufacturing the engines, they chrome plated the rotary valve. Take a look at their website where the do the timing. Look at the rotary valve (Large gear on top). You will see a chromed valve. If you look at yours, it is brass. www.mecoa.com/faq/vt/timing.htm So, Let us go through the list of things on this motor. 1.) Pin under the landing gear strap tightened to bottom casing. 2.) Bevel gear rotates on firmly mounted pin. 3.) Spacer/spacers on crankshaft pin (behind bevel gear) 4.) Check the bevel gear backlash ( should between 1/6 to 3/32) With the piston out of the upper housing and with everything in the lower housing from above, put the upper and lower housings together ( you don't need the screws) now check the gear backlash. Those little shims behind the bevel gear makes up for the backlash on the timing. If that is ok, next well look at the bearing head (replacement from the plain head) With the older (Pre-1990) VT21 Head, If you changed it over to the MECOA bearing head, there would be not enough clearance for the bearing head or too much space to where the rotary valve would bounce upward. The clearance for the bearing head to rotary valve is .010 to .020 Measure from the top of the housing head down to the rotary valve (with shims). I use a depth micrometer for this. Next, the bearing head. The top of the bearing to the face on the head. What is the difference? is it the .010 to .020 clearance? If it is more, than you need more shims, If it is less remove some shims. One last upgrade (if you want to try it) would be to order a new rotary valve that is chromed (old one may have scoring on it?) Last, and this is my observations, this motor you got from Ebay was abused. BAD SELLER! The bevel gear that was stuck to the shaft it was to turn on ( probably no oil originally filled in the bevel gear area) Excessive amount of grease in the bearing, rotary valve areas. No head gasket? And Number 1 was, the loose screws on the rotary gear shaft --- If those screws were tightened, the motor would not turn over. Last option you have is, send it to MECOA and have them work it over (probably upgrade the valve as well). Hope this help you out? I've been running the VT 21/25/49 since the mid 1980 and love them! My first and only 4 strokes I run so far. They fly the slow airplanes I like to fly and motor along at slow speeds. Never had problems with them idling down to 2100RPM. Mostly use Master Airscrew props. 10% glow/20% caster oil/ 70% alcohol I have used 10% synthetic / 10% caster oil after the engine has seen a gallon of the caster oil (initial break-in). Have always used the recommended plugs that MECOA said to use.

[@stevebloke5455]

watched the whole vid. read through a lot of comments, one thing i did not see and was my first thought is you said no matter how much you leaned the idol screw it still seemed rich , that tells me there is a problem with the idol needle and or spray bar. it does not take a lot to play buggery with them (as im sure you know) another thing i kept thinking is why dont you leave the battery connected and try tuning with the engine running? use alligator clips to connect the battery so you dont have to hold it just to see if you can get it in the paddock. a complete carb swap would tell you a lot if you have a known spare. id also try running it without the muffler as a process of elimination. i could be completely wrong but thats what id be looking at with the way its running. if im not to late and you haven't already sold this engine good luck.

[@stevebarr9604]

I've got one of the original ones that first came out and after I reset the timing gear on the head it ran awesome but before it would not run good or stay even running but I'm sure you have the timing right or else it probably won't run!

[@ringofthebrave]

Often heared of air leaks with the intake manifold causing erratic running. You may try to mount the carb directly to the "head" and take care of proper sealing. I had an relatively high idle with my (sold) HP VT 61 (made in Austria) at around 4000 rpm. The engine was flyable with a 13x4 prop in a trainer model but it is a low performer and I sold it as it is better suited to real HP enthusiasts and I am not really one of those. Edit: When I remember correctly I had similar problems on my HP. The OS 4-stroke plug doesnt fit as it is too long and would have contact with the rotary valve. I added some seal rings to prevent that and tightened the OS "F" plug very carefully. This was the only way to get the engine running acceptable. I used 10% Nitro.

[@dmrcflyr2]

I put the carb directly on the head this morning, but the throttle arm was just not in a good position at that point. I did do my 'blow in the fuel inlet' leak test each way and did not hear/feel any sort of air leaks. It was such a tight fit it took a few minutes just to get it off. Last year when I was having these issues I had also sealed the intake with permatex gasket sealer and it made no difference then either.

[@robertlane440]

Yes of course,. Very interesting Mr Bond. Too rich low down cooling the plug ? On my Kawasaki triple as it ran out of fuel (went weak) the revs would sky rocket. Rob (UK).

[@marcocruz6859]

This remind me of the Ofna Car engines.. they where so incredibly cheap but impossible to tune... I did manage to get a few of them to work somewhat around sord of decent... changing the carburetor for an OS... but they use to be a source of frustration for any one that actually try to use them..

[@vincentpremel4817]

I experienced such issues with an old fs40... intake valve was leaking. Altough it's a bit more difficult to see this kind of problem with the rotary valve design...

[@shermaddictedtorc8540]

Unfortunately I know that level of frustration. Have an engine that refuses to idle. have ran over a litre of fuel through it, tried multiple plugs , fuel mixes, checked for air leaks . Second hand engine. Now sits in box for last 12 months as every time I get it out to have another go becomes frustrating to quickly. Your language was not as bad as mine was but i was not filming myself. lol

[@TestECull]

I'm thinking vacuum leak. I'm in the process of resurrecting a Magnum 52RFS that sat in a parts bin for a few years and it did the same exact thing until I got a new o-ring in between the carb and intake. Came good then. That engine started easily and ran like a hot damn at more than 5k(11-8-3MAS at 9600 on Omega 15%) but if I tried to bring it down below 5k it just quit. Got some videos of it on my channel too. In the case of this engine, I'd almost say the recess in the head that the valve sits in is worn out and allowing air to leak in when it otherwise should not do. Get the calipers out, measure hte OD of the valve, ID of its bore, then measure your larger HP VT that runs properly. Compare the tolerance. I'd almost bet the 21's tolerance is going to be much larger than the 49's.

[@dmrcflyr2]

The carb to intake and intake to head are such tight fits that I do not believe an air leak is the issue. Last year I had also sealed the intake with gasket sealer and it made no difference then either. I did my leak test on it today and I heard and felt no air leaks.

[@TestECull]

@@dmrcflyr2 I was thinking more that it's leaking around the drum internally, rather than externally. It's so odd that your VT21 is seemingly gas-tight, yet it acts exactly like my Magnum 52 did before I replaced that o-ring. I couldn't get that engine to take a prime before then, the lowest it would stably run was about 5k, transition was 50/50 successful or shutdown, and it could run with the throttle pretty much completely closed.

[@dmrcflyr2]

I have no way of determining the internal leakage, but the rotary valve does not show any signs of damage or wear like the wrong plug was ever used in it. Still a possibility though as it was a used engine when I bought it.

[@TestECull]

@@dmrcflyr2 The drum's hardened steel, but the head it rides in is aluminum, right? I'm thinking the aluminum bore it rides in is where the wear is. Why I suggested comparing the tolerance between these parts in both of your HP VTs since you have one that runs perfectly and one that just doesn't. If that tolerance is excessive it may be where the leak is.

[@dmrcflyr2]

@@TestECull No, I do not think so. At least it does not look like steel, unless they bronze plate steel. See the video here, kzbin.info/www/bejne/mHLdgWaqfquVna8 Does that look like steel to you? I did not put a magnet to it the last time I had it apart, but it does not look like steel. Below from the manual on MECOA's site. Use a standard long glow plug. DO NOT USE a R/C or Idle Bar Type plug or Four-cycle plug. Any plug with anything protruding beyond the threads (like the Fox Miracle Plug) will cause damage to the rotary valve. Without knowing what the specified tolerances are supposed to be any measurement is meaningless especially since I cannot do anything to remedy it.

[@thomasryan5394]

I’ve only run the plain head Austrian original. It ran ran great. I wonder if the repro has the same quality control

[@TenkaDaHenkA]

I am the only one , who would like to see it flying cross the street? :D

[@ringofthebrave]

Great move at 5:26 btw.

[@dmrcflyr2]

Those are my cat like reflexes!

[@125saito]

@@dmrcflyr2 Bella would be very proud of you Dave.

[@allengentz7572]

Hi David have you tried a heavy prop (carbon fibre),I think it may need this as a flywheel. Some 4 stokes act up with light wood props.

[@dmrcflyr2]

I haven't because I don't have those type of props in the size range for this engine.

[@bthanse]

Why are you not adjusting the idle needle when the engine running and it start to run bad at 1/2 trottle ?

[@luisgarza2036]

The problem is something with this engine, not you doing something wrong blow air trough the ports to see if there were air leak there, if not maybe the carb doesn't control the fuel flow gradually from mid to low range.

[@vulturedroid9804]

Im sure one more run and it will be on song i promise haha Felt your pain :)

[@gnelson1959]

I have a pair of these HP VT21 engines. One purchased used, one brand new. Both run brilliantly at all settings. Currently using an APC 10x3 prop in a smallish Old Timer type model. The VT21 engine will idle forever, in fact I have problems trying to get the dear little thing to shut down, the opposite of what's happening with David's engine. Anyway my gut feeling is that the original owner has damaged (ie: worn away) the tight seal between the rotary valve & its housing by using the incorrect type and or percentage of oil in the fuel. Likely used synthetic oil based fuel ("coz that's all I had on hand") whereas the engine should be run in over a 2 hour period on all castor based fuel (20% according to Sceptre Engine Review). And 2 hours is no big deal, simply do that over a few weekends. I use 20% castor fuel in both of my VT21's, with 10% nitro, an OS FS plug and I did break in the NIB example over 2 hours. And definitely no synthetic oil. With David's engine we know it's not a glow plug issue, its not a head timing issue as it run well at higher throttle settings, the engine has compression. That really only leaves a fuel related issue so perhaps a dodgy carb or (my belief) the engine has lost its ability to adequately admit fuel through the rotary head valve at lower speed levels.

[@dmrcflyr2]

The fuel I have run in this engine since I got it is Omega Control Line fuel. 10% nitro, 22% total oil content 50:50 castor/syn oil. So the fuel is exactly what is recommended by the manufacturer. The instructions also specifically state NOT to use a long four stroke plug as the length may contact and damage the rotary valve, and that is why I specifically do not use that plug. I did try to install an F plug and slowly rotated the engine over by hand and it just did not feel right so I removed it.

[@gnelson1959]

@@dmrcflyr2 I should have clarified that I use extra glow plug washers to ensure the plug does not strike the rotating valve.

[@dmrcflyr2]

Oh, how many? 2 or 3? Maybe I will give that a try.

[@gnelson1959]

@@dmrcflyr2 ok have just been down to the shed to check ...... 2 THICK washers 😀

[@mikeeiben3430]

I did watch the whole video. I was hoping that you would try to set the low end richer and see if it would idle with the glow driver on.

[@dmrcflyr2]

The initial run of the engine in the beginning had the low speed set way out. I leaned it from there.

[@samreye1]

It sound to me it's timing . try moving one teeth forward you are tdc that's why it doesn't idle. Need to advance the port timing to final compresion on open spark chamber..

[@haydenbutcher73]

David, don’t feel bad all HP vt four strokes are crap. If you run your VT49 for long it will do the same. I’ve had quite a few of these pieces of crap and sold them all for spares or repair. The problem is the crap drum valve leaks too much compression when the thing warms up, they usually run better when cold. That’s why you have to spin the thing up so fast on the electric starter to get it to fire. You can make them run a bit better by adding a bunch of castor oil like 50% more and then the will idle better. The only good news is,if you put it on eBay someone will buy it, though you should put it on for parts. Forget this engine and run an OS FS20 instead.

[@capt998]

Everything you have done sounds good. I didn't see any smoke out of the exhaust. When the plug power was added on as it was running it didn't seem to make any difference.Seems to get worse as the fuel level went down? I wonder if a higher tank level, APC or A heavier prop and a heavier prop nut would help and may be higher nitro and oil content? O rings in the carb leaking? Just guessing. I know you said you don't want to spend time on it any more, but I wonder if timing it one tooth off either way just to see if it makes a difference. I have a VT49 that I just ran a week ago, it ran well at mid range and top end but didn't idle so well but it wasn't as bad as yours. I acquired two used HP21's that are in a very sad shape and I plan to rebuild them one of these days for a nice twin project. All made in Austria. Hope they will be worth my the time and money. I feel for ya man.. :)

[@capt998]

miss typed, no more oil should be needed, but higher nitro may help.

[@christosbizeras1190]

I own the same engine and have to replace bearings.can you led me how to pull out the prop driver?? In all my other (os) engines the use of heat is enough for the bearings & the driver fel apart with out effort.

[@dmrcflyr2]

Did you bother to search my channel at all? Perhaps this video will answer your questions. I no longer have this engine so I cannot be of any more help than what is on my channel. kzbin.info/www/bejne/oXemmoyYr9ilf6c

[@cmulder002]

Do you have a perry pump to experiment with? if its a problem with drawing fuel a pump might show that.

[@dmrcflyr2]

I think it it was a fuel draw problem it would not transition or have good peak RPM.

[@weofnjieofing]

Is there crank case or muffler pressurisation with this engine? If crank case is there a check valve? This might be the reason she won't idle low and cuts suddenly.

[@dmrcflyr2]

There is no check valve and I am using the standard T style fitting between the muffler, head, and tank. Same setup as I use on my VT 49.

[@francoisrivard893]

I didn't watch all the videos, looks like you tried the hotter plug. Did you try 15% nitro? The smaller displacement engines often like more nitro. Beyond that use a piece of silicon tubing to seal at least the high speed needle, maybe get an "o" ring on the joint between the carb and block. I still think it should get better after more run time, like hours more run time. You could just put it on stick type plane and fly the snot out of it to loosen it up even if the idle is not perfect you just kill it once you get near the runway...

[@johnhubbard3399]

I agree with TenkaDaHenka also it dosen't look like it has shit for compression. David will an OS carb fit ?

[@dmrcflyr2]

Unsure if an OS carb will fit it. I really do not have many on hand that size to try. Regarding the compression, it is a bit different for a rotary valve engine. It doesn't feel quite the same as a push rod four stroke engine, plus it has a Dykes piston ring and they always feel a bit lower on compression anyway. Rotating it through by hand however, it does have what I would consider acceptable compression.

[@jeremyburton9038]

That looks like a bad carb . Acts like it is sending to much fuel when you try to idle it . Bad machine work on the carb . They should have done a better job on it . Would it be possible to put a different carb on it ? Maybe a little retro fitting to try some different carbs.

[@dmrcflyr2]

Maybe.... I really don't have many small carbs on hand and I am not really willing to spend any more money or time on this engine.

[@tk1882]

Where did you get that engine test mount?

[@dmrcflyr2]

I bought it used. It is a PSP MFG test stand but they don't seem to be making them anymore. www.pspmfg.com/RCEngineTestStand.html

[@Grahame59]

Are you absolutely positive it doesn't have an induction air leak? Even at high revs you can hear it missing beats.

[@dmrcflyr2]

Now exactly HOW am I supposed to determine that besides the means I have already taken?

[@Rcguy2591]

This is how I feel with my Ys 1.20fs

[@rigididiot]

Are U sure it is not a timing issue? I found these engines ( I have a .25) not the easiest to time.

[@dmrcflyr2]

On the contrary these are about the simplest four stroke engines to time. Yes I have timed this and many other rotary valve engines many times. Here are the instructions for timing. 5>Install and time the valve with piston at top dead center. Insert valve so a equal portion of the rotary valves port window can be seen thru both intake and exhaust passages in the crankcase casting. If you can't make it exactly equal, the larger opening should be seen thru intake passage. Make sure the piston is at top dead center.

[@dmrcflyr2]

I show how to Time it here. kzbin.info/www/bejne/mHLdgWaqfquVna8

[@AmpAbuser]

Higher nitro and a hotter plug will help the idle. The wood prop is low weight compared to a APC 10x4 mass will help it idle lower. Also to avoid oil ponding tilt the muffler down some for better drainage. At 5.6k it was stumbling but running that would give you a chance to adjust the low end NV to see how it influences the mid range. Add a brass bullet spinner on the nose to help the flywheel out. It's only a .21 drop in prop size it will have enough punch to keep the prop turning over at lower idles is another option. A wood prop has a thicker airfoil more load than a thin MA 9x5 scimitar prop. MA 8x4 reported 3.5k idle.

[@daviderickson999]

Have you tried 20/20 fuel ?

[@dmrcflyr2]

First, very old video, and I no longer have this engine. Second why would i? I never needed that blend to run any of the other HP VT engines that I owned.

[@remkojerphanion4686]

The mystery continues....

[@johnsargeant2041]

Maybe put the tank higher up alittle..

[@mikemoore9757]

You met your nemesis.

[@jp-alarms]

I don’t run my engines much and my Irvine 36 needs a new carb

[@darkiee69]

Have you tried a different fuel?

[@dmrcflyr2]

No because the fuel blend I am using is exactly what these engines calls for.

[@darkiee69]

@@dmrcflyr2 But if its been run with a different fuel earlier it might prefer that. My dad had an old 2.stroke engine that wouldn't run with synthetic oil, but ran all day when it got old school cator oil mix. That was what it had been run on before.

[@dmrcflyr2]

Well if that is the case then I have no way of verifying that or what fuel so that is a dead end. The fuel I am running in it has 22% oil content, 50% being castor.

[@stevebarr9604]

Mine was off a tooth so!

[@robot797]

I dont know why you cant get it to run but I would love to give it a try XD

[@dmrcflyr2]

Well if you are interested in purchasing the engine send me an email and we can discuss.

[@robot797]

@@dmrcflyr2 will do

[@hauptsacheesfliegt]

David and all, these engines shall NEVER run on castor oil ever. Peter Demuth, who was a co-developer of these engines, stated in his manual never to do this, instead use "Glissol-R", which was an available synthetic fuel at this time. I made the same mistakes, besides running them too hot (they dont like it), which causes the castor to burn and damage the bronze bushing. Furthermore, lubrication by castor exhaust oil is the death penalty for the bushing. This area is jst too hot for castor oil. I made several new ones with a tight fit with my lathe from sintered bronze. Shrink them in, dremel the ports easily and take an adjustable reamer by hand. These repaired engines run perfectly for 100+ hours now. Even the ones without the roller bearing on top run well. The behaviour of your engine is 90% this issue. Of course, they don´t run in any conditions like a Surpass, but much better than that. And they are not very picky about glow plugs and nitro.

[@dmrcflyr2]

Very interesting. I am quite certain that I had the instructions for these when I owned them and never saw that documented. In fact, I just found this from a manual online: mecoa.com/hp/vt/guide.htm "The HP VT engines use 2 cycle glow fuel. Don't use 4 cycle fuel. It does not contain the proper amount of oil. The perfect fuel is 22% oil (all castor or at least 50/50 castor/synthetic) and 5-10% nitro. Most poor idling and performance problems are usually traced to fuel or glow plugs.” Can you prove what you say from an original manual? kzbin.info/www/bejne/p4Lbo3h-idiSrpI Running on Omega 10% control line fuel which is 50% castor.

[@hauptsacheesfliegt]

@@dmrcflyr2 btw, it is all about a good fit there. I made them a bit "too" tight and warmed the engines up before running first time. Bronze widens more then the steel part, that might bee too much when too hot with some factory clearences.

[@hauptsacheesfliegt]

@@dmrcflyr2 www.bilimuygula.com/FileUpload/bs774731/File/viertakt_model_motteren.pdf Page 214-217. It says that castor remains score out the bushing quickly.

[@dmrcflyr2]

Sounds like a poor design if pieces cannot be machined to the same tolerances consistently. Either way, I no longer have any of these and do not have the desire to own them again.

[@hauptsacheesfliegt]

@@dmrcflyr2 I totally agree, these are not perfect and cannot be used when reliability and power is expected like valve engines. I use them for vintage planes or motor gliders where they can do their sawing-machine-sound on half power. Inho, the main problem is the material pairing and it´s temperature behavoiur, where wear by time cause a narrower envelope of reliable operation. As i mentioned above, for those machinists here, make new bushings and you´ll have a new engine.

[@justinpyne968]

Could it be just a shit carb?!

[@johnkelinske1449]

Lemon. I have had a few of different makes through the years in the hobby. No matter what you tried, they would never run up to par. This is the problem with trying to turn what was once an European made engine into a (sort of) American made one, doesn't seem to ever translate real well. Rather like building Super Tigres in China.

[@dmrcflyr2]

I think this is an original Made in Austria engine. That is what the case says anyway but MECOA might have had some cases on hand too so.

[@johnkelinske1449]

@@dmrcflyr2 Could well be. I recall that HP had some issues with quality control when they were getting bounced around between owners in Austria and Germany. I doubt there is any way at this point to know for sure. As an aside, I have a Taplin Mk 3 Twin diesel, the case says "Made in England" and it has British patent #s on it, but no serial #. One engine expert who looked it over told me it was Indian assembled, but out of British parts, one of the first ones they made up out of the left over spares they bought from Taplin. I was lucky in this regard as it starts and runs very well.

[@dmrcflyr2]

Yeah, with used engines you can never tell the history or origin for sure.

[@klesmer]

This is why I don't make vodeo's. I have become grouchy in my salad years and I tend to break things when I get frustrated.

[@Rcguy2591]

This is how I feel with my Ys 1.20sf