HP VT 21 Maybe Not

[@johnkelinske1449]

Lemon. This is one of those engines it makes you really glad you don't have more than one of them.

[@francoisrivard893]

I'm assuming you tried different heat ranges for the plug. Since you use low nitro did you try a hot plug like an McCoy MC -14 or an OS type F? Also, more nitro usually helps idle , and would work with the cooler plugs... I would definitely seal both needles using silicon fuel tubing to eliminate that variable. Maybe it just needs a lot of running in before "settling down" Some of the older Enya's took hours of running before getting really sweet...

[@jeremyburton9038]

Have the tank no higher than 1 inch above the motor . Just watched another HP VT 21 and it ran perfectly at high and low idle.

[@valic000]

Good to see, you give not up so easy David! Thumbs up big time! And if other folks seem to say this,I think, your search stops here...at least with the org. carb... If I was in you place. I had a long time ago put a other carb to it, just to see, what happens.. Did you notice a long valve overlap when checking the timing?, Cheers mate!

[@dmrcflyr2]

All previous video had the timing set such that the opening was as close to equal as possible. This time I timed it one tooth further so that the opening was a bit larger on the intake opening. As seen in my PINNED comment from RC forum threads, many other people, to include the famous Clarence Lee also mentioned the inability for a consistent low idle. So this is not uncommon for this engine. I am not trying to make it idle lower anymore.

[@FedericoZampese]

Hi David, from the sound of it and it's behaviour (and not having any experience with rotary valve 4 strokes) seems like it has low compression. Have you tried using only castor oil in the mix? Should give a better seal on the valve when running.

[@wmcwings4343]

Well that's a bummer. At least it looks good just sitting there!

[@dmrcflyr2]

Here are some posts from RC forums also stating the low idle issue with the engine. The last post quotes a review from Clarence Lee. I cannot substantiate that quote because I have never seen or read that particular review. So apparently this is not an uncommon thing with these engines. www.rcuniverse.com/forum/1948127-post3.html www.rcuniverse.com/forum/1963368-post11.html www.rcgroups.com/forums/showpost.php?p=23671363&postcount=12

[@AmpAbuser]

.21 / 9x5 APC will keep from sagging the idle to a stop, may be just so weak it needs a 9x4 / cold plug issues still more nitro some 25% should keep it from coughing to a stop. It does have a lower idle but still not low enough 3.8k would be bearable.

[@remkojerphanion4686]

This engine reminds me of a girlfriend I once had: all pain and no gain.

[@dmrcflyr2]

ROFL

[@mikeeiben3430]

It almost seems like it will run a little slower until you remove the glow driver.

[@barneybetelgeuse6273]

I can see the problem, the carbs upside down 😀 i'd be cursin that friggin thing Dave you got more patients than me 👍try a different carb🤔

[@car6on14]

I had heard these were suppose to run quieter then other engines, seems maybe alil less then a typical four-stroke maybe.. what would you say Dave? The muffler looks fairly restrictive, I wonder how a straight pipe would change it.

[@dmrcflyr2]

This engine is so quiet I can run it anytime of the day or night really.

[@jeremyburton9038]

It like to run wide open . Here is a thought pylon racer maybe.

[@midwestsirens]

Try a different type of glow plug. Sounds like that may be the issue

[@dmrcflyr2]

Apparently you didn't see that 2 were tried in this video and 3 in the last video.

[@GOLTURBO555]

@@dmrcflyr2 Its possible to be a "timming" problem? What a ENGINE... If was me? Lean out, and let it blow up, and let it sit in my showroom.

[@midwestsirens]

@@dmrcflyr2 Oh my bad.

[@midwestsirens]

@@dmrcflyr2 Just one of those poorly designed engines I suppose. Perhaps maybe a bad carburetor design?

[@michael-iu7gq]

Did it ever run right?

[@dmrcflyr2]

No. I sold this engine years ago.

[@wolfgangrumpel9509]

Hi David, I know ..you tried so much to get that b..@#a good run. If IMHO its low compression engine a hotter plug e.g. Enya #3 might help. Maybe you tried already ??

[@dmrcflyr2]

Yes, I tried an Enya #3 in the first video. Nothing I have done has made ANY difference at all. It is a display engine now. besides I have made videos with it; it has served its purpose. I have no intention of ever putting it on an airplane anyway.

[@Burnersforvanlife]

Wrong plug

[@ecwhite3621]

Maybe it’s just a lousy carburetor

[@edwinator46]

this is some lame ass engine