flygilmore

So I have an XYZ 20 that I bought from Valley View RC back in late 2012 that I have just taken out of the box to install on a plane. Well, the choke plate will not stay closed and after doing some searching, I have found out that this was an issue with these. One post I read said that Tom thought that this was just a thing with Walbro carbs........sorry, but I have had lots of Walbros and have never had this issue.

Can anyone who has run this engine tell me what you did to keep the choke closed for starting???????? I really don't want to run a servo for the choke but I guess if I have to I will.

Thoughts??

Truckracer

My Feedback: (19)

This is what I did and there is just enough friction in the linkage to keep the choke closed. The black bushing on the bracket bolted to the motor is a piece of Viton fuel tubing.

All Day Dan

My Feedback: (5)

You’re not alone. We all are going to have to deal with this problem eventually. Find out which Walbro carburetor is on your engine and then proceed to these websites for help. Post your progress so we can all follow it and maybe even help.

http://thecubden.org/thecubden/how-t...lbro-choke-fix

http://wem.walbro.com/walbro/family2.asp

Dan.

Truckracer

My Feedback: (19)

I probably have 18 - 20 different engines here with various Walbro or Walbro clone carbs and none of them have a ball detent to hold the choke closed ... only open. There has always been enough friction on the shaft to keep the choke closed while starting the engine. The only time I have had a problem is when the choke plate is misaligned and will not close all the way, even when more than necessary force is applied. I understand there are some newer Walbro carbs that have almost no friction on the shaft but fortunately, I have not run into one of these yet.

All Day Dan

My Feedback: (5)

Some and maybe all of the new ones have the choke spring loaded open. Dan.

Truckracer

My Feedback: (19)

I hope I don't have to experience the "pleasure" of owning one of those carbs.

Indiomike

My Feedback: (5)

That was me who had the issue with the choke not staying in the closed position. Truckracer has the best solution in making the choke linkage with enough friction that it holds the choke plate wherever you set it.

Check your carb model number. Mine was a WT793A that had the choke plate issue. I have since bought another ValleyView 20cc engine and it has a WT962 carb on it. That choke works fine as it should.

Since you bought your engine back in 2012 I suspect you also have the odd ball 8 x .075 threading on the prop shaft. That was eventually changed to the more common 8 x 1.0 which is the same as a DLE20.

Other than the annoyance of the loose choke plate, that early (XYZ brand) engine still runs very nicely. I like it just as well as my DLE20 engines.

Indiomike

flygilmore

Ok, guys, thanks for the advice. Truckracer, that looks like a sharp setup you have there and I truly appreciate that pic!!!!!!!! It will help me a bunch.

like I said, I have never started this engine but it was run at the factory I presume as it has some carbon on the top of the piston. Do you reckon I'll get lucky and it will fire right up or do you think that the carb diaphragm etc. are shot from sittiing in the box for 2yrs? I really should try and mount it somewhere and start it I guess before I mount it to the plane (4 Star 1.20) I building for it.

av8tor1977

My Feedback: (6)

I agree, very nice, clean work Truckracer.

I have numerous times removed the choke shaft, cut a round relief in the shaft for the detent ball with a Dremel tool and a small round burr, and re-assembled the choke with a ball and spring and thus had a detent for the choke where none existed before. It's a little tricky to do, because you have to mark the choke shaft for the detent relief 180 degrees out of place. Then when you remove the shaft, you transfer that mark 180 degrees to the other side of the shaft and grind the relief there. You can test assemble the choke to see if you got it right. Also remember that the choke butterfly screw is staked into place, and you have to grind that stake off before you remove the screw or you will ruin the choke shaft when you remove the screw. Then be sure to use Loctite on the screw when you re-assemble it all for the last time.

Edit: I forgot to mention that I actually make two detents; one to hold the choke shut, and one to hold it wide open. If there isn't enough friction on a choke shaft, the engine can suck the choke shut and guess what that means..... Glider practice!

Edit again: This link, provided by All Day Dan, does a nice job of showing some of what I talk about above. Surprisingly though, it doesn't mention that the butterfly screw is staked. You will almost assuredly ruin the shaft if you take the screw out without grinding the stake off.... A small sanding drum in a Dremel does a nice job of removing the staked end of the screw.
http://thecubden.org/thecubden/how-t...lbro-choke-fix
My copy of the link here doesn't work. See All Day Dan's post above and use that link.

AV8TOR