kenh3497

I forgot to mention one thing I can't figure out about the 53 I talked about in my "53 repaired" thread. Twice now upon landing the engine had a squeaky/weezy sound at idle. The first time I thought it must be a loose mount so I checked the bolts and sure enough the bolts were in fact loose. I tightened them and the squeak went away. A couple of weeks later it squeaked again. All bolts were tight and it ran no different than any other time. The squeak was gone on the next run. It since has run flawlessly except for some hard starting which I attribute to my lack of maintenance. The starting issue only appeared late in the season long after the squeaking. I run Sig 10% nitro fuel. Tuning is easy and steady.

Any opinions as to what could cause the squeaking? Thanks!

Ken

spaceworm

I think YS say 20% oil. Does your Sig 10% nitro fuel have 20% oil? I add Klotz to my 18% oil fuel to bring it up to 20% oil. Good luck

Richard

petec

My Feedback: (58)

You definitely want 20% oil content in a YS or longevity will suffer.

Now about the sound you heard, was it like the sound of a piece of tissue over a comb or a kazoo? I ask this because I had an issue with an engine years ago that exhibited that sound and would die at throttle down intermittently. It was a piece of grass that had made its way in onto the throttle barrel on the side that leads from the crankcase to the intake valve. If you fly off of grass it might be worth pulling the throttle barrel for a look see.

kenh3497

It was almost like a wheeze IIRC. I said squeak 'cause I didn't know how else to describe it t the time. Maybe a squeaky wheeze????? LOL It idled just fine, in fact it ran perfect.

Ken

kenh3497

I think I may have found my squeak. See this thread for the full story. http://www.rcgroups.com/forums/showthread.php?t=1706494 Post 27 has photos of the pin hole. The hole I discovered returned after the JB weld "disappeared". I'll explore a couple of options before I spring for a new carb body.

Does anybody have any ideas?

Ken

petec

My Feedback: (58)

You might be able to put a spacer and a longer bolt over that hole with a dab of silicone but its a bandaid fix too. The fix I'm afraid will be a new housing.

kenh3497

I feel my first repair failed for two reasons. First I used the JB quick, which IMO, is not nearly as good a product as the long set formula. The second and I think the biggest reason is the repair was to small to effectively "grab" onto the carb body. I've been looking and dreaming a bit. I remembered a web site talking about high velocity porting on motorcycle heads. While I'm not going to do a port job I was inspired to try something. First a little modeling clay to test the theory and if that works then some more JB Weld of the long set variety. I'll post more when I get there. I feel at this point I've nothing to loose and if nothing else I'll have learned something when I'm done.

Ken

kenh3497

Well, here we go ready or not.........

I put a dab of modeling clay into the carb body in the proposed location. You will notice how the clay will make a smother transition into the disc intake of the back plate. This has to be a very turbulent area. IF... I'm lucky, I'll gain a bit of performance in the process. My major reason for this is to make a larger chunk of epoxy. It will have more surface area to grab on to and if it does come loose it shouldn't go through the engine. I actually enlarged the hole through the backplate tolet a bit more epoxy through. Again more surface area. There was also a small hole in to the hole the bolt passes through. I opened it up a bit for another place for the epoxy to grab. I'll make a masking tape template to match the disc valve opening before laying in the epoxy. I'm hoping and am confidenr this will be one big mass when I'm done.

Ken

PS more to follow when the epoxy is laid in and cured.

kenh3497

I think I have a viable repair. I was able to add one larger clump of JB Weld to the affected area. I think this will last as the long cure JB is a MUCH tougher product than the Quick JB. At least it sanded and filed much harder. Also with the larger clump there is much more surface area to glom on to. In addition I did a much better job of surface prep giving the carb body a good roughing up

A bit of clay in the throat of the carb kept unwanted JB from finding it's way to places it wasn't supposed to and a dam made out of masking tape kept the JB where it was supposed to be. I mixed and applied the JB about 11PM last night and was up a 6AM to check on the progress. My work shop is rather cool so the JB was just a tad rubbery. It was easy to work in this stage so I roughed it out ans let it set for a couple more hours. I worked it a bit more to a bit finer finish and then the mess went in the oven at 170F for 3 hours for a "post cure". The oven was turned off and was left to cool naturally. The fun began as the JB had turned into a tough to work product. I had a curved file that worked pretty good for most of the process but creating the radius on the JB was an interesting process. I CAed some emery cloth to the inside of my curved file as it is a safe inside edge and that worked OK but the emery clogged pretty quick. I wound up running a strip of emery down through the throat of the carb and out around the bend and shoe shined it. The process was then tided up with the file in the places the shoe shine method didn't work. In the photo where the carb body and the back plate are side by side, you can see where the JB was added. A photo was taken of them in proper relationship but you couldn't see in the photo the match was near perfect. Hopefully this will not detract from the performance (I'm 95% sure it won't) and may even add a bit as there will no longer be as much turbulence in the airflow. Time will tell. Some of the photos aren't so good, I apologize for that but it's a bit hard to photograph such a tiny space.

Ken

kenh3497

Forgot to ask... I removed the rotary valve to work on the back plate and to check for damage by the previous hunk of JB that disappeared. I had a devil of a time getting the pin out of the back plate, yes I removed the set screw. I had to heat the back plate and drive the pin out. I massaged the pin for a light press fit. OK to the question, how tight should the clearance of the valve to the back plat be? I assume it should not drag but, how close is to close. Is there a spec?

Thanks!
Ken

spaceworm

Very interesting repair and awesome workmanship. We used to call the curved file you have a "riffler", but I don't know why. Please, though, let me loan you my Dremel the next time you do this; it should make the shaping, cleaning, and polishing a lot easier.

Sincerely, RichardClub Saito #635; Saito 56, 100, 120abc, 130T, 180
YS F 120

kenh3497

Thanks Richard! I have a Dremel. There is just not really enough room to work comfortably in that small space! I only have about 1 1/2 hours in the repair. To do it a second time would be less now that I know the tricks. LOL

Ken

kenh3497

Here is a link to RCG where I was able to put a caption on each photo. http://www.rcgroups.com/forums/showp...0&postcount=70 I find RCG to much more friendly in the photo department.

Ken

kenh3497

I finally had some time to burn my first fuel this weekend and it all went through the 53. All the mixture and regulator settings needed to be changed. I got the rotary valve a bit on the tight side and experienced a little "black goo" out the exhaust. It cleaned up in about 4 ounces of fuel. I'm still not 100% happy with the idle but am closing in on it. Sunday morning it was about 200% humidity so tuning was at best difficult. In the afternoon it was 90F+ so again tuning was a bit off. I'm at about 2300 RPM reliably but it surges just a bit.

Power seems to be as good or better than before. I neglected to tach the top end (my bad) but it is a moot point as I didn't have a tach untill this past winter when the engine had already been torn down for repairs. So far I'm happy.

Ken

petec

My Feedback: (58)

Surging is usually an indicator of a lean condition. You might try richening the regulator a bit.

kenh3497

I was chasing the regulator a bit. I think I was making much to large of adjustments. I'm close now so maybe a 1/4 or 1/8 turn at a time will zero me in.

Should this engine idle at 2000 RPM like the larger YS's? Or is my 2300 OK?

Thanks!

Ken

kenh3497

Had some time to play and adjust this weekend and fly to test the adjustments. FWIW I'm running an APC 12X6 and the engine is mounted on a Pulse XT 40.

I'm able to get the idle down to 2150/2200 RPM. Any lower and I'm not comfortable in it staying running. It transitions well and will hold any speed from idle to full throttle. I wound up with the regulator flush with the housing and the idle mixture/air bleed completely shut. HMMM, just like the factory settings are before the new air bleed throttle plate was installed. The regulator had been one turn in and the air bleed was about 2 1/2 turns out before my second attempt at the repair. At WOT the engine tachs at 10,100/10,200 on the ground with OLD Royal analog tach with the mentioned APC 12X6. Good smoke trail and the engine hauls the Pulse around like a scalded cat (no cats were harmed during this testing session)

Unless someone here has a different view I guess I'm happy for the moment. I can try to play with the Idle a bit more but the plane just barely rolls on our petromat runway at idle.

Ken

kenh3497

Well, this YS53 is no more. It went to YS engine heaven. All I can figure out is it must have ingested something and no it wasn't the hunk of JB Weld. That repair looked as good as the day I did it. The back plate and rotary valve are scored as well as the piston, ring and cylinder. The inside of the crankcase had aluminum bits all over.

I did some looking around and found a nice first version 63 (regulator on the bottom of the crankcase) to fill the old engine mount. Looks to be almost new. Should be here this week later on if all goes to plan. More power is always better!

Ken