1QwkSport2.5r

There are two different RNV assemblies they used with the newest iteration having a completely different looking needle valve handle/knob.. The original RNV probably used the same needle valve as the older carb's with the needle valve on the carb. I suspect there's just a little bit of oxidation or something in the threaded tube.

spaceworm

The threaded part of the assembly presents a long moment arm, which in addition to the threads reducing it's effective diameter, and that it is made of brass, makes it susceptible to bending. Maybe even a light drop with the needle hitting first would bend it. The needle is steel and less likely to bend. I would check the threaded part, and replace it if necessary. Have you tried the needle in another carb? Good luck.

PS Don' t expect to hear back from MECOA, he is the worst for customer service. He acts like he doesn't even want to be in business.

N1EDM

My Feedback: (2)

I will try the oil trick and will also try the pipe cleaner trick again... I wasn't sure if I could work on the shank of the needle valve or not. I was afraid that I might do more harm than good. I'll stop by an auto parts store and see if they have some 800+ grit paper to polish the shank with. I can't find any bending in the shank of the valve.

Thanks for the tips so far - I'll let you know how I make out.

Bob

1QwkSport2.5r

Try double-nutting the threaded brass tube and unscrew it and see if the needle valve fits in the other end. The threaded brass tube may be tapered inside - more or less the needles seat.

N1EDM

My Feedback: (2)

Thanks. I'll try that. Mine doesn't look like the brass tube is a separate piece but that could just be due to the close fit.

Thanks,

Bob

Sport_Pilot

Per his description and his photo the thread has nothing to do with this. He said that the needle won't fit into the spraybar, the threads are not even close. The needle is too big or there is something inside the spraybar. I think he has the wrong needle. I doubt the needle he needs is sold. He may have to replace the roto valve, nipple, and needle.

FlyerInOKC

My Feedback: (6)

Reading the ongoing needle valve discussion I would say either the wrong needle valve or if a slow speed needle screwed too far in depending on carburetor design.

On the surging engine discussion another reason for the surge in flight could be a stuck clunk. I had this happen before.

I was considering listing my glow engines but thought I would take the cowards way out and lit the brands.

Cox
Enya
Moki
OS Max
Saito
Super Tigre

jeffie8696

Aldon Kelly of Merlin Plugs explained that during the break in process bits of metal can weld to the glow plug filament making it act like a very cold plug thus causing surging. But it is not the only cause of surging I am sure.

1QwkSport2.5r

The threaded tube that the needle valve won't fit into may be tapered internally and could have been inadvertently removed and screwed back by a previous owner/user in the wrong way putting the taper opposite the way it should be. The parts diagram shows it being a separate part from the mixture disc, so I don't see why this could be a possibility. Until this is confirmed or denied, one cannot rule out the needle being the proper part for this carburetor.

1QwkSport2.5r

The K&B Sportster carburetor is not a standard two-needle carburetor - there is no low speed needle. The mixture disc that the main needle screws into rotates as an assembly over the spraybar tube. It is considered an automixture carburetor though.

otterrc

My Feedback: (36)

I have an older Enya 90, can I run it with 5% fuel?

1QwkSport2.5r

Sure can. I would recommend 18% oil as a minimum.

otterrc

My Feedback: (36)

I use 20% synthetic in all my 4 strokes, but can I run 15% nitro in this engine?

1QwkSport2.5r

If it were me, I'd be adding a head shim. Many older Enya 4-strokes generally don't like more than 10%. My 60-4C would chuck props on 20% nitro, but it's much more civilized on 5-10% nitro. Also, I would advocate for using some castor in the fuel - but that's just me.

N1EDM

My Feedback: (2)

Hi 1QwkSport2.5r,

Getting back to the K&B Sportster 65 Carb issue, here's the latest.

The inside of the spraybar was spotless but it is very small. I can shine in a flashlight and see the shiny inside surface.

The needle was polished per your suggestion, first with 600 grit and later with 1000 grit. The finish is as smooth as a baby's bottom and shiny. I was able to fit the needle valve in to the point where I could start threading it. BUT!! The 'But' is that I could probably only put in one thread before the needle actually bottomed on something. As I said earlier, the inside of the spraybar is not blocked. I can see through it. I did try to clean the Spraybar out with a pipe cleaner but the ones that I got were too 'thick' and would not go down the spraybar tube.

Also, if you check the picture, the spraybar on the carb included with the engine is machined as a single piece and is not a separate stem that can be replaced. The tube doesn't look crushed or distorted, it seems perfectly round. I can spin a #52 drill in there with my fingers, to give you an indication of the ID.

The bothersome part now is that the needle actually appears to be 'bottoming' on something - it could be a taper as you suggest.

Thanks for your help so far, do you have a suggestion as to the next step that we should take to resolve this???

Thanks,

Bob

FlyerInOKC

My Feedback: (6)

I'm still leaning toward you have the wrong length needle for the spraybar assembly. Has this needle even been used with this carburetor/spaybar and did the engine run?

spaceworm

[QUOTE=N1EDM;12264745]Hi 1QwkSport2.5r,

Getting back to the K&B Sportster 65 Carb issue, here's the latest....Bob[QUOTE]


I forgot the very beginning of this saga, but has this engine ever run with this spraybar/needle? Is it possible that the spraybar was never completely machined so that the needle would fit properly in it? A comparison with a known good spraybar is called for, I think.

I have a .65 Sportster that had run well for a long time. It is now in storage and may be deeply imbedded in that condition. I will look for it tomorrow and if I find it, I will look at the NVA for a comparison check. I will take pics and post them if I can. Good luck.

Sincerely, Richard
AMA 861960
K&B 29, 35, 40 (4), 61, 65;
HB 15, 25, 61;
Club Saito #635; Saito 56, 100, 120abc, 130T, 180; YS F 120;
Super Champion 61; Rhino 100; Cameron 19; Fox 35,
Como .91; ASP .91, 1.08; Kraft 61; OS 15, 25, 40, 46, 60, 61, 80;
Royal 25; Evolution 36, 46, 61; Echo 16cc glow; Echo 22 cc Ign.
Zenoah G23 ECDI, Ryobi 31, Ryobi four stroke, O&R Industrial 1 hp,
Allpina A330, Various Poulan, Weedeater, and Homelite, etc, etc.

FlyerInOKC

My Feedback: (6)

I was looking at the photo of the needle again it look so familiar then it hit me that looks exactly like the needle valve on a Super Tire engine I have, are you sure it hasn't been switched with another engine in your friend's collection?

1QwkSport2.5r

Here is a carb from one of my Sportsters circa 1991. The threaded tube is separate from the mixture disc. Note the needle valve thumbscrew handle - looks identical to the one in question above. The diameter of the needle at the thickest part is .060" and the inside diameter of the threaded tube is .0605". This style carb was used on all of the Sportsters, the ringed .40, ringed .61, and the .48ABC. The Sportster .45 carb came on the .40 and .48, and I believe the Sportster .65 carb came on the .61 also.

I stand corrected - the seat for the needle is in the mixture disc and not the threaded tube.

1QwkSport2.5r

If your needle valve is thicker than .060" and the tube measures .0605" or so, send me your address and I'll send you a needle valve. The mixture disc and needle valve assembly is the exact same on all models of the Sportster from the .20 to the .65. The only other place I've seen a needle valve with the same thumbscrew as these carb's is on the old style remote needle valves and I would expect them to use the same needle valve as the others, but we all know what happens when we (I) assume...

N1EDM

My Feedback: (2)

Thanks, 1QskSprt2.5R, I will send you a pm with the address but, IMHO, I feel want to give you some consideration for it... you shouldn't have to pay for someone else's error... albeit made with good intentions - the needle valve was packed loose with the engine when I got it. As you surmised, someone probably just tossed it in to the box because 'it looked right'.

Once we get this straightened out, I will post the results here...

Thanks,

Bob

1QwkSport2.5r

We'll get it worked out. I'll send you a needle valve that I know fits my .65 carb's, so it should fit that one without issue unless the threaded tube is drilled wrong. If the latter is truly the case, either drilling it out or replacing the spraybar/mixture disc would be the remedy. That is one part I don't have a good one of. My spare mixture discs came from some drone engines and are not machined very well (the drones were really designed to be flown WOT only) so they don't throttle for crap.

N1EDM

My Feedback: (2)

Thanks. I'll be on the lookout for it... I don't have a problem drilling out the spraybar if that's the case but is there a taper inside? I wouldn't be able to match that.

Again, thanks. I sent a PM last night with my address.

Bob

1QwkSport2.5r

The threaded portion is not tapered - the seat is behind the threaded tube section. (At least on the carburetor I took apart with the removable threaded tube.) If you drilled it out, you would need to be careful to not go too deep. There should be a space between the end of the threaded tube and the seat, so you should have a safety margin. But if your mixture disc/needle tube is indeed one piece, you will need to drill some and fit the needle, drill the tube and fit the needle until it fits and seats properly. BUT hopefully this won't be necessary.

I replied to the PM. I'll go to the post office today.

spaceworm

I find it hard to believe that the threaded tube and the disc/spraybar are one piece. It would be a major job to machine all the excess metal away and also to thread the threaded tube all the way up to the disc. Expensive operations for an inexpensive engine.

I would suggest double nutting the threaded tube and then while gently securing the spraybar/disc, see if the threaded tube will separate. I would carefully clamp the disc around it's outer edge so as to not mar any of the critical surfaces. Someone else earlier suggested this.

Good luck.