Kirn NVA Issues

Thanks for the replies!

I will give the body, needle, and venturi a thorough cleaning.

Hello Allen , The KK don't have to have a Bladder to run But will bee your go to for a Bladder run if you ever decide to try one . The above response should take care of ur problem , let us know .

Don't forget that these are FINE THREAD needle valve assemblies...128 TPI.....so you need to open the needle about double the number of turns you would with a standard Cox TD 049 needle assembly-which for the latter is about 5 turns open for starting, from memory....so with the KK assembly, all things being equal...ie clean and no blockages...you could expect to need it open 9-10 turns for starting (NOTE-I'm talking suction feed settings here, not pressure!)

So if you only opened it the usual number of turns-the engine would not draw enough fuel to run-so runs out the prime and stops. In standard form, these KK assemblies had a small cylindrical nylon seal that abutted the brass body to act as an airseal on the needle OD. These did wear and leak-and quite a few users simply replaced them or supplemented them with a short length of silicone fuel line over the needle and the needle inlet-exactly as yours has.  Part of the problem is caused by quite a long needle valve overhang-which accelerates the wear-hence the original seals often wear out, letting air in-which is bad enough on suction-and far worse on any pressure system.

As a bonus, the piece of fuel tube also helps the locking effect of the seal, so the needle valve usually stays where you set it, without creep.   One final thing to check-these needles are only brass-and relatively easily bent in a crash-so if your needle is bent that might well affect the way it adjusts-though any bend is likely to occur where it exits the metering block; likewise check the very tip to see that it is not bent or burred (unlikely-but not impossible....)

Normally these are good units-and virtually all my TD 049s/051s are fitted either with these or the Ace R/C unit-which is effectively the same but with a plastic rather than brass body.

ChrisM
'ffkiwi'

Cleaning done. I will get the TD back together and give it a go later this week.

If ever needed,  Cox international has the black plastic NV seal

https://coxengines.ca/cox-.049-.074-spray-bar-seal-10.html

fredvon4 wrote:If ever needed  Cox international has the black plastic NV seal

https://coxengines.ca/cox-.049-.074-spray-bar-seal-10.html

It's always a good idea (just in case), after cleaning to replace gasket/seals. Most common place for leaks.
That black plastic NV seal gets hard and brittle. that's why you'll see a piece of fuel line over the NV and black seal.

sosam117 wrote:

fredvon4 wrote:If ever needed  Cox international has the black plastic NV seal

https://coxengines.ca/cox-.049-.074-spray-bar-seal-10.html

It's always a good idea (just in case), after cleaning to replace gasket/seals. Most common place for leaks.
That black plastic NV seal gets hard and brittle. that's why you'll see a piece of fuel line over the NV and black seal.

Yep. Looks like I may need to place an order or two for parts. I have a few reedys that need some attention, too.

Got it back together. Another issue that I found was a crack in the carb/venturi body. I'm going to take a shot at firing it up soon. Had family happenings this weekend.

Spins nice and has good compression.  Going to give it a drink of Sig Champion 25%.

Aero wrote:Got it back together. Another issue that I found was a crack in the carb/venturi body. I'm going to take a shot at firing it up soon. Had family happenings this weekend.

Spins nice and has good compression.  Going to give it a drink of Sig Champion 25%.

If you have problems with the crack, clean the engine well (alcohol or acetone?) to remove any oil residue.
Then using JB Weld, try to push the JB Weld into the crack.
It's only a temporary fix.
It is better to purchase the aluminum venturi body from our Cox vendors.

In a thread Mauricio made a ring to fit on a cracked venturi. However I couldn't find that thread.

That’s a different engine than what was originally posted. Either way I prefer the plastic carb bodies vs the aluminum ones. Air leaks between the aluminum carb body and crankcase were problems on the ones I tried. Maybe the newer aluminum ones addressed that issue.

Jason_WI wrote:That’s a different engine than what was originally posted. Either way I prefer the plastic carb bodies vs the aluminum ones. Air leaks between the aluminum carb body and crankcase were problems on the ones I tried. Maybe the newer aluminum ones addressed that issue.

Jason,
I use the "black" Permatex (very small amount using a toothpick to apply) on either end of the aluminum carb body and have had no problems.
The black Permatex is rubbery and stays that way. I've used it on PAW mufflers to seal the muffler to the head without any leakage.
Nice thing about the car body is that it tapers, so you can get the sealant on the crank case then slide the venturi body up into place.

Levent Suberk wrote:In a thread Mauricio made a ring to fit on a cracked venturi. However I couldn't find that thread.

Here I am friend, I will share photos again.
The previous thread is in the forum, but I have not looked for it ...






ring made of aluminum alloy, filed and adapted by hand, glued with epoxy.
Definitive solution, you will never have problems again!
You can do it in bronze too ... I have done it and it gives a very good appearance, especially if the crankcase is black!

here you have an engine Tee Dee .049, to which I made the repair of the crankcase with an aluminum alloy ring and I also made a bronze acceleration ring!

The original carb body was cracked and I happened to have a new black one to replace it with. I don't have much of a spare parts bin. I assumed the red and black ones were the same. I should have explained it a bit more. I will try the fixes you all have posted to have the cracked one for a spare. Sorry about that.

Just litle trick for plastiques part make them like new use wd40 it help flexibilité of matériel old plastiques part tend To dry if Not used for very long it crack in displays case just spray on part let it wit t'il its dry part gain flexibilité bad point if part is alredy crack is To late it can help new Not used engine plastiques part

Another thing to watch for is Dale made venturis with larger id for pressure fuel systems. If all is clear and it draws fuel but doesn't do it well enough to take off and flames out on take off you might check it against a stocker to see if it's oversized.
Chris...