I just received my engine back from repairs (bad piston) and now it doesn't want to start....Can't figure out what the purpose of the nipple on the right (brass colored) is for (vaccum?) and if so, where does it lead?

It's just the breather for the diaphram, nothing gets hooked up to it.

Thanks....now for my other problem......carb problems.....see: http://www.rcuniverse.com/forum/m_11443096/tm.htm

Hi Tailskid
3w reeds last for years there a really strong engine,but when they need changing its wise to replace the reed carrier its only plastic and they crack down the center,don't rush the refitting ,allsofit a carb trumpet every drop of fuel will get sucked in,and youmay needto lean the bottom end ,I had exactly the same problem engins great now .

Good Luck

flyingjohn, I will have to give that a try....guess I will have to go to AI for those items....

Check for ignition first, there are many threads here on how to do this, if you have ignition try putting a little gas in the sparkplug whole and see if the engine fires then.

Yes the engine will run - but gets very hot! We can pour gas directly into the carb and lately it has been actually starting (with the help of a starter).

I've just been back yard running my two 3w-50i motors to make sure they are working before I put them in a plane. Both carbs were bone dry and I had to take the diaphrams out and moisten them before they would draw fuel. 3W also recommends sealing the carb block to the crankcase with anerobic sealer. I've got both running now but one is missing at full throttle, and is about 300 rpm less than the other. Anybody got any ideas? I've already replaced the plug and cleaned the carb screen.
Sam

Sam, can you take a picture or two of your carb? I was wondering if it is the same as mine....

Jerry

anerobic sealer? what and where do you get that?

Try swapping your battery packs first,then ignition modules, then carbsfrom one engine to the other.
You may need to rebuild the carbs if they are old, do the diaphrams feel supple?

http://www.permatex.com/products/pro...sealant-detail

Your local auto shop should have it

Jerry,
Here is a pic of the carb on one of my 3w-50i motors. I've converted both to run on RCXEL ignitions, and when I test ran mine, I used the same ignition, battery, tank, etc. i just switched the engines on the test stand. Getting the motors to pull fuel has always been a problem until they were "wet". My first big breakthrough came when 3W suggested I use that anaerobic sealer. The second was when I just bit the bullet and took the diaphrams out and put gas on them and then reassembled the carb. If you're drawing fuel you should be able to see the fuel move down the fuel line to the carb each time you swing the prop. I've also heard that you can "bounce" the prop against compression in a back and forth motion and it will activate the fuel pump enough to pull fuel to the carb. Hope that helps,
Sam

I've converted both my engines to use RCXEL ignitions, and on my test stand I was using the same tank, battery, and ignition. I just swapped out the motors. I'm thinking I should check the timing on the engine that was missing. The more I ran it the better it got, but the missing plus the slightly lower rpm (same prop) have me thinking it's the timing or the carb.
Sam

Just a quick update on my "missing at full throttle" issue. I checked the timing on the ignition and found that it was about 45 degrees BTDC! I don't know how I could have messed it up that bad but when I reset it to 28 degrees it ran great. I also pulled the carb block and found that the anaerobic sealer had pretty much disappeared, so I cleaned the surfaces and reapplied the sealer. I also found that the carb was not wanting to close all the way which was making the idle fast and tricky to adjust. I loosened the screw that secures the butterfly and then fully closed the carb, setting the brass disk in the center of the opening, and it now has full travel and seals great.
On the test stand the motor pulled fuel by "bouncing" the prop back and forth and fired right up. At full throttle it ran perfectly, and after tweaking the needles it transitions and idles well, as well as stops when the carb is fully closed (by the OEM spring). Also the RPM is identical to the other engine now.
It is a rare day when something is attempted and something is accomplished! Jerry I hope you get your motor running good.
Sam

Sam, thanks for the post. It's always good to find out what causes all these problems we have to contend with. Dan.

I can't get my engine running...so back to the repair shop

Ralph here it comes....

Jerry