To any that can help:

I have an older 3w60 engine (side carb) with only about 3 hours running time on it, 4.8volt system. The low range and high range are great as well as the transition, but right around the middle, I have a "burble" or "two-cycling" sound that is causing me fits. It is running at 50:1 with no bad habits or stalls.

What can I do to fix this? I am running a 22x12 prop for my Byron Corsair and it flies great, temperature fine, no other issues.

Thanks!

David

sound like you are rich on low endbringi it in 1/16 at time

I'll give it a shot.

Any other ideas from others?

Thanks,

David

That's the most likely cause and solution for the burble.

I've had a 3w60k since they first came out (long ago !!!!). I had difficulty with the mid range burble and tried several things to improve it but it has never completely been resolved . The carb on mine was difficult to find the sweet spot for overall performance . If I leaned the low end enough to
smooth out the mid range it became difficult to start . I also was running the recomended 22/12 prop but found that the mid range improved with a 22/10 prop. I also added a remote vent tube to the diaghram cover and a velocity stack. The timing is at 28 degrees btdc. Having made these changes made it easier to tune and greatly improved the mid range burble ,but is still there around 3400 rpm . I have considered changing the carb but at this point its performance is good enough for me. Has anyone replaced their carb ,what carb did you use and what issues did you resolve ?

Vent tube? Is this a regular accesory or something homemade? Do you have a photo or more info?

I assume a velocity stack is the angled extension of the carb intake, correct? Vendors for these parts?

Thanks!

David

starwrek , The vent tube is a short length of brass tube soldered to the vent hole of the carb diaghram cover, with a length of hose slid over it . The hose is usualy routed to the inside of the fuselage .The velocity stack can be purchased from 3w ,or many other engine suppliers . The stack can be straight or 90 degrees. I don't have any pics but I am sure there are a few threads on the subject here on RCU

Got the medium sized 90 deg velocity stack from 3W. It makes my Corsair look like I have a giant O.S. 40 FP with a muffler hanging out the side. I am going to see if their small version will work, otherwise I may either try to make my own or live with the burble....

I saw one of these engine in fleabay for $200. It looked to be in excellent condition but without an ignition. Sound like a good deal?

Yes, but a little heavy. For another $70.00 you can pick up an ignition and have a good engine.

Pat,
I bought a club members old 3W-60K after he pulled it from a glider tug. He wanted a bigger motor for the tug. TF and I ran the motor and its a hoss with the 3W ignition. Well a few months later I blew the original igniton. I bought an RCXEL from Tom and installed it in a Wildhared Cap232 and wow this motor is a power house. I can understand why DA wants to come out with a 60 to compete with all the 55cc motors out now.

jds

PS - I think to stop that burble you need to install the ambient vent tube over the diaphram cover and route it to a static area in the fuse.

j

The carb for the 3W60 is Tillotson HS25

just got back from flying the living daylights out of my 3W-60K. All I can say is wow where has this motor been all my life.
23x10 bunny prop at over 6600 static on the ground. Pulls 18lbs straight up from 10 feet take off run.

jds

low end may be rich, if not and your settings are good, you may try running a larger diameter or higher picthed prop to load the engine a bit more