SMALL - Telemetry SMALL - Radio
Thread Tools
Old Jul 17, 2015, 10:50 AM
3dFlyingMaster is online now
Find More Posts by 3dFlyingMaster
The Bigger The Better
United States, FL, Sebastian
Joined Dec 2014
195 Posts
Alright guys, she is running PREFECT! That pump position means the world! Bent back the diaphragm and decided to leave the pump hanging, like Earl suggested. Now if I tilt it up I get maybe 50 RPM changes, just like my Saito 100.

I am so happy with this engine. It is a great little thing once you know how to set it up. Now I have the pump hanging to the left of the engine. I tested it with the pump on the motor mount and when I pointed her up, went from idle to full. Barely any rpm change to speak of now.

Took 7 months for me to find this out, but I think it is worth it. I would buy another one of these babys in a heartbeat for my next 40 size plane.

Now I am going to fly the snot out of it till it blows up!

Thank you guys for all the help!
Chris
3dFlyingMaster is online now Find More Posts by 3dFlyingMaster
Reply With Quote
Sign up now
to remove ads between posts
Old Jul 17, 2015, 11:42 AM
earlwb is offline
Find More Posts by earlwb
Registered User
earlwb's Avatar
USA, TX, Grapevine
Joined Dec 2008
15,013 Posts
Quote:
Originally Posted by 3dFlyingMaster View Post
Thanks Earl! Going to the hobby shop today, will pick up some 8/32 fittings. Did you tap one for the back plate too? What effects would a bent diaphragm have? It is bent very little.

Thanks again,
Chris
Great, glad you got it going and the kinks ironed out.

Yeah I replaced both fittings, on the pump and on the backplate. The OEM fittings have a tiny hole inside and it acts like resistor, restricting the crankcase pressure pulses. The other thing was that the OEM fittings barely fit the tubing (maybe metric versus SAE). So going with a better fitting was a plus for me.

I am not sure if a bend in the diaphragm will affect it too terribly much. What is critical is the two little flapper valves. They work as one way valves and move the fuel through to the regulator. So if they are Ok then being bent shouldn't be a problem.

One thought since you mentioned "bend". On the regulator side, the little lever that controls the fuel inlet valve can sometimes get bent. That causes it to stop regulating of course. They made the lever out of aluminum and it may be a bit soft. I forget which Walbro rebuild kit it was, but they had a mild steel lever and it worked nicely though. But if you are aware of it, it is a easy fit to straighten out the lever if it gets bent.

One problem I had was the diaphragms tended to stretch out some with age. I think it was the alcohol in the gasoline maybe. So I had to replace them over time.
earlwb is offline Find More Posts by earlwb
RCG Plus Member
Old Jul 17, 2015, 04:45 PM
3dFlyingMaster is online now
Find More Posts by 3dFlyingMaster
The Bigger The Better
United States, FL, Sebastian
Joined Dec 2014
195 Posts
Quote:
Originally Posted by earlwb View Post
Great, glad you got it going and the kinks ironed out.

Yeah I replaced both fittings, on the pump and on the backplate. The OEM fittings have a tiny hole inside and it acts like resistor, restricting the crankcase pressure pulses. The other thing was that the OEM fittings barely fit the tubing (maybe metric versus SAE). So going with a better fitting was a plus for me.

I am not sure if a bend in the diaphragm will affect it too terribly much. What is critical is the two little flapper valves. They work as one way valves and move the fuel through to the regulator. So if they are Ok then being bent shouldn't be a problem.

One thought since you mentioned "bend". On the regulator side, the little lever that controls the fuel inlet valve can sometimes get bent. That causes it to stop regulating of course. They made the lever out of aluminum and it may be a bit soft. I forget which Walbro rebuild kit it was, but they had a mild steel lever and it worked nicely though. But if you are aware of it, it is a easy fit to straighten out the lever if it gets bent.

One problem I had was the diaphragms tended to stretch out some with age. I think it was the alcohol in the gasoline maybe. So I had to replace them over time.
Thanks! Will watch the bending.
3dFlyingMaster is online now Find More Posts by 3dFlyingMaster
Reply With Quote
Old Jul 17, 2015, 04:48 PM
3dFlyingMaster is online now
Find More Posts by 3dFlyingMaster
The Bigger The Better
United States, FL, Sebastian
Joined Dec 2014
195 Posts
Building a exhaust extension out of brass tubing. Painted with high heat Rustolem paint.

Was wondering if I can use 30 minute epoxy to attach it. Would it melt? If so, any adhesive reccomendations?

Thanks,
Chris
3dFlyingMaster is online now Find More Posts by 3dFlyingMaster
Reply With Quote
Old Jul 17, 2015, 05:48 PM
earlwb is offline
Find More Posts by earlwb
Registered User
earlwb's Avatar
USA, TX, Grapevine
Joined Dec 2008
15,013 Posts
JB Weld Epoxy is usually what people use. But you could try the high temperature silicon adhesive too. One could use aluminum solder on it. There are special solder sticks that they sell that is made from a zinc alloy and it sticks to aluminum quite well.
earlwb is offline Find More Posts by earlwb
RCG Plus Member
Old Aug 24, 2015, 07:02 AM
Leo82 is offline
Find More Posts by Leo82
Registered User
Joined Mar 2011
19 Posts
Flying buddy bought one of these lil engines and we have been tweaking it, this one took some work. Pump had crappy tooling and lots of leaking past flaps. I wet sanded it carefully but ended using muffler pressure and filing the lsn to different profile.
Runs pretty ok now.

And to answer old pondering. k20-wat kit has everything: lever, needle, axle, diaphrams and mesh.
Leo82 is offline Find More Posts by Leo82
Reply With Quote
Old Aug 24, 2015, 12:09 PM
philflyer is offline
Find More Posts by philflyer
Registered User
United Kingdom, Llantwit Major
Joined Aug 2012
1 Posts
No mid range

I bought a GT9 in February and have been struggling to get it to run properly in a seagull boomerang 2. I have read most of this forum for advice and the last few comments have been very valuable. I have moved the engine down the bulkhead so the pump is almost in line with the needle valve and now have an acceptable idle and good top end but no mid range. I have ordered a k20 wat kit now. Any more ideas?
I have also ordered larger pressure nipples used in the NGH 17cc and will fit them to the crankcase backplate and pump when I have verified the thread and bought the correct tap.
philflyer is offline Find More Posts by philflyer
Last edited by philflyer; Aug 24, 2015 at 04:27 PM. Reason: Extra info
Reply With Quote


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
For Sale Prop Chart and Thread finder for any Glow or Gas Engine unclegeorge Aircraft - Fuel - Engines and Accessories (FS/W) 2 Dec 10, 2011 11:31 AM
For Sale Prop Chart and Thread finder for any Glow or Gas Engine unclegeorge Aircraft - Fuel - Engines and Accessories (FS/W) 2 Oct 14, 2011 11:44 AM
For Sale Prop Chart and Thread finder for any Glow or Gas Engine unclegeorge Aircraft - General - Miscellaneous (FS/W) 0 Oct 07, 2011 10:46 AM
For Sale Prop Chart and Thread finder for any Glow or Gas Engine unclegeorge Aircraft - General - Miscellaneous (FS/W) 3 Sep 23, 2011 11:25 PM
Sold NGH GT17cc gas engine NIB ibcinyourc.com Aircraft - Fuel - Engines and Accessories (FS/W) 4 Jun 30, 2011 10:35 AM