A guy at my field had a similar problem. The plug cap wasn't making good contact. He found that a pen spring in the cap solved the problem. K.I.S.S

It turn's out I didnt build the carb right. I didnt use the right gaskets. In the kit I got there were two extra gaskets and I used the wrong one. I hooked up with an expert at my club. He was nice enough to take a look at the plane so I brought it over to his house this evenining. It litteraly took him a couple of minutes to straighten it all out. Since I also replaced the piston ring I'm going to run her rich for a couple of tanks while I break it back in. I cant wait to take her up. She pur's like a lion.

Took her up today. Wow what a dissapointment. I must not have it tuned right as she really underperformed. Somehting not right. Anyone good engine tuners ou there than give me some good points on how to tweak this motor? I thought I had her all dialed in but she keeps sputtering in the mid range. She transitions fine to wide open throttle and she seems fine when in WOT but in the low to mid range she sputters or skips a beat. Not sure. I started with needle H 1.1/4 turns out and H on 1 1/4 turns out and ran it up WOT and tried to adjust based on RPM is this the correct procedure? What do I need to do?

On a positive note. Engine did not die on me mid flight using same old battery.

Did you do anything with the low speed needle?

I richened it up about a blade's width of a screwdriver so I went counter clockwise.
I'm going to start over tomorrow anyone have any pointers?

Fire up the engine and go to wot..Adjust the H needle for max rpms. Then go to idle and adjust the L needle until it doesnt sputter...There is a link somewhere on this forum about tuning a walbro carb and thats how they say to do it.

I switched from Mobil 1 racing 2t motorcycle oil to Redline two stroke racing oil last year and I can tell a difference, all of my gassers run better.
Does your ignition have a timing feature? Mine is set for a pitts type muffler, I have another Evolution that the timing is set for a tuned pipe.
Also, there should be a lot of gasser at GMA that could help. Out of 5 gas ingines, the Evolution 58 has been the hardest to adjust, but it has a lot of power and it was work all the time and effort.
How do you like the Bisson muffler? Any problems with the muffler bolts coming loose?

Thanks,
George

How do you set the timing? I know there are 2 screws that hold the sensor in place. Do you just play with the adjustment until you find a happy point for it?

http://www.horizonhobby.com/ProdInfo...L_Addendum.pdf

http://www.horizonhobby.com/Products...2#quickSupport

The only thing in all that manual stuff is to locate the magnet at 240/120

One of the guys was very helpful from GMA he rebuilt the carb for me and when we tuned it. It all seemed good but the next day when I took it to the field and flew it we noticed a lot of sputtering in the mid range. I'm going to reach out to a couple of other fellas at the club and see what they have to say. Most of the guys at GMA wont touch anything but DA. So it's hard to find anyone that wants to mess with this.


I found this guide from a little gas engine shop in indaina or something liket that and they have some good advice:

Let's tune up a Walbro!
Set the lowend & highend needles to about 1 to 1 1/2 turns each. Choke the carb or prime it, until the carb is wet. Fire up the engine and let it warm up. Let's set the topend first since it's the easier of the two. Go to full throttle. Adjust the topend needle for peak RPM. Leave it wide open for about a minute to see if it changes any. Should the engine go lean, open the lowend needle slightly, if this dosen't work... you will have to adjust the needle valve inside the carb.( I will explain this later) If the topend runs OK, then slowly pull the throttle down until the engine begins to "four cycle" hold the throttle there. Adjust the lowend needle until the "four cycling" stops. Now lower the throttle more until it "four cycles" again, and adjust the lowend again. Keep doing this until you reach full idle. Now, from full idle begin to throttle up until the engine starts to bog or hesitate. Open up the topend needle just enough to eliminate the bog or hesitation.

When this is done right, you will be able to set the throttle in any position and it won't four cycle, plus you will be able to transition from idle to full power without any hesitation at all.
1 1/2 turn out on LOW and 1 turn out on HIGH