I am still having a minor issue with the midrange on my new Fox 3.2. Using Amsoil Series 2000 at 50/1 , 22/8 NX prop. Sycrospark ign , not throtttle coupled like my Brison 3.2. I have tried everything from leaning the low end to where transition is lean to riching it out to where burble is worst. The problem is right around the 5000 rpm point , transition is 4,800 rpms from low to high on transition. The motor just will not smooth out until rpms are increased to around 5500 and then it is fine on up to full throttle. High end is about 7/8 out , low end all the way from 2 turns out to in to various settings of around 1 and 1/2 , ect ect ect. My Brison with the throttle coupled ign just does not have this problem i havent tounched the low or high end from out of the box. Any help would be appreciated??

My first thoughts were to take a look at the engine porting/timing, but I don't think so.

Have you pulled the plug and checked the condition? If it's ok, think about a different plug heat range. A lot of the gas we are getting around the country is not quite up to what it could be.

Bump your oil mix up to 65-1 for a tank and see what happens.

Allready bumped up oil to 64/1 no difference i am running champion plug that came with it and have tried putting in the Bosch plug that came with the Brison no difference but both are the same heat range do i need to go with a hotter plug then ??? ON the low end setting do you lean it out so it doesnt transition good then back it out rich to where it will without hestitating?? that is what i did. Thanks for the reply i dont think its a timing problem engine starts well and doesnt run irractic on high end . Oh by the way plug looks perfect medium tannish no carbon at all.

The Syncro Spark reaches full advance at 4000rpm. So your problem can be fuel, or total timing, or maybe its a new engine and isn't broken yet.

Bruce, I'm leaning more to the not fully broken in position more than anything else. The plug should be fine, and stay at that oil mix.

I don't know if the engine is on the plane or on a stand. If it's in the plane, remove the cowl and get her started. As long as the plane is positively secured, get a slotted screwdriver about 3/4 of an inch long. I like to use one of the short tips that come with a set that fits into a handle and shaft separately.

Now VERY carefully, with the engine running about 2500 to 3000 rpm, adjust the low end needle until the engine reaches peak rpm and then starts to fall off. Back up to the peak setting and either leave it there, or richen it up the width of the screwdriver blade. Whichever you feel most comfortable with.

Now, and again very carefully with the engine running at max rpm, adjust the high end needle to max rpm with a tach, then richen it up about 200 rpm. That should be pretty close.

That's how I do mine and it has worked without causing problems. If anyone has a better way, they should feel free to give it up.

Pat

Silversurfer thanks i will try and set it the way you explaned got to get me a short screwdriver to do it but sounds like the way to go, now i have just been adjusting then shutting motor down to make adjustments , motor is on the plane and has 2 gallons thru it. Runs good except for the midrange , could be it just needs some time on the motor also, i will let you know later today how adustments work out. Thanks Bruce

Ran the Fox today and adjusted as you mentioned Silversurfer and it seems a little smoother, also checked out the Brison 3.2 and it is still the smoother of the two and has far less run time on it. I think it is because of the Brison having the throttle coupled ign . It has a better idle and smoother transition all the way around. The fox is better than it was however and maybe will just take some more run time as it only has about 2 gallons thru it at the most.

Glad to see your getting some improvement. I had just come over here to send you a PM to check the situation out. I have to agree with you about the mechanical ignition and advance on the Brison. I have both the Syncro Spark advance and the mechanical advance. Power differences are non-existant, but there are minor differences in throttle up. I also believe the mechanical is smoother, but then the actual advance range of the ignitions are a little different.

Once again, I'm happy to see you getting along a little better with the Fox. I think that a combination of run time and some very small high end adjustments will bring everything into order. No more than 1/4 turn either way.

Since I forgot to mention that all the adjustments with the engine had to be done from behind the engine, without reaching through the prop, and that you have two new posts, hopefully using ALL your fingers, I can presume you kept out of the way of the prop? I was really worried about that>

Pat

Thanks for your concern Pat i have been running these gassers for 15 years so i know about the safety issues for sure , but you can never be to causious. I will flying the fox today on my Sig Suk and the Brison on the Texas Hurricane , so anyway i agree on what you said about the differences in ign> I might possibly send my fox to Gary at Brison and have him install the manual ign back on the Fox, i could have ordered it that way to begin with but chose not to. There is a difference. Anyway thanks again. Bruce