captinjohn

You can also have a needle with different taper to change fuel richness. I have a rotating barrel carb with a screw down the center...which has more of a effect than you think it may have. Just takes several turns. Capt,n

jtisch

Very successful today.
I finally got my drill bit set and drilled out a main jet to .039mm(stock is .038mm), and got a very steady 6000RPM top end on the 20x 8 Zinger with no choke and it would idle as low as I wanted (although under 1600RPM it starts to shake more than I like). Best of of all the transition with very smooth. It's amazing what difference .001mm will make. Top end was down a little (100RPM) but the high humidity today might have had something to do with that.
Speaking of high humidity, the past couple of days have been rather rainy so I went to the library and checked out the Model Airplane News back issues. In one of them was a review of the Fuji 34cc 4-stroke. According to their review, it swung the same 20x8 prop as my Briggs 40cc at 5650RPM! So needless to say I am pleased with the performance of this Briggs. Also of interest was that the Fuji was capable of swinging 22 and even 24 inch props. I think a 22x6-10 prop on The Fokker DVII would really pull it around nicely and I am going to order some larger props to see how they perform.

J

Prop Nut

My Feedback: (3)

Make sure you have 11 inches of ground clearance between the prop hub and the ground when the plane is sitting level.
I am pretty sure you do, but I anot running out into the rain to my shop to measure :P

jtisch

captinjohn, Thanks for the tip. That may be more work than I have the tools and talent for though! It seems to still be running really well with the .039 jet, so for now I think I'll leave it be.
Propnut, prop clearance seems to be OK. I wonder if BUSA lowered the gear height a little. I know they widened and lowered it on their DRI, but I can't tell by eyeballing the DVII. My Father's DVIII (not a BUSA)also has lowered and widened gear.

Here is a picture of my cut down muffler.

J

jtisch

Sorry, took a break to watch the Seahawks.

Anyway, regarding the muffler, I cut it right outside the seam in the middle and then ground it flat. I want to put a plate on it and then a tube(or pipe) near the back, close to the scale exhaust position. So let me me ask you guys becase I don't work with metal much. Can I (or should I):

A. JB weld the plate and tube in place.
B. Use solder,solder flux paste and a plumbers torch.
C. Take it to a welder.

Thanks again to everyone for their help.

J

Ralphbf

My Feedback: (27)

The only real answer is take it to a welder.

Here in California it will cost you at least $20.00 to get it welded.

Shop around there are a lot of guys with welders in their garage.

Flight Risk

My Feedback: (1)

J,
If you are going to a welder anyway, why not have them fabricate something from scratch, rather than trying to weld that thin tin. In the photo you can see an exhaust pipe I brazed together in about half an hour. The sound is only slightly louder than with the muffler.

FR

Prop Nut

My Feedback: (3)

This one worked well for me......used that aluminum welding stick and propane.

jtisch

Wow!, Prop nut, that muffler looks awesome.
Is the muffler made out of rectangular aluminum stock and then put together with aluminun welding rod?

I got my 22 inch props yesterday and balanced them(some of them were WAAAAYYY out of balance). When the clear coat dries I'll give tham a try.

thanks again guys!
J

Prop Nut

My Feedback: (3)

1" Square tupe stock, cut at several 22.5 degree angles and reassembled with that aluminium welding stick that you use with a propane torch. You see guys selling them at craft shows and toledo. They are welding pop cans together.

subarubrat

My Feedback: (1)

My brother welded a Subaru alloy wheel and a cyc head on an EA82 engine and both were fine.

jtisch

Here are some results with different props. Note: I guess I wasn't paying attention when I ordered the Zinger props because I got some Zinger Pro props when I thought I ordered the regular Zingers. However, this may turn out be a good thing!

Zinger 20x8 (Regular) 6000 RPM Same as before.
Top Flite 22x6-10 4900 RPM The engine didn't like this prop (it was on the road to overheating). It was too much of a load.
Zinger Pro 20x8 6300 RPM Very nice. This will probably be my prop choice for first flight.
Zinger Pro 22x8 5300-5400 RPM Didn't seem to be overloaded (no overheating), but the RPM drop was more than I would like. I may try
it in the air after initial flights.

It seems to me that the Briggs doesn't have the torque of the Fuji but will out-perform it when allowed to rev up a little more.

J

NM2K

My Feedback: (14)

I wish you could write up a brief synopsis of your technique and publish it here on RCU. I tried it once with propane and didn't have any luck at all. Modesty aside, I'm usually pretty handy at this sort of thing. That was a humiliating experience. <G>

jtisch

I think I will eventually try making up an aluminum muffler like Propnut's, so I decided to give the JB weld a try. I don't know how long it will hold together, but at least it didn't melt when I ran the engine today and it will fit inside the plane.



J

captinjohn

How lite can the Briggs 4 stroke be made with electronic ignition.....anyone? Thanks Capt,n

jtisch

I weighed my shaved down flywheel and the magneto and they came to 1 pound. A C&H ignition is 6-7 ounces with the battery, so weight savings would be @ 9- 10 ounces.

J

Prop Nut

My Feedback: (3)

Looks good J

Kmot

My Feedback: (24)

Hey fella's. Due to Prop Nut and his awesome Fokker DVII with the B&S 34cc and the videos he posted many months ago, I always had it in my mind to get one of these engines and convert it. I received my engine today. I have already stripped a lot of the stuff off. But I have a question: The flywheel has those two studs with the starter pulley hooks on them. How are they removed? Are the pins pushed in? Threaded in? Etc....

BTW, I read as many posts and threads as I could on this engine. Someone commented the 40cc version is lighter due to it being the same case with a larger bore. Actually, it seems it is the same bore with a larger stroke, according to the B&S manual. Another person posted it has an oil pump. It does not. I opened it up and it is a splash system. Although, it has two ports in the crankcase chamber that looks like crankcase pressure goes thru them and pressurizes the outer case causing oil to rise up the slot at the bottom of the chamber and then contacting the counterweight of the crank allowing oil to splash.

For the guys that went electronic ignition, how much does a EI cost?

Anyway, I would appreciate some help in learning how to remove those starter tabs and pins without damaging the flywheel. Thanks!

Flight Risk

My Feedback: (1)

Those dang flywheel studs! I decided they were splined in there for good, so I just ground down studs flush with the face. Then I used my bench belt sander to grind down the fins till they were flush with the face also.[X(]
I would like to see how that oil system works. The same crank pressure that goes out the side and top ports would also go out the bottom. I'm wondering if the crank pressure sucks and blows, or just blows!
I still am waiting for a plane to use mine in. If someone has put their's in a SR Batteries Eindecker, could you let me know the weight and performance? Seems like I would need the engine inverted in that one. Any problems with that? I've also been looking for a Bleriot or Morane Bullet type kit or plans. Basically I want an early scale monoplane 90-100" span, <15lbs. as I'm at 6000 feet. I would probably do the BUSA Taube 90, but the nose looks too narrow. I've even thought of stripping down a Giant Big Stik and adding antique white covering with rigging and a cockpit to make a psuedo scale plane. Any thoughts on any of these?


Rod S

tim220225

My Feedback: (4)

Hey guys I posted this in the Honda 31 thread. I did a GX31 a while back. Still no plane for it but I did experiment with carbs. I drilled the case for a pulse tap and ran a WT carb so I had 2 needles. Ran great but the tube will clog after an hour of running. Found 2 WYK 2 needle carbs that worked. A WYK-61 is a 9mm carb and a WYK-137 is a 10.5mm carb. The 61 was the first and to date only one I tried. Ran a strong 6400RPM on an 18/8 Zinger prop. Instant transition plenty of top end power and a snap back to idle. Just made a flange and a straight tube maybe 6 inches long for the exhaust header for now. Putts and purrs! I intend to make a different intake manifold to rotate the carb linkage and have a larger bore for the bigger WYK-137. I also removed the compression release stuff on the cam as it will hold the vales in certain instances and cut power when you least want it to. Also run it on a CH ignition. Works like a governor it seems. May also try an 18/4 or 18/5 or a 20/5. Don't need speed but I want to increase the torque if I can for a WW! plane. Hope this helps.

jtisch

Thanks for the info!

Just to be clear(I'm sometimes a little slow), you didn't have to use the case tap(used for the WT carb) for the WYK carb, is that correct?
I just may have to get one to play around with.

J

Bill Rademacher

My Feedback: (77)

Flight Risk,

bphobbies.com sells a Fokker Eindecker kit that I have built.

I had a US 41 on it, and it performed great. It also flew with a US 25. Might work for you. Big cowl, huge firewall., It is larger than the Balsa USA model. 95" wingspan, I think.

Flies like a sport plane, a floater.

I think I still have plans if you need measurements, or a copy.

Billrad

tim220225

My Feedback: (4)

Jtisch,

The WYK series carbs are the same barrel type carb as the stock one. Only difference is that it has the extra needle. You are correct that it does not need the pulse hole. I just plugged the hole I tapped.

Tim

Flight Risk

My Feedback: (1)

Bill,
That is a real possibility from BP. It's showing as 85" compared to BUSA's at 80". Do you think it would take a 6" wide engine in the cowl (with the carb hanging out)?
They don't have a very good photo, just from below.

Rod

jtisch

Here is the 40cc in its future home.



J