CB36

Hi all, my troubles with my Fuji 32ei continue. I posted awhile back about hard starting and due to weather, I've not had much time to try the remedies suggested; I closed off the hole in the choke plate, "bumped" many times @ TDC and got it going.

First, at an idle around 1,800 rpm, the tail shakes from vibration so much, it's a blur. The Giant Supersportster has weak tail issues to begin with, (I am using flying wires), but this is really bad vibration! Advancing the throttle smoothes things out real well, but I'll have to land at some point!

Second, after shutting off, it won't restart without a couple of bumps with the choke on.

I'm still using 25:1 oil mix, prop is 18x8, wood. The motor does not have a lot of time on it yet.

What can I reasonably expect from this engine? Will the idle smooth with time? Will it smooth with less oil? Why won't it restart well? Is rough idle characteristic to gas engines? Does it need a carb rebuild?

Sorry for so many questions!

Help?

captinjohn

I would buy a Frank Bowman piston ring for it. That will make the break-in fasterand all around running a lot better. When you get the ring.... I or more of uscan guide you through the install & the way to tune your engine. Mean-time go to the engine conversion thread and read about Franks piston rings. Capt,n

flyinwalenda

My Feedback: (5)

I second the Bowman ring . [email protected]
Otherwise, did you balance the prop? Was it really out of balance?  I would try another prop first, maybe an APC and see if that improves things a bit. At TDC make sure the prop is positioned around 2& 8 o'clock.
Is it timed correctly or did you alter the timing?
Does it easily draw fuel when choked or does it take some time? Did you make any low or high speed needle adjustments on the carb?
On a side note, I have a G-38 that was a paint shaker and it was odd as the others I had were smooth running. What I had to do to smooth it out was unbalance the prop with a heavy end and position the heavy end opposite the crankshaft counter weight. Hopefully you don't have to do that.

CB36

Thanks for the replies!
I decided to do the "easy" stuff first before getting into removing the piston and changing rings. I will probably do this though.

Here's What I did:
1. Removed the carb to see if there was an air leak due to too long bolts. There was already a spacer under the carb bolts, but it looked like a close call, so I added a washer.
2. Removed the cover to the diaphragm to see if it was stiff; it wasn't.
3. Balanced the prop.
4. Tightened the flying wired on the tail.
5. Installed the wings for the test run, (didn't have them on for the last run), hoping to add dampening.

Results....it ran MUCH better! I have no where near as much vibration at idle. I tweaked the needles and have a pretty good idle @ 1600- 1700, ( a bit of a waver here). Midrange, (~4000 - 5000), there's a surge of about 200 rpm. Transition is good and top end, (7800), is good and steady.

I still have to choke it for a couple of bumps at compression to restart. I don't get that.

I really don't know what caused the improvement, but I'm not complaining.

Comments/suggestions?

flyinwalenda

My Feedback: (5)

How much was the prop out of balance ?
When you took the carb off did you remove the pump diaphragm cover(the one with one bolt) carefully lift off the pump and see if there is dirt/gunk inside? Same thing with the metering diaphragm cover(4 bolts) and look for dirt/gunk in there?
Is there a fuel filter inline?
Dirt/gunk will cause surging ,lean conditions and rough running.
Can you view the fuel line when trying to start and see if it is drawing fuel? The fuel should still be in the line and should move quickly . If it has gone back to the tank then something else is up.
Did you check the tank and lines for leaks?
.

Kimhoff

My Feedback: (22)

Low end it too lean.

CB36

The prop only took a couple of mists of lacquer to balance.

The output line of my gas can has a filter, so the gas is clean.

All the tank lines seem to be tight.

I checked the timing, (it's a C-H ignition, I ditched the Fuji ign first thing...too much RF), and it's 29deg BTDC.

I was surprised at the last post regarding the too-lean low needle. I would have thought the low needle is out of the picture by
4000 rpm? No?

Does anybody think the 25:1 mix I'm using is having an effect?

I'm hoping to fly the thing next week, as the temps around here are supposed to warm back up to the upper 40's.

Thanks for all the help with my first gasser.

tkg

My Feedback: (1)

The low needle is ALWAYS flowing, even at WOT. The low needle also controls the mid range jet.

flyinwalenda

My Feedback: (5)

Very true. The low speed needle is active throughout the throttle curve. An engine may sound , and pull good but you can be amazed what it takes to get it running really great. Lot's of back and forth with low and high speed settings and of course once you get it set you don't usually have to touch it again for a long time.
Also even though you have a gas filter on the can, dirt can still make it inside the carb. It's like one of those life mysteries...how did that happen ? Best to check and make sure it's all clean inside.

dirtybird

My Feedback: (5)

Those filters made for glow engines are not fine enough for gas.

CB36

The one I found on the Tower site says it's for gas, glow, and diesel. http://www3.towerhobbies.com/cgi-bin...&I=LXK837&P=ML

Will this be OK?