1200SportsterRider

Thanks Gary, Lonnie and phone chatted last pm and he also made that suggestion, I'll try to contact Dan and possibly work something out, Dan and I have traded a part or two over the years and he repaired an older CHI for me. I'll PM him first.

1200SportsterRider

WR posted this on 10-05-2005, we discuss this every now and then.

Picture by William Robison. 2005

1200SportsterRider

Lonnie, this per our phone conversation last pm. interesting stuff.

er compression rations also promote better breathing and allow more benefit from a larger carburetor. Note the highlighted section below.

Quote:
Originally Posted by SrTelemaster View Post
Over the last few days I had the opportunity to test performance of 4 different versions of FA-180 engines, all burning 15% Cool Power fuel lit off with CDI. The initial advance setting for the spark was 35* BTDC. A Dynathrust 18X8 propeller was used for all tests.

The base version was an otherwise stock FA-180 with CH-Ignitions CDI.

A few days ago I did a baseline pull of 7800 RPM. This was off about 200 RPM from the best previous performance of this engine. Cold damp weather was obviously putting a damper on performance. I also did a control pull with my 12.7:1 high compression version FA-180 with the 12mm Big Bore carburetor, ported intake manifold & Bowman ring set up with .002" end gap. That engine pulled 8400 RPM with the same propeller.

Since those test runs, in the stock engine, I installed a Bowman ring on an FG-57T piston with the end gap set up at .002" just like the high compression engine.The FG-57T piston has a .016" taller compression height to maintain the same 3.4cc combustion chamber as an FA-180 in the FG-57T engine that utilizes the bore of the FA-180 on the FA-150 based stroke of gas twin.

The taller FG-57T piston in an otherwise unmodified FA-180 results in a compression increase to 10.7:1 from the stock CR of 9.6:1.

Here are the results:

Stock FA-180 CDI---7800 RPM

FA-180/FG57T piston 10.7:1 CR---8050 RPM

FA-180/FG57T piston with 12mm carburetor/manifold--- no performance gain

FA-180/.035" case deck reduction 12.7:1 CR---8200 RPM

FA-180/.035" case deck reduction 12.7:1 CR with 12mm carburetor/manifold---8400 RPM

The fact that the 12.7:1 CR engine pulled the same RPM as it did on the day that the baseline test with the stock FA-180 CDI validates the comparison of the data from the 2 different test sessions.

Conclusions:

The CR boost to 10:7:1 using the FG-57T piston with the Bowman ring was good for a 250 RPM power gain.

Although the 12mm carburetor/manifold is good for 200 RPM withe the 12.7:1 CR engine, the breathing ability of the modest 10.7:1 CR was not improved enough to benefit from the improved induction.

Increasing CR from 10.7:1 to 12.7:1 resulted in another 150 RPM gain.

The 12.7:1 CR improved breathing to a point where the 12mm carburetor/manifold induction improvement resulted in another 200 RPM.

The FG-57 piston is an easy "plug & play" modification that is a simple bolt on modification that does not require any clearance checks.

I will tear down the engine with the FG-57T piston to have the case deck reduced by .020". This will have the same result as reducing the deck by .035" with the stock FA-180 piston. The CR will be increased to 12.7:1 but valve notches will have to be checked & most likely clearanced. I will also port the manifold & employ a 12mm carburetor.

Jesse Open

Dave,
If those are big block cams, they came fitted with different tappets as well. The tappet radius is a factor in the lobe profile.

Glowgeek

Dan did some interesting experiments back then, many successful ones. The larger bore carb was indeed an effective compliment to CR increase on his 180. I saw similar results using a 100 carb on my modified HC 82 however was not pleased with how it ran in the midrange. It's not all about peak power after all. I ended up using the stock carb and Gary's custom high flow muffler. Much better behaving engine with that combo.

Jesse Open

Jim,

A few years ago our friend Pedro sent me a busted up cylinder to do a cutaway of the valve pocket area.

This is a 65 with cast in, bronze seats. Hard to see in photos but looking closely, in person you can see the tooling paths. It looks to have been finishec with a form cutter that made the throat, top and seat in one or two cuts. I am pretty much finished with the thing so I will drop it in a box and tell the lol mailman to take it to you. Maybe help further your salvage efforts LOL.

enyhoo keep ur eyes open, it should be in ur paws by Christmas .

the Wasp

My Feedback: (1)

I didn't think about it before. but I was looking at my 91 cylinder today. the 91 I have is not a true Hemi. it's chamber is more like a Chevy small block. did the newer 91s have a Hemi chamber ?

Jim

the Wasp

My Feedback: (1)

Lonnie, you say your Hot 82 had been finicky in mid range at times. here is something new for you to try with it. try changing the length of it's Intake Manifold. longer produces more torque, and shorter produces more RPM. I say try lengthen it first.

Jim

1200SportsterRider

Captain Crunch to the rescue, a 150 cylinder is on it's way and a big thankyou goes his way. The RMJ ring is already here.

Jesse Open

Dave,

Should I toss your favorite muffler into the box that is going your way this week? Should be swell on your newborn 150!

Classic old salt shaker muffy.

1200SportsterRider

Sounds good, I can polish it up in the lathe. Thanks a million.

PS, I already have the elbow.

Jesse Open

Fine Bizz,

You are all set then. I will toss a pair of new lock nuts in the box.
Also, a special pipe that I hope you will keep and use. A "Merry Christmas" keepsake.

1200SportsterRider

Thanks again and more.

Jesse Open

Dave,

Have a fine Christmas. Memories are richness beyond gold.

FlyerInOKC

My Feedback: (6)

I made a discovery this pass week. I like to use Remote Glow Plug Adapters on aircraft with the engine located in a cowling or the glow plug is hard to reach. It saves propeller bites. I discovered Hanger 9 (Horizon) had some still available on Amazon.

the Wasp

My Feedback: (1)

any one notice something in those FA65 pics above. the Valve Guides are not presses in, I can't remember the term they use to call that, but they are casted in. then machined

Jim

1200SportsterRider

Jim, that would be interesting to know more about.

El Capitain is sending to me a a 300 T-L to freshen up. I am learning some 270 and 300 facts while trying to help this gent: Backplate on Saito 300 twin

Jesse Open

Jim,

My bad, that is actually a 50 or 56 cylinder.
The valve pocket is bronze, not brass and yes, it is cast in place. Look carefully and you can see the brass edge of the cylinder in one shot too.
The valve pocket is probably pre machined or at least partially machined befgore casting in place.


Dave, The 300T is a blast to work on, one of my favorites. You may find the factory instructions on cam timing are a bit ambiguous. Remember it is an even fire with dual and the timing is different from the odd-fire Saito twins

1200SportsterRider

Thanks Gary, I'm looking forward to it and the Christmas box. I hope it has good cams.

the Wasp

My Feedback: (1)

some good info here, hope it helps if needed
Jim

FlyerInOKC

My Feedback: (6)

Great video!

Jesse Open

Just as long as no motorcycles are involved.

the Wasp

My Feedback: (1)

what?? not even the 70+HP 700cc 2stroke dirt racer

Jim

Jesse Open

Especially two strokes!

Hyjinx

Happy Christmas all youse guys eh!
Let's Go Santa