There is a .6 oz. weight savings compared to factory supplied insulator.

I opted not to bother with routing a pulse port thru the insulator. Last one I drilled to midway 3/16"on beraing surfaces and then drilled intersecting holes from the sides and then tapped the holes and inserted small setscrews with sealant.

Is there a preferred location to drill and tap the case for a pulse fitting, like the type used on glow mufflers?

Rotate the carb 180 degrees, drill the G10 through to the pulse hole in the cylinder...Put the carb gasket on the G10, mark the pulse location that's now at the back...drill a 3/32 hole about 1/8 deep at that localtion..connect to the through hole with a 1/16 wide passageway about 1/16 deep...There's enough room if you don't make the passage too wide..All mine are made that way, saves making intersection holes, takes only a few minutes with a Dremel and a 1/16 ball tood....Go slow, it tends to wander....

A few cautions in making the rotated insulator. There is probably a reason the manufacture made the carb bore and the intake port just a little undersized to the opening. It was not because they had extra material to waste on sloppy engineering. Luckily one side had sufficient meat clearance. to allow a direct thru hole 3/32". The worm hole is a one slow pass. I used an old 1/16" round dentist burr depth set to cut its maximum width.

The second insulator with different engine mount dimension depicts other pit falls. No CE stuff here!
Throttle arm from a shaft collar some copper clad 'project board' Radio Shack, solder and CA. A Dubro 2-56 ball link was used. The carb return spring was too strong so I unhooked it from the throttle lever and let it unwind one turn, too loose (no tension), rotated the spring to let it anchor on another spot on carb body and trimmed it to clearance length.

A Zenoah steel heli muffler is about 6 oz with long allens, This 'diverter' attaches with M5 x 30 allens and is a lite weight. (Cut up a elecrtrical conduit box and trimmed a threaded fitting, with a 5" .625 pipe it weighed almost as much a the diverter pictured)

I would appreciate some input on making a plug for the rear case half to replace the seal when the crank gets cut off. I have the seal & bearings for reference. When making a plug seal of similar material, aluminum, should I make it the same diameter as the steel bearing? A plug with flat interior face seated against the clip decreases the case volume about 1.42cc or 5.6% of the engine displacement. From other threads I believe reducing the case volume is a benefit. Not sure just why; maybe someone can explain for us only semi mechanical hobbists.

Reduced crankcase volume leads to improved primary compression, increasing the ability of the engine to generate power and to feed the combustion chamber at higher RPMs.

Thanks Ryan, I knew there were fellas smarter than me using this forum. Haven't looked recently, can builders get Yama bond or similar from DDM?

Anyone have a preference other than Yama bond? Might as well add to the various tubes on the shelf.

We're in process of stocking it, but its not in yet...

Make the plug for a tight press fit, use Loctite and press it in....
Three Bond 1104 sealer works well, and Permatex Ultra Copper...Permatex is less messy, both seal well...I think the 1104 is what Zenoah puts on the G38 cases.....
Cut both ends off the return spring..It keeps the throttle plate centered in the bore at WOT...Without the spring pressure against the clip on the end of the throttle shaft the plate vibrates and wears out the plate and the carb bore, then it leaks enough to not shut off...

Could you give me a reference to say the diameter of the bearing. bigger, smaller, I can relate to a measurement. I do not know if you mean tight if I were tapping it in with a plastic mallet or so tight I should take it someplace with a small hydralic press and use like a socket to get it uniform pressure.

edit:
Probably would not need a sealer probably if it were a hydralic press tight diameter.

Tight for tapping in with a plastic mallet...Too tight will crack the casting...Plastic mallet tight with Loctite is good, the pressure in the case is only 5 or 6 lbs and not constant...

this is some info on yama bond and threebond 1104 [link=http://www.thesamba.com/vw/forum/viewtopic.php?t=116079]same stuff[/link]

Same install procedure for the bearings; Tap in with Locktite?

I have done this to install bearings. Warm case in oven. Cool bearing in deepfreeze or use dry ice. Take case out of oven and bearing should go in easy. May even fall in. A little locktite may be needed. Not always. Capt,n

Mikenlapaz where did you get that alum. box picture in pic #3 .

Thanks

This [link=http://image.rcuniverse.com/forum/thumbnails/41393/Gd93773.jpg]one?[/link]


Mouser Catalog 625 - Page 1439*
http://www.mouser.com/catalog/625/1439.pdf
http://www.mouser.com/catalog/625/1442.pdf

and details: http://www.hammondmfg.com/pdf/1455C1201.pdf

captinjohn
Have the freezer and a heat gun both handy to work area. I'll stop diameter reuduction at bearing OD and chill it out. I have another old case with same bearing size, I'll test on it.

Only engines I have seen with Loctite on the bearings from the factory is 3W...All others are a press fit...Chainsaws with magnesium alloy cases are the tightest, usually need some heat to get the crank out...Zenoah cranks are a very slight press in the bearings..The bearings are a tighter fit in the cases, but no heat needed, maybe heat the case with the blower...

You guys can forget about Yamabond. We tried it years ago and had ton of leaking crankcases. I think DA found this out also and they now use a gasket. Yamabond will disolve in gas and when we used it for a crankcase sealant it washed right out. The absolute best sealer for our two cycle engines is Loktite 5900 or the same thing found in some automotive parts stores is Permatex brand called The Right Stuff. A second best is permatex ultra black silicon. As for your bearing press fit it is always best to heat the crankcase and drop in the bearing. We use a propane torch to heat the case. As a manufacture we do not have time to heat every case so we use an arbor press to push the bearings in. The key is to make sure they are started straight and use a driver to fit the outer race only. Most every engine uses a .0005"-.0008" press fit on bearings. Any looser the aluminum case will expand enough during normal temperatures to turn loose of the bearing which is real bad and any tighter will make the bearing feal tight and prematurely fail. We use loctite 609 on all of our crankshaft bearings along with a press fit. If you do not have a press fit and only use loctite it will turn loose when the case expands with heat. The loctite sticks real good to the steel bearing but not so good to aluminum.

I second that

Third try and got a keeper! A little weight gain over the seal but maybe improved performance. Trimming the rear crank will give a nice weight reduction. Are plugs to replace seal available like from bearing shops?

Doesn't need to stick out past the case....

It is the same thickness as the seal, just sat it there for reference.