Just a quick question...

I need to bore the stock carb spacer block to match an 11mm carb. The hole is 1/2". 11mm is about 9/16". I don't have a 9/16" drill. Can I bore the block bigger, say 5'8"?

Thanks for replies.

EERRiiicchhhh.. (Brake sound)

You really don't want to try to drill out the carb spacer. There is a VERY good chance the drill will catch, and destroy the spacer. I just use a sanding drum in a Dremel tool to ream mine out... only takes a few minutes, as the material isn't very hard. You want the spacer to have the same size hole as the outlet of the carb. Also, if that makes for a step where the spacer fits to the intake port, you need to blend the step out as it will be an obstruction to flow.

Good luck,
AV8TOR

Thanks AV8TOR.

I guess then the hole doesn't have to be perfectly round? I hadn't thought about the port side of the hole. I would have enlarged it all the way thru.

Another question.

I've done the porting mods on the intake and exhaust ports following the directions for blueprinting the engine and modifying the ports from the 0catch website, but the transfer ports on my Homelite 30cc are different than those pictured on the Old Homelite and New Homelite instructions.

Both transfer ports are divided by an isthsmus so it appears there are 4 transfer ports. This is a fairly new engine, less than a year old. Is the web information out of date? To make mine look like the pictures, I would have to mill out about 3/8" of material the entire height of the port

I use a dremel sanding drum in a drill press and slowly feed it through the carb adapter to increase the dia of the bore. Seems to work. Drilling seems to crack em....been there. Capt,n

sorry for the teeny tiny image.

Try this.

They do pretty good with the stock block not opened up when using a 11mm carb

I try to make the holes the same size.

I enlarged the hole in several carb blocks by chucking a drill in the drill press and turning the chuck by hand while feeding the table up by hand. The material is soft and cuts easily. After the hole was to size I then put a Dremel bit in the chuck and powered up the drill press. The block was maneuvered by hand for the Dremel tool cutting.

Bill

I would leave the transfer ports alone, except for raising them to get whatever timing number you are after. And even at that keep the original angle in place.

To the best of my knowledge, yes, there are 3 transfer port designs and you have the newest. I have a Homey 30cc that I hopped up, and it turns an APC 16 x 8 prop at 9400 rpms. Not bad, and it has the oldest transfer ports. I bought a couple of cylinders with the larger, second design transfer ports, but still haven't gotten around to trying them.

If you end up making your carb adaptor opening so large it breaks into or gets too close to the pulse hole, you can close that hole with epoxy and run a pulse line from the block to the carb itself.

Have fun,
AV8TOR

All this stuff about opening the transfer ports and boreing the carb. spacer sound's good but I'm thinking of leaveing mine pretty much as is mabe till I have more experiance with theses engien's.

I just did a Homelite 25cc for a student. The only tricky thing we did was add a pin to the piston, use a Frank Bowman ring made for use with a pinned piston, and then ground out the bridge in the exhaust port. A gutted carb with two large outlets and a 11mm carb were added. Stock magneto ignition. It turned an APC 15 x 8 prop at 9000 after only one tank of fuel. That would be about 8200 or so with the more normal 16 x 8 prop. Not bad for so little effort... If you are nervous about modifying the piston like that, Frank Bowman will do it for you for a nominal fee.

Of course the 30cc doesn't even need that done as it doesn't have a bridged exhaust port.

AV8TOR

It is a smart move to go slow until some experience is under your belt.

Bill