Chainsaw Repair

Here is my John Deere weed whacker 30cc. I bought it new as a short block from the local Homelite dealer. I have no clue as to the origion of the flywheel. I broke the fins off with pliers and cut down the stubs with a A11 burr in a small die grinder. I balanced it with the aide of a model airplane prop balancer. The carb is from a Red Max. The Plane was a Bridi Old Timer Kit.



The following is a Makita 3.2 saw engine that was converted to be a model airplane engine. The plane is a Bridi Big Bee Kit.

The engines in the pictures are not hopped up for the very reason you mentioned.

The Homelite 30 runs 7500 rpm with a 18 X 8 prop and the Sachs/Makita 52cc runs 7,000 with a 22 X 8 prop.

Any more rpm and you get the prop buzz.

The boat engines can run high rpm so it is not unusual to see 15,000 with a racing boat engine.

The boat engines also run the single apex cone pipes.

Would'nt that sharp bend right at the engine kinda defeat the benefit of the expansion pipe?

I dont think so. Becuase the one on the MVP166 piped racesaw. Bent right and did a U straight back to right side.

Here are some pictures of my Brison 3.2 model airplane engine. It is made using the P&C and rod from a Dolmar 111. They even use the same Walbro carb that comes on the straight 111, the WT76A. They have a CNC crankcase and their own cantilever single ended crankshaft. Mine has a fixed timing ignition module. The ignition timing sensor is mounted on a nylon ring that is controlled by an extension of the throttle rod. The timing is 2 degrees BTDC at idle and 28 degrees at full throttle. Some of them have a automatic electronic advance on the timing. It uses a 22" diameter prop with  8" pitch. It runs right at 7000 rpm at full throttle on the ground. I also have a twin one of these that is a 6.4 size. The carb intake ports have a plate over them and the crankcase has a vee shaped reed block and single up draft Walbro.











Here is a manufacturer's picture of a 6.4 twin. Mine has a blue anodized case.