Checking/Setting timing on GT150

[badss350]

My GT150 is not turning up the RPM that it should..only getting 5100-5200 WOT with nose in the air and sitting on back pad...its on a 18ft Charger with 6" jack plate...could the timing be an issue with it not turning up like it should? has all new plugs, filters etc..and I belive the CDI box was recently replaced as it looks brand new...the motor was rebuilt not long before I got it....have heard some shops will "detune" and engine after a rebuild...So how would I go about checking the timing, and if needed, setting it? Sticker on air box says should be at 28 BTDC...do I check it with timing light like my truck? Flywheel has markings for #1 & 2 cylinders...

 

[tashasdaddy]

Re: Checking/Setting timing on GT150

year ? Model #?

 

[badss350]

Re: Checking/Setting timing on GT150

91 Gt150

 

[jonesg]

Re: Checking/Setting timing on GT150

nose in the air sounds like a trim problem.

 

[emdsapmgr]

Re: Checking/Setting timing on GT150

The timing should be set according to the label on the airbox-in this case 28. Set it at 5000 rpm in gear, under load. You can set it on either #1 and #2. Best to set it to the lowest spark advance between the two, at 28. Did the engine ever run higher rpm with that prop? Are you sure you are running the correct prop? The normal operating range for that engine is 4500 to 5500. Current thinking is to prop the rpm's to the upper end of the normal range, 5500, even up to 5700. You are not that far off now, perhaps just one prop size too big. Factory replacement power packs have rev limiters at 5800.