Wanted: 25ss Carb - KC16A

[dndsam]

Have you corrected the wire lengths on the tiny tach so you can mount it on the dash and installed the red wire 3 wraps on both plugs as I posted above? If so does it work and what rpm are you getting with your the best prop? BTW I find with my Wetback the 2 blades 7.3" x 13.3" works best for me running with prop shaft level to bottom and shaft end 5/8" below bottom. Pulling about 7200 rpm @ 63mph. I tried a 3 blade Dewald he made for a fellow boater with a 25ss on a hydro and it was not as good as the 2 blade.

Pete,
I have not done anything more with the tiny tach. Been busy rebuilding a 25ss and working on a 44ci project. I haven't had my boat out since last fall. I plan to get it out once the weather warms up, then I will have some better info for you. I do have a 2 blade 7-1/4x12 that runs well. It did not have the top end of the 3 blade, but performed better overall. I have a 2 blade 7-1/4 x 13 and 14 that I will try soon.

[ZUL8TR]

Testing

Pete,
I have not done anything more with the tiny tach. Been busy rebuilding a 25ss and working on a 44ci project. I haven't had my boat out since last fall. I plan to get it out once the weather warms up, then I will have some better info for you. I do have a 2 blade 7-1/4x12 that runs well. It did not have the top end of the 3 blade, but performed better overall. I have a 2 blade 7-1/4 x 13 and 14 that I will try soon.

Doug

The 25ss is 16.75" vertical from prop shaft center to the rear top corner of the transom bracket. To run near best top speed and be controllable with those higher pitch props you need to be in the 1/4 to 1/2" below the bottom range to the center of the prop shaft and shaft level with the bottom as a start. If the engine is strong you should turn that 13" prop at about. The 14" might be a bit to high unless you get that shaft center at the bottom or higher. At those heights the hydro is probably not very controllable due to less gear case fin in the water so be careful. My best top speed testing with a 7.3" x 13.3" 2 blade Pinner was just about 64 at 7000 with the prop shaft 3/8" below and level. Engine to high for competition circuit racing. Probably there was more speed there if higher but never tried that since ran out of transom.

With your transom at 14-1/2 " you need to add to it to have enough left to clamp on to with the 1/4 to 1/2" prop shaft depths I note.

Also I was using Champ L61Y at 0.50" gap and indexed plugs with ignition set at 39 degrees. I found the 25ss does not need high spark advance for top speed runs, factory states max 38 degrees at 6600 rpm.

Pete

[Shane_B]

What model Tiny tach do you have? ... One thing that TT tech dept told me was to wrap the red lead 3 times around each plug wire for correct rpm reading with the 1C on this 2 cylindere engine. Did that after first test with one plug wire wrapped when rpms were 1/2 what they should be?

Once you get the red lead around both plug wires cut off any extra red so you do not pick up any stray signals.

Just want to verify - the tech told you to wrap red lead around both plug wires? Do you wrapped the TT red lead around both sparkplug leads together (i.e., both sparkplug leads close together and then wrap the TT lead three times around both of them) or individually wrap the TT lead around each sparkplug lead three times? What setting did you put your TT on (180, 360, or 720 if you have that option for your TT)? Reason I ask is that I have a commercial gas Tiny Tech - DTI tech told me to wrap TT lead around one sparkplug lead but I sometimes get inconsistent readings with my Y302 (probably interference from other sparkplug lead). Thanks.

[ZUL8TR]

TT setup

Just want to verify - the tech told you to wrap red lead around both plug wires? Do you wrapped the TT red lead around both sparkplug leads together (i.e., both sparkplug leads close together and then wrap the TT lead three times around both of them) or individually wrap the TT lead around each sparkplug lead three times? What setting did you put your TT on (180, 360, or 720 if you have that option for your TT)? Reason I ask is that I have a commercial gas Tiny Tech - DTI tech told me to wrap TT lead around one sparkplug lead but I sometimes get inconsistent readings with my Y302 (probably interference from other sparkplug lead). Thanks.

First I have the older TT model 2c. It works well on my CD ignition 25ss with 3 wraps around each plug wire separately (in series). I have a Y80 that regardless of 1 plug wrap or 2 plugs wrapped separately it crashes the TT. The TT tech said the point ignition has a dirty signal and the TT has interference issues. The 25ss CD is a very clean signal. Try separating the plug wires from each other, also try wrapping one of the plug wires in alum foil to isolate the signal and wrap the other wire. Keep the remaining tail of the red wire away from the unwrapped plug wire Trial and error definitely needed.

[Shane_B]

First I have the older TT model 2c. It works well on my CD ignition 25ss with 3 wraps around each plug wire separately (in series). I have a Y80 that regardless of 1 plug wrap or 2 plugs wrapped separately it crashes the TT. The TT tech said the point ignition has a dirty signal and the TT has interference issues. The 25ss CD is a very clean signal. Try separating the plug wires from each other, also try wrapping one of the plug wires in alum foil to isolate the signal and wrap the other wire. Keep the remaining tail of the red wire away from the unwrapped plug wire Trial and error definitely needed.

Thanks - had a Y102 with 18mm plugs that had the interference issue - the Y302 with 14mm plugs has a cleaner signal... I'll try your lead in a series technique and play with TT setup to see if that produces consistent readings - if not, will try moving/shielding other sparkplug lead. Thanks again - Shane

[ZUL8TR]

Tt

Thanks - had a Y102 with 18mm plugs that had the interference issue - the Y302 with 14mm plugs has a cleaner signal... I'll try your lead in a series technique and play with TT setup to see if that produces consistent readings - if not, will try moving/shielding other sparkplug lead. Thanks again - Shane

Shane

Let us know your results. I also had issues with the Y80 with the 14mm plugs with adapter. I will also try the alum foil on one lead and connect the red lead to the other plug wire

Pete