Other 61X Powered Mini Jet Boat

[JC-SuperJet]

What Exhaust System are you running?

The MSD Enhancer would require some fine tuning (Carb Adjustment Screws) versus the Stock CDI. The MSD Enhancer has more Timing Advance which requires a little more Fuel at the Low Adjustment Screw. And if the Engine is revving higher due to an A/M Tuned Pipe and/or Flame Arrestors, more Fuel up top.

The Front Cylinder running hotter could be caused by a Front Crank Seal Air Leak. Crank Seals are a wear/consumable item as the Crank spins and wears the Seal Center over time. Most don't think about NEW Crank Seals breaking-in or wearing-in to the Crankshaft. That's why Grease is required at the Seal Inner Lips.

If you remove the Flywheel Cover and there's a pool of Fuel at the bottom, then the Seal is leaking. Can also do an Air Leak-down Test to find any an all Air Leaks.

You will find that 2 Stroke PWC Carb Tuning is a lot trickier and fickle then Land-based Vehicles. Differences in Traction, Power Band and Transmission. I fine tune my Carbs every 10 degrees of consistent temperature change.

 

[RBS145]

What Exhaust System are you running?

The MSD Enhancer would require some fine tuning (Carb Adjustment Screws) versus the Stock CDI. The MSD Enhancer has more Timing Advance which requires a little more Fuel at the Low Adjustment Screw. And if the Engine is revving higher due to an A/M Tuned Pipe and/or Flame Arrestors, more Fuel up top.

The Front Cylinder running hotter could be caused by a Front Crank Seal Air Leak. Crank Seals are a wear/consumable item as the Crank spins and wears the Seal Center over time. Most don't think about NEW Crank Seals breaking-in or wearing-in to the Crankshaft. That's why Grease is required at the Seal Inner Lips.

If you remove the Flywheel Cover and there's a pool of Fuel at the bottom, then the Seal is leaking. Can also do an Air Leak-down Test to find any an all Air Leaks.

You will find that 2 Stroke PWC Carb Tuning is a lot trickier and fickle then Land-based Vehicles. Differences in Traction, Power Band and Transmission. I fine tune my Carbs every 10 degrees of consistent temperature change.

Exhaust is an R&D wet pipe, you can see a pic of it in post #17

I would think this might matter as well, the water temps on the rivers up here are really cold compared to lakes down south. Average is mid to low 60s.

Here is the current list of parts:

701 62T Case/61X Cyl (Stock porting)
35cc ADA Head (180psi on test)
R&D Wet Pipe
MSD Enhancer
Carbon tech reeds
Tau Ceti flame arrestors

I've been running 91 octane with Amsoil interceptor oil at 40:1, but after a bunch of reading was going to switch to Amsoil HP marine at 50:1 like it says on the bottle.

I have taken the flywheel cover off recently and no fuel or mess in there, I was double checking the timing alignment of the stator. I'm unsure if the builder had greased that seal or not, I would hope so. I don't have block off plates, so haven't tried a leak down test.

 

[JC-SuperJet]

Can use Plumber's Plugs aka Expansion Plugs to block any Round Holes; two for the Intake Manifold and one for the Exhaust Manifold. Test thru the Pulse Line.

 

[tomski]

First problem.

 

[RBS145]

Can use Plumber's Plugs aka Expansion Plugs to block any Round Holes; two for the intake Manifold and one for the Exhaust Manifold. Test thru the Pulse Line.

View attachment 437527

That's a great idea. I'll pick a few up and test it out. Thank you!

First problem.

View attachment 437528

I thought so too, but it's just a clean spot from me dropping a socket extension through the plug hole to push the piston down while using an endoscope to look at the wash. Hindsight, I should have just turned the coupler.