Squish 787 engine too big?

[Dr Honda]

Let's see,

On mine I've tried:

Replaced mpem
Replaced pickup coil
Replaced stator
Replaced Regulator/Rectifier
Replaced ignition coil
Replaced wires
Replaced caps
Replaced raves
Leakdown tested
Rebuild carbs
Replaced fuel selector
Replaced water seperator
Replaced fuel lines
And reinstalled top end with proper gasket for squish
Replaced rotary valve

And still wtf!! :facepalm: Actually none of this even made a difference!!


Does yours sound like this ?
[video=youtube;V6kjnpPvCXo]https://www.youtube.com/watch?v=V6kjnpPvCXo[/video]

4500+ is all good but below that is just not right.

Your pilot circuit is just a tad rich. Also... I know the camera makes the sound strange... but it REALLY sounds like your pipe is too dry. You may want to check the regulator, it's adjustment... and the orifice that goes into the head pipe. (They clog up)


But, 2-strokes aren't really "Smooth" until they hit the section where they like to run. And the 800 engine is very "Dirt-bike" like.

 

[Mekanix]

I used to be able to run down to 2800 before it would start to get rough. Oh yeah, I also replaces the water regulator. I will check orifices though and take another shot at a video without the casing to see if the audio comes through better.
It sounds like its backfiring into the pipe constantly while below 4500.
I set the idle and then the oil pump up line to line.

 

[fleroux99]

Your pilot circuit is just a tad rich. Also... I know the camera makes the sound strange... but it REALLY sounds like your pipe is too dry. You may want to check the regulator, it's adjustment... and the orifice that goes into the head pipe. (They clog up)


But, 2-strokes aren't really "Smooth" until they hit the section where they like to run. And the 800 engine is very "Dirt-bike" like.

- If we have the stock pilot jet (PILOT-70)... what should be done to fix that problem ? Should we increase the pop- off pressure ?
- My engine sound like this too. But it's not because pipe is too dry. I checked the 2 orifices that goes into the pipe/exhaust manifold and they are not clogged up.
I also played with adjustement of the WR at all screwed down to see if it's make a difference and the problem is worst when more water goes into the pipe. I set it as per maintenance manual after many trying.
The engine still running too rich.

 

[Mekanix]

You can get pilot jets and springs from:
http://www.winnerscirclecanada.com/marine.php
If you need to.

I know they are closser to you than me and it only takes 2 days to get to halifax.

Ive tried the 67.5 and 43 pop off before but that was too lean ( engine dies ) and didnt affect the problem

 

[fleroux99]

Today, i checked ignition timing. I bought the timing mark pointer from seadoo and an brand new automotive stroboscopic light. I mark my PTO flywheel in line with the pointer exactly at 0.133" when piston go down clockwise. My timing is perfect at 3500 rpm and between 3000-4000 rpm.
I also checked my WR (water regulator) valve and i found the calibrated brass fitting clogged.
Do you think it was my problem?

 

[fleroux99]

- I also checked the compression at hot this time and it was at 151 PSI in both cyl.
- BAD NEW. The PTO flywheel cover was removed and i took the opportunity to checked PTO crank seal. I sprayed carb. cleaner all over PTO crank seal and RPM wanted to go down after 5 sec. of spraying.
- After all test done and 3 min. idling at 3000-3500 rpm, i checked immediately the spark plug and PTO plug seem to be more "lean" than the MAG. one.
BUT, both spark plug was WET of gasoline.

What do you think everybody?