88 175 hp black max timeing

[shankforce]

If someone could assist.
When you set the timeing. The Mercury manual says TDC #1 piston and set flywheel to .464 then it stops I dont get it do you time it from this spot to hit the 21 degree mark on the flywheel BTDC or move the wheel to 0 and hit the 21 degrees BTDC mark.Everything else in the instructions make sense.
I have had conflicting answers to this.
Do I leave my flywheel at .464 and time this from there or do I put the flywheel at 0.

 

[shankforce]

Re: 88 175 hp black max timeing

I guess I figured out my own question.
.464 is BTDC not TDC this is Mercurys way to get the most percise positon of the flywheel. You are actually setting the flywheel .464 before TDC (which is 0) so when the flywheel is at TDC it is 0.

 

[j_martin]

Re: 88 175 hp black max timeing

At TDC, the piston moves a thou for a degree or so. At .464 before TDC the piston moves considerably for a degree of rotation. By probing into the cylinder with a depth gauge, you can set the piston top at that point, then set your timing pointer on the .464 mark, and TDC will be spot on.

I made a tool that enables me to do this with a 20 buck digital caliper. When I get to work, I'll post pictures.

hope it helps
John

 

[shankforce]

Re: 88 175 hp black max timeing

Thanks it does help. I have digital calipers maybe I can make something simular.
My motor seem off right now it stalls in nuetrall and runs rough.
I removed the Idle stableizer per the forum so I will time the motor again my next question would be.
If it still runs rough after I set the high spark to 23 deg BTDC and primary pickup at idle 10 deg ATDC then what do I trouble shoot next?
This motor has been nothing but a pain since I got it.

 

[j_martin]

Re: 88 175 hp black max timeing

It's a two cycle, it goes squish-bang.

Needed are compression, fuel, and ignition.

The details. Check your compression before you go nuts on troubleshooting. Without good even compression, all else is mute.

In addition, idle can be affected by reeds, small vacuum leaks, bleed lines (misrouted, leaky, or bad check valves) and carburetion (flooding, low float setting, dirty idle circuits)

A sleeper is a leaky diaphragm in the fuel pump floods a cylinder, and makes it rough and smokey.

Fuel delivery, of course, is important, and ignition at all speeds.

hope it helps
John

 

[j_martin]

Re: 88 175 hp black max timeing

Reeds affect idle and low speed operation. At high speed they stand open, and theoretically could be missing with no effect.

Final picture for .462 mark setup.

 

[MarshMan73]

Re: 88 175 hp black max timeing

I hate to sound like an idiot, but I see in the pictures how you are doing it. Question is if I didn't make that jig you have, can't I still hold the end of the same caliper you're using flush against the head and get the same reading after zeroing the caliper?

 

[j_martin]

Re: 88 175 hp black max timeing

I hate to sound like an idiot, but I see in the pictures how you are doing it. Question is if I didn't make that jig you have, can't I still hold the end of the same caliper you're using flush against the head and get the same reading after zeroing the caliper?

Hell, I don't know. I'm a shakey old man. That jig is a old gutted out spark plug and a short piece of strap iron welded to it. I bet I spent 16 minutes making it.

hope it helps
John