Any 2-stroke gurus in here? Detroit 8v71 with misfire need help

He is now working out of his acreage outside Nashville TN

 

Not much of a 2stroke guy. But how about putting a dial indicator on rocker to verify actual lift, even if lash is ok. Or compair side to side? Just a thought if you happen to have a cam lobe laying down. Just a thought.

 

To me that engine sounded pretty good. Sounds like it has an exhaust leak. Likely at a manifold to produce that type of noise.
Low compression would smoke heavily especially at cold start up. Like Boxcar said the racks may be unbalanced left to right.
Fuel pressure at the secondary filter outlet should be around 20psi idle 60 or so at high rpm.
If you do get into the exhaust manifolds the studs screw into the water jacket. If the studs come out with the nuts you're gonna
get a bath.

 

Sounds like an exhaust leak. I had an old mack with a blown head gasket that sounded just like that too. It blew to the outside and it had that ticking sound.

 

Looks like someone beat me to the exhaust leak theory.

 

You referring to the round tube or pipe running from the front to rear of head as the control tube with a bent bracket….

 

Well, if that’s the case…. I’d check to insure that all 4 injectors are properly synchronized. They all may be fueling but not synchronized.

The pic I showed was from my 1980 General, it had set for 11 years. 3 injectors were stuck, after loosening the injectors and priming the heads along with the fuel filter, it rolled over 3 times and it was purring as if you shut it off yesterday…..

 

The rack adjustment is very important! Its been a long time since I worked on a two stroke over 35 years. If a injector is not set right it can cause a rough idle and what can sound like a miss. Setting the governor was done before setting the racks. Then the governor gap and the idle and the buffer screw. The injectors setting on the 71 series was 1.460" the 92 series was 1.484. Is there a data plate on one of the valve covers with the valve and injector settings?
The two fuel lines to the injectors are prone to leaking fuel into the oil. Do not over tighten them!! Looking at your pictures I have never seen a 71 series with the spring loaded rack levers those came out on the 92 series. Your engine may have been updated.
If an injector rack seized in the full fuel position it held all the injectors in the full fuel position as in "run away" the 71 series had a flap over the blower inlet that was released by a pull cable for emergency shutdown. The spring loaded rack lever allowed the other 7 injector racks to close if one seized open.