1988 EL75 #1 cylinder not firing or firing intermittently

[johnstout]

Do I need to look at the exhaust side as well? I have a gasket kit coming that will cover that as well.

[Solarman]

Unless you know there is a problem, i dont think i would disturb the bolts. I have found those bolts tend to break off easily (don't need any of those broken). If they break they have to be removed and replaced, due to leaks from exhaust into waster system.

Think I'd stick to seeing if compression comes back with head gasket first.

Good luck. Post back how its going when able.

[johnstout]

Do you recommend lubricating the bolts? They were pretty corroded and hard to get out.

Also, do you recommend using gasket sealant on the head gasket or installing dry?

[Solarman]

I would clean threads well, then yes, lubricate threads, then make sure surface is clean for gasket. It is intended to be installed dry.
Then torque per manual specs.

Good luck, let us know what happens.

[johnstout]

Hey Solarman, while I'm waiting for a head gasket I have a question for you. The one thing that has impressed me about this engine since I purchased it is the fact that it starts so well. All I have to do is pump the bulb and turn the key and this thing starts in less than one revolution of the crank. I would think that if there was a major problem I would have starting issues as well.

Just a thought. May mean nothing.

[Solarman]

Yes it seems strange, that it could still run. With all the little things you've tweaked, and admitted it runs better. But 2 strokes are very simple, and they run, as long as it has fuel, fire at the plugs, and compression.

And, you described it best, when you mentioned the coloring of the tops of the piston. The bottom cylinder with 75psi compression, showed the most completed burn pattern. The middle cylinder with 10psi less, showed about half completed burn pattern. Lastly, the top with 20psi less, just a partial burn pattern. So basically, the 75psi is the minimum compression on your motor for a complete burn pattern.

While you're waiting on gaskets it would be a good idea to check if the cylinder head is flat/even across the mating surface. Can use/ get a piece of glass (how we checked heads for being flat across all cylinders), and either lay the cylinder head flat on the glass, to look for any gaps, wobbles, other deformities; or can use a fine grit sand paper (800 grit wet), and move the head's flat surface around enough to see an "even" scuff pattern across the head. It could easily be warped from top to bottom, given compression readings.

If any major problems with the head, you might take to machine shop to get it checked/leveled/surfaced, otherwise you may have same problem over.

Have to go for now. Good luck, post back how it's looking when able.

[johnstout]

Solarman, I received the head gasket late today and will install it tomorrow morning. I have the torque specs from the manual but it doesn't talk about re-torqueing after running the engine for awhile. Should this be done or not?

[Solarman]

If you want to run it till it gets warm, then check torque, that's all I'd do. Once that's done recheck compression, if still same numbers, best bet is either keep for parts motor, or part it out and sell it piece by piece.

If compression is better, you should notice it right off.

Good luck, post back when able to let us know.

[johnstout]

Well, I did find one more problem. The intake manifolds for number one and number two cylinders were leaking air. I replaced gaskets and the engine did run a little better but still has low compression. So, to the scrap yard it goes. Anyone interested in this EL75 (DT75) for parts. This engine sat for 8 years so I suspect the rings are stuck. Don't know for sure.