1991 60 hp 3 cylinder partial rebuild project questions

[Theeplaymaker]

Hello all!

I did something stupid at the beginning of this year (running it hard first time out of hibernation without a working tach) and toasted the top cylinder on my engine. I finally am getting around to figuruing out what I am going to do with it and I have some questions. I'll try to post pictures of the damage when I get a chance.

It came down to either try to salvage a few hundred bucks on this thing or try to tear into it and learn something. I have a factory manual and I am mechanically inclined but I have never delved into an engine before. I am going to try to do this project right but the cheapest way possible, yes they don't usually ever go together but I'm gonna try.

I am thinking this was caused by dirty carbs and a fuel issue since my primer bulb was messed up and I had some half *** looking fuel lines that I hadn't noticed before I took it out. Anyways it appears that a piece of piston ring or some type of metal got between the top of #1 piston and the head and put a bunch of indents into both.

I don't have this motor on the stand yet but will hopefully next week so I can't remember for sure but I don't think there was horrible scoring in the cylinder. Now for my questions and game plan.

1. I was planning on just re-ringing the other two cylinders unless something else causes me to change plans.

2. I am hoping that a hone job will be enough to clean up the cylinder on #1 and hopefully find a used/new piston somewhere.

I guess my main question at this point is: is this motor worth trying to do this on or are there certain dumb little things that will make it a pain in the butt?

Also is there anything specific I need to pay attention to during the tear down and rebuild?

I have to build a work bench and I plan on being organized/clean and label every nut and bolt in a bag.

Thanks for any ideas/tips/suggestions that may come and I'll hopefully be able to come here and get answers when the problems are bound to come up that I am not sure about.

THanks!

 

[orbanp]

Re: 1991 60 hp 3 cylinder partial rebuild project questions

Your diagnosis sounds plausible as for the cause of your problems.
I think it is worthwhile to rebuild the engine.

Did you do a compression test before you opened up the engine? It is also possible that you do not even need new rings for the other two cylinders.
There is the possibility that you need to have the bad cylinder rebored. You will know when you measured the ruined cylinder.
There could be also other surprises (not very likely), that you find out when you fully disassemble the engine, the required parts would add to the cost of the rebuild.
When you add up all the costs, that would tell you if it is worthwhile for you to go ahead with the rebuild.

Good luck, Peter

 

[Theeplaymaker]

Re: 1991 60 hp 3 cylinder partial rebuild project questions

Thanks. I was planning on honing out the other two cylinders while I had it apart. I am trying to do as much research and such before hand and I have my first question.

The cylinder bore is 3.188" or 80.97 mm as stated in my manual. Looking on the flexhone website there smallest hone is 83mm and I have a buddy who has one and has done a cylinder on a car that was 81mm with that. Would that work on my 2 stroke though or do I run the risk of messing up the ports?

I am hoping for no surprises but I would be happy if I can do everything or most things myself and correctly that I can stretch my budget for rebuilding this thing quite a bit. I feel if I do most the work that its going to be worth it since I got quoted $2200-2800 from a shop to do it all.

Thanks again and I am sure this is only the beginning of my questions.

 

[fishfeatures]

Re: 1991 60 hp 3 cylinder partial rebuild project questions

Post pics but these are an ok motor to rebuild. there was a service bulletin issued about relocating the telltale to the the top of the exhaust block as there were issues with air getting trapped in the cooling system. if this wasn't down then i'd look at doing this too, you can find it by doing a search in here i'd say.

If your fingernail can catch on any scratches in the cylinder then it'd be more like a rebuild. a broken ring would cause the damage you've seen too. You may need a new piston too. I'd suggest getting your local shop to do the work at the very least get them to look over the block. anyway take photos when disassembling it and label parts when removing them.

Did your overheat alarm go off?? if not i'd troubleshoot that too in case it's bust.

 

[orbanp]

Re: 1991 60 hp 3 cylinder partial rebuild project questions

Read up on honing/deglazing!
Here is one thread: Hone or deglaze?*/ 556659
Interesting is item #14. No personal experience though...
Do look at other places as well!

Peter

 

[Theeplaymaker]

Re: 1991 60 hp 3 cylinder partial rebuild project questions

I did the re-locate last winter and was getting a strong stream of water. The alarm did not go off and nothing seemed out of the norm when I pulled the cover off after it lost power and started tapping.

I will get the pics soon as I am at work now and can't get on photobucket. I'd like to do the work myself since I am using this as more of a learning experience that hopefully works out instead of just taking it to a shop and getting it fixed.

Is the fingernail catching a good basis as to wheter it needs honed or bored out? The pics will show you guys a lot more about what might have happened and I am not sure that the head will be salvagable either.

Anyways this should go a little easier once the pics are up so I will get them up asap.

Thanks!

 

[Theeplaymaker]

Re: 1991 60 hp 3 cylinder partial rebuild project questions

Head damage pics. Waiting on pics of the piston to upload.

 

[Theeplaymaker]

Re: 1991 60 hp 3 cylinder partial rebuild project questions

Piston pics:

 

[Theeplaymaker]

Re: 1991 60 hp 3 cylinder partial rebuild project questions

Here is a video of it right before it detonated.

Here is a video of what it sounded like when I limped it back to the dock.