1984 J90 HP .060" over. Why not?

[rebuilt]

If .040" doesn't clear the scoring on my block .060" over pistons are available. The walls would be thin. Ok... rings don't wear against anything but the sleeve walls anyway. Right now it looks a lot better than buying some one else's used block which will then have to be bored as well. It's a $300 difference between buying another used block and going with .060" over on mine. My pistons are done. They need replacing. So why just hone a worn unknown block to put new pistons in? I've only seen one seller on eBay who posts bore diameter. The one he's listing that I can use is at the outer limits of an .040" oversize bore job. With only .0004" to spare. "According to his measurements." "His measurements" opens up questions of its own. Cons?? The pros are obvious. Thanks

 

[jimmbo]

Since your Mind is made up about going with a 0.060" overbore, I won't waste any time regarding the reality of what will likely happen. Better you learn first hand... Good luck

BTW, even a 0.040" Overbore is not considered Practical

 

[racerone]

Need to be patient to find a good used block.----Lots available in some areas.

 

[rebuilt]

I was posing the question as if there are no drawbacks. Overheating, warping, flex. etc. I'm not building a race engine. I bought this as a fixer upper. Cruising speed will not exceed 4K. My '89 60 hp I3 rumbles along nicely at 3500 to 4000 rpm. It planes quickly with a cupped stainless prop, thereby taking the load off the motor. Once in a while I blast it at 5,500. There are 3 blocks available at wildly differing prices on eBay. The problem is NoOne, and I mean NoOne lists usable bore sizes. The one who did list a wear figure showed a # that is already out of the .030" bore range. He listed it in mm. So when the conversion was run, it was already out of the usable .030" overbore range. So some guy who is listing "slightly scored-honing will do" or "slight scoring-buildable" may be selling a worn out block that even a .040" won't clear. Sleeving and porting is insanely high. $400 a hole where I live. It's all a gamble. In the hundreds. With no refunds. Lucky for me mine did clear at .040" I use high end oil run rich at 40 to 1 on my 60, I premix, and take care of my carbs and cooling system. I plan on running a pre-roller bearing mix of 24 to 1 on this V4. Let her smoke. Running lean because of dirty carbs, bad nasty paint thinner smelling gas (I only run e-free 89 octane) or unmaintained cooling systems leading to poor water flow, not prepping for down time, and not doing plain old periodic maintenance is the killer of these engines. I hand built my first one at considerable expense after saltwater submersion. Still a lot cheaper than a new one. A storm spun it off anchor, put the transom under the dock at low tide, then high tide did the rest. Sank it at the dock. A quick pickle saved it for a total tear down and rebuild. It's a very satisfying engine. So I take care of it. This one will cost quite a bit more, and I will take care of it too. Thanks for the input. This forum has been a huge help over the years. From fabbing fiberglass to installing roller bearings. I remember when it was mandatory to start your post with model #'s. You'd get fussed out it you didn't. Now folks don't even own a manual. Much less a real JE service manual. Seloc sucks. Clymer isn't much better. A real JE engine specific service manual can still be found. Wouldn't trade either of mine for 10 Clymer's or 20 Seloc's. Now I'm ranting. I'll post up if I run into a problem with this build. I've already sent the lower out to be resealed. It's 39 years old too.

 

[Faztbullet]

The cooling system has to be "perfect" to run a .040/.044/.064 piston or it will seize. Let me look as I have several blocks stacked in corner.

 

[rebuilt]

The cooling system has to be "perfect" to run a .040/.044/.064 piston or it will seize. Let me look as I have several blocks stacked in corner.

I have either gone through the cooling system ... or bought for it, new everything. Thermostat, connector hoses, not installed yet, water pump, including stainless plate, took care of that when I had the lower off. It's since been sent out to a retired JE genius for a complete reseal. But I certainly cannot say it's "perfect". This motor was so badly corroded I question whether the water jackets will flow right. I sure am willing to hold off on boring until I hear back from you. The shop I'm dealing with has done quite a few of these 2 strokers back when they were on about every transom. He told me it'll clear a .040", but he's waiting on me to supply him pistons so he can measure and cut each hole exactly for it's designated piston. He'll label them for me. The guy is good. He set up my 60 hp for me when I took it to him. I asked him about chamfering the port edges, he said he would if I wanted him to. I have a ball stone I can chuck it up in an air grinder if he doesn't. So.... long story short, it would be great if one of your blocks will come in at a .030" cut or under. J90MLCRD. BRP part #'s 0394283 which was replaced by 0431659 Some one has put a tilt-trim on it. The # says manual, it's not anymore. I remember you from years ago. Not sure if some of the others are still contributors. Ezeke, Chinewalker, and more. I read TD passed quite a while back. I've got an unknown powerhead I bought off of him on Ebay a long time ago. I've lost what info he gave me. But that's another thread. I've had fantastic success with one engine, that J60TLCEA. Doesn't mean I know enough to be a regular here. Live is life. BUSY I look to this forum when I need help. I've got genuine JE manuals for each of my motors. That keeps me out of a lot of trouble. 'Preciate your input.

 

[jimmbo]

Ball Hones are not good for 2 stokes, they can cause issues with the Ports. Same goes for Chamfering the Ports, doing so can make changes to the Port Timing, as well as cause other Damage

 

[rebuilt]

Ok... still learning about some of the finer points on these engines. I was lead to believe mild chamfering ports after a bore job lessened the chances of a ring hanging on them. Your thoughts?

 

[racerone]

When I rebore a block , I put a wee chamfer on the ports.

 

[jimmbo]

If a Ring End is going to catch on a Port, a Chamfer is not going to make any difference.

 

[racerone]

The ring ends are not going to catch on the ports.

 

[rebuilt]

So... I've put everything on hold until a suitable block...3.529" bore wear or under can be found. It depends on who's reading the micrometer too. The hangup is the majority of ebayers don't post and won't warranty a block to come in under a specific range. One does, a guy from Washington, The one he has is too far gone. I'm looking at one that might make it. I'm about ready to get an inside micrometer set for myself. Looking at used ones now. A used set Starrett would be real nice. I've got two outside mikes, they're too small to use with telescoping gauges. So the search continues.

 

[rebuilt]

There are dozens of Starrett inside mikes out there. Just depends on what. guy is willing to pay. Looks like a decent used set is around $100 or less.