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Cylinder bore question

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PhilSch

Regular Contributor
I just picked up a 1988 Stratos bass boat that is in extremely good condition and lavishly equipped for very little money because the seller had overheated the motor. I removed and dissembled the powerhead hoping the damage was minor but the cylinders need to be bored out. One cylinder has a gouge at the top that is approx .220" wide, .5" long and best I can measure it is .022 deep at the deepest point. I determined these dimensions by applying epoxy putty into the gouge and measuring the impression after the epoxy hardened.

I am on a tight budget so I would like to avoid sleeving that cylinder. Assuming the gouge is truly only .022" deep and I used a .040 over piston the bore job would not completely eliminate the gouge but leave a very minor depression behind. Could I get away with something like that?

I suspect the ever so slight remaining gouge would cause a slight loss of cylinder pressure/power loss but I am willing to accept that if it is the only result.

I appreciate the thoughts of those that are experienced with these matters.
 
Not all motors are the same !---Care to post a model #-----And an oft repeated statement is ---" if you can't afford to fix it properly the first time, can you afford to fix it twice " ??
 
racerone said:
Not all motors are the same !---Care to post a model #-----And an oft repeated statement is ---" if you can't afford to fix it properly the first time, can you afford to fix it twice " ??
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It is a 1988 Johnson 110 hp J110TLCC

I can afford to do it the more expensive way but if there are no appreciable ramifications to leaving a very shallow divot then why not? OTOH if there are issues doing such I won't.

Phil​
 
In many areas it would be cheapest to find a used block.-----Bore it out and fit 4 new pistons.------Your location may dictate ability to find a used block.----Block was the same for many , many years.
 
racerone said:
In many areas it would be cheapest to find a used block.-----Bore it out and fit 4 new pistons.------Your location may dictate ability to find a used block.----Block was the same for many , many years.
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That has occurred to me and looked but did not find any. I will search further knowing they are not that hard to find. Thanks!
 
Depends on your location.-----Got one missing the lower unit.----$200 and on teardown found 4 new 0.020" O/S pistons with just a few hrs run time.----All in perfect condition.----Last one was complete $150 low hrs but 2 damaged pistons.
 
racerone said:
Depends on your location.-----Got one missing the lower unit.----$200 and on teardown found 4 new 0.020" O/S pistons with just a few hrs run time.----All in perfect condition.----Last one was complete $150 low hrs but 2 damaged pistons.
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Northern CA....prob the other side of the country, correct?
 
Correct 3000 miles away.-----Time to call some dealers and scour craiglist and E-BAY.----Donor motors are out there.----Too bad you can't walk over to pick up a block
 
I can't speak about your particular model motor. But I have personally bored many cylinders. In most cases it is possible to fudge the rebore vertically up or down. In such cases, there is plenty of side clearance in the rod/wrist pin/piston to allow it. Take a critical look at what you have before proceeding.
 
I read that the 90 HP version is better as the smaller ports provide better ring support. If I could find a 90 HP block would I need to rejet my carbs and/or do anything else? Also what about the 100 horse version?
 
You are WRONG about the smaller ports and better ring support.-----Just as many 90 HP blocks have piston ring problems !!------All the V-4 and V-6 crossflow blocks from 73 to 98 suffer from broken rings.
 
racerone said:
You are WRONG about the smaller ports and better ring support.-----Just as many 90 HP blocks have piston ring problems !!------All the V-4 and V-6 crossflow blocks from 73 to 98 suffer from broken rings.
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Is there anything that can be done improve ring reliability? Synthetic oil, keep revs down, other?


I also read Wiesco might be a better design for ring reliability with these motors.
 
Now I need to find a competent marine machine shop that can install a liner. There are no machine shops specializing in marine engines around here so I guess I am left with shipping everything unless someone knows of a quality outfit in the bay area. Can anyone recommend such a shop, preferably but not necessarily, closer to the west coast?
 
Would you take the block to an automotive machinist for boring and sleeve installation? I have not found any machinists that specialize in marine engines here in Northern CA and I don't like the idea of waiting two months for LA sleeve.
 
find a well established machine shop and ask them, they should have no problem doing it and if they haven't done it before they will tell you.
 
Would you take the block to an automotive machinist for boring and sleeve installation?​
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Only if they have a boring bar..not a honing machine. Before I would send the money to have sleeved I would shop around even if out of area for a motor or block.. These thing are everywhere if you look. Heres one in my area.
[FONT=Verdana,Arial,Tahoma,Calibri,Geneva,sans-serif]https://nashville.craigslist.org/bpo/d/hendersonville-100-hp-johnson-for-parts/7090945861.html[/FONT]
 
Agreed----I have lots of them on hand and parts motors are plentiful in my area.-------I do know where to look.----I would say there should be lots of them in northen California.----Perhaps post a WANTED ad in your craiglist / super market etc.------You will find one !!
 
PhilSch said:
I just picked up a 1988 Stratos bass boat that is in extremely good condition and lavishly equipped for very little money because the seller had overheated the motor. I removed and dissembled the powerhead hoping the damage was minor but the cylinders need to be bored out. One cylinder has a gouge at the top that is approx .220" wide, .5" long and best I can measure it is .022 deep at the deepest point. I determined these dimensions by applying epoxy putty into the gouge and measuring the impression after the epoxy hardened.

I am on a tight budget so I would like to avoid sleeving that cylinder. Assuming the gouge is truly only .022" deep and I used a .040 over piston the bore job would not completely eliminate the gouge but leave a very minor depression behind. Could I get away with something like that?

I suspect the ever so slight remaining gouge would cause a slight loss of cylinder pressure/power loss but I am willing to accept that if it is the only result.

I appreciate the thoughts of those that are experienced with these matters.
Click to expand...

I am not known for my math acumen, but wouldn't .040 overbore remove a .022 score mark? Or am I figuring it all wrong?
 
???-------The cylinder would have wear already so perhaps 3.503"----Add 2 X 0.022" to that would make it 3.547"--Depending on where the deep score was there is an option.------The machinist could offset it a bit if owner of the block would take full responsibility.------Easier to find a good used block.----Just my opinion here.
 
I have still not been able to find a block in the area so I took my block to a recommended machine shop who is capable of boring and also installing sleeves although he thinks we might be able to get away with boring the worst cylinder to .040 over rather than sleeving.

I would like to diagnose what caused the engine failure so I need to do some detective work questioning the seller and hopefully getting some inputs from the experts here on this forum. I'm thinking the VRO failed due to the fact that the engine internals are somewhat dry and the water impeller is in good shape. The bearings have next to no oil residue on them. There is a blue coloration on the ends of the wrist pins (some worse than others) and a brownish copper coloration on the crank journals, picture attached. The rod journals mic well within spec, towards the larger end of the OMC specification range and there is no longitudinal play in the rods when assembled on the crank nor any longitudinal play on piston/wrist pin. All the journals are as smooth as could be. The center main crank bearing sounds kind of dry when rotating.

I am concerned about heat damage to the crank journals that could cause problems downstream. I included pictures of piston scuffing on both intake and exhaust sides of piston # 4. Cylinder #1 had very little scuffing. Cylinders # 2 and 3 had broken rings along with scuffing.

I am going to replace all the bearings along with the pistons. Is the brown/copper discoloration of the crank journals indication of excessive heat? If so should I have any concerns about that heat affecting the temper of those journals and long term wear issues?

As always I really appreciate your expert inputs!

Phil
 

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  • Piston A.jpg
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Simple facts for you.------I have seen pistons much worse!------There is nothing wrong with the crank journals.----Remove center bearing for inspection.----Nothing wrong with wrist pin.----New pistons usually come with new wrist pins anyway.
 
Is it possible an overheat led to the piston scuffing and then then water pump impeller was replaced prior to unloading the boat?
 
I've seen pistons much worse also. I stuck a motorcycle piston so hard at TDC that the crank ripped the wrist pin out of the piston!

Do you think it was a VRO failure? As mentioned, I am not thinking it was lack of cooling. A lean fuel mixture is a possibility and I will go through the carbs to rule that out. No signs of detonation so I doubt timing is off. Maybe a weak spark causing washing away of oil? Any other possibilities?
 
????------" weak spark washing away the oil "------Where did that wild idea come from ?-------Just more proof that oil / lubrication inside a 2 stroke is not well understood !!
 
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