General Engine Rebuild Questions

[Bosunsmate]

In your top photo it looks like the gallery where the 3rd cylinder conrod spins has some debris in it

 

[Faztbullet]

Don't resleeve as you can get a used block cheaper, don't bore .044/.064 as sleeves get to thin and cooling and jetting get real important. The most I will bore a customers block is .030. I will offer them a option for .040 max but I do all the jetting, new housings/impeller/gromments and break-in for it to have a warranty. Wiseco pistons are not my 1st choice as they require several heat cycles to temper up the piston/rings...The forged material that Wiseco uses for their forged pistons does require ?a little? more clearance and a little longer break-in that typical ?cast? type pistons ? but that is not the unresolved design issue?. It?s the rings. The piston ring material that Wiseco uses is a very tough material that takes much longer than average to ?seal? to the bores. While the Wiseco pistons themselves are not a particularly close clearance fit to the bores, the Wiseco rings are. In truth, the Wiseco rings are made brand new with an end-gap that is much too small for full temperature high rpm operation. However if a Wiseco equipped engine gets the slightly longer than average break-in period it deserves, the outer-skin will wear off the rings to result in an ideal ?running? end-gap that will give excellent long term wear and service. If however, you try to run Wiseco piston rings prematurely hard, those rings will quickly expand until the ring ends make contact and literally ?bite? the full bore diameter in the ring path

 

[fmjnax]

Bosunsmate - correct, there is debris in that picture. However, the debris was from me. That picture was taken some time after I had cracked it open and removed the pistons. I was taking off gasket material and gunk before I thought better of it to remove the crank. I don't have a picture after the fresh split, but debris was the first thing I looked for after splitting and I didn't see any. So nothing of concern in those regards, but thanks for looking out!

Fazt - If Wiseco isn't the best to go with, what would you suggest? Understood on going over 030.

3 of the 4 wont need to go larger as I think a hone is all they need. The machine shop quote I got was for one to be resleeved, but I will see if they will hone it first and give me their recommendation. The shop is a full time outboard rebuild shop with excellent reviews so perhaps their judgement will be best.

 

[Brock O]

Yea great write up Faztbullet, valuable information, ill be purchasing these as soon as my nightmare ordeal is sorted with one of the marine parts suppliers in the states, struggled to find anything other than factory or sierra so after the read on these pages I'm happy to try my luck with wiseco.

No I have no affiliation with them.

 

[fmjnax]

Well, I'm still weighing my options here. The more I inspect the gouge in the cylinder wall, the less I think it needs to be resleeved. It's really not as deep as I originally thought. It's smooth with no raised and sharp edges. no chunks broken off. No cracks. Perfectly vertical from the BDC to TDC of the ring travel. As a result, my thoughts on how to proceed are changing. I'm still waiting to get the block in to the machine shop for a wash and measure to help determine my final course of action, but I am leaning toward two new options.

I have been asking around and researching .044 on this block. It seems to be a fine option, as long as I jet up. I'm currently running the stock orifice plugs for a 115hp; #34's in the throats, #27's in the top of the bowl, #58.5C's in the side of the bowl. If I bump up to the stock 140hp jets (#36, #25, #67C), would that be enough [or too much]?

I am also thinking that I may just deal with the gouge. There are no raised or sharp edges. I'm thinking a good hone will knock at least half of the gouge out, providing the results of the bore measurements are within spec. My question here is that I don't know the implication of leaving a small vertical gouge in the cylinder. In a 4-stroke, I would imagine it would burn some oil, have a touch lower compression, and possibly some blow-by. What are the implications in a 2-stroke, though?

As for the pistons, both the rebuild shop and my local marine shop recommended the WiseCo's. I haven't seen or heard any other good recommendations, so it will be WiseCo's for me unless I find otherwise in the next couple of weeks.

 

[racerone]

I believe your engine had O/S Wiseco pistons in it.

 

[fmjnax]

Thanks racerone. I know they are O/S, but I didn't know they were Wiseco's. I couldn't figure out what the "KD" stamp was. The part number matched up with Wiseco's, but the KD was throwing me off. I don't fault the piston or the rings for the failure, though, so no sour taste for me right now. It was an overheat for a number of reasons; stuff the previous owner had done (or not done).

 

[racerone]

KD refers to the type of piston ring material shipped with those pistons.---Chrome bores require a different ring and does not apply to your engine.

 

[Bosunsmate]

Well, I'm still weighing my options here.

I am also thinking that I may just deal with the gouge. There are no raised or sharp edges. I'm thinking a good hone will knock at least half of the gouge out, providing the results of the bore measurements are within spec. My question here is that I don't know the implication of leaving a small vertical gouge in the cylinder. In a 4-stroke, I would imagine it would burn some oil, have a touch lower compression, and possibly some blow-by. What are the implications in a 2-stroke, though?
.

Yes thats what you will get on a two stroke too.

In my opinion!!!!! it wont make any real risk of danger of damaging the motor. A couple of mine have even bigger gouges than what you describe and they are going happy as. I never venture from running 50/1 and im so glad i didnt put the extra money into trying to perfect it. What if i hit a submerged log or something and the whole motors a right off anyway.
Just do a decarb every six months or rather to loosen up any carboned rings if you are concerned, mine havent carboned up at all years on and i dont decarb i just run cheap two stroke oil and get it running hot most trips to burn off any carbon.
It wont be that gouge that kills that motor, it will be running dry in a cylinder, or a water pump/water circulation failure.
Id just buy a honer for $20 and cut out the machine shop altogether

 

[Faztbullet]

Any groove in a cylinder wall will eventually cause a piston failure whether you decarbon or not. Hot exhaust pressure will travel down the groove and will erode a slot in the piston causing ring to overheat and failure. It may take some time to happen but it will happen. I would bore all to .040 and slap a set of WSM pistons in it. As for jetting the 140 is incorrect as carb is different, you would need #36,#30 and #60 in high speed...

 

[fmjnax]

I appreciate the personal experience bosunsmate. Normally, that's probably how I would proceed on something this old, and I really want to take the easy way out... but I'm leaning more towards doing it right [better?]. Money and time aren't a factor (save for going all out and resleeving or buying a new block) and I don't want to take shortcuts to better options. Plus, I am also restoring the hull, so if I am going to have an essentially new hull, why not do the best I can on the motor as well.

Thanks Fazt. That's the exact information I need!

I'm taking the block in to be cleaned, measured, and inspected next week. If the measurements are out of spec or if the gouge is worse than I am making it out to be, then I'll certainly plan on having it bored out to .040, will pick up some of the 3.54 pistons from WSM (and save about $100 over the Wiseco's, at that!), and get 36/30/60 jets. If it measures in spec and cleans up nicely with the hone, I will consult with the shop and go from there.

I know it's hard to diagnose and recommend without being able to see it in person. I know the best and correct way is to have it machined, but I also know practicality sometimes trumps correctness. I greatly appreciate ALL of the advice and information from you all If I get roughly 5 years on the rebuild, it will be worth my time and money (though I obviously would want it to last longer so that I can get what minimal return possible when I sell it).

 

[racerone]

Myself I would be searching for a used ( standard ) block.--Here there are lots to choose from and I would think the same where you are.--These blocks were the same year after year.-Properly done it should last far more than 5 years of normal use.----I have lots of these blocks but international shipping would be the problem !!

 

[fmjnax]

I did spend a little time looking for a good block at less cost than machining mine machined, but haven't been successful so for. However, I was looking specifically for the '84 block. I think I came across some from 82, 83, and 88 that were in my price-point, so if those are the same blocks I may take another look.

 

[fmjnax]

I was talking to my local marine shop and got him to give me the contact of the machine shop he uses when he does rebuilds (and is just down the road from work). I called them up for some pricing. Free wash/measure/inspection. $45/hole to bore and $20/hole to hone. So if I plan on boring all 4 up to .040, I'll be looking at about $280 after tax, plus whatever they charge to remove the one bolt that was broken off. Comparing to the dedicated outboard rebuild shop quote of over $600, plus a 250 mile round trip, the decision is easy. I'll be taking it over to them in a couple of weeks (after I get more work done on the hull).

 

[fmjnax]

Taking the block to be cleaned/inspected tomorrow. I'm starting to round up parts to complete the rebuild. I've got new wrist pin bearings and retainer bearings on my parts list (the ones between the rod end and the crank). Do these really need to be replaced or is there an indicator of decision to replace them or keep them? I don't want to cheap out over $100, but I don't want to be replacing things that don't need replacing.