[KiwiRider]

I've done a bore-camera tour through as much as I could of Sunstrike's engine (86 700). You can see that video at

.

I'm wondering if I should split the engine and replace the bearings now, given she has near 100,000 miles on the clock, or since there were not problems I'm aware of with the gearbox, just leave her as is?

She was taken off the road due to a bad head gasket. A small leak turned into a bit more of a problem. No measurable warping of the heads though I will re-check when I go to fit them.

I do plan to give her a good washing with diesel (not "D Cell" as some in the US seem to pronounce it! ) or something else to get rid of the traces of gunge and perhaps some bits from liquid gasket that shouldn't be in my engine, but otherwise I'm at least 60% happy to not split the case and just rebuild her, paint her and get her riding again.

I would appreciate your thoughts. I can film any other parts you want more detail on, but bear in mind my scope was cheap and it's not the greatest device for such jobs!

 

[CSRoad]

If it is not broke.
Looks like normal wear on the gears.
I'd keep the bottom end together, why make more work for something that is a beech to get parts for?
If you are looking to drag it out for entertainment purposes, that's another thing.

 

[KiwiRider]

An oil-related question..

I have a full gasket set for this engine. I understand that using fully synthetic oil can cause older gaskets to leak. Would it be worth splitting it and installing the new gaskets, or is it a bit more myth than fact? What's your thoughts please @swifty2014? (Probably you're thinking "we need another expert around here so I don't have to answer these bloody idiot questions all the time! )

 

[crazyoldman]

My opinion ,put it together as is. No synthetic oil. Change one a year. At the bottom of the oil container , it will say Resource Conserving or Energy Conserving. This has friction modifiers and are bad for a wet clutch. Look for motorcycle specific, high mileage, or diesel oil. It will have a blank in the half circle. I say just use diesel in it .Its old and will run just fine. I just use t4 shell 15-40 diesel in mine.10-w 40 should be on the fill cap though. Diesel is high zinc helps stop internal rust but bad if its got o2 sensors or converter on it. I also use it in 50s cars.

 

[CSRoad]

In the early years of 60's and '70's with synthetic oils you could get weird things happening with oil seals based on their formulations, but I consider things more mature now and having to meet proper oil standards, however the stories live on across generations.
Like @crazyoldman I use Rotella T4 in my Shadow for the same reasons. I switched back from T6 synthetic.
I don't see any advantage to me in using a synthetic based oil in the old girl despite the stress I make her live under.
The main advantage of synthetics in such applications is longer mileage change intervals and in my case oil changes come about due to age rather distance.

Save your gaskets on the shelf until you need them. (-:

 

[PhantomRider64]

As csroad said in the early years the synthetic oils would do bad things to seals and gaskets. Nowadays it is a situation of the gasket would leak if it did not have all the gunk on it and synthetic cleans so well that it will clean off the gunk and a leak will form. So if your seals and gaskets are in good shape I would say it does not matter. But I would probably just use a good dino oil and 4-5k oil changes.

As far as splitting the case,,,

I have never done it so I really cannot say, but (you knew there would be a but) if the bike is basically a play bike (project bike) and you have the gaskets,,,I say go for it. Personally I would prefer all new bearings and bushings.


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[KiwiRider]

Look for motorcycle specific, high mileage, or diesel oil. It will have a blank in the half circle. I say just use diesel in it .Its old and will run just fine.

Thanks. Normally I do use diesel in it though one of the Valvoline models, I've never seen other stuff for sale where I normally shop, but I should look for a place that sells to haulage companies (or find a good friendship with a mechanic at a trucking firm who can "spill" a couple of litres each change ). The diesel had become expensive lately so I'd been using actual motorbike oil for a bit.

 

[KiwiRider]

I don't see any advantage to me in using a synthetic based oil in the old girl despite the stress I make her live under.
The main advantage of synthetics in such applications is longer mileage change intervals and in my case oil changes come about due to age rather distance.

Well, I do have a habit of keeping up with people on litre+ bikes, especially through twisties

I'd not really want to lengthen the change intervals myself. The benefits I am after are "within budget" and "makes the engine last longer" (see "budget").

Save your gaskets on the shelf until you need them. (-:

I suspect the current bike will get them, she's had a harder life. She was using oil long before I got to her.

 

[KiwiRider]

So if your seals and gaskets are in good shape I would say it does not matter. But I would probably just use a good dino oil and 4-5k oil changes.

That makes sense. There's some suspicion with the current bike that there is a leak but it is extremely rare for there to be any drips. I might see a new spot on the garage every 4 or 5 months, but there is oil underneath and I don't tend to spill during changes.

As far as splitting the case,,,

I have never done it so I really cannot say, but (you knew there would be a but) if the bike is basically a play bike (project bike) and you have the gaskets,,,I say go for it. Personally I would prefer all new bearings and bushings.

I have 2 '86s, a 700 and 750. The 700's engine is on the bench, the 750 was brought cheap as a parts bike, but has done well (around 40,000km under me, and a couple of long trips in that time). The 750 (one I'm riding now) is in need of rings and a few other things would be nice too.

I have split cases before, and learned a few gotchas like being very careful that a stack of washers/spaces goes back EXACTLY how it came off (best to take them out without separating them if you can, and keep them together in such a way you know which was at which end), likewise keep the gear pack intact unless you have to separate it. Little shifts in parts mean wear grooves no longer align, and you get new lots of wear as a result or things jam. It's not really hard but you need to be methodical and organised - two words I'm surprised I can even spell let alone do!

I know from experience that a mistake can lock up the gearbox. I was a teenager on my first engine with no manual working on the lounge floor when this happened, and thankfully in my case it was first gear if you kicked it into gear too hard.

New bearings and bushings sure sound nice. I can get the bearings at a good price for high-quality generic bearings, bushings I'm not sure about but I may be able to find an engineering firm that can make new ones from scratch, though it won't be cheap.

I'm still weighing up the options but new bearings would be nice. I don't know if there's anything wrong with the existing ones but the best time to change things like those is when you already have the engine out and on a work bench