Cylinder replacement 850 T3

[bobra5037]

I’m considering replacing the chrome cylinders on my newly acquired 1977 850 T3. How difficult is it?  I’m not a mechanic but, then again, I’m not completely useless.  Should I attempt to do this or refer it to a professional?  What can go wrong? 😱

Thanks

Rob

[Antietam Classic Cycle]

Here's the assembly process:
https://www.thisoldtractor.com/projects_roy_smith_2013-03-19_install_the_right_piston_and_cylinder.html

You be the judge if it's something that you can handle.

[cliffrod]

What can go wrong?

Soon after I got my V7 Sport in the early 90’s, I “just” replaced the chrome cylinders and pistons to remedy stuck pistons and peeling chrome resulting from a decade plus of dormancy…. within a couple of years, the entire engine needed a full rebuild.  Loose chrome had already taken its toll.  Since the proper full rebuild, the engine has been bulletproof & fantastic.

Maybe my experience is atypical, but I learned my lesson. I’ve got a couple more chrome bore engines here that will probably run as is.  But I will do everything properly the first time this time- full disassembly, inspection, service as needed, etc- not just replace the chrome cylinders & pistons and hope the rest is ok. 

[bobra5037]

I must admit, it I'm in a bit of a quandary over this.  I'm only the second owner of the bike so I know its full history.  18,000 miles on the clock but has spent the last 20 years or so idle in a garage in a very dry climate.  The bike run well and I can't see any obvious blemishes in the cylinders using an endoscope.  The bike is a hobby and will probably do less than 500 miles a year until I'm too old to get my leg over it (maybe not that far away!).  So, do I ignore it and just ride the thing or do I succumb to my anxiety and get the cylinders replaced?  Only I can answer that question but I'd be interested in others experiences.

Thanks

Rob

[cliffrod]

For comparison, my V7 Sport was used/ridden hard between purchase new here in town (Spartanburg, SC) and when it was apparently parked around 1981.  The speedometer showed around 23k or 25k when I got it iirc.  I have no idea how accurately that reflected actual mileage on engine.

You can just swap cylinders and pistons and see how it goes, especially if the original cylinders look great.     It will either be fine or it won’t be.  But if there is already notable chrome loss when you get in there, doing more at that point would make sense.  Your engine has an actual oil filter, which is better than my engine with no filter.

Your bike, your rules. 

[Tkelly]

If you don’t get it done the resale is minuscule.It might run fine for your purposes the question is whether or not to bring it to  long term reliability.

[moto]

Historically, on this site, the rule of thumb has been that not having replaced the chromed cylinders takes $1000 off the value. This is about the cost of buying a Gilardoni or other set of Nikasil-coated cylinders and matched pistons/rings and putting them in yourself. The standard question about a newly available bike has been whether it has the Gilardonis, not whether it was completly dismantled to chase chrome particles.

So spending $1000 and doing the job yourself is a good investment that will likely be rewarded accordingly on resale. If you have average mechanical skills for an old motorcycle rider, it is not a difficult job simply to swap the cylinders and pistons. (Consult the relevant parts of the instructions that were cited in the first response.) It is a satisfying project to do that may impress your friends.

On the other hand, there are plenty of other fish in the sea who will buy your bike for about what you paid for it, odds are. Assuming it has no signs of impending doom.

[bobra5037]

Thanks for the responses, it all helps.  One odd factor is that the previous owner thinks the cylinders are nikasil coated (or similar).  He didn’t replace them but claims it was done “in the factory”. This seems improbable in an 1977 bike and there is no hint of magnetism in the cylinder walls.  However, they are not shiny chrome either.  So, how reliable is the magnet thing?  Were there other cylinder coatings used at the time?

[chuck peterson]

I’ve been keel hauled for suggesting not to worry..but

I think you need to find out what you have. You state right off they’re chrome, but later you suggest the PO says Nikasil…or a factory solution. Maybe…

My 76 Vert was iron liners. No fear there

[Antietam Classic Cycle]

However, they are not shiny chrome either.  So, how reliable is the magnet thing?  Were there other cylinder coatings used at the time?

This is hard chrome, not cosmetic chrome, so it wouldn't be shiny. If you're using a strong enough magnet and do the test correctly, the "magnet thing" is 100% reliable. The only 850 in '77 with anything other than chrome was the 850 Le Mans which had iron liners.

[Offcamber1]

Pull the heads, take a good look and if chrome and they appear ok I'd replace them anyway.  If you lucked out and they are iron/nikasil your good.  If there is any indication of flaking I'd do a complete tear down.

Either way, service the heads while your there, make sure the guides are good and the rocker shafts are not worn.

As Dr. Haynes likes to say: "Assembly is the reverse of disassembly."