Old Red Project (Performance question)

[TheBigRed]

Ok, I'm starting to look forward to the winter here, and moving the 550 project forward. Anyway here is my question for the day/week/till I get an answer.

Some time ago, when I first started this journey, I religiously watched fle-bay for parts that I would need to make the engine like new. As such I came across one size over piston rings (+.05), I purchased them for, well a fair price (been so long I forget what I did pay for them). Anyway, I was assuming I would just be able to use them with my current pistons, and have the cylinders honed to match. However recently, I have noticed that people are also buying pistons that are oversize to match the rings. So, I'm guessing that in order to use these, I will have to purchase the oversize pistons to match.

Can anyone give me this answer for sure?


btw, the rings are Teikoku Piston Ring Co., LTD 12140-47031-050

Amos

[tkent02]

In a pinch you could use them in the smaller bore, probably need to file the gaps down a bit.
Make sure they are the same in all other measurements, ring thickness, ect. The cylinder should fit the pistons tightly, you wouldn't want to bore it larger and use original pistons.
Rings are cheap, get the right ones or get the oversize pistons and bore the cylinders to fit.
How is the condition of the cylinders now?

[TheBigRed]

My original engine was running fine when I tore it apart, however I was having transmission issues, thus why the entire project started. In my quest for a good transmission, along the way I picked up a pair of 550 engines for $50 on ebay, and, well have both of those engines also in the 1000s of pieces that they are (ie 3 gs 550 engines in bits and pieces in boxes stacked on shelves in the garage). That being the case, I'm not 100% (due to two moves in the middle there somewhere) which parts go with which other bits. So basically, I have the feeling I'm going to have some boring done to match the bits together.

If that is the case, I need to make some decisions here. Do I just sell these rings to someone else? Do I source the pistons to match and pay to have the jugs matched? Or, since the last option would be spending more money anyway, do I look at doing Nerobros 6/550 modification?

Also, on another angle here (I just keep adding them don't I....) I won another ebay auction for the bottom end for a 550 for 99 cents that I will be picking up sometime this week. Also I have a line on a complete 550 engine that was just having clutch issues.

All that to say, my current thoughts are to pick up the complete 550 engine to put into Old Red for the time being, to get her back on the road. Then as I get the bits and pieces take the bottom end I'm getting and mod it to the 6/550 ala Nerobro, and put it in next winter.

My original intention was to keep the bike stock, but the more I'm thinking about it any of these changes will be pretty much internal, and the appearance will remain stock, so in essence, it will look completely stock, but essentially have a "big bore" kit, which isn't too far off of my original intention.



Amos

[tkent02]

I would be all over the 650 conversion, with another 550 engine to pop in there in the meantime. You could throw any of those parts together to get something running temporarily while you do the 650 mod.

I'm looking for a 550 to stick a 750 engine into.
But that's just me.

[TheBigRed]

Yeah, that is the way I've been leaning for the past couple of days. Just going to mean spending more money.

I should just keep my eyes out for the 650 bits that I need over the next couple of weeks. Maybe try to just get the conversion done this winter as it is, rather than spending the money on that complete 550 engine. However, knowing how things may end up going, that could keep Old Red from hitting the road come spring.

Ok, I'm rambling now, and have myself talked back into picking up the 550 engine to get the bike back on the road (though as you can see in my avitar, it is a long way from that at the moment). For now I need to spend the money on other bits of the project (fork rebuild bearing replacements etc). So, the 650 conversion is in it's future, but not this winter.

Anybody interested in these piston rings????

Amos

[Guest]

I'm looking for a 550 to stick a 750 engine into.
But that's just me.

Have fun with that..

Wanna race my 2 valve 550 if/when you do get it done?

[duaneage]

If you have several engines and parts, all is not lost nor confused. You need to get some measuring devices. You'll need a micrometer, inside bore gauges, and some plastigauge. A new set of feeler gauges is a good idea too.

Set the parts up on a workplace and start measuring. All the internals of an engine can and should be measured so that judgement can be passed on them. It is entirely possible that you will have 4 pistons and a set of cylinders that will be within specs enough for a hone job and re-ring, although not for the new oversize rings you have. I would stick with standard size if you can because pistons and bore jobs cost money, a lot of money, and the 550 might not be worth the effort. At most you would get 20 cubic centiliters and 3 HP.

You can find bore gauge sets at flea markets and other places, starrett makes real good ones as does mitoyo. There are usually several sizes in a set and they expand to fit the bore. Plastigauge is good for checking the crank journals, although roller bearing cranks are probably different in that respect.

I don't live too far from you, PM when you decide to decide and I can take a trip up and help you if you need it.

[TheBigRed]

Duane,

Good to hear from you. Thanks for the feedback, at this point I've got a line on a running 550 engine that was having clutch issues (I believe I stated this before) And I just about have the funds to source it (selling a couple more spare parts I have should do it).

As for my decision. I am 90% on building yet another 6/550 such as Nerobro has done. That being the case, I'm on the lookout for a 650 top end setup. However that is a project that I can take my time on to find the best deal possible. So, it will be sometime probably closer to next fall till I'm ready to actually build that engine.

Also, in all honesty it will probably be spring until I'm getting close to putting any engine in the frame anyway. I've got to get the frame down to the local mcycle shop to have them press in the tripple t bearing races, and little stuff like that that is beyond my skills/toolset.

Thanks for the offer, I may very well take you up on it. Especially once I get to the point where I need to tune things, as I know you've got some experience with that.

Amos

If you have several engines and parts, all is not lost nor confused. You need to get some measuring devices. You'll need a micrometer, inside bore gauges, and some plastigauge. A new set of feeler gauges is a good idea too.

... I would stick with standard size if you can because pistons and bore jobs cost money, a lot of money, and the 550 might not be worth the effort. At most you would get 20 cubic centiliters and 3 HP.

...

I don't live too far from you, PM when you decide to decide and I can take a trip up and help you if you need it.