1977 R75/7 sat for for too long

[Gurstang]

I got this bike in 1987 for fixing the brakes on a Toyota Supra.
Here is a picture of it.



Unfortunately it sat from around 2004 to 2010 outside under a bike cover. Then from 2010 in a garage. It had around 30k miles when I stopped riding it. I didn't know about storing at TDC at the time.

The right cylinder has rust in the barrel.


At this point I'm wondering what my options are. I don't believe I have the Nikasil liners.

Would a rebore to 1st oversize be enough?

I think I read that 2nd oversize pistons are very rare.

It seems like finding a used barrel that is pit free is doubtful.

Should I just get a power kit instead? (I don't really want to do this for a few reasons. The cost is not a big deal though)

[robert]

It can be bored to fit 800cc pistons. You may want to check the availability and price. Used 800cc cylinder assys. from those that have converted to 1000cc may be available. Look around.

[SteveD]

Pre 9/80 should be iron bores so can be bored. How deep is the rust I wonder?

You might get lucky on used barrels.

There's alway Siebenrock?

[Kurt in S.A.]

There's alway Siebenrock?

When I decided to do a top end on my R100/7, I looked at going 1st over and using OEM stuff. Pretty expensive. Plus the liners on the 1000cc engines are iffy going 1st over as there's not that much to take out. I decided get the Siebenrock kit. All the parts are lighter, the jugs are completely aluminum, and the cylinder walls are Nikasil coated. Better cooling and lighter components makes things nice. The kit worked out well and was cheaper than spending the money to bore my old jugs and buy new pistons and rings.

Kurt in S.A.

[Seth]

I redid the top end of a friend's R90S this past winter.
The cylinders looked in similar condition as yours
I contacted Ted Porter of Ted's Beemershop to redo the heads.
http://www.beemershop.com/
Ted recommended using PowersealUSA to redo the cylinders.
http://www.powersealusa.com/
Assuming your pistons are in good condition, they will slightly bore your existing cylinders, plate them similar to the Nikasil process and machine them to fit to your pistons.
First, contact Ted to make sure you can get rings for your 750 compatible with the Nikasil walls.

He also had a second location that did the Nikasil process, but they were in the mid-west USA. I worked with Powerseal because I live about 1.5 hours away from them.

Just another option.

[Wobbly]

Storing at TDC is a myth. Storing where there are extreme temp changes is the issue.

The Really Cheap Option
The fact that the engine was NOT at TDC gives you options. The cheapest is to hone and install new rings. The corrupted area is not at TDC, therefore your engine may burn slightly more oil than normal, but it will run smoothly. The further the rust area is from TDC the better off you'll be. The only way to learn if the area of rust is far enough down the bore not to be a huge issue is to run the bike. I'm not saying for an instant this option is optimal. I'm saying a bike being used suffers less deterioration than a bike sitting under a tarp.

The Next Cheapest Option
Buy a single pre-Nikasil cylinder off Ebay and put it back together with a hone job and new rings. Good used parts are everywhere for these bikes, and can be had cheaply.


► You should, of course, renew all the gaskets and especially the push rod tube seals at the same time.

► You are also going to experience the same rust issues in your brake master cylinder and caliper(s).

[disston]

You have pre-Nikasil iron bores. That right cylinder doesn't look so bad to me. I'd go for the new rings, a hone job and new gaskets. Should be fine.

Of course doing more is more expensive but may give better results.

[Gurstang]

I appreciate all the replies. Thanks so much. I have been trying to reply but the board has been giving me problems.

I think I will either do nothing (which is new rings and hone job) or the folks at http://www.powersealusa.com/ It would cost $240 to have it bored and plated to use my original cylinder.

I know someone who restores British cars who can check the bore with a micrometer to make sure it is still in spec and do the hone job.

[Rob]

Gurstang, the board has been giving everyone problems, but probably none as much as the owner, Matt.

I am glad you hung around.

[richard t]

I appreciate all the replies. Thanks so much. I have been trying to reply but the board has been giving me problems.

I think I will either do nothing (which is new rings and hone job) or the folks at http://www.powersealusa.com/ It would cost $240 to have it bored and plated to use my original cylinder.

I know someone who restores British cars who can check the bore with a micrometer to make sure it is still in spec and do the hone job.

let us know how this works out