Cylinders and pistons

[Trainraider]

I already started the discussion on the pimp-my-ride section, but since this is more on technical side, I rather move these bits here and keep the other section for the work updates.

The main problem is that I am lazy (aren't we all? ). So I don't want to split the whole engine and tear it into the smallest possible bits including stripping of the crankshaft and the gearbox.

I was wondering if it is possible to grind/hone (is hone correct word?) the cylinders without removing the crankshaft? So could I just take half of the engine to workshop and they would do the job. Or should I just go ahead and buy the sander (again I don't have correct word) and do the work by myself? It is not rocket science after all.



As you can see from the image, the cylinder is like a mirror with some scratches at the bottom part, which probably are part of the problem and caused the muck on the pistons and then again losing the compression.

The second concern is pistons.

Should I replace them? They don't have any dents, so I would be really happy if I only need to change the piston rings, which are obviously worn out.

And the bottom line is: Do I need to drill the cylinders to oversize and get new pistons?

Or would it be enough if I hone the cylinder by myself (or workshop), fit new piston rings and I would be good to go?

[scott02464]

The main problem is that I am lazy (aren't we all? )

I'm not no :-)

[benny hedges]

Feel free if you want to fill the engine with metal lol.
Plus you would only hone half the bore
If youre doing it, do it proper, bearings, shells, gaskets new.rings etc or invest in high compression pistons while its in bits

[Trainraider]

scott02464: Is that double negative?

Benny: Could you explain what you meant that I only lose half a bore?

If I understood correctly, that means that if I only hone the cylinders then I am only half way to the oversized piston?

Of course, there is a problem with iron dust when doing the honing, but it seems that it is possible to fill the engine with old rugs and prevent the fine dust going to the engine. After all, honing does not make any iron chips like drilling it to supersized...

I was also thinking about the high compression pistons, but that is way over my budget. So I am trying to go with poor man's solution. Gaskets and seals I already have. Only thing missing from the cheap-ass solution is piston rings. Hopefully I don't need any extra bits for the valves... But that is then another case.

Luckily I have 4 months minimum of winter, so there is no hurry.

[VTRDark]

Could you explain what you meant that I only lose half a bore?

I think with the honing you have to go right past the other side of the cylinder so the crankshaft will be in the way. It's like spraying a panel, start outside the area and move across to the outside of the opposite end. If you pause at either end to to move the other directions you are going to take more off at either end. You also need to drill with the honing tool square on to get a nice even cut all the way through and I believe you need to chuck some lube down as well. In all honesty it's best done on a bench drill.

Even if you put some rags down to catch any shavings, some are going to get past the rags. especially when it comes to removing them.

Personally if it was me, for a job like this, I would have the engine out and stripped down.

(:-})

[Trainraider]

After some more research (and good comments from here) it seems that I need to strip the whole engine. Darn.

The honing itself is not anything difficult and I could easily do that by myself. But when I called to a workshop, the honing work would be about same as buying the honing tool. Not worth of the trouble as I anyway need to strip the engine.

Unfortunately I haven't yet won in the lottery so I can't have high compression or oversized pistons. And old Stormy has enough power for the next summer (the summer after that is a new chapter), especially if I am changing the front sprocket to one-two teeth bigger to get some rideability at downtown as well.

In conclusion: you could do honing by yourself. You just need tool like this:

some oil (diesel fx) and you are good to go. You could do it even with the crankshaft on place (it cannot block the work), but the oil would anyway go to the engine and the cleaning would be a mess.

Good thing was that the price of the honing itself was much cheaper than I was afraid of.

[benny hedges]

I am changing the front sprocket to one-two teeth bigger to get some rideability at downtown as well.

one tooth Less (smaller) on the front or 3 up (larger) on the rear will give the desired effect.
get yourself a 15 tooth front sprocket & you won't need to adjust the chain length = same number of links.

for more info on gearing changes use http://www.gearingcommander.com

[tony.mon]

What on earth is the difficulty with stripping it?
It's only a few bolts, once the engine is out of the frame.

And no, a honed already worn bore would be useless, even with brand new std size pistons.

If you don't strip it all of the grinding paste from the oil and hone will drop into the bottom end, and you'll never get it all out.

[VTRDark]

68.00 Euro for standard oversize pistons.
http://www.cmsnl.com/search.php?model_i ... =2#results

You can also check out the price for other bits here as well.

(:-})

[benny hedges]

A more effective way of detroying your engine would be to remove the spark plugs and fill the cylinders with caustic soda.

That will shift all the glaze off the bores and rings, but also completely dissolve the pistons and casings

[tony.mon]

68.00 Euro for standard oversize pistons.
http://www.cmsnl.com/search.php?model_i ... =2#results

You can also check out the price for other bits here as well.

(:-})

Check they're in stock in the UK, though- last time I ordered some they were special order from Japan; we had to wait 3 weeks until there were enough orders for them to schedule a batch to be made.

Same with rings; shiny new pistons are no use unless the rings are also in stock.