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Piston Ring question

  • Thread starter Thread starter qslim
  • Start date Start date
Q

qslim

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So I've ordered a nice Vesrah gasket set per your recommendations from DennisKirk, and I figure that as long as everything is apart there is no excuse for not replacing the rings. I did some looking around, and the only place I can find them is on BikeBandit. However, on the fiche there are two lines for piston rings, 25-1 and 25-3; http://tinyurl.com/86q5o . I don't know why there are two options for rings and a $4 difference between the two.
I've sent a couple of emails to them, but have yet to receive a response. Can anyone here shed some light on it or know of another source for rings?
 
Replacing rings can be an undertaking of sorts, I would not replace them unless you feel it truly necessary. Proper prep and careful measurements of the internals are necessary or your not going to be happy. If the engine did not smoke and there are no scores on teh cylinder walls I would just button it back up again.

Just my .02 thats all.
 
qslim, Look on ebay for a motorcycle parts seller by the name of "MrsSuperDeals".. I scanned over an excess of 1500 parts on her listings last night. Rings and pistons out the wazoo.
 
Davedanger, you are the man. Mrssuperdeals does indeed have the cure for what ails me. Now we'll just sit back and hope they'll fit. Thanks.
 
Re: Piston Ring question

qslim said:
I don't know why there are two options for rings and a $4 difference between the two.
Click to expand...

simple!! 25-1 is for stock size rings, 25-2 was for half (.5)MM over sized (no longer available) 25-3 is 1MM over sized rings.
note the three differant pistons? 24-1, 24-2, 24-3 you can still get half over pistons, but not the rings.

I am running 1mm over pistons in my 1000. (from 998cc up to around 1030cc)
 
Ah, so the over sized pistons & rings would be used should I need to bore the block out?
 
Exactly qslim.

The pistons do try and slide perfectly centered up and down in a cylinder, but in ANY piston engine, the sideways force of the connecting rod is transferred to the piston, and it tends to wear the cylinder into an oval. When it's checked with a bore gauge (micrometer) it will measure wider in diameter in a plane perpendicular to the crankshaft than it is parallel to the crank. When that out of round measurement exceeds a specific tolerance, it's time to hone or bore the cylinder up to the next larger piston and ring size. With much larger bore air-cooled piston engines, it's possible to go to a slightly oversize ring set while still using a standard piston. I have no idea if that's possible with metric bike engines though.
 
Some bozo on a website criticized honing as being unnecessary. Piston slap and thrust forces elongate bores and surface honing and button honing correct this.

We had a pretty good thread going on about that last month
 
Piston Ring Question

Piston Ring Question

I am also looking at reboring my 1150. I was losing compresion on 2 & 3 cylinders and was unable to maintain an idle. So done the compresion test and leak test. I have now discovered I cant get first size over rings but can get pistons?
Seems you have experienced the same, Does this mean I do need to go 1mm over? Or is it just the smaller GS's that dont have rings? Seems odd that I can get pistons but not rings. If anyone knows where I can get 1st oversize rings please let me know.
Thanks
Jock
 
you could give wiseco a try but I would not hold my breath.

odds are that if you are loosing comression that bad, you are already way past the first over size already.

I had reasonable comression but was burning way to much oil, it turned out that my bores were already worn 1mm beyond stock (for/ aft) the machine shop just trued the cylinders.
this was on a bike with just under 100,000 miles on it (98K and change)

Suzuki just quit producing the .5 rings, the pistons are left over NOS they probably stopped making the rings due to the fact that more often than not, the bores are past the .5mm range when compression issues crop up.
 
Jock, do your shopping online or wherever and determine exactly what pistons and rings can be obtained, then after you've disassembled the heads from the bike, take them to a machine shop, automotive or bike...and have them measured for diameter and out of round with a bore gauge. This is standard practice for any engine rebuild. You need to know first how out of round your cylinders actually are, before you can start buying parts. To be considered also, is the fact that it's not likely that the cylinders will wear very differently. If one or two cylinders are out of round, the others probably will be as well, by a similar amount. Whether they are identical or not, consider determining the cylinder that is the most out of round, and bore or hone all cylinders to the exact same oversize.
 
a good machine shop will measure the bores and let you know what they will need to be taken out to , to get the bores round and true (top to bottom) and then using the new pistons bore match the cylinders to match the new pistons.
 
You shouldn't have trouble getting pistons for an 1150. Check places like Star Racing and such. They are still so popular in drag racing you can get parts.
 
Just an update on my rebore.
I have had the cylinders rebored and have a new set of pistons and rings on order. Should I replace the cam chain at this time? If so can I use a riveted one? or should it be endless? Any Ideas or preferences / experiences? Cant wait to get the old girl running again. I have been using my Guzzi for everything this last couple of months but do miss the Suzuki. Happy New year to all.
 
The manual tells you to measure 20 streched links and gives you a max length. When I measured mine, I was far enough under max that I didn't consider replacing it.
 
Jock, are you saying that you had your cylinders bored before you got your pistons? That's a big no no!!! There's no way to know what the bore should be without measuring the pistons. I bore cylinders all the time but I won't do it without pistons to measure from. Mike J
 
Mike,
I have a set of Cosworths and a couple of extra blocks. One of the blocks has a piece of one liner busted off so one liner needs to be taken out of one a dropped into the other. Would you be willing to do the work? The cylinders shouldn't need much more than a clean up. The pistons are only .05mm over. That's not a mistake, .05mm is correct. They were one off pistons made for a bike Britt Turkington used to race. They are brand new pistons and I have Total Seal rings for them.
 
Billy, that job shouldn't be a problem. The .05 over size is nice because it gives you an allowance to hone on the stock bores. All I would need to know is the recommended skirt clearance for the Cosworth pistons and where they take the clearance measurment from. PM me with your number and we can discuss it more if you like. Mike J
 
Once you're down to the cases, it's pretty easy to just keep going and split the cases and replace the cam chain. That way you can check the tranny for unusual wear and clean the goo out of all the sumps

Warning, you will be tempted to start cleaning, polishing and painting everything before you put it back together so it will look like new!
 
Hi Mikej,

Happy New Year to you all at GS Resources.
Sorry for the delay in replying, work seems to be in 6th gear and at full throttle.
Anyway to answer your question it seems I jumped the gun a bit, they waited until my pistons arrived prior to reboring them. They told me it its a tight tolerence of 0.05 to 0.1 thou they opted for 0.075 as an optimum clearance. Things are going well so I hope to have her at least running soon.
 
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