# Can that scored cylinder be re-used?



## Manugoss (Feb 24, 2008)

Short version
What should I expect if I use that cylinder again? Of course the cylinder will be sand papered, and stones will be run in it along with a new piston kit. Will GB or Gulf piston fit this mahle Cylinder? Is mahle cylinder the oem part.

Long version
I just bought a Husqvarna 51 on ebay as a project saw and got some bad surprises. The saw ingested saw dust caused by a bad air filter and has now improper compression. By looking at it, I would say that the ring broke and scored the piston and cylinder. The most amazing part of this story is that the saw ran numerous hours after the incident because the remaining part of the ring is as thin as it can be near the broken end. Well that is what I think. That makes me wonder? How can a saw work with only 75% of its ring left? Does that make any sense. The scoring on the cylinder wall is not that bad I would say but a finger nail could catch. I don’t know if it is worth it to put the saw back together with the proper parts. My plan is to split the crankcase open, to remove all debris, change bearing and oil seal and put a new piston kit in it. For the cylinder, I would use fine sand paper to remove the positive part of the scratch, and run the stones in the cylinder to get as best as finish as possible. I attached some picture so you can have a look at the cylinder damages. 


If I do the best that I can with the cylinder and use it again what possibly could happen because of the scratch in the cylinder wall? What kind of power loss should I expect? I know someone who works as a mechanical engineer for B.R.P (they make bombardier ski-doo) who has tried everything with a 2 stroke engine. He said that one 2 stroke engine used in a ski-doo that he rebuilt had bad scoring. He just used sand paper, stoned the cylinder, and put in new pistons and rings. The engine has countless hours on it without malfunction. For the engine power, he said that one could not tell the difference by running the engine. I am not an expert at all but in my mind scored cylinder can only cause 2 things: local improper lubrification and loss of compression. How does the space between the ring-ends compare with a small scratch on the cylinder? In my mind it is not that significant. That means that loss of compression from the cylinder scratch is much less than the ring ends. Is there any data for the gap in new rings vs worn rings in comparison with the compression with new rings vs worn rings. I think that with that data and the scratch dimension, it would be possible to know the significance of the loss of compression from the cylinder scratch. Thanks


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## Four Paws (Feb 24, 2008)

Yeah, you can reuse the cylinder. Hit it with a hone, throw in a new piston, and call it good. I would use a Meteor piston from site sponser uwharrie (Tony) - he has his own forum in the sponsor section - Amicks Super Store.


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## JONSSTIHL (Feb 24, 2008)

that sounds like quite a project. 

you are right, the small scratch probably won't change the compression too much compared to the ring gap but I think it will erode and become a larger scratch and cause problems but how long that will take to happen is up for debate. 

that cylinder doesn't look too bad. I would probably clean it up. sounds like you will be using a brake cylinder hone. you might run into problems with the stones catching in the ports, I would use a ball hone instead.


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## bcorradi (Feb 24, 2008)

Four Paws - have you had a chance to use any of those meteor pistons? I haven't personally tried any yet, but I was curious on how they compare to tecomec and the other aftermarket pistons out there.


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## Manugoss (Feb 24, 2008)

Thanks for your fast reply!

Few more questions

1)Is the mahle cylinder the original husky part?
2)What sand paper grain size should I start with?
3)Is there any good source of husqvarna parts online like bearings, gaskets etc (I checked on ebay for bearings and 11$ a piece is quite expensive if you compare to 3$ a piece for oem shindaiwa 488 on hhcle). Would it be cheaper to buy the SKF part directly?
4)I have to buy a filter and it is not the screw type one. I might be missing a part on the saw but I did not get how to hook the filter on the saw. Is there A clip or some other thing that I might be missing on the saw.

It is a good thing that I dont need the saw in the near future. I dont know if I am normal but opening a saw crankcase is the kind of thing to do during the week-end when there is too much snow to go in the woods. It is a good thing my fiancee doesn't mind the smell of dirty 2 stroke engines too much...

Thanks


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## Four Paws (Feb 24, 2008)

bcorradi said:


> Four Paws - have you had a chance to use any of those meteor pistons? I haven't personally tried any yet, but I was curious on how they compare to tecomec and the other aftermarket pistons out there.



I'm going to call Tony and order some tomorrow.

The pictures look great, and I have talked to a couple guys that have tried them and they seem pleased.


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## Manugoss (Feb 26, 2008)

*Few more questions*

1- What sand paper grain size should I start with?

2- Is there any good source of cheap husqvarna parts online like bearings, gaskets etc ?

Thanks


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## Griffbm3 (Feb 26, 2008)

*Check your PM's*

Sent you a PM


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## NuConcepts (Feb 26, 2008)

i would personally use 320 grit sand paper


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## Manugoss (Feb 26, 2008)

Thank you for the tips guys.


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## Dan Forsh (Feb 26, 2008)

Mahle is OEM


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## Cowboy Billy (Feb 26, 2008)

I hate to disagree. The scoring is not bad. But gouge in the wall above the scoring is bad. It looks to be wore all the way through the chrome plating. The new ring will never seal in that area and thats where you have most of your compression. The ridge where the ring stops looks to be about .015 deep the new ring hitting it might break. And ring tryihng to expand into it is going to make it work in and out of the ring lands wearing out the piston.

Billy


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## motosierra (Feb 26, 2008)

I agree......................................


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## Manugoss (Feb 26, 2008)

I tell you what I will do. I don't know alot about cylinder but I am pretty sure that I can have a better idea of the cylinder shape once it has being through sand paper and ball hone. It does not cost much so I will try that first. The scratch on the picture especially the one on the corner looks worse than what it really is. On most of its lenght, the scratch is not that deep at all. In fact there is 2 little scracth side by side. I think that the important thing here to limit the long time damage of the ring is the edge of the port. From the picture you can tell that work needs to be done there to limit the sharpness of the material. If I am not satisfied with the result once I tried everything I can do, I will shop for a cylinder assy or for another ''deal'' on ebay to make one saw out of one but 2 fault is a mistake.... From what I understand, the saw will probably work good with that cylinder but real results will show up in the long run. So if I get that 51 to work with that cylinder, I will give it to my brother since he is looking for a spare saw for its 266Xp so I bet he would be happy with that old 51 project saw under the crismas tree next year. I am sure he would never get the end of it since he would put only limited hours every year. If by any chance he like it so much that he sells he's 266Xp and use the 51 too much to break it, I will get him the new 55 cylinder kit for another cristmas....


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## rmh3481 (Feb 26, 2008)

*Should clean up*

Start off with a brake hone, which will allow you to reach all the way to the top cylinder ridge using the flat stones. Use extra oil on the hone and keep the inside of the cylinder wet. 

When putting the hone in the chuck of your drill, just lightly hand tighten it. This way if the stones get stuck in the ports, the hone stops turning rather than messing up your job. 

Finish up with the ball hone to give a nice cross hatch. Can you find a new piston or are you going to try to clean the old one up? 

You will need a new set of rings to finish the job and it should work out well.

Best wishes,
Bob


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## Manugoss (Feb 26, 2008)

I was thinking of buying a new piston and ring. The piston does not look good on the side. It has bad scoring. On the other sides, it looks good. Would it be wise to try to reuse the piston or it is just not worth it. We always here that once you have the engine open that you might as well change the piston and ring...


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## Manugoss (May 8, 2008)

*Back to life*

I got tired of waiting for a good deal on ebay to fix my 51 so I bought a 55 cylinder/piston kit with gaskets. I also bought 2 new bearings. Last night I put everything back together. It started on the 4th pull but needs a good carb ajustment. The crank seals looked ok so I reused them. I do not have a vacuum pump to test for crankcase leak. Here is my question: How do I know that the seals are good. Here in Canada they sell for 12$ a piece so it is a 24$saving if they are good. Thanks


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