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Post by ballvo on May 3, 2017 11:33:47 GMT -5
I just dropped off a set of new Wossners to the guy that's boring my cylinders. He said, from experience, he tends to go a bit looser than what's specified on the box.
Just wondered what others are using for clearance for Wossners.
thanks, N.
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Post by Walms on May 3, 2017 11:55:39 GMT -5
Idk, I think you are best to just follow the directions imo. H1 Wiseco's were .003" and guys were taking that down to .0025" Wossners calm out for .0026" So I'd ask him what he plans to do? I would only consider tightening the clearance on the Wiseco's myself, only to make up for weak skirts.
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Post by Walms on May 3, 2017 12:08:47 GMT -5
To put it another way, tell him his tolerance is what the oem suggests as a max to minus .0002" and keep your fingers crossed. It's difficult to measure .0002" anyway... in fact, I'd be surprised if his roundness is within .0002" to be honest.
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Post by pipe welder on May 3, 2017 13:24:31 GMT -5
I did my H2 with Wiseco's at .0025 and the piston sizes were all over the map so make sure he bores each hole to match each piston. I did several heat cycles after the rebuild before any hard running and I generally don't run it hard anyway. I have had no issues and several other guys also bored to .0025
I feel that the piston manufactures have to recommend significant clearance to avoid possible issues that can occur due to things like lean mixture or hard running after new pistons are installed and things of that nature that can cause a piston to stick and they don't want customers blaming the piston.
If your machine shop has good tools and equipment they can measure and bore very accurately and if your careful running it after the work is done the tight clearance makes for less rattle in the future. You can also pull the cylinders after some run time to check the pistons for high spots and remove them with light sanding to reduce risk of sticking if your concerned.
I seem to remember someone recommending that you check that the deck surface is accurate before boring. (90 degrees to bore). I think some issues were found on some cylinders that had been bored if I remember correctly. Most shops will assume there is no problem there so it seems like good advice to check it.
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Post by JA-Moo on May 3, 2017 13:33:50 GMT -5
He is playing the CYA game. Go with manufacture recommendation.
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Post by Jim on May 3, 2017 13:33:54 GMT -5
Wössner specified 0.0027" in the information that came with my H2 pistons and that's what I had the cylinders bored to. I measured carefully and determined that they were probably right on that clearance.
Sometimes the machine shop guys like to tell you how experienced they are, and why you should deviate from the manufacturer's instructions. Every time I've had my H2 cylinders bored, I was told that they normally bore the center cylinder with extra clearance because it runs hot, and every time I have to ask them to please make them all the same.
The last set of pistons I bought were Wössners. I measured them very carefully with a micrometer, and they were all the same size within a ten thousandth of an inch, so I took only one to the machine shop. They were concerned until I explained that they were all the same.
Pipe welder, did you mean 0.0025"? If the .025 was millimeters, you were under 0.001".
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Post by Walms on May 3, 2017 13:44:21 GMT -5
Funny you mention that Jim. The last bore on my motor barely cleaned up because the previous bore was cock-eyed. Maybe it depends on the piston manufacturer as well. I found the skirts were much thinner on the last set of Wiseco's I had compared to the Wossners. I suspect Wiseco uses the same forging regardless of oversize. Wossners are machined inside to eliminate this issue (again guessing) My motor was a rattle trap with the Wiseco's after 1 season. The skirts were already collapsed .004" That was the time that I specified the tighter clearance as well. I suspect that guys who get longer service out of them simply don't push the motor as hard? Wossners still sound good with the prescribed clearance so far. As far as accuracy goes, I trust no one and question myself when measuring. It's easy to tell people what they want to hear when you are 98% sure the customer can't call you out on it! Lol I recall a local crank guru that I caught fudging the numbers on me... just another respected local vendor that I'll never use again!
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Post by pipe welder on May 3, 2017 14:09:39 GMT -5
Oooops, Yes I meant .0025" - Corrected
My Wiseco pistons were marked for .0030 (0.076mm)clearance and the machinist Highly recommend that I do not go with .0025.
I wanted to avoid the rattle so that was my main objective. I had the Wiseco pistons at that I bought with the bike otherwise I would have purchased Wossner. I don't think we have anyone here who has ever had any issues with Wosner's.
I sure wouldn't go with looser than Wossner recommend as your guy is said. A good bore gauge and mic isn't cheap. It would be nice to bring them to a second shop to check the work after it's done.
Your cock-eyed bore must have been the story I recall. I wonder how common that problem is? JaMo, have you seen the cock-eyed bore problem before? Must be lazy setup work I suppose.
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Post by Jim on May 3, 2017 14:27:17 GMT -5
For my last bore, the machinist found the bores a bit out of alignment. Rather than make me go to another oversize, he straightened them up only partway. I think it's pretty common for the bores to be slightly off perpendicular to the crank. One oversize is only 0.010" on the radius, so it only takes a few thou out of alignment for the bore not to clean if the guy just bolts them up and starts boring.
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Post by kawonda750 on May 3, 2017 15:05:13 GMT -5
My guy said that Wossner measurement were very precise. Specs put the bore right to 0.5 mm bore. EG 60.5 for first over.
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Post by Jim on May 3, 2017 15:07:39 GMT -5
That's what Wössner says, if you bore to the exact size, like 71.500 mm, the clearance will be correct.
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Post by ballvo on May 3, 2017 17:56:18 GMT -5
Thanks for all the input, boys. I'll pass on the meat of it to my guy tomorrow. He won't be getting to them until early next week.
N.
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Post by H2 Dude on May 3, 2017 23:39:09 GMT -5
Not Wossners but I had a set of aftermarket ones done at .0025. First ride was when the Temp was 40c then the Huron Tour came soon after
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Post by roco on May 12, 2017 15:28:12 GMT -5
Just for my two pence worth had my H2 cylinders nicasil plated because the standard cast iron bore is soft and I have had them wear out on the intake side in as little as 2000 mile, then the dreaded piston rattle became apparent, from then on its more rattle quicker wear, quicker wear more rattle and so on. I had Wiseco pistons fitted at .002inch ran it in for about 800 mile with extra oil in the tank, standard oil injection and many heat cycles, I triple checked the ignition timing and was only after I bought a dial gauge type depth indicator that I was happy with the timing , with a vernier type gauge each time I did the timing it was different. The bike has now done 4500 mile and is still tight, very easy to start, pulls at all revs strongly and is reasonable on gas. The biggest single improvement I did for the motor was to have the heads and cylinders done for squish type combustion chamber this stopped all the pinking on hard acceleration and stoped over run rattle caused by poor cylinder head design the engine runs cooler as tested by a heat gun and had to go one to two ranges hotter on the plugs. The guys that did the nicasil have state of the art gear and do all their machining in controlled temperature rooms so that measurments are very precise.
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Post by acceleration on May 13, 2017 7:06:47 GMT -5
I have had several original bore original piston 500'S that were running great and had good compression @150 PSI That were running well.Last one that I rebuilt and put pictures of in the projects thread.Was running real well.I took it apart for a rebuild and detail and because of minor leaks and I wanted to clean up the cases and rebuild the crank.We have a dial bore gauge and all the tools needed to take measurements. When I took it apart the cylinders looked good and so did the pistons.Measured it up and it had .005 clearance.It ran well and didn't hear excessive piston slap etc..Brother Duane rebuilt the crank for me here in our shop. Re-bore cylinders and factory pistons and clearances at .0025 Back together and it does not sound any different running? I ran several bikes in the past and from my own experience have found that they still ran good with a fair amount of piston clearance like this bike.Wiescos are a dense forging and don't expand as much when at operating temperature and can be run as tight as .002 But usually set them at .0025-.003 .I have no experience with Wossners.I still have a few set of Wisecos on hand so I use them for now.We recently got our own boring bar with the help of our good buddy Adam CANKAW so be sides rebuilding our own cranks in house we can re-bore our own cylinders and have all the tooling to re-bore and rebuild cranks for any two stokes.Duane has rebuilt quite a few triple and RD and RZ cranks including Adams crank for his current H2 project.The cranks for our RD'S & RZ'S along with the cranks for the 400 triple my 500'S and the H2 projects we are currently working on. Really nice to have the tools to do it ourself and not have to wait on or rely on someone to get things done.
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