Cyl/Head o-rings why so small
My question is why are the cylinder o-rings on the GasGas undersized compared to the o-ring groove?? They need to be stretched alot to fit into the groove, resulting in a smaller cross section. Are they undersized for thermal expansion?? :confused: http://catalog.precisionassoc.com/pr...lication-data?
I'm a mold designer and spec out o-ring grooves all the time. When we size a o-ring groove we match either the outside or inside of the o-ring to the groove, depending on if it has internal or external pressure. The groove is designed so that the o-ring protrudes above the surface but is wide enough to accomadate the o-rings cross sectional area. Bob in MN 2 weeks till the Wudi! :D |
What size bike do you have? You could have got 200 O-rings. I find using some grease helps keep them in place.
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I'm wondering the same thing. The o-rings I have put in my 250 fit well and only one was a hair small. It only took a small amount of massaging to get it to fit.
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They shouldn't have to be stretched excessively. Just a light stretch through your fingers with a light coating of grease. Drop in the groove and run your finger around a few times, they will then stay put with no issues. Drop the head on square and rotate slightly back and forth, it should feel smooth. I agree with the above post, if its more trouble than that you may have the wrong o-rings, it has happened to me.
o-ring specs/grooves have a lot to do with the material, pressure, temp, and if its a static or dynamic seal. I'm no expert but have some experience in both medical and industrial applications. Published guidelines are available. The GG head /cyl design has never caused a problem if assembled correctly. I have seen o-rings pinched causing a leak. Thats why I rotate the head slightly on install, if an o-ring jumped a groove you will feel it. |
When I did my 250 awhile back I was afraid I was going to rip the o rings in half. I tried putting them in hot water and everthing else finally stretching them seemingly to the point of tearing.
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That is just not right. Likely you got o-rings for a 200.
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I had the same problem the first time I got an outer o-ring in the mail, it was way too small. The next o-rings I got in another order were just a little small but fit with minor stretching and stayed in place. I believe the first one sent to me was for a 200 and not a 250.
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Well the first try I did have the wrong o-rings now the inner is correct, still a little small but the outter is way small again and is much smalled than the ones I took out. :(
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Sometimes the dealer gets sent the wrong parts. Back a few years, I was buying 250 head o-rings and the dealers whole stock was wrong, under the correct part#. Not his fault, you expect people to pack things correctly.
If you can't get the right part just order from a supplier, the size is in the parts manual. |
I received the corect o-rings and they were pretty easy to install.
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