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S3 Head Install ?

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Newbie to the site....

I just finished assembling the motor on my 2004 1.25T and installed an S3 Star Head. Looks great but leaks coolant around each of the 6 cylinder studs/ nuts. All o-rings are in place and are flush/ flat against the cylinder and head surfaces. Head nuts are torqued to 10 foot pounds etc. The head insert is aligned with dowel pin on the head. What have I missed??? The leakage is around the stud at the nut no where else.

Just a couple of other issues if you plan to purchase one of the S3 heads: I had to turn down the head nut shoulders to allow for enough room for them to clear the head and then turn down a 10mm socket to fit over the nut and between the head as the clearance is very tight.

Thanks in advance for any insight and input.

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Newbie to the site....

I just finished assembling the motor on my 2004 1.25T and installed an S3 Star Head. Looks great but leaks coolant around each of the 6 cylinder studs/ nuts. All o-rings are in place and are flush/ flat against the cylinder and head surfaces. Head nuts are torqued to 10 foot pounds etc. The head insert is aligned with dowel pin on the head. What have I missed??? The leakage is around the stud at the nut no where else.

Just a couple of other issues if you plan to purchase one of the S3 heads: I had to turn down the head nut shoulders to allow for enough room for them to clear the head and then turn down a 10mm socket to fit over the nut and between the head as the clearance is very tight.

Thanks in advance for any insight and input.

A friend of mine had a problem with his S3 on his gasser. He may chime in and clarify...but I believe it had to do with the size of the head gasket. Ill check into it and see if I can find out.

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A friend of mine had a problem with his S3 on his gasser. He may chime in and clarify...but I believe it had to do with the size of the head gasket. Ill check into it and see if I can find out.

I don't have a gasket it is an inner and outer oring with six individual orings around each cylinder stud. The photos on the S3 website show the sherco motor with head bolts and what appears to be a copper compression washer between the head and bolt.The seal around the inner oring is good as it holds compression when I put the compression gauge to it. Appreciate the quick reply.

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Right the O-Ring. That's actually what I meant. I believe one was a different size or something.

I sent him an email to check this thread.

Edited by motofire

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Newbie to the site....

I just finished assembling the motor on my 2004 1.25T and installed an S3 Star Head. Looks great but leaks coolant around each of the 6 cylinder studs/ nuts. All o-rings are in place and are flush/ flat against the cylinder and head surfaces. Head nuts are torqued to 10 foot pounds etc. The head insert is aligned with dowel pin on the head. What have I missed??? The leakage is around the stud at the nut no where else.

Just a couple of other issues if you plan to purchase one of the S3 heads: I had to turn down the head nut shoulders to allow for enough room for them to clear the head and then turn down a 10mm socket to fit over the nut and between the head as the clearance is very tight.

Thanks in advance for any insight and input.

Have you installed the six small o rings in the top of the barrell? if there is a small circular recess you need them: if the top of the barrell is flush ie no recess you dont need them,,,hope this helps,,

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250 gasser had a head leaking problem. note: Only has an inner and outer oring - no individual stud orings on the gasser. my problem (I think) was that the inner OEM oring was stretched too tight as the s3 head groove was aprox 2.5mm larger than stock head. Mine was a very small leak and a PITA to track down. After several failed attempts, with new stock orings, I recently installed a larger oring and that fixed the problem on that bike. (many Thanks to Brad at RYP for help finding larger oring - great customer service!)

Another thing - 10ftlbs sounds low - are you re tourqueing the head after a heat cycle? you should. Call RYP is problem persists.

Edited by laser1

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It might be worth swapping the cylinder head studs for the latest flanged bolts and copper washers as found on the latest bikes, these use a 8mm socket so you won't have a problem with clearance.

The orings should seal though, is the head and the top of the barrel flat.

10 ftlbs is actually a little higher than recommended, it should be nearer 8ftlbs.

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It might be worth swapping the cylinder head studs for the latest flanged bolts and copper washers as found on the latest bikes, these use a 8mm socket so you won't have a problem with clearance.

The orings should seal though, is the head and the top of the barrel flat.

10 ftlbs is actually a little higher than recommended, it should be nearer 8ftlbs.

Thanks for the replies. I will call RYP on Monday to follow up on the email I sent on Saturday.

Yes the top of the barrel/cylinder is flat as I even milled it down 10/1000th to make sure it was good and flat. The inner and outer orings have a good seal as I checked with a compression gauge and there was no leak down after 5 minutes!!.

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With the S3 head you need to use the copper head bolt washers that come on the 2010 Sherco's.

On the S3 head the head bolts go directly through the water passage, where on the stock head they are sealed off from the water.

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With the S3 head you need to use the copper head bolt washers that come on the 2010 Sherco's.

On the S3 head the head bolts go directly through the water passage, where on the stock head they are sealed off from the water.

Sirhc,

That makes sense... The head studs are exposed to coolant. Do you know if you still need the 6 small stud orings in additon to the the copper washers? hopefuly RYP has the copper washers and M6 1.00 (8mm) head bolts to replace the studs and nuts as someone else suggested. Wish I would have known this when I ordered the head:(

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It might be worth swapping the cylinder head studs for the latest flanged bolts and copper washers as found on the latest bikes, these use a 8mm socket so you won't have a problem with clearance.

The orings should seal though, is the head and the top of the barrel flat.

10 ftlbs is actually a little higher than recommended, it should be nearer 8ftlbs.

Yes, I believe the spec is 10Nm, I have seen the studs swist off at 10ft/lb. Use caution here. The rest makes sense! Should get you on track.

BTW, seems obvious you have some machinist capability. I have a "04 125 head that is a bit beat up, yet recoverable if you want to play with it! :rolleyes:

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Yes, I believe the spec is 10Nm, I have seen the studs swist off at 10ft/lb. Use caution here. The rest makes sense! Should get you on track.

BTW, seems obvious you have some machinist capability. I have a "04 125 head that is a bit beat up, yet recoverable if you want to play with it! :rolleyes:

Not one to turn down a part that has potential!!! Send me a pm and lets see how easy I can make it on getting it to me.

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Not one to turn down a part that has potential!!! Send me a pm and lets see how easy I can make it on getting it to me.

Just a quick update: Talked with RYP and they are sending some small washers to replace the individual head stud orings long with copper compression washers. Apparently the S3 Star Head is designed with late model bikes in mind however, they can be used on earlier models with the parts mentioned above. Appreciate the fact that RYP was quick to get back with me. Good customer service!!!

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Just a quick update: Talked with RYP and they are sending some small washers to replace the individual head stud orings long with copper compression washers. Apparently the S3 Star Head is designed with late model bikes in mind however, they can be used on earlier models with the parts mentioned above. Appreciate the fact that RYP was quick to get back with me. Good customer service!!!

Update: Received the washers from RYP and installed them accordingly. Essentialy you have to omit the use of the 6 small orings and replace with a small fiber washer and copper washer between the head and nut.

Head still leaks between the nut and cylinder stud. I am going to replace the studs/ nuts with a tapered bolt like the 2010 models. Hopefully this will stop the leak. I really want to run this head!!!!!

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Update: Received the washers from RYP and installed them accordingly. Essentialy you have to omit the use of the 6 small orings and replace with a small fiber washer and copper washer between the head and nut.

Head still leaks between the nut and cylinder stud. I am going to replace the studs/ nuts with a tapered bolt like the 2010 models. Hopefully this will stop the leak. I really want to run this head!!!!!

sirhc

Posted 28 November 2010 - 02:35 PM

With the S3 head you need to use the copper head bolt washers that come on the 2010 Sherco's.

On the S3 head the head bolts go directly through the water passage, where on the stock head they are sealed off from the water.

Did you use the copper washers that the 2010's use on top of the head? The older studs should work fine if you use those. If you do use the newer head bolts be sure they don't bottom out in the cylinder since the S3 head isn't as thick where the bolts go through the head as the stock head. If it was me I wouldn't mess with the bolts, I would just install the washers, part #2390

The washers that you got from RYP are so the inner head o-ring doesn't blow out, not to stop the coolant from coming out around the studs. We went through a bunch of the inner head o-rings on my son's 125 before we figured it out.

Edited by sirhc

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