top end rebuild

[xscorex]

Ok Im planning on a top end Rebuild on my 76. I see 706cc big bore piston. Can anyone explain what my options are and the benefits and costs of maybe doing this vs a slightly oversized piston and rings? 50cc isnt really alot But if the cost isnt a lot more should I do that?

 

[TwoManyXS1Bs]

Back in the day, we advised customers that oversize/overbore kits like that were best used when trying to save severely damaged cylinders, not so much for performance upgrade. As a practical matter, with standard oversizes, you have more cylinder sleeve thickness, and room for the next bore job.

 

[hooser]

I would not advise going to Just a 700 alone(even though I sell them) If you want to do a complete performance then do that.. 700 with a cam and good carbs. and exhaust you will see a difference. The 700 is as big as you can go with the stock sleeves.
The next step would be a 750 you need to re-sleeve but you can then go to different over bores a it you wear one out.
email me at gary@hoosracing.com for more info. pricing Gary

 

[650Skull]

If your slevers have some life left in them then i think it is a wast to max them out.

If you bore them to 4th oversize at least there is room to go the 706cc route before having to re-sleve.

Cruzinimage sells pistons that are acceptable and are way cheaper than mikesXS. They have a lot of XS650 gear for good prices.

 

[hooser]

I bought a set of the 700 piston just to compare to my JE's no comparison on quality.

 

[650Skull]

I bought a set of the 700 piston just to compare to my JE's no comparison on quality.

I am posting information for the OP to give him alternative options.

I am not Dissing your products or any part of your services.

 

[650Skull]

xscorex, Here is a link to a thread on the cruzinimage pistons. The thread starts 2 years ago and there are up dates and follow ups till the last post a couple of months ago. Good quality pic comparisons as well. Read through the whole thread.

I am in no way associated with these guys, am sharing information to help give you information and options only

 

[hooser]

I will send pic tomorrow if I get time of my JE, but as I mentioned a while back if I am just building a stock motor that would be the way I would go , but with mikesxs . If I building a performance motor which is what I mostly do. Go with JE.
I support Mikesxs becasue they have been around even though different owners, then I dealt with years ago, and they have helped keep the 650's going. It is also why I sell Shell performance parts. Pistons,Pipes,cam, etc. He was the master in my opinion and a friend. the more others get in the pie is getting smaller and smaller. So I like to support the ones that got us here. I still have an original Mikesxs AND Shell catalogs.
Sorry that was on the long side. I read the thread you sent. Thanks,

 

[650Skull]

Caution Hijack.

I wasn't going to go into this hooser............

Mikes has raised prices 10-12% across the board since buying out the business from Mike L. Probably had to as they are the retailer now and not a wholesaler as Mike L was.

Doesn't account for a price rise of 33% for their Standard Tanks, 25% for their petcocks to fit the Standard Tank. The Oil filter/cooler has gone up 100%. Postage to Australia is a min of $47.00.

I just done a costing of a set of Standard, (same price for oversize up to 4th over), Pistons/pins/clips and rings.
MikedsXS
US $246.00, shipped to Australia.

Cruzinimage,
1 Set, (2 of), of Pistons/pins/clips and rings.
US $102.50 Shipped, to Austalia.

706 Bigbore kit + gasket US $145.60 Shiped to Australia.

As per the thread i linked to and the Quality of the, (out of date), forged pistons, (as are MikesXS), I know where my next set of pistons are coming from.

Cruzinimzge supply all Japanese manufacturers and most of the older bikes. I have an XS850 and they have piston kits for US $155.00. 3 pistons/pins/clips and rings.

They have such a range, and i see they are now offering fork tubes for some models so i presume they are expanding their parts inventory, i can't see them going out of business especially when the XS phase thins out, because they aren't relying on such a narrow selling base.

I appreciate what Mike L done for the XS community, (me really and my bikes), but in no way do i have any love or respect for the new owners, just as they don't have any for me.

No brain er for me....................

 

[Jack]

Ok Im planning on a top end Rebuild on my 76. I see 706cc big bore piston. Can anyone explain what my options are and the benefits and costs of maybe doing this vs a slightly oversized piston and rings? 50cc isnt really alot But if the cost isnt a lot more should I do that?

Those "706"cc pistons are junk and would be best used for boat anchors that would add to the vibration factor.You could go 78 mm oversized but bore distortion could be an issue if the motor where to be placed under severe stress. A ductile iron sleeve would eliminate those issues.Boring isn't cheap,so I go at least 1mm oversize with cast piston to reap the over bore displacement.

 

[Jack]

I would not advise going to Just a 700 alone(even though I sell them) If you want to do a complete performance then do that.. 700 with a cam and good carbs. and exhaust you will see a difference. The 700 is as big as you can go with the stock sleeves.
The next step would be a 750 you need to re-sleeve but you can then go to different over bores a it you wear one out.
email me at gary@hoosracing.com for more info. pricing Gary

you forgot porting improving the XS head breathing qualities would and should be on the top of list first,the head is the real key in unleashing real power from this engine over any add ons,IMO

 

[funky]

If your bike has stock bores you can hone measure and fit oversize pistons and rings up to 1mm + they go in increments of .25,.50,.75,and 1mm.... if bores are over that option would be big bore kit. I am no expert but these chaps are ,,,,
if your saying you have 706 pistons in there at the moment I would check the tolerance and see if you can get pistons and rings to fit within spec when I looked at mine and priced it up with all the machining and parts it was cheaper to buy the big bore kit assuming you do the fitting ... To be honest its a bit of a minefield and one issue leads to another ... if budget is not an issue then its not a real problem, if your conrod are worn and you put new stuff on them that produces more power it would exploit any movement and create more problems. thats the issue i had.. do it properly or keep your tools out because you will be going back in lol
All the best funky

 

[hooser]

You decide!

 

[TwoManyXS1Bs]

Thanx for the piston pics, Gary. Several subtle differences in those.

I've always been curious about various design features in pistons, like wristpin boss and oiling, offset, oil ports around the oil control rings, anti-flutter grooving, land/groove pressure ports, retention (clip or button), oval or round skirt grind, expansion control ring in skirt, underdome webbing, cast vs forged, choice of alloys, ...etc.

This stuff filled a book back in the day. I bet a lot has happened in the last 40 years.

 

[hooser]

toomany, even these could be updated again.. After taking them over we (JE) changed a couple of things, rings for one. Shell use to run wider rings at the top. Shell said that was a good idea, he said he never change because it was just easy for him to keep the old style.