Another big bore question

[Flash1977]

So I have read numerous post on the big bore kit,but probably not all of them. Basically I plan to do either the 9.0:1 or the 10.0:1 bigbore swap with the recommended cam this spring to my 1978 xs650 hardtail build. The bike smokes a little on start up and probably needs rings anyways, plus I would love more power. It is currently a single seater which I love but I would like the option to make it 2up so my wife can ride. That always helps justify the money I spend on the bikes. What I need is help deciding which way to go. With all I have read I am still not sure. Your opinion would be appreciated. Thanks.

 

[zrx1100]

You will need to go through the head and check the valve guides if the bike smokes on start up. I did a 700cc upgrade per Gary Hoos. You can read about it here. https://www.xs650.com/threads/700cc-kit-with-a-shell-1-cam-in-a-78xs650e.65405/

All my machining was done by Roger from R&D motorcycles.

So I have read numerous post on the big bore kit,but probably not all of them. Basically I plan to do either the 9.0:1 or the 10.0:1 bigbore swap with the recommended cam this spring to my 1978 xs650 hardtail build. The bike smokes a little on start up and probably needs rings anyways, plus I would love more power. It is currently a single seater which I love but I would like the option to make it 2up so my wife can ride. That always helps justify the money I spend on the bikes. What I need is help deciding which way to go. With all I have read I am still not sure. Your opinion would be appreciated. Thanks.

 

[Flash1977]

I have spoke with Gary via email

 

[46th Georgia]

I have spoke with Gary via email

Smart move!

 

[Flash1977]

Smart move!

I also clicked on your build and read threw that

 

[Flash1977]

What I really need is more pros and cons on more ore less compression on the 80cc kit. Anyone experience or opinion.

 

[EarthHeavy]

I chose the 750 80mm 9:1 comp ratio over the 10:1 because I’m building the engine as kick only and the bike is just a cruiser

 

[EarthHeavy]

Also, I found a service on EBay that rebuilds xs650 heads for $320 plus shipping I think. I spoke with the fella over email last week and am considering his service to rebuild my head for my cam spec. He will check and true the surface if needed, checks and polishes your valves, replacing them for extra $ if needed, then installs new bronze guides, three angle valve job and lap plus setup proper spring pressures then ships back to you within a week.

If you’re burning oil it might be a good solution for you if there’s no machine shops near you that know xs650 stuff as it seems that’s all he does. He also offers porting etc…here’s a link to his auction:

https://www.ebay.com/itm/2312214631...ZcNYmvlIW8vqwNi3BsVXwzkTU=|tkp:Bk9SR-74qsGQZQ

 

[46th Georgia]

Also, I found a service on EBay that rebuilds xs650 heads for $320 plus shipping I think. I spoke with the fella over email last week and am considering his service to rebuild my head for my cam spec. He will check and true the surface if needed, checks and polishes your valves, replacing them for extra $ if needed, then installs new bronze guides, three angle valve job and lap plus setup proper spring pressures then ships back to you within a week.

If you’re burning oil it might be a good solution for you if there’s no machine shops near you that know xs650 stuff as it seems that’s all he does. He also offers porting etc…here’s a link to his auction:

https://www.ebay.com/itm/2312214631...ZcNYmvlIW8vqwNi3BsVXwzkTU=|tkp:Bk9SR-74qsGQZQ

Personally, I'd send my cylinder head to Roger at R&D. Nothing against anyone else, but Gary Hoos and Roger have been at this game a long time and I've never heard anything negative about them.

 

[46th Georgia]

What I really need is more pros and cons on more ore less compression on the 80cc kit. Anyone experience or opinion.

Detonation could be an issue with the higher compression pistons

 

[Flash1977]

I chose the 750 80mm 9:1 comp ratio over the 10:1 because I’m building the engine as kick only and the bike is just a cruiser

Thanks

 

[Flash1977]

Also, I found a service on EBay that rebuilds xs650 heads for $320 plus shipping I think. I spoke with the fella over email last week and am considering his service to rebuild my head for my cam spec. He will check and true the surface if needed, checks and polishes your valves, replacing them for extra $ if needed, then installs new bronze guides, three angle valve job and lap plus setup proper spring pressures then ships back to you within a week.

If you’re burning oil it might be a good solution for you if there’s no machine shops near you that know xs650 stuff as it seems that’s all he does. He also offers porting etc…here’s a link to his auction:

https://www.ebay.com/itm/231221463149?_skw=xs650+service&itmmeta=01JJ21AQH38WVD12QBT22PNC4S&hash=item35d5df886d:g:vMQAAOxyHIlTZIg3&itmprp=enc:AQAJAAAA0HoV3kP08IDx+KZ9MfhVJKm1kDj9U5KZYZErkYROEldI87LY+SDZGDL4E+AaU+hr+0apQ/h4Z/5H01y2za/SUsfOv+fKogi7DGKoxunlUvq0KX34MhvV584a0WNm7KkhBIYTzqM+LTVq7TTXinigQkC3C6JSlH0uc0t7ng9uPqiSrqNRzwgPmB20uvYM0xDc2yZ9tE04ELektNr0IszE4i6qQh4XFLE66J+zhb3/ijssJaJRQCP5YcRQ9sNnpbZcNYmvlIW8vqwNi3BsVXwzkTU=|tkp:Bk9SR-74qsGQZQ

Thanks,I'll look into it.

 

[Flash1977]

Personally, I'd send my cylinder head to Roger at R&D. Nothing against anyone else, but Gary Hoos and Roger have been at this game a long time and I've never heard anything negative about them.

I couldn't find any info on Roger at r and d. Do you have a link to his business?

 

[zrx1100]

I had Roger do my head. No complaints after 4K miles and countless dyno runs

 

[46th Georgia]

I couldn't find any info on Roger at r and d. Do you have a link to his business?

R&D Motorcycle Service Princeton, IA. roger4k@msn.com 563-340-2837

 

[Flash1977]

R&D Motorcycle Service Princeton, IA. roger4k@msn.com 563-340-2837

Thanks

 

[Citizen Clive]

Also, I found a service on EBay that rebuilds xs650 heads for $320 plus shipping I think. I spoke with the fella over email last week and am considering his service to rebuild my head for my cam spec. He will check and true the surface if needed, checks and polishes your valves, replacing them for extra $ if needed, then installs new bronze guides, three angle valve job and lap plus setup proper spring pressures then ships back to you within a week.

If you’re burning oil it might be a good solution for you if there’s no machine shops near you that know xs650 stuff as it seems that’s all he does. He also offers porting etc…here’s a link to his auction:

https://www.ebay.com/itm/231221463149?_skw=xs650+service&itmmeta=01JJ21AQH38WVD12QBT22PNC4S&hash=item35d5df886d:g:vMQAAOxyHIlTZIg3&itmprp=enc:AQAJAAAA0HoV3kP08IDx+KZ9MfhVJKm1kDj9U5KZYZErkYROEldI87LY+SDZGDL4E+AaU+hr+0apQ/h4Z/5H01y2za/SUsfOv+fKogi7DGKoxunlUvq0KX34MhvV584a0WNm7KkhBIYTzqM+LTVq7TTXinigQkC3C6JSlH0uc0t7ng9uPqiSrqNRzwgPmB20uvYM0xDc2yZ9tE04ELektNr0IszE4i6qQh4XFLE66J+zhb3/ijssJaJRQCP5YcRQ9sNnpbZcNYmvlIW8vqwNi3BsVXwzkTU=|tkp:Bk9SR-74qsGQZQ

I've used Chris a number of times, excellent workmanship, he really knows his stuff. Just about to send him a set of Ducati 900 heads.

 

[zrx1100]

I found the delivery boxes , currently popular for prepackaged meal delivery, to be very well suited for shipping engine parts. They are sturdy and come with good insulation/ packaging. Factor is one of my favourites.

 

[Pat D]

I'm not sure you will be able to feel any extra oomph from the higher compression in your butt, and if you do, is it worth the other complications/offsets of higher compression? (kicking it, possible detonation/pre-ignition, feeding it fuel it likes)? That's all your call.

 

[Flash1977]

I'm not sure you will be able to feel any extra oomph from the higher compression in your butt, and if you do, is it worth the other complications/offsets of higher compression? (kicking it, possible detonation/pre-ignition, feeding it fuel it likes)? That's all your call.

Are you saying that both the 9.0:1 and the 10.0:1 big bore kit are bad or that you would recommend the 9.0:1(lower compression) .