Topic: The SinCity750SS build

[SinCity750SS]

So, I figured it was time I introduced my project that I picked up. It is a 1978 CB750 Supersport that came to me as a bunch of parts. Apparently it melted a piston and the previous owner started tearing it all apart. Once he found out how difficult it is to find pistons for the Super Sport. After that, he let it sit in his garage for years before I saw it while I was helping him move.
A few years ago, I got rid of a '78 CB550 that i picked up on craigslist for a couple bucks and got running. The whole point of that bike was to flip it after it was running. I literally just had top clean out the carbs and gas tank to make it start.
I really enjoyed the short time I had that bike to ride around. And now that my ex got away with my Harley, I want to get this thing going.
As far as the bike itself, I want to go with a bit of a bobber look, possibly make it a hard tail.
My primary concern at this time though is the engine. I'd either like to find another 750 Supersport engine to rebuild or transplant a more modern fuel injected engine into the bike. I could also keep this block and go with a big bore kit, but it kind of depends on what I find available and affordable first.
This forum is great for tips and ideas that I'm surer I'll feed off of to make my decisions.
I will be adding pics soon.

[754]

 Welcome aboard. 
 You probably have to make 5 posts , before you can post a pic.
 We would like to see the bike.

[Davez134]

I would just get the next size up pistons, or big bore kit and go that route. Do you know the reason for the melted piston? I am also in Las Vegas and have recommendations for some good machine shops if you need.

[SinCity750SS]

That's great to know. I only know a couple people in Vegas that play with these bikes and I've been looking for suggestions for machine work. I'll definitely keeps in contact. Thanks so much

[SinCity750SS]

I've been looking into this engine build some more and have just been searching old posts for info. I'm pretty firm on keeping this block and installing a big bore kit. So, it's a decision between spending the $450 for Wiseco or is any of the cheap stuff good? Those kits on ebay for less than $200 don't have a brand name and I have a hard time trusting that. Then CycleX is right in the middle around $300. Just options that I'm curently looking at. I'll keep searching old posts but if anybody has input, I'm willing to listen.
Thanks

[SOHC4 Cafe Racer Fan]

I've been looking into this engine build some more and have just been searching old posts for info. I'm pretty firm on keeping this block and installing a big bore kit. So, it's a decision between spending the $450 for Wiseco or is any of the cheap stuff good? Those kits on ebay for less than $200 don't have a brand name and I have a hard time trusting that. Then CycleX is right in the middle around $300. Just options that I'm curently looking at. I'll keep searching old posts but if anybody has input, I'm willing to listen.
Thanks

I haven't seen Cycle X 836 pistons for $300.  http://www.cyclexchange.net/Engine%20Parts%20Pistons%20Page/836cc/836cc%20Pistons.htm  The ones listed on their web-site are Wiseco kits. 

If all you want is a bump in displacement and a small performance gain, the $200 cruzinimage kit will provide a modest improvement.  They have approx the same compression as stock.  If you want to extract more performance, to with a higher compression piston like the Wiseco offerings.  You can extract even more pep with a cam and port job.

[slikwilli420]

Wiseco and Cycle X are both very good. Cycle X pistons are made by JE or Wiseco so no worries there. The ebay kits are fine, but are standard compression just bigger bore, and good for a small power boost. If you want to make real power (still very reliable) you need to up compression as well. With 836 you can get away with mostly stock internals, depending on budget restraints. You could just punch it out and put it back together and likely be just fine. If you want more though you should think about head porting as well as having the rotating assembly balanced. There is a lot to making one of these engines really good, and its hard to go back and do more later, so its best to plan everything out now.

[SinCity750SS]

I've been looking into this engine build some more and have just been searching old posts for info. I'm pretty firm on keeping this block and installing a big bore kit. So, it's a decision between spending the $450 for Wiseco or is any of the cheap stuff good? Those kits on ebay for less than $200 don't have a brand name and I have a hard time trusting that. Then CycleX is right in the middle around $300. Just options that I'm curently looking at. I'll keep searching old posts but if anybody has input, I'm willing to listen.
Thanks

I haven't seen Cycle X 836 pistons for $300.  http://www.cyclexchange.net/Engine%20Parts%20Pistons%20Page/836cc/836cc%20Pistons.htm  The ones listed on their web-site are Wiseco kits. 

This is the CycleX I found: https://www.ebay.com/itm/Honda-CB750-SOHC-Big-Bore-Piston-Kit-Cafe-Big-bore-Chopper-Bobber/202199081236?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D2%26asc%3D44040%26meid%3Deb0446d5c18745da98b1c64551482034%26pid%3D100005%26rk%3D4%26rkt%3D12%26sd%3D122493583005%26itm%3D202199081236&_trksid=p2047675.c100005.m1851

Maybe it's just an Ebay trick...?

I'm not looking at it for power. The block just needs to be bored because of piston/cylinder damage and it's been difficult trying to find a stock piston for the Supersport.

[slikwilli420]

If you're just trying to freshen up what is there, get this kit at the bottom of the page:

http://www.cyclexchange.net/Engine%20Parts%20Pistons%20Page/2nd%20Over%20(+.50%20Over)/2nd%20Over%20Pistons.htm

Comes with a nice street cam that will wake up the engine but in no way compromise rideability.

[SOHC4 Cafe Racer Fan]

Looking back at your original post, I think upgrading the components of the existing motor is probably the best of the options.  Depending on the donor, transplanting a new EFI motor may exceed the strength of the CB750 frame.

[Davez134]

If you're just trying to freshen up what is there, get this kit at the bottom of the page:

http://www.cyclexchange.net/Engine%20Parts%20Pistons%20Page/2nd%20Over%20(+.50%20Over)/2nd%20Over%20Pistons.htm

Comes with a nice street cam that will wake up the engine but in no way compromise rideability.

That seems like a great deal. I'll second that one!

[SinCity750SS]

Looking back at your original post, I think upgrading the components of the existing motor is probably the best of the options.  Depending on the donor, transplanting a new EFI motor may exceed the strength of the CB750 frame.

Thanks so much! That definitely is my first choice now.

All the help is much appreciated from everybody.