Topic: CB500 performance Q's

[Scott S]

 The racing board said to keep it hardcore over there, so I'll ask here. Remember, I'm 100% new to SOHC's, so....

 My '72 CB500 turns over easily after sitting for 28 years. The potential problem is...it turns over easy, and I mean EASY. I have some concerns about the compression. I've been reading and searching about big bore kits(555cc and 605cc).

 *Most 605cc kits I see come with new liners. Can you bore the stock liners for the 555cc kit?

 *What about the cam chain? On Yamahas (my area of experience) you can tie the chain up and work around it for piston/cylinder work, cam swaps, etc.

 *I've seen some mention of 650 cams in 500/550's, right? Is this a reasonable upgrade?

 *What other options do I have for overbore pistons (first overbore, second overbore, etc.)?

 My goal isn't to have the baddest, most fire-breathing bike. I'm just thinking stock carbs, 4-1 header, mild upgrades for performance if I end up going into the engine. Thoughts? Tips? Hints or tricks?

[Spanner 1]

Hi Scott and welcome, When you say 'turns over easy' is that with plugs in or out ? I think you could 100% get the bike running as stock before considering big-bore kits IMO... and you might love it stock and ridable within the next week !. BTW, camchain can be left 'unbroken' to remove head/ cylinders on the 500..... time to test compression I think.

[Scott S]

 That's with the plugs in. The P.O. said he was riding the bike daily before parking it 28 years ago. I can turn the engine over with the kick starter by hand. And fairly easily.

 I just like learning about this stuff and usually collect info, parts and inspiration for quite a while before diving in headlong. I also have a project I need to finish first, then I'll be all over this one.

[Scott S]

 Maybe this should have been posted in the Racing/Hi-Po section?

[bryanj]

Remember its only 125cc per pot so they do turn over easy

FIRST get the compression checked and report back

THEN see if it will run reasonably and re-check compression HOT

[dave500]

itll have stuck valves after 28 years maybe,you might be able to free them up without disembling the head,wd40 on the stems maybe and try levering gently on the stuck ones.the seats might be in bad shape to.

[Scott S]

 Oh, the plan is to DEFINITELY get it running before I do anything serious to the engine. I was just asking....I'm somewhat prone to mild performance stuff on all my projects. (Ever driven a 200HP bored and stroked air-cooled Bug?)
 That makes sense about 125cc/cyl. I'm used to kicking over these big twins.

 The bike HAS been kicked over several times a year for the last 28 years, just not run. I'll check for stuck valves, too.

 I still like learning about all the little Hi-Po tricks, though...