Topic: Will a 650 SOHC fit in a CB500 frame. .

[toolguy]

Yes I did ao search for this but didn't find a definitive answer for putting it in a 72 CB500 frame. . .
If it fits the mounts are there any mods needed for the mount brackets?

And if someone has a picture of one in the 500 frame I'd love a link to it.
Thank you. .

[calj737]

The 650 bolts straight in. The 500 and 550 share the same frame, with the small exception of the right side upper motor mount bracket to retain the clutch cable (550/650 clutch cable is on right vs. left side for 500). Easiest to remove breather cover, oil pan and sometimes exhaust flanges to wrestle it in. Nothing to it, and a very nice power upgrade for little effort.

[Tews19]

Look up Scott S, a forum member here. He has done it. As Cal mentioned yes it will work. Best bang for your buck also. Much more powerful than the 500/550 engines. My next bike will be the 500/550 with 650 engine. Only downside is the exhaust selection. Very limited market

[Scott S]

 I'll post pictures later but, yes....it fits. I removed the sump....it's deeper than a 500/550  sump...and it was actually easier to get in the  frame than a stock motor.

[toolguy]

Thanks for the answers. . .
 I picked up an almost complete 82 650 that "was" running fine in 2006. . .  and here's the bad part - before it hit a curb and took out the front forks. . The  rim survived but the owner removed most the front end except the bent forks and the wheel [which also survived amazingly], then lost the parts he removed, and left it sit outside for 9 years, which didn't help the remaining bike. . . .
I'm trying to decide if I should resurrect it. .  as it needs an entire front end and a gas tank. .  OR  pull the motor for another CB500 build. . .  I like the style and handling of the early 500 much better that the later 650's. .
Now if I can find a nice older 500 that's minus a motor, the question would be simplified. .

[BomberMann650]

If a hiyabusa motor can be made to fit the DS650 atv I have***.  Then all is possible!

***=the atv was made to fit the motor really....semantics

[calj737]

Easy to grab a frame for a 500/550, a used gsxr front end and drop it all together. Best of all worlds- HP, style and modern braking/suspension.

[Scott S]

 Engine swap info starts on page 4:
http://forums.sohc4.net/index.php/topic,67907.0.html

[pangloss]

http://forums.sohc4.net/index.php/topic,114345.msg1287569.html#msg1287569

[roach374]

Sorry for resurrecting a dead thread, but I'm considering doing this and want to know if the 650 engine will mean less room for the carbs (my aftermarket carbs barely fit int he cb500 frame as-is).

[bryanj]

There are 2 different heads with different carbs on 650 so yours may not fit the head

[Scott S]

 The 650 has the "manifolds" cast into the head. It only uses the rubber connectors to attach the carbs to the engine. The '79-80 engines used slide style carbs and the '81-82 used CV carbs. You can't swap carbs from early to late (and vice versa) without also swapping the head.
 I would measure the inlet spacing on the engine you're looking at and see how close it is to your carbs inlet spacing.