Topic: CB500 Conversion to 650 New Motor and CR 29

[pangloss]

My old CB500 now has a NEW 650 (1982) motor installed complete with a new set of CR29

The Engine was purchased as a New Crated Motor out of Whoop Whoop ( Somewhere near Dallas I believe) in Texas and Sent to Whoop Whoop in the Northern Territory of Australia  (Darwin)

I adapted the electrics to the old cb500 electrics using new regulator and spark units with "adaptor loom" so that it can be returned to original as the project rolls on. Only annoying problem was the fuel tap... Totally disproportionate PIA

She started up right off ( following an external oil pressure feed via oil switch oriface)   and runs like a bird..
(Subject to running  in care/limitations  so far)

 Carburates cleanly and all.! (CR starter circuit not needed in 35 degree ambient of Darwin !!

Now to confuse our motor registry with the new motor S/N and capacity

J

[luap]

 looks NICE- im guessing you dont get a warranty on the motor- But If you can affod shipping from Whoop whoop texas to whoop whoop Darwin then it doesnt matter anyways. job well done thanks for sharing

[pangloss]

Thanks luap.  It was an impulsive eBay bid that I didn't expect to get. However I'm pretty thrilled with the end result...j

[dave500]

how did the engine go into the frame?any spacer mods etc?

[Dimitri13]

I like that you kept the 500's pipes Best looking ones out of the bunch IMO.

[pangloss]

Engine went straight in. Used all the 500 bolts etc. I turned up adaptors for the header. The motor that came out was a 500 to 602 big bore which I had been running standard exhaust system with so figured that the new 650 can cope with the smaller header diameter ok for a while. Once this motor is settled in I intend to drop the head off, clean the ports up and reseat the valves. I'll revisit the exhaust setup then but I'd like to keep it 4 into 4.

[Retro Rocket]

how did the engine go into the frame?any spacer mods etc?

Go on Dave, you know you want to.....

[Greggo]

Well done!  And, I bet 9 out of 10 folks can't tell you've done a thing

[dave500]

if i come across a 650 motor ill keep it then.

[Retro Rocket]

if i come across a 650 motor ill keep it then.

I'll keep my ears to the ground Dave....

[pangloss]

I didn't think they sold the 650sohc here in Oz..?

Anyway, I got it registered today without any hassles so I'm now riding it legally.  I'm pretty pleased with the carburation so far. No wide throttle yet. I'm not sure of the gearing as the 650 has different primary gearing and I kept the standard 500 final gearing.  The rev counter is telling lies of course because of different gearing at the camshaft take off.. But it always lied anyway so thats not too big a deal.

[dave500]

i wonder if the 650 primary gearing is the same as the 550s?which is different to the 500s,which would make yours taller than it should be?what was the 650s final gearing?500 is 17 x 34 and 550 is 17x 37,youve done well pangloss.

[luap]

my choice for the botm. think you have to accept if you want to

[Tews19]

No #$%*, BOTM.. I second that... But I wanted to nominate Rusty Olive's too..... I am curious to hear how she sounds! Could you post a video?

Absolutely love the original color of the bike...... Honda must have signed a contract with the devil to continue this success 40 plus years..

OK I had to look it up real quick and edit this listing..... WIKI states 63BHP...This seems like a huge upgrade for an easy swap..

[pangloss]

Thanks Guys.... BOTM...?   Its actually a bit tatty as this is just stage 1 of my cb500 restoration.. I bought the bike new in 1975 and although its been pretty well looked after, it's showing its age with rust on frame etc

Sounds nice... Quite loud when on the bike but Okay around town on low throttle.   mainly due to not being able to fit the little rubber connectors between the muffler ends... I'll try do a video

Dave,  I'm now a bit confused by the gearings according to several manuals I have..  The 500 has the 17 X 34 final as you said . I understand they  RAISED the primary gearing on the 550 and then again on the 650 so the clutch was spinning faster therefore reducing torque loading and chronic slippage as per the 500. So I need to LOWER my final drive
 I actually want to spin the motor at the same revs/ km/hr as the 500 had  so it seems like I need to use the 550 final sprocket size.   37 maybe.  .?  The old 500/602 motor pulled up to red line in top easily so this one should do it just as well if not faster.  (without smoke too.!) 

[Godffery]

I would think that the CR29's are a bit much for the 650 motor..?

How is it with quick execration?

[pangloss]

I'm quite surprised actually at this stage. It carburates fine mid and 3/4 throttle. Needs a few revs to start pulling more than that. I ride the thing always well above 3 Grand revs anyway and will be tuning it to do its best 5 ~ 9+ K .

It'll be nice if I can get a similar power band to the CB400 only with more lift.. (I had a nice cb400 a few years ago which impressed me with its power delivery)

[Godffery]

That is surprising.
I'd be interested to know what jetting & needles you end up with.

[pangloss]

It's got 120 main fuel jet.   

Y9 needle at centre position.  Don't know the other jets unfortunately, forgot to check them before installing the carbs on the bike.  Idle jet screw 1 turn out.

They were supplied as 650 setup by Buzz at Dynoman... So someone knew their onions...!!!  I'm very impressed..After doing a lot of reseach on the forum I was worried they would be  difficult children ! 

I'm using the supplied Keihin Velocity stack which I consider essential as it is designed to flow air directly into the 29mm throat.  The air compensation is EXTERNAL to this which rules out the use of K&N pods.  (Someone reckoned the K&N has inbuilt stacks...NOT so..!   and even if it did,  it would NOT isolate the main flow through the tapered stack and the air comp circuit)

I had to shoehorn the Keihin Stacks inside a larger K&N dual filter to keep these features.  see photo on first post

[Godffery]

Humm... That's good to know,
Thanks man!

[Scott S]

 I'm very interested in this swap. Can you go into a little detail on what you had to do about the electrics and regulator?
 What was the PITA about the fuel tap?

 Pics are always good.....

[pangloss]

I used a regulator/rectifier from the cb650/750/900 series.. They are all the same and a straight plug int/out of the 650 alternator.  Output of regulator then just picked up the existing batt/Switched and earth circuit

The 650 has electronic ignition so had to buy two "ignitor" boxes and wire them to the existing 500 coils and pick up

I used a couple of neat coloured wiring diagrams from somewhere on cb650.com and this forum for the 500..
Used these as reference..

The standard fuel tap for the 500 is too big and the CR29s are further forward than standard so theres no room for a tap there.. Had to make up a tatty looking work around as seen by the pic. Mark II is under design review

[pangloss]

OOPs posted the same pics

[Scott S]

 Do you think the petcock would have interfered with stock carbs?

 What did you do about the tach?

[pangloss]

I don't know about the stock carbs.  I never had any as the motor came without them.  I suspect the 650 tank had the petcock in a different position.

Tach reads VERY high...  I have a set of 750 guages that I'm hoping won't look too out of place which I m planning on fitting.