Topic: What all can be done with the little CB550? (Turbo perhaps?)

[FunJimmy]

Amazing what you find when you do a search first.

http://forums.sohc4.net/index.php?topic=24605.15

Still would be nice to find the CB650 specs, if anyone has them.

Also wondering about valve springs with a CB650 cam in a CB550 head.

Jimmy

[Soos]

Any of the US SOHC 650 cams are the same(ok there is a 50HP cam out there, but it's overseas mainly).

And as for dropping a 650 cam in a 550 head, it might have enough clearance.
But if you do drop a 650 cam in a otherwise stock 550, turn the motor over by hand VERY GENTLY to begin with to ensure there is clearance with the extra lift/duration.

You may want to remove the head, and place clay on the pistons where the valves are likely to contact the pistons, and re-assemble, and turn motor over 1 or 2 rotations, dis-assemble, and check clearances to be sure.

Better to be safe than sorry.


l8r

[paulages]

Amazing what you find when you do a search first.

http://forums.sohc4.net/index.php?topic=24605.15

Still would be nice to find the CB650 specs, if anyone has them.

Also wondering about valve springs with a CB650 cam in a CB550 head.

Jimmy

yeah, i was gonna point you to that thread. the 550 and 650 cams are identical, except for the actual lobe profile. i haven't actually tried a 650 cam in a 550 head, so i can't say anything about valve to piston clearances, but if you could find specs from a hot 550 cam that is known works to compare, that would tell a lot. i have certainly heard of it being run before. don't know about duration, but i could measure the lobe height of both cams, and the difference should indicate the increase in lift. the manuals list total lobe height specs if anyone has them handy.

For those of you who sugested it, what all would I have to do to my 550 to put a 650 cam in it and what are the advantages.  Still have the topend apart and thought about replacing the cam with a mild street cam, but I have a spare 650 cam from an 81 laying around.  Any thoughts............Chris

you will definitely have to use the 550 cam sprocket, and the tach gearing is rumored to be different on the 650 cam (though they look identical to the naked eye).

[paulages]

Any of the US SOHC 650 cams are the same(ok there is a 50HP cam out there, but it's overseas mainly).

And as for dropping a 650 cam in a 550 head, it might have enough clearance.
But if you do drop a 650 cam in a otherwise stock 550, turn the motor over by hand VERY GENTLY to begin with to ensure there is clearance with the extra lift/duration.

You may want to remove the head, and place clay on the pistons where the valves are likely to contact the pistons, and re-assemble, and turn motor over 1 or 2 rotations, dis-assemble, and check clearances to be sure.

Better to be safe than sorry.


l8r

if you clay the cylinder, oil the head side so the valves won't stick. after running the engine through, take an oiled razor blade and slice out a cross section so you can see where the valves were in relation to the piston.

[FunJimmy]

Checking valve to piston clearance with the clay method is real good advise.

Thanks

[bwaller]

If the engine is assembled and there is no need to remove the head, you can also set up a dial indicator to measure off the valve spring retainers. Check a few degrees or so either side of TDC when the valves are opening and are closest to the piston. Pry the valve down GINGERLY.

[MRieck]

If the engine is assembled and there is no need to remove the head, you can also set up a dial indicator to measure off the valve spring retainers. Check a few degrees or so either side of TDC when the valves are opening and are closest to the piston. Pry the valve down GINGERLY.

That is the method I use. I modified (cut out the inside) a tappet adjuster cover to lever the pry bar against.

[DarkRider]

Hell im thinking im actually learning more from this one topic then what i learned from having the 750 lol

[mlinder]

All the articles I’ve read (and I have a good book with all the past road tests) give the CB550 approx. 38HP off the showroom floor.

Quoted crank HP is 50.
Hell, the 350f makes more than 30hp at the crank. I'd hope the 550 makes substantially more.

[FunJimmy]

Cycle magazine claims 38.2 HP at the rear wheel.
Tested on a dyno, so 50 crank HP would probably be about right.

[mlinder]

21% drive train loss? That sounds a bit high. I could be worng, though.

[edbikerii]

Honda reported 50HP SAE.  After 1972 SAE net horsepower ratings involved an engine dyno testing HP at the flywheel, with all accessories installed, stock exhaust, stock intake, alternator etc.

Cycle World tests in the 1970's were certainly not as consistent or accurate as Society of Automotive Engineers standard J1349 testing.  This standard is available for all interested parties to see.

24% losses through the transmission and simple chain drive sound completely ludicrous.  Based on this, I have some severe doubts about the accuracy of the Cycle World testing methodology used on the CB550 back in the '70s.

[blackhog02]

I put my little 550k on the Jennie Craig diet.  Not sure how many lbs she took off but here is a partial list of some of the heavier stuff. (shocks, fender, center stand, gauges, seat, swing arm)  She does not have the top end speed of my 750 but up to about 80-90 mph she is quite zippy and an absolute blast to ride.


http://mptrackclub.com/Photos/cb750f/cb550_left_side.JPG

[DarkRider]

Well after some thought and looking through some catalogues at Max motorsports a plan has come about....The search for CB650 pistons and head begins soon...Still in the planning stages at this time but heres a brief summary as to my goals..

Reducing the bikes weight to 350 lbs if possable via the following methods

changing out the wheels for aluminum 18" wheels
eliminating the center stand
eliminating the rear fender (proteal style)
replacing the front fender with either fiberglass or plastic..or leaving just the brace remaining
replacing the stock headlight assembly with a lighter plastic housing and H4 headlight
replacing the handle bars with lightweight aluminum handle bars
replacing the seat with a cafe or tracker style seat
replacing the exhaust with either drag style or 4 into 1
replacing the rear sprocket with an ultra light aluminum one
cutting off the passenger rear pegs and mounts
eliminating the electric starter as soon as the bike runs well enough to start with the kick start only,
replacing the signal lights with light weight LED signals
replacing the tail light with a light weight LED unit
replacing the stock headlight ears with some lighter cafe ones
running a smaller battery due to reduced load with the elimination of the starter and use of LEDs
removing any unneaded tabs on the chassis
replacing the stock air box with pods (i know im in for some tuning headaches but i have a good friend thats an experienced mechanic helping me with this)


now for the engine
upgrade to 650 pistons and head
upgrade to 650 carbs
megacycle cam
as mentioned replacing the stock exhaust with either baffled drag pipes or a 4 into 1

finally onto suspension tuning
replacing the rear shocks with slightly longer ones to give the bike a forward rake for quicker turning
replacing the front springs with progressive springs and filling the forks with 20 wt oil
adding air valves to the fork caps or converting the fork caps to preload style

Overall i see this bike taking me about a year or so to build mostly due to time and money constraints

With that said let me introduce you to Project Reaper  pics of the bike in its current disassembled state will come as soon as i pick it up and i can get my camera to upload to the computer.

[DarkRider]

ok...gonna wind up bumping this up to the top but maybe someone can answer this one for me. What is the offset of the front triple trees on the 550? I know the 400 uses a 60mm offset. Also what sort of effects would be there from changing said offset?

[FunJimmy]

Don't know off the top of head what the CB550 offset is, but I'll measure it and get back to you.

Offset effects trail. Here is a good motorcycle geometry article.

http://www.american-v.co.uk/technical/handling/geometry/body.html

FJ

[DarkRider]

Don't know off the top of head what the CB550 offset is, but I'll measure it and get back to you.

Offset effects trail. Here is a good motorcycle geometry article.

http://www.american-v.co.uk/technical/handling/geometry/body.html

FJ

now what im trying to figure out after reading this...could i safely assume that if the 400Fs offset is greater then the 550s it would increase trail?

[CrisPDuk]

Missed this thread first time around, but I'm glad I've just read through it.

My new head is in the very capable hands of Mr Rieck as I type, the motor will be coming out over christmas and taking a trip down to Bryan J's house for a full, no holds barred rebuild, and the frame will be stripped to the bone for blasting and recoating

But I'm having big trouble getting in touch with Megacycle to find out about their cam regrinds   Anybody have any contact details for them?

[FunJimmy]

now what im trying to figure out after reading this...could i safely assume that if the 400Fs offset is greater then the 550s it would increase trail?

Correct. More offset will give you more trail. More trail will give you better high speed stability at the expense of slower steering and possably a heavier feel at the bars.

Do you still require a measurment from the 550 triples?

[Kevin400F]

I just got a CB650 cam from eBay, and the taller lobes foul with the exhaust side of the head casting on #4, (also slightly on #3).  This may be a "rogue" head with a casting core shift...I'll test fit in another head.   If I decide to use this head and cam, the situation can be resolved easily by a little work with the Dremel.

[DarkRider]

now what im trying to figure out after reading this...could i safely assume that if the 400Fs offset is greater then the 550s it would increase trail?

Correct. More offset will give you more trail. More trail will give you better high speed stability at the expense of slower steering and possably a heavier feel at the bars.

Do you still require a measurment from the 550 triples?

Yes please if possable..Thank you in advance.

[FunJimmy]

The '77 CB550F triple measures at 45mm of offset.

Hope that helps.

Cheers
FJ

[FunJimmy]

I just got a CB650 cam from eBay, and the taller lobes foul with the exhaust side of the head casting on #4, (also slightly on #3).  This may be a "rogue" head with a casting core shift...I'll test fit in another head.   If I decide to use this head and cam, the situation can easily by a little work with the Dremel.

Thanks for that Kevin. It'll be interesting to see if another head has the same clearence issues.
If you have any other fitment and or spec info on a 650 cam in a 550 engine please share.

FJ 

[DarkRider]

Thank you for the info man...hmm seems if i were to use trees at the same settings as a 400F i would be adding 15mm more offset...which in turn would increase trail...along with making the bike more stable at speed at the cost of heavier feeling bars..Now the decision..keep it stock offset or go to the 400Fs...hmmm

[FunJimmy]

Outlaw

What is the attraction to using the CB400 triples?
What are you looking for with the change?

FJ