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

[DarkRider]

Outlaw

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

FJ

The  main thing i was looking at is that the Billet triple trees that TTR400 offers are for the 400F..I had inquired about him doing a set for the 550 earlier on..but i also want to enhance the bikes handling while loosing weight.

[FunJimmy]

Have you given consideration to a complete (modern) front end swap?
Maybe a Yamaha R6 or CBR600 setup. That would certainly provide a handling improvement and look stouter too.

[DarkRider]

I would love to go with a modern front end swap if i could somehow mount a matching rear wheel onto the bike. or mount a spoked wheel onto said modern front end.

[FunJimmy]

You can! It takes some machine time but it's quite doable.

http://forums.sohc4.net/index.php?topic=27159.0

[DarkRider]

ok man you def got my attention now!! I was about ready to just use Kawasaki EX500 front and rear wheels and front end..but now that i have read about how you went about it..im def intregued...

[DarkRider]

what needs to be modified on the 750 pistons to make them work in the 550 engine? i am giving a second thought to the idea of goin for broke and just modifying the parts i have on hand, I was looking into the idea of punching out the cyls to 62 mm possably.

[FunJimmy]

Apparently not much!
A little off the top and a little off the bottom any you’re ready to go.

Check out the Gentleman’s Express article for more information.

http://forums.sohc4.net/index.php?topic=20601.0

[bwaller]

You'll like the results with that size bore and a cam. Plus the fact that you plan to reduce the heft overall makes the bike very much fun!

[DarkRider]

Rough estimate of displacement with 62 mm pistons works out to about 610 cc..anyone know if the 550 cyls can handle that large of overbore? If not i will go with 61 mm for the 605 cc version. Im also looking more into the idea of using a full dunstall fairing on this bike now to create a sort of CR replica. So keeping that in mind im shooting for a weight of around 360-370 with full fairing work on the bike. even if i have to keep the e start im pretty sure with the use of carbon fiber and other light weight alloy bits on it i should still be able to get it down there.

[DarkRider]

Ok bringing this back up to the top...rather then asking new questions in a new thread. What sort of end result would i have with using 61 mm pistons with a CB650 head? Would the displacement be much larger then the 610 from using the 550 head? Also i have considered the use of a small turbocharger to bring the power even further up. Anyone know how much boost one of these little engines can take?

[mlinder]

Ok bringing this back up to the top...rather then asking new questions in a new thread. What sort of end result would i have with using 61 mm pistons with a CB650 head? Would the displacement be much larger then the 610 from using the 550 head? Also i have considered the use of a small turbocharger to bring the power even further up. Anyone know how much boost one of these little engines can take?

Paul is using a 550 case, and i believe a 650 topend with his 750 pistons.
http://forums.sohc4.net/index.php?topic=13519.0

As far as turboing goes, it depends on the CR. Turboed engines generally start with lower compression. You wont have intercooling, and the engine is aircooled, limiting the amount of boost you can have. Half a bar at low compression would be my guess at highest safe boost levels, maybe a bit more, maybe a bit less.
Lower compression with 610 CC will give you, at most, 55 or 60 hp. half a bar would add 20-25ish HP, and it would change depending on the weather and tempurature. Turbos are not light. forget about a 380lb faired turboed 550. Not likely to happen.

[DarkRider]

I have scrapped the idea of using a fairing on the bike because of the weight gain of the turbocharger. The turbo idea was just a random idea i had recently its things like this is why im spending my free time planning out the project..other direction to go would be a 610 cc high compression all motor build. If its possable to get around 70-80 Hp out of the engine this way i will go in that direction.

[mlinder]

I have scrapped the idea of using a fairing on the bike because of the weight gain of the turbocharger. The turbo idea was just a random idea i had recently its things like this is why im spending my free time planning out the project..other direction to go would be a 610 cc high compression all motor build. If its possable to get around 70-80 Hp out of the engine this way i will go in that direction.

No reason you cant pull 70 crank HP out of a 610cc NA engine. Gonna be mostly from cam (that shifts power up to a higher rpm range) and extra RPM. Find out what you need to get another 1500 or 2000 reliable RPM out of your bike. I'm sure paulages or others here can tell you what you need. Probably not much more than rods (or at least strengthened rod bolts), improved cam chain and tensioner, headwork and big brass balls.

[paulages]

I have scrapped the idea of using a fairing on the bike because of the weight gain of the turbocharger. The turbo idea was just a random idea i had recently its things like this is why im spending my free time planning out the project..other direction to go would be a 610 cc high compression all motor build. If its possable to get around 70-80 Hp out of the engine this way i will go in that direction.

No reason you cant pull 70 crank HP out of a 610cc NA engine. Gonna be mostly from cam (that shifts power up to a higher rpm range) and extra RPM. Find out what you need to get another 1500 or 2000 reliable RPM out of your bike. I'm sure paulages or others here can tell you what you need. Probably not much more than rods (or at least strengthened rod bolts), improved cam chain and tensioner, headwork and big brass balls.

the great thing about using the 650 cylinders, crank, rods, and head is that honda REALLY improved the design with that model. red-headed stepchild or not, it is the reigning supreme of the SOHC4 bunch IMO, as far as engine tech goes. from top to bottom: improved port design, hotter cam than the 550, domed pistons matched by a true hemi- head, decent rods, hyvo-cam chain (no need for heavy-duty here), stock cylinder bolts that are stouter than the stock 750 studs, hy-vo primary chain (550 has this too, but not the 750), primary and cam chain oiler coming straight off the main oil galley, and a trans primary/final gear ratio that results in a more reliable clutch.

honda claimed 67 RWHP for the '69 cb750, and 62 RWHP for the american model cb650.

my complaints about the 650: they made it look dumb.  okay 650 guys, let your back hair down... how about this: it lost the classic look. they did however, have the sense to make the lower right frame rail remove with the engine mounts for easy engine removal.

i think the best possible SOHC4 is a 550 with the 650 engine used in some manner. in my case, i'm going through a lot of trouble to keep the 550 kick start and overbore it a lot, but the bike i'm putting together for joe cantrell is just a 650 engine dropped into a 550 frame. combined with progressive shocks, cartridge emulators, and tapered steering bearings, i think this will result in a great bike.

[DarkRider]

Ok looking back at the idea of using the 650 pistons and head i just have a couple more questions...

It was mentioned i could use 750 carbs with the 650 head..so i would be able to use CRs correct?
and Just how far can i deck the cyls...aka how much can i bump the compression up before i run into interferance problems?

[paulages]

i would assume that you could use CR carbs with the 650 head, but i haven't tried to source the intake insulators for that application, which is where the problem could be. the 750 carb spacing may be the same as the 650 (PD carb models), but the actual intakes on the 750 are much wider.

regarding your compression ratio question: are you referring to bumping up the CR with stock pistons, or with 750 pistons? in my case, i had to bump DOWN the CR into a sensible street riding range (10.58/1) with 64mm pistons, but i started with pistons that wouldn't even fit in the head without turning them down.

in general though: my machinist recommended .050"-.060" clearance from head to piston to allow for rod stretch (mike reick told me he thought .030" would be enough, i believe), and .050-.070" clearance from valve to piston. if you are going to go about decking the head, the only way to test both is by claying the cylinder and measuring the dissection of the clay after turning the engine through. valve clearance alone can be measured by depressing the valve until it hits the piston at TDC, and measuring the travel.

[Sam Green Racing]

I have scrapped the idea of using a fairing on the bike because of the weight gain of the turbocharger. The turbo idea was just a random idea i had recently its things like this is why im spending my free time planning out the project..other direction to go would be a 610 cc high compression all motor build. If its possable to get around 70-80 Hp out of the engine this way i will go in that direction.

No reason you cant pull 70 crank HP out of a 610cc NA engine. Gonna be mostly from cam (that shifts power up to a higher rpm range) and extra RPM. Find out what you need to get another 1500 or 2000 reliable RPM out of your bike. I'm sure paulages or others here can tell you what you need. Probably not much more than rods (or at least strengthened rod bolts), improved cam chain and tensioner, headwork and big brass balls.

honda claimed 67 RWHP for the '69 cb750, and 62 RWHP for the american model cb650.

Paul, all Hondas claimed HP figures were at the crank. You would be lucky to see 55bhp at the rear wheel of a CB750.

When we first dynoed the CR with the stock motor with just the open 4 into 4 exhaust it was only 54bhp at the back wheel.
The ignition and carbs took it to 60bhp and the mild tuned 836 took it to 86bhp.

Sam.

[paulages]

I have scrapped the idea of using a fairing on the bike because of the weight gain of the turbocharger. The turbo idea was just a random idea i had recently its things like this is why im spending my free time planning out the project..other direction to go would be a 610 cc high compression all motor build. If its possable to get around 70-80 Hp out of the engine this way i will go in that direction.

No reason you cant pull 70 crank HP out of a 610cc NA engine. Gonna be mostly from cam (that shifts power up to a higher rpm range) and extra RPM. Find out what you need to get another 1500 or 2000 reliable RPM out of your bike. I'm sure paulages or others here can tell you what you need. Probably not much more than rods (or at least strengthened rod bolts), improved cam chain and tensioner, headwork and big brass balls.

honda claimed 67 RWHP for the '69 cb750, and 62 RWHP for the american model cb650.

Paul, all Hondas claimed HP figures were at the crank. You would be lucky to see 55bhp at the rear wheel of a CB750.

When we first dynoed the CR with the stock motor with just the open 4 into 4 exhaust it was only 54bhp at the back wheel.
The ignition and carbs took it to 60bhp and the mild tuned 836 took it to 86bhp.

Sam.

funny you say that, 'cause there are plenty of people on here that will claim their K0's will pull 67+ rear wheel with no mods (and spin to 18,000 RPM, and fly to the moon... ). i figured those figures were crank, but the point is that honda's claimed HP from the 650 was only 5 less than what they claimed for the '69 750. i'd love to see some real world 650 dyno numbers. maybe we'll dyno joe's bike when it's up and running. i'll be dynoing my 550 race bike and 718 this spring anyway.

[Sam Green Racing]

I'll be looking forward to it Paul, I'm off home now...been a long night

Sam.

[DarkRider]

i would assume that you could use CR carbs with the 650 head, but i haven't tried to source the intake insulators for that application, which is where the problem could be. the 750 carb spacing may be the same as the 650 (PD carb models), but the actual intakes on the 750 are much wider.

regarding your compression ratio question: are you referring to bumping up the CR with stock pistons, or with 750 pistons? in my case, i had to bump DOWN the CR into a sensible street riding range (10.58/1) with 64mm pistons, but i started with pistons that wouldn't even fit in the head without turning them down.

in general though: my machinist recommended .050"-.060" clearance from head to piston to allow for rod stretch (mike reick told me he thought .030" would be enough, i believe), and .050-.070" clearance from valve to piston. if you are going to go about decking the head, the only way to test both is by claying the cylinder and measuring the dissection of the clay after turning the engine through. valve clearance alone can be measured by depressing the valve until it hits the piston at TDC, and measuring the travel.

I would be more then likely going about it with the stock CB650 pistons. Otherwise it would be with custom 61 mm 650 style pistons.

[DarkRider]

Ok another handling question...Does a CB550 with an upgraded engine need more then a single disk up front? been pondering doing a modern front end swap with the spare VF parts i have which would give me dual disks up front and swapping the swing arm from the VF to the rear which would give me a single disk in the rear...would this be overkill for this bike?

[dusterdude]

i wonder if the 650`s hp figures were net and not gross like the 750`s were.

[mlinder]

I have scrapped the idea of using a fairing on the bike because of the weight gain of the turbocharger. The turbo idea was just a random idea i had recently its things like this is why im spending my free time planning out the project..other direction to go would be a 610 cc high compression all motor build. If its possable to get around 70-80 Hp out of the engine this way i will go in that direction.

No reason you cant pull 70 crank HP out of a 610cc NA engine. Gonna be mostly from cam (that shifts power up to a higher rpm range) and extra RPM. Find out what you need to get another 1500 or 2000 reliable RPM out of your bike. I'm sure paulages or others here can tell you what you need. Probably not much more than rods (or at least strengthened rod bolts), improved cam chain and tensioner, headwork and big brass balls.

honda claimed 67 RWHP for the '69 cb750, and 62 RWHP for the american model cb650.

Paul, all Hondas claimed HP figures were at the crank. You would be lucky to see 55bhp at the rear wheel of a CB750.

When we first dynoed the CR with the stock motor with just the open 4 into 4 exhaust it was only 54bhp at the back wheel.
The ignition and carbs took it to 60bhp and the mild tuned 836 took it to 86bhp.

Sam.

funny you say that, 'cause there are plenty of people on here that will claim their K0's will pull 67+ rear wheel with no mods (and spin to 18,000 RPM, and fly to the moon... ). i figured those figures were crank, but the point is that honda's claimed HP from the 650 was only 5 less than what they claimed for the '69 750. i'd love to see some real world 650 dyno numbers. maybe we'll dyno joe's bike when it's up and running. i'll be dynoing my 550 race bike and 718 this spring anyway.

Mine makes 167 rwhp at 30k rpm.
Oh wait, no it doesn't. It's broken.

[paulages]

I have scrapped the idea of using a fairing on the bike because of the weight gain of the turbocharger. The turbo idea was just a random idea i had recently its things like this is why im spending my free time planning out the project..other direction to go would be a 610 cc high compression all motor build. If its possable to get around 70-80 Hp out of the engine this way i will go in that direction.

No reason you cant pull 70 crank HP out of a 610cc NA engine. Gonna be mostly from cam (that shifts power up to a higher rpm range) and extra RPM. Find out what you need to get another 1500 or 2000 reliable RPM out of your bike. I'm sure paulages or others here can tell you what you need. Probably not much more than rods (or at least strengthened rod bolts), improved cam chain and tensioner, headwork and big brass balls.

honda claimed 67 RWHP for the '69 cb750, and 62 RWHP for the american model cb650.

Paul, all Hondas claimed HP figures were at the crank. You would be lucky to see 55bhp at the rear wheel of a CB750.

When we first dynoed the CR with the stock motor with just the open 4 into 4 exhaust it was only 54bhp at the back wheel.
The ignition and carbs took it to 60bhp and the mild tuned 836 took it to 86bhp.

Sam.

funny you say that, 'cause there are plenty of people on here that will claim their K0's will pull 67+ rear wheel with no mods (and spin to 18,000 RPM, and fly to the moon... ). i figured those figures were crank, but the point is that honda's claimed HP from the 650 was only 5 less than what they claimed for the '69 750. i'd love to see some real world 650 dyno numbers. maybe we'll dyno joe's bike when it's up and running. i'll be dynoing my 550 race bike and 718 this spring anyway.

Mine makes 167 rwhp at 30k rpm.
Oh wait, no it doesn't. It's broken.

  ...man that thing sounds awesome...listen to it wind up!...wow, all the power!..........BANG! ...oops. 

Ok another handling question...Does a CB550 with an upgraded engine need more then a single disk up front? been pondering doing a modern front end swap with the spare VF parts i have which would give me dual disks up front and swapping the swing arm from the VF to the rear which would give me a single disk in the rear...would this be overkill for this bike?

the stock modified dual disk stops great, IMO. i'll be upgrading to a brembo master cylinder soon (off an '06 ducati sport classic)-- i'll let you know how that works out. i think a VFR suspension would look wacky on a 550, but that's just my opinion.

[DarkRider]

The main reason i was looking at using the VF parts is because my bike only has a single front disk...did the 550F get dual front disks? Because if so i would rather use factory parts instead to keep the spoke wheel look. Otherwise i wouldn't mind finding some comstars or some other mag wheels that will fit this bike.