Topic: How much can you lower a stock CB550F?

[calj737]

I’m a 2-foot guy, always in gear, clutch pulled and right hand on brake to illuminate the tail light. I get the preference and don’t disagree with your rationale. And I’m 6’4. Always have out two feet down partly because I can, mostly for better slow speed take-offs. Too many people “pop” their feet up as they take off and unbalance their ride.

At your weight and oft passenger, I am going to re-encourage you to move to 17” wheels and a tapered seat cushion. Geometry changed that reduce handling are massive safety issues. Even for a city-go commuter. Don’t be “that guy” and think it doesn’t matter. It does. And it will when it’s least convenient.

[carnivorous chicken]

Not sure if I want to swap to a 550K swingarm to fit those brackets, it's a bit backwards as I'm trying to do something cheap and quick. Honda changed the swingarm for a reason, and I'm curious now as to why, I assume the "Super Sport" one would be superior in some way...

Somneone who knows better will probably correct me, but it might be because the 550F (supersport) has a stock 4/1 and the Ks have 4-4...

[calj737]

Not sure if I want to swap to a 550K swingarm to fit those brackets, it's a bit backwards as I'm trying to do something cheap and quick. Honda changed the swingarm for a reason, and I'm curious now as to why, I assume the "Super Sport" one would be superior in some way...

Somneone who knows better will probably correct me, but it might be because the 550F (supersport) has a stock 4/1 and the Ks have 4-4...

Correct. No “improvements” over a K.

[scottly]

Geometry changed that reduce handling are massive safety issues.

Cal, just sitting your lard-ass on a stock 550 lowers it and changes the geometry more than anything Greasy is considering.
Grease, don't rule out the lowering blocks just yet; they actually soften the effective spring rate, which may be beneficial for your low weight. I don't recall any specific swing arm being required?
As long as you lower both the front and rear the same amount, any geometry changes will be minimal.

[calj737]

Cal, just sitting your lard-ass on a stock 550 lowers it and changes the geometry more than anything Greasy is considering.

Actually, not true. As you point out, rider weight moves the suspension on unison. So the effect is equal on the geometry, even with your lard-ass opinion on the bike. Static sag on the front and rear are measured to make suspension adjustments so the dynamic effects can be achieved as close to ideal geometry. But you know this. And these vintage bikes don’t have those adjustments available in stock form.

Given his “size” I’m not sure that he can even get the bike low enough to suit his goal short of dropping to 14” wheels. And of course, the lower he makes the bike the less clearance he will have in cornering as the engine cases will be vulnerable to scraping.

[Tracksnblades1]

Cal, just sitting your lard-ass on a stock 550 lowers it and changes the geometry more than anything Greasy is considering.

Actually, not true. As you point out, rider weight moves the suspension on unison. So the effect is equal on the geometry, even with your lard-ass opinion on the bike. Static sag on the front and rear are measured to make suspension adjustments so the dynamic effects can be achieved as close to ideal geometry. But you know this. And these vintage bikes don’t have those adjustments available in stock form.

Given his “size” I’m not sure that he can even get the bike low enough to suit his goal short of dropping to 14” wheels. And of course, the lower he makes the bike the less clearance he will have in cornering as the engine cases will be vulnerable to scraping.

And as if Grease Monkey moves his suspension (mechanically) in unison as your weight does the effect will also be equal to the original geometry..

With old school handlebar setbacks (for shorter arms) nothing stops the fork tubes from sliding up.. My kidney, height, and weight challenged buddy had his 836K4 so low he had to modify his RC side winder so he could make right  turns..

[Little_Phil]

I'm less than 5' 5" and under 140lbs and old. And find 500/550s fine but only one foot down and lots of traffic and red lights around here. Pushing around or up any slope less easy.

[GreaseMonkey]

Okay, so bit of an update. I sat on the bike yesterday, may have even been for the first time. No idea what I was worried about.

Backstory: Bought the bike two years ago and immediately put it in storage. Been pretty sick till recently so never got around to going through the bike. Girlfriend sat on the bike when I picked it up and told me it felt huge and that she hated it (this is the one that steals my first gen 900RR and loves that bike). She's exactly my height. So, it seems my assumptions about how tall/large the 550 is are unfounded and were just based on my girlfriends "feelings". No idea why I decided to take her words that day as possibly being objective... Don't think I ever even sat on the bike.

I measured the rear shocks at about 12.125" compressed under the bike's natural load (so seems stock length) and the front forks were in the factory position in the triple clamps. It has basically brand new (though now 20 year old plastic) Kenda Challengers in 100-90-19 up front and 120-90-18 in the rear. Seat is definately shaved (poorly) maybe half an inch to an inch in the rider seating area. Also, the bike has some odd low height handlebar that is 29.5" accross. Too wide, initially mistook it for the CB400F handlebar, happy it isn't as that's what I want to install. With the bike in it's current state and me in my running shoes I see no real reason to lower the bike (and I'm taller in my riding boots). I may do 1" max at the triple trees and via custom shorter shocks if necessary, no more than that.

Unfortunately the bike is more of a basket case than I thought though. Price was right and there was no visible concerning rust or damage to the frame, swingarm, or motor so I just paid the guy immediatley and loaded it up. Upon closer inspection yesterday I'm a bit concerned. The bike was originally owned by an older gentleman who was slowly modding it and doing some low speed lapping at his local track. It seems someone who didn't know what they were doing had the bike in between the older gentleman and me and started going to town tinkering with the bike. I can tell bolts are in incorrect positions and things are done just plain wrong and missing here and there. Lots of evidence of real amateur assembly/wrenching/tinkering on the bike. Whoever worked on the bike between the older gentleman and I didn't have a clue. Going to take a bit of effort to go through the whole bike and make it safe/reliable.

Not doing any of that till I do a compression test and make sure I have a decent motor to work with. Because if I don't have a good motor I'm not sure where I'd source one for the bike. On a positive note she does have oil in her and does turn over! Build thread to come if the motor checks out, will need lots of help trying to figure out this bike, mostly all the hardware and unhacking. I can tell everything is in the wrong place and/or crappy Home Hardware bolts/nuts were used whenever possible. I have a feeling the bike sat in pieces for a bit and the person who did the reassembly wasn't the one who took it apart.

While I was with the bike for fun I took off the tail light and turn signals. Holy crap I didn't think it would be this easy to get weight off this bike. I thought my goal of 425 lbs wet would be difficult to attain but I'm not concerned at all after feeling how heavy components on these bikes are. Still have to change the gauges, change the handlebar, get rid of the center stand, lighter exhaust, lighter battery, etc. Crossing my fingers on that motor checking out. If it does I'll bring the bike home so I can start chipping away at it.

Pictures for your viewing pleasure:

[calj737]

A couple of helpful hints: all the bolts, nuts and fasteners are metric. Every screw that looks like a Phillips is actually a JIS; and they’re rather different. Buy a set of JIS screw drivers and virtually every screw will come out. Vessel makes a set of 3 sizes with an impact driver and using those, you can avoid stripping out the screws.

If a previous owner used SAE threaded bolts, you’re in for some trouble. A decent set of taps “might” be able to repair the threads, but you’ll likely have to use helicoils or timeserts to repair the holes.

That seat is not stock. Or at least it’s not the true stock cover. So a decent upholsterer can reshape the foam and cover it back nicely for you.

The dual discs up front are not stock either. Likely the speedo drive has been removed from the right side so your gauge for that is apt to be disabled. Front fender looks to be either backwards or missing the second strut.

[newday777]

A couple of helpful hints: all the bolts, nuts and fasteners are metric. Every screw that looks like a Phillips is actually a JIS; and they’re rather different. Buy a set of JIS screw drivers and virtually every screw will come out. Vessel makes a set of 3 sizes with an impact driver and using those, you can avoid stripping out the screws.

If a previous owner used SAE threaded bolts, you’re in for some trouble. A decent set of taps “might” be able to repair the threads, but you’ll likely have to use helicoils or timeserts to repair the holes.

That seat is not stock. Or at least it’s not the true stock cover. So a decent upholsterer can reshape the foam and cover it back nicely for you.

The dual discs up front are not stock either. Likely the speedo drive has been removed from the right side so your gauge for that is apt to be disabled. Front fender looks to be either backwards or missing the second strut.

The Supersport front fender in the USA only had the one brace at the rear. It isn't backwards.

[seanbarney41]

sounds like you have a good plan...except get it running for 100 miles or so before you base any expensive decisions on a compression test

[GreaseMonkey]

A couple of helpful hints: all the bolts, nuts and fasteners are metric. Every screw that looks like a Phillips is actually a JIS; and they’re rather different. Buy a set of JIS screw drivers and virtually every screw will come out. Vessel makes a set of 3 sizes with an impact driver and using those, you can avoid stripping out the screws.

If a previous owner used SAE threaded bolts, you’re in for some trouble. A decent set of taps “might” be able to repair the threads, but you’ll likely have to use helicoils or timeserts to repair the holes.

That seat is not stock. Or at least it’s not the true stock cover. So a decent upholsterer can reshape the foam and cover it back nicely for you.

The dual discs up front are not stock either. Likely the speedo drive has been removed from the right side so your gauge for that is apt to be disabled. Front fender looks to be either backwards or missing the second strut.

Have all the JIS tools and impact drivers and thread repair kits and bolt extractors and helicoils and etc. I'm not new to working on old rusty junk, lol. I haven't found any SAE cross threaded threads so far but I haven't gone that deep. All the JIS hardware heads have been obviously stripped by philips drivers.

I'm aware the seat cover is aftermarket, but does the foam look stock? The driver seating area is poorly shaven down, I can tell as it's not smooth underneath the cover. The pillion area feels smooth and uniform and factory like stock. I would like to buy stock foam and a stock cover for it.

Yes I know the dual discs aren't stock, the older gentleman was doing some light mods as he tracked what used to be his street bike, and I was told that was one of them. So bolt on oem dual discs mods mean I can't have the mechanically driven speedo?

Front fender isn't supposed to have the second brace if I'm correct for the 1977 CB550F Super Sport model. Lots of little defferences like that between the 550K and 550F models. And even then there are quite a few little differences between the 1975, 1976, and 1977 CB550F Super Sport model years themselves. It's a bit annoying as people generalize that the 550F is the same as the 550K. Lots of little aftermarket and oem parts incompatabilities because of that. The 550K was the vastly more popular model in production numbers, so they got the parts.

[GreaseMonkey]

sounds like you have a good plan...except get it running for 100 miles or so before you base any expensive decisions on a compression test

Front calipers are probably seized and the master is empty, so I'm not sure how much work it's going to take to get the bike rideable. Discs look decently thick though, so that's a plus. Have a feeling the pads are rusted and toast also.

That's why I was going to start with a compression test, before I put time/money into the brakes. Also I see cracked intake air box adapter boots, cracking wiring harness groungs, frayed wiring, dodgy wiring, etc. She needs lots of little things here and there before you can reliably trust riding it. I just quickly skimmed the bike yesterday, I'm sure there's a lot I missed.

My main concerns with projects are rust and damage to the frame, swingarm, tank, forks, and motor. So that's all I really checked before I bought it. She didn't have any visible structural rust, the inside of the tank was perfect, the frame and swingarm and front end didn't look bent, and the motor turned over and had oil in it, so I gave the guy my money and ran.

Is there something a hundred miles on the motor/bike would help it before I start digging into it?

[GreaseMonkey]

A couple of helpful hints: all the bolts, nuts and fasteners are metric. Every screw that looks like a Phillips is actually a JIS; and they’re rather different. Buy a set of JIS screw drivers and virtually every screw will come out. Vessel makes a set of 3 sizes with an impact driver and using those, you can avoid stripping out the screws.

If a previous owner used SAE threaded bolts, you’re in for some trouble. A decent set of taps “might” be able to repair the threads, but you’ll likely have to use helicoils or timeserts to repair the holes.

That seat is not stock. Or at least it’s not the true stock cover. So a decent upholsterer can reshape the foam and cover it back nicely for you.

The dual discs up front are not stock either. Likely the speedo drive has been removed from the right side so your gauge for that is apt to be disabled. Front fender looks to be either backwards or missing the second strut.

The Supersport front fender in the USA only had the one brace at the rear. It isn't backwards.

You beat me to it.

[scottly]

 So bolt on oem dual discs mods mean I can't have the mechanically driven speedo?

Yes, you can have a working speedo with dual discs. It looks like the speedo cable is there.

[GreaseMonkey]

 So bolt on oem dual discs mods mean I can't have the mechanically driven speedo?

Yes, you can have a working speedo with dual discs. It looks like the speedo cable is there.

Thats what I thought, I must be misunderstanding something from calj737's post then?:

The dual discs up front are not stock either. Likely the speedo drive has been removed from the right side so your gauge for that is apt to be disabled.

[scottly]

 So bolt on oem dual discs mods mean I can't have the mechanically driven speedo?

Yes, you can have a working speedo with dual discs. It looks like the speedo cable is there.

Thats what I thought, I must be misunderstanding something then?:

The dual discs up front are not stock either. Likely the speedo drive has been removed from the right side so your gauge for that is apt to be disabled.

No, you didn't misunderstand, Cal misspoke.

[bryanj]

The seat shape looks standardish but non standard cover.
DO NOT take the brakes apart before putting fluid in and pumping the pistons/pads out
Stainless caliper piston and seal about £28 in UK Dave silver repop master(decent) about £50, easier than stripping and rebuilding

[RAFster122s]

Another brake piston option is phenolic from Godfrey's Garage...
Or with some custom brackets and some machine work you could fit the dual piston calipers from 80s bikes, but, personally, the stainless discs suck for brake performance and fitting a restomod std right side up front end is a better from my point of view, but that would run you 1500...
Std stock dual discs with the HH pads a better first step

Definitely get your brakes sorted and bike running. Some things pay long term dividends...the compression numbers won't settle down before at least 100 miles or more, so you cannot judge compression numbers as more than a rough order indicator initially.

[seanbarney41]

sounds like you have a good plan...except get it running for 100 miles or so before you base any expensive decisions on a compression test

Front calipers are probably seized and the master is empty, so I'm not sure how much work it's going to take to get the bike rideable. Discs look decently thick though, so that's a plus. Have a feeling the pads are rusted and toast also.

That's why I was going to start with a compression test, before I put time/money into the brakes. Also I see cracked intake air box adapter boots, cracking wiring harness groungs, frayed wiring, dodgy wiring, etc. She needs lots of little things here and there before you can reliably trust riding it. I just quickly skimmed the bike yesterday, I'm sure there's a lot I missed.

My main concerns with projects are rust and damage to the frame, swingarm, tank, forks, and motor. So that's all I really checked before I bought it. She didn't have any visible structural rust, the inside of the tank was perfect, the frame and swingarm and front end didn't look bent, and the motor turned over and had oil in it, so I gave the guy my money and ran.

Is there something a hundred miles on the motor/bike would help it before I start digging into it?

yeah, if the bike has been sitting for a few years, rings are likely stuck in piston grooves causing low compression readings, also valve faces and seats are likely to be at least slightly corroded or dirty also causing low compression numbers.  Both of these conditions are easily remedied by a certain amount of run time.  It can take a bit of an Italian tune up to get these engines to clean themselves up but they can and do more times than not.  I just hate to see these engines get torn apart for nothing.  Honda really put these things together and there are few that can duplicate even when the parts, materials and know how are available....

[calj737]

 So bolt on oem dual discs mods mean I can't have the mechanically driven speedo?

Yes, you can have a working speedo with dual discs. It looks like the speedo cable is there.

Thats what I thought, I must be misunderstanding something then?:

The dual discs up front are not stock either. Likely the speedo drive has been removed from the right side so your gauge for that is apt to be disabled.

No, you didn't misunderstand, Cal misspoke.

Cal didn’t misspeak, he said “apt” as he didn’t know whether the cable/gauge were functional. Since he said many PO mods were hacked, it was a caveat. 

[Stev-o]

Expect low compression readings if it has set for a number of years.  The more important number is if they are within 10% of each other.   Very rarely is there a motor that cant be revived.  Old fuel sitting in the tank and/or carbs is typically the culprit if it wont start.