Topic: 43.5k miles, time to rebuild?

[jasonbox]

As stated earlier, I'm restoring my other older '75 550F, not one in avitar, that's the 'new' one...

The old one starts easily, runs, but some issues I perceive that make me consider an engine rebuild are:
1. minor oil leakage from cylinder head.
2. engine performance not great.
3. clutch seems weak, lever requires much less effort and has little distance to disengage, has slipped, only occasionally.
4. 43.5 k mileage

Should I just replace the clutch and call it ready for sale?

or, since I have my other '75 550F in better working order, should I make the rebuild my winter project?

How major a job is an engine rebuild?

Is rebuild co$tly? I'm already in $500 on the restoration (rebuilt: front forks; friont brake caliper; new signals; new rear fender; rebuilt carbs; rewrapped wiring harness; found 1 side cover, still need other, forget which side right now) on top of the nominal $550 value of the 'run down' bike. I commuted on it for 5 years in Boulder, Colorado. I suppose the bike is now worth $1000 as is. But all this effort to restore makes me wanna keep it. 

What are major parts to replace in rebuild? gaskets? what else?

Please foregive my ignorance  , but I think I'm up for the rebuild. Someone wanna talk me out of it?

Turn it into a racer?

Any input welcomed.

with thanks,

JBOX

[jaknight]

Hello jasonbox------------>

     I ain't nowhere's near the best in this group of Honda Choir Boys, but, I would submit that your bike may be just in need of a Major TuneUp.  The clutch could need some good, fine adjusting.  Changing to motorcycle racing oil can help clutches quite a bit too..........

     The motor.......... valve gap setting, point adjustment, spark plugs (maybe cables too) carb work........ etc., etc.......

     Unless the bike has had major abuse (running without oil or very low; blah, blah, blah) a major tune up on everything can work mind blowing miracles.  Unless you know of some bad treatment it has had.............. tune up would be the way to go first........ don't skimp on the fine tuning work

     ~ ~ ~ jaknight ~ ~ ~

[Tim.]

A head gasket doesn't equal a rebuild.  A top-end rebuild typically includes all your top end gaskets and o-rings etc, as well as re-seating valves, checking valve guides, replacing piston rings, honing cylinders...

You need to check your compression and do a leakdown test to see if you need to worry about rings.

[Noel]

My 500 engine was in about the same situation when I bought the bike.

I rebuilt the clutch with NOS parts from David Silver. Pretty simple job, cost a bit less than $100.

The bottom end and tranny looked to be okay, so I only redid the top. Collected pistons, rings, and gaskets from Ebay. Parts totalled maybe $100. Paid a local fellow $35 per hole to bore the cylinders to first oversize and did the rest of the work myself. Also threw in a new camchain, $30 from David Silver.

So I guess I spent about $350 total, more or less. Really ought to have done the valves, which probably would have added another $200 or so. Probably didn't need to go to the oversize pistons and could have saved some money there. Honestly, I probably could have gotten by with nothing but rings and gaskets; a few hours work and maybe $100 total. The bores looked fine, but I wanted to start from fresh, so there you go.

[Dennis]

You need to do some testing before you start spending money and taking thinks apart. Do all of your adjustments, especially the valves then as tintin suggested compression and leakdown or at a minimum the compression test. Then you will know what REALLY needs to be done.
I never take an engine apart unless I know why I need to get inside it.

[750goes]

Does the bike show any other signs of abnormal wear and tear - like leaving a blue cloud behind you as you are riding.  If it isn't blowing smoke and its not too noisy, give it a good tune up and wait for the next 40 odd thousand to click over.IMHO

[Noel]

I dunno. He's got 40,000 miles on the engine; it's bound to be a bit tired. If nothing else, the cam chain really ought to come out.

Moreover, he's got an oil leak, and he can tell that performance is down a bit -- and he does have another 550 to compare with.

Don't know how much testing is required to prove to himself what seems fairly obvious. If he's got a compression tool he can use it, but what do we really expect him to find? Good compression on a 40,000 mile engine with known performance issues?

Regardless, he does need a camchain, and it sounds like he wants to address the oil leak. The engine's got to come apart anyway, so he might as well throw in a new set of rings and check valve sealing at the same time.

IMHO, as always.

[dusterdude]

Does the bike show any other signs of abnormal wear and tear - like leaving a blue cloud behind you as you are riding.  If it isn't blowing smoke and its not too noisy, give it a good tune up and wait for the next 40 odd thousand to click over.IMHO

agreed

[cmorgan47]

can't imagine that the columbus riding season is that much longer than the detroit one.

can you wait till then?
i would.

other than that, like the others have said, how's the compression.  give it a tune up, then decide.

[mikes]

The older honda 750s would go a zillion miles without a major enjine teardown. So long as regular maintainance is done, and the main issue is how the bike is ridden. If you abuse it with hard accleration and continually revving the engine through the gears, in other words, plain abuse, you can screw up any motor in a very short time. I have seen abused motors in need of a major overhaul with less than 10,000 miles, and i also had a good friend who bought a new CB 750 and rode it nice and easy for 17 years, put 165,000 miles on it with no major work done to it, and when he passed away it still ran great! Its usually comes down to the owner and his riding and service habits. Same with tires. Do burnouts, you will need tires in 1000 miles. Start out easy and dont try to be Kenny Roberts in the turns, they will go very many miles. Often this issue is overlooked, but its a fact.

[bryanj]

Now the 550 DONT have to come out to work on BUT here are a few things to check.

At 40K the cam chain will be tired but not totalled. Only need the top cover off if you get a "Soft" link

To do the leak you only need to take the head off--probably a good idea to change the valve stem seals --ask Tintin! BUT once the head is off the cylinder base gasket should be replaced as it is ALWAYS disturbed.

At 40K, if its had a moderatly hard life, the primary chain MAY need replacement--Pull the sump pan(which is supposed to be removed and cleaned every 12k anyway and i bet its never been off!) and check visually and with finger if the chain has touched any of the oil galleries--If it has its an engine out  strippdown with new seals etc.

[jasonbox]

I'll follow your advice and do the tuning first and see/feel the improvement.

I'll to a top end overhall if I get ambitious.

Yah, the riding season is coming to an end in 2 months or less.

It sure is convenient to have two to compare. THere are a lot of subtle differences.

Thanks all for the wisdom.

JBOX

[mikes]

Jason, i would think the most serious issue you could be facing is the cylinder bore alignment. If the bike was ridden hard or even idled for long periods in heavy traffic and hot weather this often occurs with the honda 4bangers. Cylinder warppage will cause numerous problems, one is lack of power with a good tune.Just a thought to keep in mind in case you decide to pull out the motor at some point in time. Its not uncommon nor is it that difficult to correct, however it can get a bit costly.  Good luck and hope a few minor tweeks do the job.

[Tim.]

Well, my engine is apart down to the casings, and here's what I'm doing (for the 2nd time in 15 months by the way)

Tappets - tappet ends cleaned up where necessary to prevent any damage to valves
Head - all new exhaust guides (and the o-rings under them), all new seals, valves seated etc.
Cylinders - fresh 0.5mm bore/hone on another stock set of cylinders
Pistons - new set of 0.5mm over pistons/rings/pins/clips from Classic Cycle Parts
Gaskets - new Honda OEM gasket kits A and B from Western Hills Honda - everything from the base gasket up will be new
Carbs - finally going to put on a fresh low-milage rebuilt set I've had for a year - the current ones are very very worn and difficult to synch.

www.conceptsonwheels.com is doing all the machine work on the tappets/head/cylinders.  I'm doing the labour/tuning.  Points and Condensors are only a year old and were Honda OEM parts.  Cam chain and sprocket were replaced with new last spring, as were the slippers/guides.

This had better work!  I'm anticipating reassembly in the next 2 weeks once all the parts arrive and the machine work can be completed (need the pistons to do the bore and the guides).

Funny thing (yeah, real funny) is that all of this was caused by bad valve stem seals.  I had the same work done last year but at a different machine shop.  I gave them new seals to put on, and my friend had his 750 head done at the same time as me.  We think perhaps the new seals ended up in the 750 head, as it ran like a top afterwards with no problems whatsoever.  The only problem with my head was my seals were shot.  When they took the springs etc. off the head, apparantly the valves literally fell out on their own - seals weren't holding anything in.  They had split and fallen apart.  The same shop put in bronze sleeves into two of the exhaust guides - apparantly these have held up just fine, but the other two guides were shot - should have done all 4 of course.

Excess oil into the cylinders = lots of smoke and glazing of cylinder walls.  Perhaps I could have simply redone the head and de-glazed the cylinders and put it all back together, but frankly for the extra few hundred $ I'm happy going with all new parts and a fresh bore.

The lesson I've learned is you get what you pay for.  I only paid $120 for the first head job last spring, including them bead blasting and repainting the head.  Looked like a million $ after they were done, but obviously they rushed the work and should have done more in terms of the other guides.  The current head job is costing $270 + parts, and I have all the confidence in the world in the work they're doing and also that I can go back to them if there's a problem.