Topic: Rebuild for Dummies Redux - v2.0, Mulligan

[ev0lve]

Tapered Bearings
http://forums.sohc4.net/index.php?topic=38242.msg417997#msg417997
RearSets
http://forums.sohc4.net/index.php?topic=38242.msg422608#msg422608
Painting - Body, rims, frame
http://forums.sohc4.net/index.php?topic=38242.msg423177#msg423177
Lacing and Truing Rims
http://forums.sohc4.net/index.php?topic=38242.msg423202#msg423202
Dual Disk/Brake conversion
http://forums.sohc4.net/index.php?topic=38242.msg426222#msg426222
Brake hoses and bits
http://forums.sohc4.net/index.php?topic=38242.msg513681#msg513681
Kreem - HowTo
http://forums.sohc4.net/index.php?topic=38242.msg650129#msg650129
GL1000 Frontend conversion info
http://forums.sohc4.net/index.php?topic=38242.msg719805#msg719805
H4/HID Conversion
http://forums.sohc4.net/index.php?topic=38242.msg783030#msg783030
Coils, condensers, points and caps - oh my
http://forums.sohc4.net/index.php?topic=38242.msg607959#msg607959

The original Rebuild for Dummies thread is a huge inspiration and source of info for me so I thought, since I'm rebuilding my engine, I'd do the same. Chuckpen posted to my introduction thread and seems to be in the exact same place so hopefully he'll hop in here as well.

Here's the dummies thread: http://forums.sohc4.net/index.php?topic=29364.0

Quick story: I'd decided I wanted a 750 about 6 months ago and got serious about 2 months ago. Looked at or tried to contact 6 or 7 over the course of that time (Craigslist seller's are weird birds it seems) and either ended up looking at machines that were overpriced and non-running basket-cases (that's right non-running 76 CB750 rustbucket for a grand, I'm talking about you) or couldn't get the sellers to even reply.

So one RSS feed at work and an understanding boss that let me split at 1 in the afternoon on a Thursday and I had my bike. Picked it up July 4th.

Seems it will need just about everything as the front caliper is seized, the heads leak, tires and chain are ten years old (out of registration since 1998), clutch is adjusted all the way out and some random electrical weirdness that's hopefully just bulbs (yeah, right).

Pics from the day I picked it up - CB750K-5, $500, 27,000 Miles, runs strong:


So far I've pulled and rebuilt the carbs and just got the engine out and heads off of it this weekend. Far simpler than anticipated and really only required patience. Lots and lots of patience




My intention is for this to be a daily rider so reliability and safety are first concerns.

As for cost in parts I'll total that up when it's done and put a number on it. Right now I don't want to think about it too much

Like I said the tear-down so far has been cake-like. Ran into stuck bolts. Zapped em with penetrating oil and walked away. My inclination as a teenager was to just apply more force and it scarred me mechanically for life (broken head studs, rounded nuts etc.)

Everything looks really nice internally. Oil was black as could be but there was almost nothing in the pan or on the oil-pump screen. Just a few small unidentifiable black bits (rubber?) and very small metal shavings. Should have taken a pic while I had a chance.

There's a ton of carbon build up but the cam chain is nice and tight (using the pull at the top of the cam sprocket method) and the main chain roller(?) visible in the case with the oil pan off looks pretty pristine (again didn't grab a pic).

So, the questions:

Cam chain roller. Seems a little chunky. Does this need to be replaced?


Best way to clean the heads and should I bother cleaning up the pistons?



The pistons themselves seem free of wear and the jugs look good as well. Best way to measure? Should I replace the rings?

Currently I can only work on it over the weekends. I've coated a few shop towels in WD40 and shoved them in the head. Is that sufficient to stave of rust? Will it rust? Is there a better way to do it when it'll have to sit for 5 days?

Many thanks to all you guys,
Iggy

[rbmgf7]

nice find

if the engine was running strong, why bother to rebuild? what was the compression reading? every 70's bike i came across leaked a little oil here or there.

well, since you took the initiative to remove and teardown it's too late.

a rebuild can cost anywhere from a couple hundred into the four figure range. depends on how new you want your engine to be. i bet you can guess the correlation between price and performance. if you say money is not important, might as well do it the right way.

Cam chain roller. Seems a little chunky. Does this need to be replaced?

yes, replace the tensioner, guide, and the two rubber holders. might as well go all the way to replace the chain

Best way to clean the heads and should I bother cleaning up the pistons?

yes, clean both. various solvents and very fine/soft wire wheels (brass ones used on dremels. avoid valve seats). you can look into media blasting using a soft media like walnut shells or corn cob. may be albe to step up to AlO. be sure to CLEAN enerything and remove all the media. or, be on the safe side and have a pro like APE or MRieck do all the headwork. you will need to either lap the vales or go with the best solution and get a valve job. depends on the specs.

The pistons themselves seem free of wear and the jugs look good as well. Best way to measure? Should I replace the rings?

measuring pistons: micrometer. measuring bores: telescoping bore tool (can't remember the PC term) and micrometer. should all be in the manuals for limits. not sure, i only have the dealership manual. yes replace rings. if everything specs fine, just use a light hone.

as long as you don't live in a desert, super humid conditions, or next to the ocean. just toss a trash bag over everything to keep dust/debris out. the casings are aluminum but the internal are steel. if you haven't degreased the parts, the oil will protect them.

this is just barely covering a rebuild. try searching for more indepth guide. you are not the first to rebuild a 750

good luck

[ev0lve]

if the engine was running strong, why bother to rebuild? what was the compression reading? every 70's bike i came across leaked a little oil here or there.

It was a bit more than here and there  All out the front, back and tach seal. Not enough to get my shoes wet but would get on the headers eventually. You can see where the PO couldn't get the pressure washer to it 



HD studs are ordered and hopefully show up this week. Dribbling penetrating oil on each every day hoping I'll get lucky pulling them out.

a rebuild can cost anywhere from a couple hundred into the four figure range. depends on how new you want your engine to be. i bet you can guess the correlation between price and performance. if you say money is not important, might as well do it the right way.

Oh money's important but not so much that I'd like to do this twice (or three times as I've seen in some of the threads)

yes, replace the tensioner, guide, and the two rubber holders. might as well go all the way to replace the chain

Aaargh. Deep down I knew I'd be splitting the case but I didn't want to admit it.

yes, clean both. various solvents and very fine/soft wire wheels (brass ones used on dremels. avoid valve seats). you can look into media blasting using a soft media like walnut shells or corn cob. may be albe to step up to AlO. be sure to CLEAN enerything and remove all the media. or, be on the safe side and have a pro like APE or MRieck do all the headwork. you will need to either lap the vales or go with the best solution and get a valve job. depends on the specs.

I'd like to do most of the work I can do myself so more reading for me.

measuring pistons: micrometer. measuring bores: telescoping bore tool (can't remember the PC term) and micrometer. should all be in the manuals for limits. not sure, i only have the dealership manual. yes replace rings. if everything specs fine, just use a light hone.

More tools to buy! Any suggestion on good brands/price for the micrometer and bore tool?

as long as you don't live in a desert, super humid conditions, or next to the ocean. just toss a trash bag over everything to keep dust/debris out. the casings are aluminum but the internal are steel. if you haven't degreased the parts, the oil will protect them.

Excellent!

this is just barely covering a rebuild. try searching for more indepth guide. you are not the first to rebuild a 750

good luck

Oh yeah. I'm scouring the boards. Hopefully I can answer most of my own questions from threads already here (and point to them as well).

Thanks for the detailed reply and I'll take the luck too! 

Iggy

[manjisann]

I love these "How I did it" threads, I always learn so much! I am wondering, how did you remove the engine from the frame? I have seen several methods, such as laying it down and removing it with rachet straps, so I am just wondering how you did it? Hopefully I am a ways off from rebuidling my CB500 engine, but I would like to know how to when the time comes.

Thanks,
Brandon

[ev0lve]

I love these "How I did it" threads, I always learn so much! I am wondering, how did you remove the engine from the frame? I have seen several methods, such as laying it down and removing it with rachet straps, so I am just wondering how you did it? Hopefully I am a ways off from rebuidling my CB500 engine, but I would like to know how to when the time comes.

Thanks,
Brandon

I did it the old fashioned way. Got a second pair of hands and then did the budge it to the right, find what it's hung up on, budge it to the right, find what it's hung up on dance. When it was about half way I put a milk crate down to support it while the last of the left hand side was still in the frame then just tried to suppress the terror while heaving it up on the bench.

Not too hard really and didn't damage the paint on the frame. I might be tempted to throw some rags in for the reinstall though.

Iggy

[WFO]

I hear ya about craigs list CB sellers being weird and over priced and non responsive hopefully i can find a deal like yours this winter.

[ev0lve]

Well, there's a hold up getting parts. Seems I'll be asking folks (that's right Old Bike Barn I'm talking about you) that the part listed is actually in stock before ordering.

So engine's apart and, after a couple weeks of waiting for head studs that will never come, I've been putting penetrating oil on the stock studs everyday. Took them out yesterday using the bend em' over method and no issues at all. I put a pair of vice grips about an inch up on each and then supported it with my hand while bending the studs over with a length of pipe. Didn't take much either, maybe 30 degrees and then using the pipe and vice grips broke them loose bending the other studs over and out of the way as necessary. They all just came right out. Beginner's luck I think.



So now, as I wait for my reordered studs to arrive I'm going to drop the cylinder head off at a machine shop for a dunk in some solvent. And wait

Slow going and the biggest problem so far is just the logistics of getting the parts here when I need them. No questions this week but hopefully next weekend I'll be putting it back together if the cam chain etc show up.

Iggy

[ev0lve]

Hey! A real question and I can't seem to find the answer on the board anywhere so maybe it will qualify as a dummies question.

I think these are valve guide seals (let me know if I'm calling them the wrong thing) and I need to remove them and replace. How is it done? I've already destroyed 2 with a pair of needle nose and I'd rather not score up the guide itself. You can see the one I destroyed in the background.

Thanks for any clarification!
Iggy

[ev0lve]

Hmmm,

Ended up just cutting the retaining rings off. Even then they didn't just pop off and were pretty stiff.

At any rate another question. I've ordered up sprockets (18/48). Poking around on the boards here I see a few posts from folks saying a 530/100 chain is proper and a few (very few) saying 530/102. I neglected to count the links on the chain I took off but suspect 100 is the one. Also, this is the chain I'm eyeballing. Should be sufficient?

http://www.denniskirk.com/jsp/product_catalog/Product.jsp?skuId=11195100&store=Main&catId=415&productId=p11195100&leafCatId=41505&mmyId=

Thanks,
Iggy

[andy750]

I hope you ordered the HD studs from Dynoman for $80 -they are very good!

Sprockets - JI sprockets can be had from Z1 Enterprises - fast shipping

The chain will work, no problems - personally though Id spend another $20 and get an O-ring chain. But the one you listed will work. I was one of the few that got a 102 link...no regrets  (CB750K4 and K2 both have them).

Good thread and good luck with those valve oil seals - pretty essential.

cheers
Andy

[ev0lve]

Good to hear! I'm thinking the standard chain after running down posts here about o-rings not having sufficient clearance and chewing up cases. Figure better safe than sorry and I don't really mind taking the lube to it every couple weeks.

I haven't posted much on the rebuild (and taken fewer pics) but I did get the studs and they are installed at this point.

Really it's gone pretty well. I passed on taking the heads in and hit them with some easy-off oven cleaner. We'll see if that was a mistake on reassembly but it seemed to work really well and took the carbon right off. The jugs just got the fins done and very careful to mask off the cylinders. Then I ratttle-canned the fins with hi-temp paint and baked them in ye olde propane BBQ for 30 minutes at 400 degrees. I would have left them longer as I see folks saying 400 for an hour but it gave me the willies so I pulled them out.

Got a (huge) Mac valve spring compressor off of ebay,pulled the valves (easier than a noob would think) and dropped them in easy-off for a couple hours. Intakes cleaned up entirely. Exhaust cleaned up pretty well. I lapped the valves after the cooking and I think they look pretty good referencing other peoples pics here on the board. Have to put some gas in there this weekend and see if it leaks. We'll see!

Assuming all the rest comes in by Friday I may get it back together, timed and in the bike this weekend (probably not) but I still need to polish up the valve cover. Lots of good info on here as well about polishing up aluminum.

For folks like me doing this for the first time the cost may be a surprise. I think I was a bit naive about tools and such. A solid half of the price of the rebuild is tools. On the bright side I'll never need another pair deep well circlip pliers... ever (thanks freakish master cylinder Otherwise it's about a grand for parts all the way down to tires.

Still, having the celebratory beer at the end of the day staring at the thing knowing I haven't borked anything to date is pretty satisfying.

[andy750]

Good to hear! I'm thinking the standard chain after running down posts here about o-rings not having sufficient clearance and chewing up cases. Figure better safe than sorry and I don't really mind taking the lube to it every couple weeks.

Clearance is only an issue for the CB550/CB500s. No problem running an o-ring or x-ring chain on a CB750. Both of mine have had o-rings for years/thousands of miles of riding.

Good luck and keep us posted on how it runs.

cheers
Andy

[ev0lve]

Ahh, that was my confusion then on the o-ring.

I wasn't real clear on why a 100 or 102 link chain made sense. Easier to put on? Would you run out the pro's and cons for that?

Thanks,
Iggy

[ev0lve]

Ahh, a fairly productive weekend. The engine is back together and after a few starts at getting the pistons in the jugs a post from here specifying fingers and a screwdriver did the trick. Had the fear for a bit but someone somewhere on this forum has faced it before

Really easier than it seems to tear down and put the top-end back together. Mike Nixon's manuals take a lot ( pretty much all ) the guesswork out of it.
http://www.motorcycleproject.com/

Waiting on parts ( a carb kit was missing the float jet and seat ) but it's all bench tuned as well as I can do it and I think it'll go back in the frame next weekend. Pretty damn happy!

One question on this go around. I'm rebuilding the master cylinder so I can unstick the piston in the caliper. Got a pair of the circlip pliers with the long reach and I can compress the cylinder and get it placed but try after try I can't get the circlip out. Is there a trick to that?

Basically I get both ends in the holes, pull the circlip together without much problem but from there, when I try to move it or pull it, the ends of the pliers pop out. Can't reckon what I'm supposed to do to unseat it.

Thanks to All!

EDIT:

Search and the board provides Now to actually make it happen.

http://forums.sohc4.net/index.php?topic=22759.0
http://forums.sohc4.net/index.php?topic=5927.0

[ev0lve]

Master cylinder woes and steering stop questions but the engine is back in the bike and the bars are drilled!

I installed a new master cylinder rebuild kit but it's not performing right. Currently it only seems to circulate fluid out of and into the reservoir, really well too as I almost caught it in the eye with the cap off. I was pretty sure I took note of how the parts came out of it and got them back in there the same. The only thing I can figure is the cap in between the plunger and spring is in backwards or slipped at an angle. It doesn't snap the plunger back out immediately either, just kind of slowly works it's way back. Would that account for the cycling of fluid but none coming out the banjo end?

I put it in plunger, cap (open side facing plunger), spring. Is that correct?

Also, these bars will hit the tank if I don't rig something up to reduce the travel. Has anyone made steering stops and could you tell me how or point me at a thread? Searching for "steering stop" doesn't bring anything up.

One last question, I drilled out the bars by making two holes with a 3/8 bit then cutting between with a disc. Afterwards I cleaned up the edges with a grinding bit and laid in some duct tape just to be sure. Would that be sufficient to make sure I don't chafe the wiring (which is still in it's sheath)?

Thanks,
Iggy

[ev0lve]

Master Cylinder Rebuild

So, it seems I had my head deep in my ass when I took note of how the things came out of the MC. Looking at the old parts, and the cup on the end of the spring in particular, I think I got the spring in wrong and not the rubber cup. The fiche helps a bit (mostly for showing the small end of the spring on the plunger end) but looking at the cup on the end of the spring and it's tiny holes makes it pretty clear that I've plugged the banjo end.

Would someone confirm this is the proper order?

Thanks,
Iggy

Edit: Oh and for anyone like me the fiche is at
http://www.cmsnl.com/honda-cb750-four-k5-us_model482/partslist/
also found via this board.

[Redman]

The smaller end of the spring sits inside the open end of the cup. Both cups face in the same direction. Hope this helps.

[ev0lve]

So I've got the rubber cup turned around as well?!

The reason I ask is because the original rubber cup that came out of the MC has an indentation on the outside face, bottom of the "cup", slightly off-center, exactly the size of the cap on the small end of the spring. arrggg

Should be this then?

Edit: The fiche does appear to show the cup facing that way. I suppose the PO's PO rebuilt it and got it wrong too. Double arrggg.

[Redman]

Now you`ve got it.

[ev0lve]

Thanks RedMan! Now maybe I can get the caliper piston free 

Iggy

[Redman]

The best way to free up a stuck piston is to pump grease into the caliper where the banjo bolt goes.

[ev0lve]

I've read that (as well as turning the caliper into an air cannon) but I lack a grease gun at the moment so hopefully a working MC will be sufficient. Once the piston is out and if it's pitted what do you suggest?

I've read taking sandpaper to it and other folks saying replace it entirely but if I don't have to spend $40 on a new piston I'd rather not.

[Redman]

If the piston is pitted you really don`t have much choice. Using a pitted piston will score the seal and leakage will follow. Someone on the forum may have a good used one.

[ev0lve]

If the piston is pitted you really don`t have much choice. Using a pitted piston will score the seal and leakage will follow. Someone on the forum may have a good used one.

Well, got the diaphragm and spring in there properly and the piston came right out. Cleaned it up and it looks to be usable I think so now I just have to pick all the gunk out of the seam the gasket sits in insode the caliper and that (at least should be out of the way. Many thanks RedMan for your help on that one!

[ev0lve]

OK! It runs! Not well but I didn't really think it would be perfect on the first go.

I set up the carbs using the 1/8 in drill bit technique
http://forums.sohc4.net/index.php?topic=5410.0

and it came straight to life at 5000 rpm (gasp!). Turned the adjusters out to get it down to something reasonable and now it'll idle at around 2000 without the airbox.

The paperclip method might be better and I'll try that when I pull the carbs back off.
http://www.salocal.com/sohc/tech/carb/asmpg3/syncprep.htm
(just added for any goons like myself that run over this thread

There are problems though.

One, I don't know what normal is so the first question is... It should make this sucking sound using the kickstart yes?

Two, it's only running on 3 cylinders and there's some rattling I'm afraid of. Looks like #1 is out entirely. Pulled the plug and turned it over just to see if I could see some spark but no. Dead it seems. As I understand it 1 and 4 run on the same coil so if 4 is working so should 1?

I took some pics of the plugs after running it for a few minutes and it's attached here. #1 looks entirely clean and had just a little black oil on the post but no sign that it had actually fired.

Here's a quick vid running

There are a few wires in the bucket I need to track down but they don't "seem" to be part of this problem. The two bundles in the attached pic are left - ignition ( one spare/brown white ) and right - turn signals ( 2 spare/orange white - skyblue white).

Any advice or sympathy gladly accepted 
Thanks,
Iggy