Author Topic: CB750 F1 Restoration Project - not for the faint hearted (Read 26168 times)

SOHC4 Cafe Racer Fan · « **Reply #75 on:** April 14, 2015, 08:20:26 PM »

That remover looks positively nasty, but if it works . . .

eddiebpool · « **Reply #76 on:** April 17, 2015, 03:18:26 AM »

I have come across a problem identifying crank case and connecting rod bearings. Actually, that is only half true - I am reasonably confident about the crank case though a sanity check is required. The casing has BBBBB and the crack shaft has what looks like AACCA. I have attached a pic. I couldn't get a decent photo of the crank etchings (they are faint at best) though I have done my best to faithfully recreate the scratch marks. The 2nd set of numbers / letters / whatever don't make sense. As I said, this is as close to exactly what is on the case as my artistic skills will allow. The conrods have 3333 on them. My research suggests that the only answer on the crank shaft can be either a 3, 4 or 5. They might be 4's though written by different people from different angles. Is this normal? Has anyone seen something like this before?

As far as I can tell, I need Green / Green / Brown / Brown / Green for the case. *IF* these are 4's etched on the crank shaft, then I need another 4x Brown bearings. I can go ahead and just do the case bearings. They are not bad, the odd mark here and there, only one is scored and not badly. There are the odd scratch here and there though they are not in a straight line, like something foreign has got in. Does that make sense? I have to confess, my garage is filthy and the top end has been off the bike since before Christmas. Anyone come across that before?

The bike was low mileage and my work on it so far suggests it was looked after. I would probably get away with not doing the bearings at all. My instincts are telling me I should do the whole lot though, for the sake of thoroughness. Any suggestions appreciated.

eddiebpool · « **Reply #77 on:** April 17, 2015, 03:27:08 AM »

Another query. I noticed the piston pins were scored and will obviously be replaced. I thought the scoring was quite heavy. Is this normal? I can attach a pic if that helps.

Also, I noticed the pistons had slight wear at the front and rear. Not much, just enough to almost rub the machine marks off the pistons but not quite. Is this normal?

eddiebpool · « **Reply #78 on:** April 18, 2015, 09:18:24 AM »

I made a wee discovery that I wanted to share. I measured the wear on the primary chains based on the measurement from the crank case edge to the flat spot on the tensioner. The chap who does Hackaweek on Youtube does an excellent job of describing this procedure. I would recommend checking him out. Anyway, I believe that 70mm is the limit at which you should consider replacement. Mine was near enough, around 68-69. The bottom end sounded like a bucket of bolts and I believe my primary chains were the problem. I have taken a pic showing clearly that, under tension, one of the chains is slack and sags below the other. There is no surprise that this would have been rattling around.

If you have a rattly bottom end the primary chains may be the issue, even if they are within serviceable tolerance like mine. One chain might be worse than the other.

To think, I almost decided on not splitting the cases. Glad I did. New primary chains and tensioner ordered.

eddiebpool · « **Reply #79 on:** April 18, 2015, 09:38:57 AM »

I decided to order a set of brown bearings and two sets of green for the crank case. One set of the existing brown and existing green look perfect so didn't see the sense in replacing them. One of the greens are scored (number 1 or whatever the one furthest to the left is called), not bad but replacement required. Number two is also green and has a couple of scratches from what looks like something foreign got in - apart from the scratches it was a nice dull grey and it is a shame if I have spoiled them with my mucky garage and messing around. I decided replacement was required. The brown which was number 3 was much the same as number 1, not terrible but replacement was the right thing to do. So, 1 - 3 are getting replaced and 4 - 5 are just fine as they are.

I have bumped the scratchings. Can anyone read "Honda"? I have ordered a set of conrod bolts and will take each apart. If they are good, I will leave well alone and put in the new bolts and torque to spec. If they are bad, I need to make a decision and hopefully the bearings themselves tell me what they are. The conrods all have "F" one side and "3" on the other. Any help in the meantime much appreciated.

HondaMan · « **Reply #80 on:** April 18, 2015, 06:22:36 PM »

Quote from: eddiebpool on April 18, 2015, 09:38:57 AM

I decided to order a set of brown bearings and two sets of green for the crank case. One set of the existing brown and existing green look perfect so didn't see the sense in replacing them. One of the greens are scored (number 1 or whatever the one furthest to the left is called), not bad but replacement required. Number two is also green and has a couple of scratches from what looks like something foreign got in - apart from the scratches it was a nice dull grey and it is a shame if I have spoiled them with my mucky garage and messing around. I decided replacement was required. The brown which was number 3 was much the same as number 1, not terrible but replacement was the right thing to do. So, 1 - 3 are getting replaced and 4 - 5 are just fine as they are.

I have bumped the scratchings. Can anyone read "Honda"? I have ordered a set of conrod bolts and will take each apart. If they are good, I will leave well alone and put in the new bolts and torque to spec. If they are bad, I need to make a decision and hopefully the bearings themselves tell me what they are. The conrods all have "F" one side and "3" on the other. Any help in the meantime much appreciated.

The "3' is the rod's weight: they were rated 1-4. Honda limited themselves to matching the rod+piston (assembled) weights to be within 0.5gm of each other in production. You're fortunate to have all the same weights!

eddiebpool · « **Reply #81 on:** April 20, 2015, 07:03:08 AM »

Just back from the powder coaters - lots of lovely shiny things! They did a beautiful job of the frame - I love it. Pretty much went with everything frame related with Frame Plates, Swing Arm, Main and Side Stands, Triple Tree / etc, Headlight / Flasher Frame, Rear Brake Brace, Battery box and additional electrics bracket, Seat Hinge, Footpeg parts, and even got the little plates at the top of the air box done (they were in a terrible state - didn't come out perfect but certainly better than they were).

I'm starting to see the potential for this restoration and it has given me the motivation to push on.

eddiebpool · « **Reply #82 on:** April 22, 2015, 08:44:39 AM »

I was not happy with my No3 carb (choke slide was sticking and I couldn't get it to slide freely) and decided to use my original No3 carb, though it would need some work. It was pretty gummed but a bath of acetone for a couple of weeks sorted out the worst of it. A toothbrush and come carb cleaner took care of the rest.

A wee tip in case anyone comes across the same issue. I'm not sure what it is called, but the guide for the needle was not shifting at all. I didn't want to put force directly on the top in case it spread and would never come out. I found a 3mm punch fitted perfectly on the flat area inside the guide. It means you can give it a good tap without ruining anything, though don't go nuts. As you can see from the picks, mine was well gummed and didn't come out without a fight. Hopefully that helps someone out.

eddiebpool · « **Reply #83 on:** May 01, 2015, 11:35:55 AM »

I finally finished the wheels - two days of my life polishing every spoke and nut, both rims, and painting / polishing hubs. I tried an experiment which I think worked and might help someone else. I had made the decision from the beginning that the rear hub was getting painted so that was easy. I used VHT Engine Enamel and was very impressed with the result. If you have not used it, I would recommend it for any part on the bike, not just the engine. It goes on very nice. As long as you follow the instructions very carefully you get an excellent result. I went for Grey Primer and followed with Cast Aluminium. I decided against a clear coat. I like the Cast Aluminium finish and it should be tough enough as is.

I did something that the purists might hate but I think it worked well on the front hub. I couldn't decide on paint or polish. The outer parts polished fine. The problem was the inner parts where the ridges are was badly pitted, to the point that no reasonable amount of sanding would remove it. I decided to paint the inside (same VHT paints as the rear hub) and leave the polished parts as they are. It was not such a crazy idea. If it didn't look right I would simply scuff up the polished parts and complete the paint job. As it is, I'm happy. The tricky to reach parts have a tough (I hope) finish that doesn't require polishing, and the polished bits are accessible. It works for me!

A wee query, in case someone has laced the same wheels as me. I have Akront aluminium rims front and rear and they don't tighten like the stock. I have laced wheels before so know what I am doing. With these though, you get them all lined up even on thread counts then start to bring them to tension. Problem is the outers tighten about 6 threads before the inners and the difference in the inners can be anything up to 9 threads (9x360 degrees tighten). I just want to make sure I have laced these right. I can't see any other way to do it.

SOHC4 Cafe Racer Fan · « **Reply #84 on:** May 01, 2015, 11:37:53 AM »

Eddie,

The wheels look terrific. Did you cure the paint (oven bake it) on the hubs?

calj737 · « **Reply #85 on:** May 01, 2015, 11:40:55 AM »

I may be wrong, but your pattern does not look right, especially in the rear wheel. Perhaps it's the model/year that's different to me-

eddiebpool · « **Reply #86 on:** May 01, 2015, 11:50:23 AM »

I didn't. Should I have? They are a bit big to go in the oven now if so!

I read the VHT stuff will cure fully at room temperature fully over a 7 day period, though I'm sure you could apply heat to hurry that along. I don't need the wheels to be weather / road proof for a while yet so 7 days is no problem for me. If need be, I can hit it with a heat gun. The paint feel very hard after 24hrs. Some of the outer spokes were a very tight fit and I had to push then in, the ends catching the hub on the way through. I expected to do a bit of a touch up after, but there wasn't even a mark. This is tough paint!

calj737, I'm with you on the rear pattern. I read somewhere it is one less crossover on the stock wheels / spokes so has a different pattern from the front. My two wheels have the same pattern. I'm not sure if this is because they are after market, or maybe I have done it wrong. I can't see any other way to do it. I know lacing wheels is a bit of an art form, any "Lacing Guru" advice mush appreciated. I have them pretension now. I have built the forks, put brass bearings in the swing arm. Tomorrow I will put the forks and swing arm on and mount the wheels, see where they are on the true / wonky scale.

SOHC4 Cafe Racer Fan · « **Reply #87 on:** May 01, 2015, 11:58:53 AM »

I would not use a heat gun, at least not a direct blast. Curing the paint in an oven is optimal. The paint will be more resistant to chemicals and road chips. Since you now have laced wheels, that will be difficult. Other members have come up with a great option: Place the wheel in a box large enough to encompass it, make a hole in the box to run hot air from a heat gun and seal up the seams. You can also line the box with aluminum foil. An hour or so of the hot box should help harden the paint so it is more durable.

eddiebpool · « **Reply #88 on:** May 01, 2015, 12:06:55 PM »

That's a great tip. I really like thinking outside the box (so to speak), particularly a solution using the stuff around you to solve a problem. I'm the sort of guy who likes to come up with my own solutions to problems and hopefully one of my mad experiments helps someone else.

I will give that a go, much appreciated.

eddiebpool · « **Reply #89 on:** May 01, 2015, 01:06:10 PM »

I found an old pic - I took loads when I first got the bike as a reference. Two inners and two outers cross over to make a diamond pattern, which is what I have now both front and rear. It could be that it was wrong before and wrong again now.

It was interesting to see a before and after difference. There was no damage on the wheels though lots of crappy paint and oxidisation to contend with. The rims required a good rub down with a scotch brite green pad. I spent a plenty of time doing this until I got rid of all the oxidisation and had a good even matt finish. I then took it to the bench grinder - stitched cotton wheel with green compound, then loose wheel with green, then finally loose with blue. A once over with Mothers and they were done.

I did the spokes the same scotch brite then hit them with a sisal wheel and green compound. The oxidisation on the spokes was bad, hence the sisal to catch any pitting. A quick once over with a loose wheel finished it off. The sisal wheel did most of the work and the spokes looked good. Not sure if the final spin on the loose wheel was required but did it anyway.

The spoke nuts were the biggest problem. They are too small to be fiddling about with scotch pads so they went straight to the bench grinder. Sisal wheel and green compound, held at top and bottom in the teeth of old waterpump pliers (I chose those because the adjustable jaws and worn out teeth were just what I needed). I just needed to get a shine on them and remove the crud, and the sisal wheel and green compound did the job. They looked good, so no further polishing required. I think the nuts are not aluminium, they have a slightly yellow tinge to them. The oxidisation on them was green so I'm assuming something with copper in the mix.

Two solid days at it and happy with the result, and happy not to do it again for a very long time!

eddiebpool · « **Reply #90 on:** May 01, 2015, 02:05:37 PM »

Steering head bearing question ... I have tapered bearings from Pyramid Parts. They don't come with any washers and installation instructions doesn't mention using the original. Problem is, I can't find the original washer. Has anyone experience of Pyramid Parts tapered bearings, and if the washer should / shouldn't be installed? I know All Balls come with a couple of washers - 2mm and 4mm - which has me confused.

It sounds like a small thing, but my belief with caged bearings is to mess around with them as little as possible. They go on, do their job, and come off when they are worn out. If anyone has come across this before I would appreciate the heads up.

SOHC4 Cafe Racer Fan · « **Reply #91 on:** May 01, 2015, 02:17:40 PM »

I had a set from Pyramid. When I purchased a new set from All Balls for my next project, I decided to use the AB parts since the "kit" appeared more complete. Same concerns as yours.

eddiebpool · « **Reply #92 on:** May 02, 2015, 12:59:37 AM »

I think I will fit them as the manufacturer recommends, without the washer. It the clearance isn't right I will knock off the bearing and order a set of All Balls. I will report back on success / failure.

eddiebpool · « **Reply #93 on:** May 03, 2015, 01:22:53 PM »

Mixed day today.

The good news, it is finally starting to look like a motorcycle (almost). It has been a jumble of parts in bags and boxes for too long. I was delighted to throw a few parts together today so I could see how true my wheels are. I was very surprised to see the rear was barely 2mm out on first spin. Tiny bit of up and down so a bit of work to do on that one. I was concerned about that wheel in particular and not as bad as a feared. The front had a definite wobble though it was only side to side, no up and down movement at all so should be a straightforward job. Plan for tomorrow is to true the wheels and get some tyres on, main stand, and it will really start to look like something destined for the road.

The bad, I had a "bearing nightmare" today. I have been accustomed to smaller bikes and my bearing driver set didn't have anything big enough. I managed to get two of the three rear on with the 3 / 6 / 9 / 12 tapping with a punch. I made a mess of the third when accidentally hit the rubber seal and split it. That's a new bearing and a better set of bearing drivers on order.

I had a bit of fun (not) with the Pyramid Parts Tapered Steering Bearings. I was not sure if they needed a spacer, as posted previously. Pyramid Parts instructions say not and I was concerned about this. I couldn't find the original washer. As it turned out, it needs a good couple of mm spacer to give enough clearance. The lower bearing was very tight, far too tight. I realised if I put the bearing all the way down, and it was wrong, I was never getting it back off. I didn't want to risk it and decided to reverse course. The lower bearing was destroyed in the process. Pyramid Parts, your steering head kit is incomplete and your bearings stink! All Balls will be ordered.

Some progress, some problems, but it wouldn't be fun without a bit of both.

SOHC4 Cafe Racer Fan · « **Reply #94 on:** May 03, 2015, 06:32:36 PM »

One of my good guesses!

eddiebpool · « **Reply #95 on:** May 06, 2015, 06:27:54 AM »

I should mention the failed experiments as well as the successful. I watched a youtube video where a chap used zip ties to squeeze the tyre beads together and put the tyre on in one go. I hate fitting motorbike tyres, it is a horrible job. I thought I this would be a short cut. It wasn't. Long story short, the recess is not deep enough or wide enough for both beads to squeeze into. The Avons I'm fitting are stiffer than the stock vintage tyres so don't have enough give in them to be forced over the rim. So, not a success. I wasted time and in the end had to put the tyres on old school - tyre irons, sweat and bad language!

The tyres are on and holding air. I am cleaning up the discs - stripping off the old black paint and generally making presentable. I am thinking I may not repaint the discs, leave them all stainless. I will see how they look stripped and decide. I want to restore the bike to original but I am not a slave to it if small details like that look better to my eye. For example, I'm going K&N dual filters (two carbs into each) which will look very different from the stock air box, but will be a significant upgrade (I hope) and will look smart too. I can always add paint in the future if I feel it is needed.

Lots more jobs to do. The brake calipers are rebuilt but I haven't done the master cylinders yet - that's next. I still have to paint the crank case halves - clean, paint and hone the cylinders (jugs) - decide which cylinder head I am using (I have 3) and do the necessary on that too - and polish my cylinder head cover. I have crank case and conrod bearings on order so once those arrive I'm ready for the rebuild. I have separated all my parts into the correct "department".

I decided to replace as much of the electrics as possible. I have a new wiring loom - nothing wrong with the old one and everything seemed to work though 40yr old wiring and insulation can't be 100% trusted.

I'm sure there are a few twists and turns to come but I can see the end of the road now.

SOHC4 Cafe Racer Fan · « **Reply #96 on:** May 06, 2015, 08:35:34 AM »

You may want to resurface the rotor to remove the glaze and make sure you have a uniform flat surface.

eddiebpool · « **Reply #97 on:** May 06, 2015, 11:17:48 AM »

The rotors are surprisingly nice for their age. There appears to be very little wear. Only one score of any note on one side of one of the discs. I assume these discs don't wear like lesser metals because they are stainless steel? I have a 300cc scooter that is my daily runabout and it eats front discs for fun - I am lucky to get 8000mls out of one (and they ain't cheap). My plan was to give the discs a good scuff so they would quickly key with the pads.

I poked a hole my rear tube, only found out when I came back from a bit of shopping. Just a wee hole, but enough to spoil the party. Anyone any thoughts on puncture repair vs replace tube? I assume always new tube is better, though this is a new tube and only my unsuitable cheap and nasty tyre lever spoiled it. It is a shame to throw out a tube with no miles on it.

calj737 · « **Reply #98 on:** May 06, 2015, 11:32:10 AM »

Patch it and ride!

eddiebpool · « **Reply #99 on:** May 06, 2015, 11:37:43 AM »

Short and sweet advise, that'll do for me!

News:

Author Topic: CB750 F1 Restoration Project - not for the faint hearted (Read 26168 times)