Author Topic: CB750 F1 Restoration Project - not for the faint hearted  (Read 26167 times)

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Offline Bee Joenz

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Re: CB750 F1 Restoration Project - not for the faint hearted
« Reply #100 on: May 06, 2015, 01:19:26 PM »
Hey Eddie - can I ask how much you're into this project by now... first time builder as well and looking at probably at least what you're doing and then sum

Offline eddiebpool

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Re: CB750 F1 Restoration Project - not for the faint hearted
« Reply #101 on: May 06, 2015, 03:01:51 PM »
Hi Bee

Do you mean money or time? 

In terms of time - I bought the bike almost a year to the day planning on getting the bike on the road last summer.  I spent far too much time messing around and not making decisions, the biggest one on whether to split the engine cases and do the full works.  In the end, I did.  I wish I had made that decision immediately.  With the benefit of hindsight, I would recommend just tearing everything down and doing it right.  Do it right, do it once.  I should have the bike on the road by end of June.  That's the plan.

In terms of costs - I would assume a shopping list to get started including:

Primary chains and tensioner
Crank case and conrod bearings (you won't know immediately what colour codes you need by you need 10 crank case and 8 conrod - the colours are irrelevant to price).  There is plenty of good advice on this site on bearings and wear - and get familiar with plastigauge.
Hondabond or equivalent (I have Three Bond)
4x Rings kits
Cam Chain replacement kit (chain, tensioner, guide, etc)
Seal kit
Gasket set (if it doesn't include O'rings and oil seals you will need to get those too)

Do the engine right and you can can make decisions on everything else - use, restore or replace.  For example, my front shocks were usable as they were but I made the decision to replace the tubes, install progressive springs, and keep the original lowers and polish them, new seals and new copper washers of course.  Depends what you want to do.  I would heartily recommend rebuilding brake calipers and master cylinders, even if they appear to work.  If you don't know the history, do the work.  And don't cheap out on the frame - get everything that is supposed to be shiny and black powder coated.  I toyed with the idea of painting myself (more time wasted on that).  Glad I didn't.  Get the engine and frame parts perfect - spend what you need to spend and don't cut corners - the remainder you can make a decision on.  I made the assumption that the electrics could fail at any time so are to be replaced, but that's a personal thing (I have had too many bikes with moody electrics in the past).  I assume all rubber parts are perished or close to perishing so need replaced too.

If you don't already have one, invest in a good quality bench grinder.  Set yourself up with mops and compounds for stainless steel and aluminium.  There are loads of great youtube videos on polishing metals and I spent many hours absorbing information and experimenting with the grinder.  I will do all my aluminium parts myself and there are plenty of steel fixings been done and still to do too.  I have experimented with lots of different paints and the best I have found in VHT engine enamel.  It comes in lots of colours and, if you follow instructions, gives great results out a can.  If you are tearing down the engine then it is worth giving it some fresh paint (if it needs it).  Some parts might be too far gone to polish so a good paint job is essential.  You might try a bit of both - I have attached a pic I posted recently where I polished the outside of my front hub but the inner part was too far gone and got painted instead.  It actually looks very good and I'm glad I did it that way.

There are lots of costs you don't really expect - specialist tools for example.  Honda like their bearing retainer rings and my F1 has three different types, each requiring a specialist tool.  I was lucky to get all three for £33 (about $50).  If you don't have a well stocked garage, expect to pick up tools as you go.

I love that people on this site pick bikes up for under $500 but in the UK I think SOHC4 bikes are much less common.  Finding something worth restoring under £1000 ($1500) is difficult.  I paid the bottom of the scale at £900 for mine.  I think the finished project total will be £2700 with purchase price, parts, powder coating, tools, paint, polishing, sanding and sundries.  I am not that far off that now and I still haven't decided if I am to paint the tank myself or get it done professionally.  I want the work to be of a very high standard.  Going back to what I was saying and making a decision early on tearing the bike down.  There are things you might compromise on, there are things you definitely shouldn't.  One compromise I am happy to make is standard nuts and bolts.  An old Honda will have loads of M6 nuts, washers and bolts in the 12 / 16 / 20 / 25mm range.  I got a pile of stainless steel M6 nuts bolts and washers for not much money.  Throw in some stainless M8 and M10 nuts (hex and flange), washer and spring washers too.  They will last better than the original Honda stuff and for a fraction of the price.  And you will have plenty left over for the next project.  I decided to replace all the bolts on the top of the crank case, the ones that show, but decided to clean and polish the ones underneath.  Standard replacement stuff and getting full use of your bench grinder can save a fortune on fixings.  If you are lucky to live in part of the world where rust is not a problem then you can ignore all that.  In the UK, Scotland in particular, it is a problem.

My CB750 had not moved for 26yrs but was a low mileage bike when it was put into storage.  The engine was free and there were nice bonus items such as aluminium rims and spokes that could be restored, and an aftermarket Motad exhaust that was in very good condition.  Brakes were shot, carbs gummed and tank full of varnish.  However, once the carbs were cleaned, oil changed, points set, she fired right up.  I think I was lucky.  I thought at that point it was going to be easy.  Whatever you think it might take in time and money - it will be more.  If there is anything on the shopping list above you want to remove, you better have a damn good reason.  If you are lucky enough to have bought a bike of known history then you might get away with doing certain jobs.

I don't know if you wanted all that but that's my 2c worth.  Tear it down, do the engine right, do the frame parts right, rebuilt the brakes for safety, replace bushings and bearings on wheels / steering / swing arm, replace everything rubber, buy a bench grinder and learn how to use it.  It is easy enough to price all this up, and anything else that is obviously needing done on your particular machine.   You can then add in a healthy contingency fund for all the stuff you haven't thought of.  Hope that helps!  ;D
« Last Edit: May 06, 2015, 04:03:50 PM by eddiebpool »

Offline SOHC4 Cafe Racer Fan

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Re: CB750 F1 Restoration Project - not for the faint hearted
« Reply #102 on: May 06, 2015, 08:28:01 PM »
If it's brand new, I'd give a patch a try.
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Offline eddiebpool

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Re: CB750 F1 Restoration Project - not for the faint hearted
« Reply #103 on: May 07, 2015, 10:37:44 AM »
Bought a new tube, seems tubes are easy to come by though no-one wants to sell you a repair kit.  I will order one online and patch the other tube as a spare.  New tube fitted, job done this time (I hope).

Quick query on tyre pressures.  I have fitted Avon Roadriders front and rear and am looking for the best tyre pressure.  There is so much information - fronts ranging from 28 psi to 40 for example.  I plan to be cruising around at relaxed, mostly highway speeds and some twisty turns around Loch Lomond.  I'm 300lb so need to factor in my larger frame.  Any ideas?  I was going to try 30 front and 35 rear though just pulled those numbers out the air.

Offline eddiebpool

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Re: CB750 F1 Restoration Project - not for the faint hearted
« Reply #104 on: May 10, 2015, 12:47:47 PM »
Doing the final preparations for my last engine parts arriving.  That's one half of the crank cases painted, the top half next.  I really like the "hot box" idea suggested and I'm going to treat each case half to their own private sauna.  I appreciate the paint could be baked "in running" though I want the paint 100% during the rebuild, not just after.

I experimented with various cleaning methods and found a hobby tool mini wire brush the most effective, the little paint brush style.  There was a fair amount of oxidisation under the horrible paint the engine had on it.  Once I had it looking the way I wanted, I vacuum cleaned thoroughly, then a couple of wiped downs with acetone to ensure a clean surface.  VHT Engine Enamel again - I love that stuff.  I have already done the sump pan and oil filter housing so know it will look good.  You have to be very clumsy to get runs.  Just follow the instructions on the can and you can't go wrong.

I have set myself a challenge to finish the project in 6wks.  Hopefully I will get there, one job at a time.  :D

Offline eddiebpool

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Re: CB750 F1 Restoration Project - not for the faint hearted
« Reply #105 on: May 16, 2015, 12:05:48 PM »
I finally got the All Ball steering head bearings and they are fitted.  It is a much better kit than Pyramid and worth spending the little extra on.  A few other wee jobs getting done.  I have dismantled my seat.  The seat pan is rotten so a new seat is required.  I had a feeling that might be the case and it was in the budget anyway. 

I have attached a couple of pics of my foot pegs.  I had the metal parts powdercoated and ordered in all the little metal bits that were rusted.  The new rubber arrived in the same package as the All Balls so did that little job too.  I'm very pleased with them.  If I approach every job with attention to details then the overall finish will be what I want. 

More work to be done this weekend ... lots of jobs.

Offline eddiebpool

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Re: CB750 F1 Restoration Project - not for the faint hearted
« Reply #106 on: May 25, 2015, 02:17:34 PM »
Finally got round to the 2nd half of the crank cases today.  I love the VHT paint, goes on lovely and looks great.  Very impressed.  My last parts order should be with me tomorrow and the engine rebuilt will begin next weekend.  Same as last time, most of the time spent was in prep.  I got all the old crappy paint off with my favourite stripper, parts cleaner and acetone to clean it up, 320 grit sand paper and green scotch brite pad did most of the work getting rid of the old grime  and oxidisation under the paint, couple of washes with acetone, then ready for paint.  It is worth it to spend the time.  The painting was easy after all that.

I will be watching videos and reading up this week in preparation for the build.  I have never build an engine from the ground up so want to be sure I don't mess up.  Any tips much appreciated.  :)

Offline eddiebpool

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Re: CB750 F1 Restoration Project - not for the faint hearted
« Reply #107 on: May 30, 2015, 11:52:44 AM »
A few pics of the rolling chassis.  I got some cheap rear shocks which will do until I make a decision on something else.  I like the classic Hagons though haven't decided yet.  Any suggestions appreciated.

So far so good, the parts that are done are looking good.  The engine is next and I'm looking forward to getting it done!

Offline HondaMan

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Re: CB750 F1 Restoration Project - not for the faint hearted
« Reply #108 on: June 06, 2015, 07:01:53 PM »
Finally got round to the 2nd half of the crank cases today.  I love the VHT paint, goes on lovely and looks great.  Very impressed.  My last parts order should be with me tomorrow and the engine rebuilt will begin next weekend.  Same as last time, most of the time spent was in prep.  I got all the old crappy paint off with my favourite stripper, parts cleaner and acetone to clean it up, 320 grit sand paper and green scotch brite pad did most of the work getting rid of the old grime  and oxidisation under the paint, couple of washes with acetone, then ready for paint.  It is worth it to spend the time.  The painting was easy after all that.

I will be watching videos and reading up this week in preparation for the build.  I have never build an engine from the ground up so want to be sure I don't mess up.  Any tips much appreciated.  :)

Wow, those look great!
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Offline eddiebpool

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Re: CB750 F1 Restoration Project - not for the faint hearted
« Reply #109 on: June 09, 2015, 01:56:04 PM »
Thanks Hondaman, much appreciated.  One wee tip I forgot to mention.  The VHT instructions mention 2x light coats followed by 1x medium.  To get the finish I got I did a very light dust coat from a fresh can at the end.  It really makes a difference.  Simply hold the can a little further away and spray like you are doing a tack coat.  It helps to give the cast aluminium look (if that is what you want).

Offline eddiebpool

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Re: CB750 F1 Restoration Project - not for the faint hearted
« Reply #110 on: August 23, 2015, 01:50:28 PM »
I haven't posted for a while though I have been busy.  The engine is finally complete (almost).  I still have to do the clutch but that's next on the list.  I decided to paint the valve cover instead of polish.  I'm going to pick up some new tappet covers and polish them, that'll be enough bling for the top.  I couldn't find my old tappet covers.  I may have thrown them away because I remember them being beat up and ugly.  The points cover in the pic is the old one, I put that on because I'll be dropping the engine on that side. (no sense marking up a new shiny one). 

It went together surprisingly well.  The chap that does Hackaweek is a visitor to this site and I wanted his videos more than a few times.  It took several weekends and I really took my time.  Just a few issues

-  I ordered the wrong piston rings.  I didn't realise the F1 had two different pistons.  Mine are the later ones, which I think are the same as the K7.  I'm just the wrong side of the line.  Lesson learned.

-  A couple of the bolts that hold the cam towers to the cylinder head torn their threads.  I pondered trying longer bolts but decided to helicoil instead.  Helicoil is cheap, easy, and definitely stronger than the original thread.  I alway build up my torque and they were all good to 7 ft lb but two tore at 9 ft lb.  After the helicoil and took them all to 8 and no more.

- As mentioned, I decided to paint rather than polish the valve cover.  I had two valve covers to choose from but neither were good enough to polish.  My polishing skills are pretty good but there are dings and deep scratches that will never polishing out.  The VHT cast aluminium paint has a fair bit of sparkle to it in the sunlight, and some polished bolts and polished tappet covers will hopefully complete the look.  I will try to source a good valve cover in the next couple of weeks.  If no luck, it is going in the frame as is. 

I have been doing lots of other little jobs and, once the engine is in the frame, it should all come together very quickly.  I'm thinking I'm 4wks away from completion.  My exhaust is solid but pitted.  I'm going to use it for the moment and maybe get a new one in the spring.  Some of my other chrome is not too hot too.  My thoughts are put the bike together so it is usable, then replace as I source suitable replacements.  More of an issue is my seat pan - rotten and falling apart!  I need to source a new one. 

I've still to do my master cylinder rebuilds.  Tank, side panels and cowl need painted too.  Still a few jobs, but the end is in sight!

Offline eddiebpool

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Re: CB750 F1 Restoration Project - End is in sight
« Reply #111 on: September 05, 2015, 01:11:55 PM »
Progress being made, finally got the engine in the frame and it should come together quickly now.  I still haven't done my master cylinder rebuilds but apart from that I'm ready to throw everything together.  My tank and seat need work but they will be the last to go on anyway.

Quick query for anyone with experience of rebuilding an F1 / F2 seat.  There are small rivet clips on the inside that hold the colour strips on.  The clips were destroyed in the removal (mostly rotten anyway) but I can't find them anywhere.  I am toying with the idea of getting a cheap tap and die set and putting a thread on the rivets.  It's not the maddest idea I ever had (at least, I don't think so).  I'm thinking there must be a suitably big headed screw out there that would work but can't find what I need.   Any suggestions would be much appreciate.

Offline eddiebpool

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Re: CB750 F1 Restoration Project - Bolt query
« Reply #112 on: September 05, 2015, 01:41:23 PM »
There is a 10mm bolt hole near the points cover that doesn't have a bolt in it and the diagrams online don't tell you what should be there.  I don't know how essential it is but I have a bolt the right length and I'm tempted to put it in with a nut and washer and torque it down.  I'm assuming it is go give extra support to the cases at that point.  Is it optional?  Any ideas?

One more thing, my bike is lovely and shiny but the the plastic parts (inner rear fender, tool box, air box, etc) are dull.  Has anyone any experience with polishing black plastic?  I'm handy with a bench grinder and buffing but I'm guessing my mops and compounds are doing to be too much for the job.  Any advice on how to get old black plastic looking new would be much appreciated.

Offline eddiebpool

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Re: CB750 F1 Restoration Project - not for the faint hearted
« Reply #113 on: March 24, 2016, 01:31:30 AM »
It has been a few moons since I have worked on the bike.  Life gets in the way, and Winter is cold in Scotland!  Anyway, Spring has arrived and the Easter holidays start tomorrow.

I've added a pic of the K&N filters on the engine.  I was worried they might look a bit "Cafe" but they really don't.  I think they look excellent and should, I hope, perform better than the stock airbox.  I've upgraded the jets to 115s to take account of the improved airflow.  115 was just a guess and I may have to make further tweaks.  I read the F1s were set up originally to run a little lean.  I'm looking for a nice healthy mix.  If anyone has any ideas on this that would be much appreciated.

The plan is to get the wiring in, test fire the ignition system, then all being well feed the old girl some fuel and see what happens.  Next week - fingers crossed.

Offline Jerry Rxman Griffin aka MuthaF'er

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Re: CB750 F1 Restoration Project - not for the faint hearted
« Reply #114 on: March 24, 2016, 08:59:52 AM »
Looking good! Keep at it.

Can you pass along the K & N filter part number?
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Offline eddiebpool

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Re: CB750 F1 Restoration Project - not for the faint hearted
« Reply #115 on: March 24, 2016, 09:28:06 AM »
Thanks Jerry

The Filters are K&N RC-2240.  They fit just right with about 1mm gap in between.  The trick to putting them on is a little bit of grease to help them along.  Squeeze / wriggle the filter on to the outside carb (1 or 4).  Once it is on, it should pop onto it's neighbour.  It does need the smear of grease though - too right otherwise and you might damage the filter if you force it too much.

I've read that pods are a pain to set up right.  My thinking is the 4 into 2 K&N offers a shared resource like the stock airbox (avoiding the single pod issues), but better airflow - and they look sweet too. 

I'll let you know how it runs. 

Offline eddiebpool

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Re: CB750 F1 Restoration Project - not for the faint hearted
« Reply #116 on: August 19, 2016, 06:51:46 AM »
I've not posted for a while though this summer I have been much more active.  I was slowed down considerably by getting an email from the people I bought the cam chain tensioner set from to say the rubber used was dodgy.  They were kind enough to refund the money but didn't send anyone round to do the engine rebuild for me!  I had to tear down and start again, but glad I did so.  I was able to check a couple of things that were on my mind at the same time so not a total waste of time.  So, the build started again and I finally got the old girl started today:


I forgot I hadn't picked a final route for the clutch cable (any suggestions much appreciated) and melted it on the exhaust!  I also realised I hadn't set the cam chain tensioner so that was one rattle I had to deal with.  Brakes need done front and rear.  Just picked up a mini honing tool to clean up the insides of the masters.  I'm hoping the rear will be easy.  The front is proving troublesome.  Two questions I hope people can help me with:

1)  Front brake caliper won't seal between the caliper and hard pipe.  The flare at the end becomes crooked and I can't work out why.  It looks fine inside.  The screw in part doesn't look like it is going in straight but the seems to follow the threads fine.  I'm not sure if I'm dealing with a cowboy repair from the past.  This is the original caliper body.  I have made up a few double flares (done it from cars in the past so know what I'm doing) and every one of them suffers the same fate.  Do I need a new caliper body?  Will that sort the issue?  I'm out of ideas and didn't want to buy a new body to find the same problem.

2)  I had to shorten the return throttle cable because it was around 3 inches too long.  The pull cable was fine for length.  These are after market cables and I heard it is normal for them to be iffy lengths.  The return doesn't seem to do much and the carbs open and close perfectly well without it.  I shortened it and added anyway.  Throttle seems to come on very quickly.  I barely get the handle moving and it is revving up, and just add a bit of pressure and it is starting to tickle up.  I don't remember my smaller bikes being so quick to rev.  Is this normal?  I'm hoping I've done such a lovely job that the carbs are dialled in sweet.  I'm more inclined to believed I made a mess somewhere.

It wasn't a difficult job to shorten the cable.  The hard part, believe it or not, was drilling the wee barrel part to accept the shortened cable.  I blunted two HSS drill bits and gave up on them.  A titanium bit soon got through it but not straight.  I had to then get the hobby tool with a diamond ball bit to clear a central path.  Bit of soldering, tidy it up with a file, and I was done.  There are some excellent Youtube videos that show you the principles.

I need to paint the tank and the cowl.  Side panels and tank flap are done for base coat but awaiting a clear coat to finish (did those with a rattle can).  I've ordered a new spray gun for the job.  My compressor is not big (2.5HP and 50L) so I've opted for an 1.3mm LVLP gun.  Never used one before so will do a bit of experimentation before doing the important stuff.  The bike was originally red but I'm going yellow, very 1970's!

Offline eddiebpool

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Re: CB750 F1 Restoration Project - not for the faint hearted
« Reply #117 on: August 20, 2016, 06:47:37 AM »
Rebuilt my rear brake master and very happy with the result, and saved money too.  Rear master cylinder kits are expensive.  The hardware was OK and it was only seals requiring changing.  I read somewhere that the seals in after market front master kits are the same.  Just so happens I had one of those!

I was going to rebuild my front master but my front had a deep score in the bore (caused by me trying to get a rusty piston out).  I took the path of least resistance and got a ready built master from David Silver.  It is an after market job, not exactly the same in appearance, but I popped an original cap on it and it looks good.

Preparation work for the rear master was having 600 grit wet and dry wrapped round a felt tip pen, followed by 900 grit, and 1200 grit to finish.  I took my time and made sure I covered all internal surfaces evenly.  Looked very clean when I finished.  There is a tiny hole, I think return hole, which was blocked.  I tried to get it with my smallest carb jet cleaner tool but even that was too thick.  I flooded it with brake cleaner and after a little fiddling around the puddle above started to drain.  Another few squirts and it was clear.  Gave the whole thing a good clean, and good to go.  The front master kit seals went in the rear master and the rebuild went smoothly.

One tip.  I took the full rear system off the bike to set it up.  I had the caliper raised in the vice, tilted to make sure the bleed nipple was the highest point in the system.  I was maybe being too fussy about the bleeding, but the other reason for doing this is there isn't much room to work when the master is on the bike.  Put it on the bike, one last bleed, and I have a very firm and reassuring rear brake pressure.

I will be keeping an eye on the rear to see if the seals hold up.  I don't see any reason that they won't though.  Very happy.  Still have the problem with the front caliper body and think I will have to bite the bullet and buy a new one.  I wish I knew this last week, I could have ordered from David Silver and saved another postage fee! 

Progress ... it goes, stops, and glows in the dark.  One step closer.  ;)

Offline 01Thomas

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Re: CB750 F1 Restoration Project - not for the faint hearted
« Reply #118 on: August 26, 2016, 10:11:41 AM »
Good Going, Eddie!
1971 Honda CB750 Four K1 [Engine: CB750E-1113521 / Frame: CB750-1113838]
1977 Seeley Honda CB750F (F1) [Engine: CB750E-2551214 / Frame No: SH7-655F]

'96 Yamaha YZF750SP & '81 Moto Guzzi SP1000 & '80 Moto Guzzi 850 LeMans II & '82 Bimota KB-3 [Frame No 49] & '66 Ducati 50 SL/1 & '53 Miele K-50 & '38 Miele 98

Offline eddiebpool

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Re: CB750 F1 Restoration Project - not for the faint hearted
« Reply #119 on: September 17, 2016, 11:26:50 AM »
I've mocked up the bike to get an idea of how it might look finished.  Tank and cowl obviously just primed at the moment.  I really like the primed look but I'm not going to leave it like that.  It has been 2yrs since the bike was torn down so could hardly remember how it looked.  I have a snagging list as long as my arm which I need to get through but I'm getting there.

The front brake was not firming up at all.  I read some excellent tips and tried a few things.  The one that worked was taking the caliper off and letting it hang down.  This stretches everthing into as vertical a run as possible.  I tapped all the pipes / hoses all the way from bottom up a few times over a number of days to release any trapped air.  I had heard that air can be trapped at the banjo bolts so moved them around while tapping to chase any bubbles out of those too.  It seems to have done the trick, almost.  The lever moves about 1 inch at the end before it bites, but when it does its solid.  I notice that the hoses move a bit under pressure which makes me think they are not the best.  I'm considering investing in some better hoses.

One problem, clutch is binding.  I can't get it to free up.  I've stripped it and rebuild to make sure I hadn't done anything stupid.  It all looks good.  I didn't replace any of the friction discs / plates or springs because the all measured within tolerances.  My bike was stored away for 26yrs so I'm thinking it might be an issue with the friction discs, but they measured well within spec.  Any ideas?

Lots of wee jobs to do so hopefully finished soon.