New project CB750F1

[Loki]

Top overhaul next, stripped head barrels and pistons and now assessment time, the cam chain tensioner looks bad, the top wheel not the bottom, so new one on the shopping list, guide strip is fine.
Pistons and rings cleaned up nicely, all rings free in their grooves and spring out nicely so will leave them alone.
Now the bad bit, bike was stood in a damp shed for several years and some moisture must have sat in the head for some time as the port is corroded next to one of the valve seats so will need to recut to recover the seat width, hopefully a friend of a friend has cutters I can borrow.
Bores are all good but I'll give them a light hone to deglaze and get the crosshatching back.
Valve gear all good, no problems with camshaft, rocker arms, etc.

 

[Loki]

Here's a photo of the offending seat :- (

 

[dirtdigger]

If you dont put new rings in I guarantee you will burn oil. It is and has been general practice forever that if rings are removed from bore you should replace rings and do a deglaze/hone if the bores are round and straight. If you check ring end gap they are more than likely worn past limit anyway. I NEVER reuse rings. This is the main component in having healthy compression so why skimp?

If the timing tensioner wheels are bad then the flat guide is bad, the material will start breaking off. Need new tensioner and both wheels. Honestly if they are that bad I would pull the case apart and change timing chain and primary chains along with the more than likely bad primary chain tensioner....its the same material as the timing chain wheels. Timing chain is one of the main weak parts in there. Check valve guides as the exhaust tend to wear fast.

 

[Loki]

Having worked on all sorts of engines from 50cc mopeds right up to marine slow speed engines of 1500mm bore I have reused piston rings on countless engines and never had any issues except when they've been trapped in the grooves and blow by has removed their spriginess.
As stated I will be honing the bores which also helps the rings to bed back in after being removed from the bores, I'm already in much deeper than I intended with this bike and I'm sick of tripping over the engine on the garage floor so top overhaul it is.
The flat guide has no wear at all and the lower wheel is similarly unworn, I suspect this engine has been down before and a replacement tensioner fitted instead of a genuine Honda one which is what I will be fitting.
The knackered valve seat was a heartbreaker, I'm taking it to my local shop to see if it can be recovered with just cutting but suspect it will need a new seat to get it serviceable so yet more expense that I can't avoid.
Any further expenditure will be in the absolutely neccessary category with no more nice to haves!
Please don't be offended I'm sure your advice was given in good faith but my accountant is breathing down my kneck every time anothr parcel arrives at the door :-(

Loki

 

[Old_Crow]

Any further expenditure will be in the absolutely neccessary category with no more nice to haves!
Please don't be offended I'm sure your advice was given in good faith but my accountant is breathing down my kneck every time anothr parcel arrives at the door :-(

Loki

Have 'em shipped to your work address. Used to work for me. My wife never did find out how much I spent (and it was a pile, I'll tell you) on that old Shovehead I used to have.

 

[Loki]

Have 'em shipped to your work address. Used to work for me. My wife never did find out how much I spent (and it was a pile, I'll tell you) on that old Shovehead I used to have.

When I was working I did that quite a lot but in retirement it's no longer an option, plus of course disposable income is not the same so have to watch the pennies!

Loki

 

[Loki]

Got my latest parts delivery today from David Silver so I can get started on the build of the engine, I'm going to my local machine shop tomorrow to see if they can help with the valve seat, the more I look at it the more I think it will need a new seat insert so more expense.
I've decided to postpone the fork repairs and just make do with a clean up and see how the new seals hold up.

Loki

 

[hinksy]

Loki , have you looked on e-bay for front forks ? I look at other countries on there and there are quite a few sets for sale in the UK

 

[Loki]

I did look as part of my research but all I found were worse than mine or stupid money. I’ll keep looking but they are like hens teeth.

Loki

 

[Loki]

Good news and bad news at the machine shop, Bruno who did all their engine machining was in for his last day so I'll have to find another machine shop for any future jobs, good news was as he was retiring he gave me a freeby! Managed to get a good seat without going too deep so just a lap needed and I can start to put something back together instead of pulling yet more stuff apart.

Loki

 

[Loki]

Just had a look and only one single correct NOS in Germany £300 shipped to UK all others I found are the wrong length even though they say for 76/77 F1, I wish these sellers would get their act together and describe the parts correctly!

Loki

 

[Loki]

Spent today putting my engine back together, took my time and head bolted down, valve gear next then it'll be time to finally get it back in the frame.
Latest on the forks I have a firm to do the refurb at a good price and a reasonable turn around, will keep you posted.

Loki

 

[Loki]

Forks arrived this morning at the works so that's the first step in the process.
Engine assembly completed and valve clearances set with my shiny new feeler gauges after I discovered that my set of 9 was now a set of 6 and the ones I needed were among the missing ones!
Hauled the frame out into the sunshine and fitted the new taper roller headstock bearings and the top and bottom fork yokes then I flipped it over and fitted the centre stand.

 

[hinksy]

Loki , are you going to drop the frame over the motor or do the jig thru from the side ?

 

[Loki]

Hi m8 I lifted the frame off the motor and discovered what had to be removed to make it easier so will go that way I think, I’ve already removed all the exhaust studs so with the oil filter off I’m hoping it will drop on without too much drama, I have some foam packing to tape around the frame to protect the nice new paint.

Loki

 

[Loki]

Nice silver engine back in the frame, lifting the frame over the engine on its side worked a treat, took about five minutes to get the frame in position and start bolting up with the help of chief accountant!
Just for the help of others if you remove the following items it's a piece of cake, as above exhaust studs, oil filter and the one I forgot the breather housing cover and the foam packing round the frame worked a treat, no damage to the paintwork at all.
Next step the wiring then I'll find out if my repairs to the harness have been sussessful.
Hoping the refurbished fork legs will come back soon so I can get the wheels on.

Loki

 

[Loki]

Didn't get much done today as it was pretty cold, made and fitted 2 new battery cables and fitted the front part of the rear mudshield, attached the battery earth to the gear case to give the best chance for all the amps to get to the starter motor.
I have 2 mystery wires sticking out of the main harness near the coils, a blue and a yellow which I had labelled coils but now see that is incorrect as the blue and yellow for the coils comes from the points! Only other blue I can find is to the headlight but can't find another yellow anywhere, any suggestions?

Loki

 

[hinksy]

Blue and yellow normally are for the coils and go thru the harness from around the battery up to the coils and frame earth . Blue is for 1-4 and yellow is 2-3 , maybe your harness has been modified and has a rewire direct to the coils

 

[Loki]

That's what I thought but then where would the points fit in? Positive to coils is the black/white lead then the points make and break to earth(negative) to switch the coils on and off to make the spark.

Loki

 

[hinksy]

Mine come from the points and go into the harness at the rear brake switch , then onto the coils