CB750 Barn find project - First Timer

[Bryanj]

The collar is the steel bit that the bushes pivot on mate NOTE:- NOT the bolt that goes through the inside of the collar ( I call it a pivot but Honda call it a collar)

[Underdog1]

The collar is the steel bit that the bushes pivot on mate NOTE:- NOT the bolt that goes through the inside of the collar ( I call it a pivot but Honda call it a collar)

Do you mean number 9 in this diagram?



Is there anything i should check for specifically to see if its worn beyond the point of reuse?

[Bryanj]

Yup, but I think you have to use the earlier (K1,2,3) one as the later one is NLA

[Underdog1]

Yup, but I think you have to use the earlier (K1,2,3) one as the later one is NLA

just checked mine over and it looks hardly worn at all so probably going to stick with it.

Looking forward to the future i intend on doing away with the tacho and just having a speedo, I've seen the speedo centre mounted before and it just looks a little..big.



I love the styling of these old speedos though and don't want to buy anything new. Does anyone know of any bikes similar looking speedos that are a bit smaller?

[mickwinf]

500 fours and 250/350 use smaller versions.

[Underdog1]

500 fours and 250/350 use smaller versions.

Perfect.

[Underdog1]

So being the tight arse that i am i made my own bearing retainer removal tool today



Worked pretty well.



Didn't get long to work with the bike, didn't manage to get either wheel bearing out, should they just slide out each side at this point or do i need to be pushing them through and out the other side? My haynes manual just states that at this point the bearing can be removed. Might be a case or trying to yank them out with a screwdriver i suppose.

The threads on the bearing retainer look mega delicate being very fine aluminium, is this something that is usually replaced when changing wheel bearings?

Current state:

[Chris400F]

500 fours and 250/350 use smaller versions.

Do they all have the same 'ratio'? I believe some tachos differ between models; I had a couple with different ratios printed on the back of the casings.
Note also that 250/350/360 twins and 350/400 fours have 18" front wheels while 500 and above have 19", may also affect your choice.

[Underdog1]

500 fours and 250/350 use smaller versions.

Do they all have the same 'ratio'? I believe some tachos differ between models; I had a couple with different ratios printed on the back of the casings.
Note also that 250/350/360 twins and 350/400 fours have 18" front wheels while 500 and above have 19", may also affect your choice.

Ok cool that's given me something to consider, although I doubt an inch difference in diameter is going to affect things massively as its only roughly 5% difference in running circumference. I'm sure these speedos are pretty inaccurate anyway #maths

[Underdog1]

Oooookay,

So a few bits arrived in the post today, my replacement ignition and remote tank which got me a little excited as finally i can see if this thing starts right?

So first thing i notice is in key position 1 i seem to have power, the neutral light comes on, if i press the horn i get a very weak sounding fart noise,no headlight and unfortunately I've already stripped off the brakes and rear light so can't check those right now. Key position 2 the neutral light goes out and the horn ceases to work so somethings going on there. The connectors that go into the ignition connector block short with each other mega easily but i made sure they weren't touching each other and still no luck. Electric start also didn't do anything.

Anyway i thought its worth trying to kick it anyway to see what happens, plumbed in my remote tank (credit to Jamesh_sussex for the link) and fuel just immediately pissed out of carb 1&2 from the areas circled. Haven't got my haynes manual to hand so apologies for the lack of technical terms (and knowledge hah).



is this likely to be stuck floats? Was hoping i could see if it would run first before rebuilding the carbs but looks like this is going to be my next job. Just want to hear the old gal growl 

[Rob.b (Rob Birkett - RIP)]

Oooookay,

So a few bits arrived in the post today, my replacement ignition and remote tank which got me a little excited as finally i can see if this thing starts right?

So first thing i notice is in key position 1 i seem to have power, the neutral light comes on, if i press the horn i get a very weak sounding fart noise,no headlight and unfortunately I've already stripped off the brakes and rear light so can't check those right now. Key position 2 the neutral light goes out and the horn ceases to work so somethings going on there. The connectors that go into the ignition connector block short with each other mega easily but i made sure they weren't touching each other and still no luck. Electric start also didn't do anything.

Anyway i thought its worth trying to kick it anyway to see what happens, plumbed in my remote tank (credit to Jamesh_sussex for the link) and fuel just immediately pissed out of carb 1&2 from the areas circled. Haven't got my haynes manual to hand so apologies for the lack of technical terms (and knowledge hah).

is this likely to be stuck floats? Was hoping i could see if it would run first before rebuilding the carbs but looks like this is going to be my next job. Just want to hear the old gal growl 

Hi,

I'm pretty sure position 2 on the ignition switch is the parking lights ie. the front pilot light and rear tail light only, and nothing else..

if so you should be able to take the key out when its in position 2.

keep at it.

[Underdog1]

Oooookay,

So a few bits arrived in the post today, my replacement ignition and remote tank which got me a little excited as finally i can see if this thing starts right?

So first thing i notice is in key position 1 i seem to have power, the neutral light comes on, if i press the horn i get a very weak sounding fart noise,no headlight and unfortunately I've already stripped off the brakes and rear light so can't check those right now. Key position 2 the neutral light goes out and the horn ceases to work so somethings going on there. The connectors that go into the ignition connector block short with each other mega easily but i made sure they weren't touching each other and still no luck. Electric start also didn't do anything.

Anyway i thought its worth trying to kick it anyway to see what happens, plumbed in my remote tank (credit to Jamesh_sussex for the link) and fuel just immediately pissed out of carb 1&2 from the areas circled. Haven't got my haynes manual to hand so apologies for the lack of technical terms (and knowledge hah).

is this likely to be stuck floats? Was hoping i could see if it would run first before rebuilding the carbs but looks like this is going to be my next job. Just want to hear the old gal growl 

Hi,

I'm pretty sure position 2 on the ignition switch is the parking lights ie. the front pilot light and rear tail light only, and nothing else..

if so you should be able to take the key out when its in position 2.

keep at it.

Yeah you're correctomundo, realised shortly after i posted 

Any idea how i get the bearing retainer off this side of the wheel hub?



Managed to get the other side off with a home made tool but not sure about this side..

[hairygit]

There isn't one on the wheel that side, just a thick oil/grease seal. Try levering it out with a tyre lever or large screwdriver, a little at a time on opposite edges at a time. Try not to gouge the alloy of the hub as you do it. Or you can use the bearing to remove it by knocking it through from the other side.

[MarkCR750]

Yes stuck floats, take the carbs off, take the float and float needle valve and jets out of carb no1 , the primary jet is pressed in, gently pull out with pliers, thoroughly blast out the passage ways and components with good quality carb cleaner, check the float needle seats for damage, check the black rubber tips on the float needles aren't worn, replace and do the same on the other 3 carbs, or send the carb bank off the NRP to have them ultrasonically cleaned and any worn components replaced, I did my own and they are fine but it's always down to personal choice and pocket.

http://nrp-carbs.co.uk/

[Underdog1]

There isn't one on the wheel that side, just a thick oil/grease seal. Try levering it out with a tyre lever or large screwdriver, a little at a time on opposite edges at a time. Try not to gouge the alloy of the hub as you do it. Or you can use the bearing to remove it by knocking it through from the other side.

Are you sure about that? I think its no. 4 on this picture in my haynes manual: