Honda-SOHC
SOHC.co.uk Forums => CB750 => Topic started by: david451 on July 04, 2011, 12:40:30 AM
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Bought two usa cbs, 750, 74 and 77 models they have the oil tanks with the cap on the outside.
What's the best way to get the engine out, lift it out or lift the frame off the engine on it's side.
The chain drive was a bit noisy so took off the chain and had a look at the front sprocket, it seems to be a bit loose on the shaft, it needs a new chain and sprocket set so perhaps the wear is in the sprocket?
Is it acceptable to spray and lacquer the frames or does it have to be powder coating, don't know much about these things in my day the frames got painted.
Anybody give me some ball park figures for chroming, say a wheel perhaps and perhaps my exhausts once I repair them, they seem to be about 1k to replace so that's most of my budget out the window, so it is going to have to be a repair.
Do I need to restore the painted areas on the engine or can I polish all the engine up, and if it's going to have to be painted again, that grey primer colour is there a special paint you get to prevent it flaking off with the heat or can I use normal paint with heat resistant lacquer.
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Hi there, and welcome, if you are going for a rebuild I would definately recommend taking lots of photos during the process, and storing parts in labelled ziploc bags. When you come to put it all back together it can be a pain trying to remember cable and tubing runs and a lot of the detail stuff.
For engine removal I took everything that I could off the bike and was left with a frame and an engine, the engine drops out of the frame side, though it would be easier to lay it on it's side and lift the frame off. I've not removed an engine that way only replaced one in it's nice shiny powdercoated frame.
I powered coated my frame as the powder coating process produces a tough long lasting finish, it's not as shiny or smooth as paint, so you pays your money and you takes your chances.
The front engine sprocket is a loose fit on the shaft due to the way it is retained.
Most chromers will not touch old exhausts as they mess up their bath, so rechroming is not usually an option.
For engine paint I used VHT aluminium paint, a lot of engines are bare aluminium but I would not recommend it on a UK bike, use the "search" funtion on the site to look at types of paint. There's a lot of info here.
Hope this helps
Cheers
Den
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Hi there, and welcome, if you are going for a rebuild I would definately recommend taking lots of photos during the process, and storing parts in labelled ziploc bags. When you come to put it all back together it can be a pain trying to remember cable and tubing runs and a lot of the detail stuff.
For engine removal I took everything that I could off the bike and was left with a frame and an engine, the engine drops out of the frame side, though it would be easier to lay it on it's side and lift the frame off. I've not removed an engine that way only replaced one in it's nice shiny powdercoated frame.
I powered coated my frame as the powder coating process produces a tough long lasting finish, it's not as shiny or smooth as paint, so you pays your money and you takes your chances.
The front engine sprocket is a loose fit on the shaft due to the way it is retained.
Most chromers will not touch old exhausts as they mess up their bath, so rechroming is not usually an option.
For engine paint I used VHT aluminium paint, a lot of engines are bare aluminium but I would not recommend it on a UK bike, use the "search" funtion on the site to look at types of paint. There's a lot of info here.
Hope this helps
Cheers
Den
The gearbox sounded a bit clattery, at 25k is there problems with them that's why I thought the sprocket was to blame, is there a check I can do. I was running it on the centre stand mind you and just comparing it to the other one which is not so noisy.
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Hi David the clattery sound you describe could be clutch noise which is common on these 750's usually at tickover if your carbs are out of balance they can sound like a bag of spanners :o usually opening the throttle slightly or pulling in the clutch can quieten things down some, i would imagine by the time you have given it a thorough tune up most of the noises will disappear ;), cheers Mick.
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As Mick says these bikes can sound terminally ill on tick over if not set up right, some sound terrible at tick over even when set up right !
Cheers
Den
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As Mick says these bikes can sound terminally ill on tick over if not set up right, some sound terrible at tick over even when set up right !
Cheers
Den
I was running the old girl through the gears on the centre stand, not a good idea but I can't run her on a road at the minute, no brakes is one of the reasons.
One of my bikes has two new tyres on it and it's a spitfire on the front, you making tyres on the side then.
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The gearboxes are really quite tough in my experience especially for a standard output motor but they can sound a bit jangly if the tickover is not as smooth as you can get it.
Oil in good condition is an absolute must to look after many aspects of smooth running and long life on these, many owners are not aware of just how much this pays off so if you are not confident of this it's one of the first things to do.
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Oh also forgot, check the Rear wheel cush drive as if you are running on the stand through the gears if this is worn/baggy the inertia of the rim will certainly help clatter the gearbox if not under constant load.
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The gearboxes are really quite tough in my experience especially for a standard output motor but they can sound a bit jangly if the tickover is not as smooth as you can get it.
Oil in good condition is an absolute must to look after many aspects of smooth running and long life on these, many owners are not aware of just how much this pays off so if you are not confident of this it's one of the first things to do.
Probably have to wait and see what happens on the road, hope the gearbox is ok, honda reliability.
Doing a bit of research and I recon mine are the K model, if its as simple as that then one would be a k4 because it's a 1974 model and the other a k7.
Would it be a sin to convert one to a cafe, I still have the bug in my bones from the 70s and need to complete this before I get too old to ride her.
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Oh also forgot, check the Rear wheel cush drive as if you are running on the stand through the gears if this is worn/baggy the inertia of the rim will certainly help clatter the gearbox if not under constant load.
Took the chain off to see if it got worse, probably needs to be under load on the road, might try it again tomorrow with the brake applied if I can get it working.
Found somebody to powder coat my frames 120 quid for each so gona go that route instead of painting them.
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I thought the K7 had the oil tank cap covered, and maybe had a 630 size chain and sprockets similar to F2.
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I thought the K7 had the oil tank cap covered, and maybe had a 630 size chain and sprockets similar to F2.
Both look the same other than the early one has the tank tap on the right.
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K7 also had 17inch rear wheel and is more related to F2 engine-wise with the later type carbs that have the lift mechanism enclosed unlike earlier models.
Seems as they are between K2 and K6 models from your description.
The oil tank filler was cover by the side panel from F1 through F2 and K7 so if original gives a clear distinction.
Fuel taps can differ from model to model and also have dual/single pipes running to the carbs depending on fitment. My K2 has a tap on the right, I would guess that the position on most bikes may have been more standardised to the left on later models as it's easier to switch to reserve and still be in control of the throttle.
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K7 also had 17inch rear wheel and is more related to F2 engine-wise with the later type carbs that have the lift mechanism enclosed unlike earlier models.
Seems as they are between K2 and K6 models from your description.
The oil tank filler was cover by the side panel from F1 through F2 and K7 so if original gives a clear distinction.
Fuel taps can differ from model to model and also have dual/single pipes running to the carbs depending on fitment. My K2 has a tap on the right, I would guess that the position on most bikes may have been more standardised to the left on later models as it's easier to switch to reserve and still be in control of the throttle.
The early one has a 18 and the later one a 17 as you say, both carburator lift mechanisms are external and the same
Both the oil caps are exposed, they look like the model that came after the sandcast ones, the side panels don't have the vents on them
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The 17inch wheel maybe a bit of a curve-ball and could have been retro-fitted to it.
They certainly sound like mid production series models from the details.
I guess if you "cafe" one of them you'll only be doing what others have and will only know how you feel about in years to come. It's quite personal how anyone has their bikes though so free choice really.
If you didn't get them they may not have been back running at all, and it can be done so that it's possible to return to original if the mods are all bolt together.
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The 17inch wheel maybe a bit of a curve-ball and could have been retro-fitted to it.
They certainly sound like mid production series models from the details.
I guess if you "cafe" one of them you'll only be doing what others have and will only know how you feel about in years to come. It's quite personal how anyone has their bikes though so free choice really.
If you didn't get them they may not have been back running at all, and it can be done so that it's possible to return to original if the mods are all bolt together.
One of the reasons I might cafe one is that the exhausts are holed, it has a king and queen seat and high rise bars. I thought if I am changing all these bits then I'm half way to cafe. At 1k for a set of exhausts thats a lot of my budget gone for a rebuild.
Don't get me wrong here if it's getting a cafe makeover then it will be done properly, a bit special and being a retired mechanic will take the time to get it right. But it wont be a bolt together job it will need attacked with an angle grinder to get a few ugly bits off. Thats if I go that route of course.
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The 77K DID NOT have a hidden oil filer cap, only the "F" did, so I think you have a 77 "K" which were not common in the UK, did not sell very well and are a nightmare to get original parts for as some bits are different so if it was me thats the cafe one!!
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The 77K DID NOT have a hidden oil filer cap, only the "F" did, so I think you have a 77 "K" which were not common in the UK, did not sell very well and are a nightmare to get original parts for as some bits are different so if it was me thats the cafe one!!
That's strange hearing that because looking at the 74 and the 77 they both look identical other than one has the fuel tap on the left when the other the right. I am going to rob parts from the 77 to make the 74 complete to start off and then look at what fate the 77 is going to be dealt.
I spoke with a chap who deals in the states and he says that following the cafe program that there has been an explosion in cafe racers, and that it should head this way at some point.
In terms of resale value they might be worth more in the cafe than restored to original, but I am in no hurry to do them since they are not losing money sitting in the garage.
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they have been making cafe racers out of these old Hondas and the like for the last 5 years or more to my knowledge
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Mick, I think you missed a number out, shouldn't it be 35 years!
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Mick, I think you missed a number out, shouldn't it be 35 years!
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I thought it was going to take me 35 years to get the engine out, everything off and just a frame laying on its side and it still refused to come out, mr Honda never left much room for that job the swine. But it's out now and the project begins.
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The engines are awkward buggers to get in and out of the frame, i found that having the sump off exhaust studs off and all the casings made the job a bit easier, but now i have done a frame mod so i can dismantle the top end in the frame, this is probably one of the best mods you can do on these 750's , it makes working on the engine a real pleasure , and being able to disasemble the engine's top end also lightens the load to make engine removal a doddle
Pete
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The engines are awkward buggers to get in and out of the frame, i found that having the sump off exhaust studs off and all the casings made the job a bit easier, but now i have done a frame mod so i can dismantle the top end in the frame, this is probably one of the best mods you can do on these 750's , it makes working on the engine a real pleasure , and being able to disasemble the engine's top end also lightens the load to make engine removal a doddle
Pete
I tried to get the cam cover off, it would have made such a difference to getting the engine out but it was not to be as you say, it didn't help having my wife on the other end of the frame mind you, having to direct her and watch she didn't get her fingers jammed at the same time is pure hell, worse than her map reading to be honest. :o
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From memory I think that when you've removed the housing on top of the cam cover you have to rotate the front of the engine upwards until it virtually touches the top frame tubes, this allows the back of the gearbox to pass the frame mounts next to the kick start as they are both nearly the same shape.
Once you get the correct move on it you'l find it easier than it first looks.
The Cafe stuff you are thinking about, Honda has some really cool stuff that could give you an influence from the racers of that era. Just google CR750 and flick it to images to see some of the designs/colours/stance that was running then.
I guess traditional brit cafe racers just ripped off the racers of their day with long alloy tanks, single seats and dropped bars from track stuff all black and silver/bare metal so it would seem right to go the same way with Honda's own heritage.
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From memory I think that when you've removed the housing on top of the cam cover you have to rotate the front of the engine upwards until it virtually touches the top frame tubes, this allows the back of the gearbox to pass the frame mounts next to the kick start as they are both nearly the same shape.
Once you get the correct move on it you'l find it easier than it first looks.
The Cafe stuff you are thinking about, Honda has some really cool stuff that could give you an influence from the racers of that era. Just google CR750 and flick it to images to see some of the designs/colours/stance that was running then.
I guess traditional brit cafe racers just ripped off the racers of their day with long alloy tanks, single seats and dropped bars from track stuff all black and silver/bare metal so it would seem right to go the same way with Honda's own heritage.
I love your style, you an old bastid from the 70s as well??
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Been to bike racing since I was born with family and friends doing bits of racing, so completely indoctrinated I guess.
Ran 750 SOHC Hondas in late 70's, CB900 and CBX 750 in the eighties, We really smoked these things around then and they treat them so gently now.
Funny enough I had a conversation today with someone that was happy to persuade her son-inlaw to give up bikes and sat there thinking I've never thought of being without a bike, ever.
Guess it keeps me out of trouble!
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Been to bike racing since I was born with family and friends doing bits of racing, so completely indoctrinated I guess.
Ran 750 SOHC Hondas in late 70's, CB900 and CBX 750 in the eighties, We really smoked these things around then and they treat them so gently now.
Funny enough I had a conversation today with someone that was happy to persuade her son-inlaw to give up bikes and sat there thinking I've never thought of being without a bike, ever.
Guess it keeps me out of trouble!
Ok here's a tough question for you then, two really and I know that you will have the right answers.
Is a cafe racer worth more than a standard bike, a cr750 even nicer
Can you point me in the direction of where I can get a long tank, seat etc for a cafe, perhaps even a twin disc conversion would be nice. I am guessing that there must be somebody out there with the parts for these.
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When i was in the trade a "cafe" was worth less than standard as everybodies taste is different, Parts are always out there, just some of it is expensive!
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When i was in the trade a "cafe" was worth less than standard as everybodies taste is different, Parts are always out there, just some of it is expensive!
I was looking at some of the parts and you are correct, and cafe and cr style are nice but probably to the minority as you say much the same I guess in relation to what some folk do with cars. But more importantly as with cars you never get the money back you threw at it so it might be the same for bikes and once you get into the 5-8k bracket there are so many alternative modern bikes out there for that kind of money and it's the sensable side of me that's fighting with the red blooded side.
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Take a look at Carpy's website and see what he does with these old bikes may not be your cup of tea but just gives you an idea.
www.cb750cafe.com (http://www.cb750cafe.com)
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It seems that CR stuff is more US based suppliers but you only really need a tank and seat to get the overall look right. Although various suppliers do some things that are advertised through Classic Racer in the UK.
Thought the K2 had fork legs to accept calipers both sides, making for an easy conversion with just another caliper and new pipes.
As you say you'd be off beam to sling loads of money at it without very good reason, but if it's what you want you'd have to judge the budget for your own means. If you just want a fast ride you're right in that there is so much modern suff that will do it better.
I guess what I'm trying to get at is that trying to make it a brit-style (i.e. Norton/Triumph/BSA) seems out of sorts for a Honda as valid racer history for that engine looks pretty good anyway. And some of those Candy colours zone it right into that era. Perhaps just a little bit of Daytona or California!!
Some of Carpy's stuff looks nice, I'm just not so struck on the more ornate examples and lean more to the function driven stuff as it has a style of it's own. If you geta look at a 4 or 8 leading shoe drum front brake from the sixties you'll get what I mean, it looks sooooo cool but it's not dressed up in any way just pure engineering magnificence (if that's a real word).
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It seems that CR stuff is more US based suppliers but you only really need a tank and seat to get the overall look right. Although various suppliers do some things that are advertised through Classic Racer in the UK.
Thought the K2 had fork legs to accept calipers both sides, making for an easy conversion with just another caliper and new pipes.
As you say you'd be off beam to sling loads of money at it without very good reason, but if it's what you want you'd have to judge the budget for your own means. If you just want a fast ride you're right in that there is so much modern suff that will do it better.
I guess what I'm trying to get at is that trying to make it a brit-style (i.e. Norton/Triumph/BSA) seems out of sorts for a Honda as valid racer history for that engine looks pretty good anyway. And some of those Candy colours zone it right into that era. Perhaps just a little bit of Daytona or California!!
Some of Carpy's stuff looks nice, I'm just not so struck on the more ornate examples and lean more to the function driven stuff as it has a style of it's own. If you geta look at a 4 or 8 leading shoe drum front brake from the sixties you'll get what I mean, it looks sooooo cool but it's not dressed up in any way just pure engineering magnificence (if that's a real word).
I have a blackbird for frightening the shit out of me, and I doubt there is much out there that would make much difference to how fast you want to go because I imagine that it ticks the boxes for most folk. I also have a cb1000 "big one" and it's hard work to ride, did 7 days touring on it and it raped me.
In terms of the cafe and cr stuff, to me it's just the simplicity of it all, a nice clean frame without all that other shit stuck on if you know what I mean. Soon nobody will know what a kickstart is or how to use it. I remember my mates dad kick starting his old bond car, lifting the bonnet, stuck his leg in and whoosh away it went, or my dad starting his commer cob with the starter handle. perhaps it's just old age eh, gone through the mid life crisis and now trying to relive my teen years before I become an old dobber.
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If you're planning on doing any work on the frame (delugging/powdercoating) I'd strongly suggest getting hold of a Gordon frame kit from one of the fellas on the US SOHC4 site. You chop out a section from the two supporting struts under the main spar under the tank and weld in threaded inserts that allow you to take the top off the engine whilst it's still in the frame.
For various reasons I've had to take the head off my K2 a few times in the recent past, and if I didn't have the kit fitted, what currently takes me an hour or so would have taken me days pulling the engine out and putting it back.