Topic: Period sohc Pro Stock project .

[Greg H]

I've managed to get a couple of things sorted out for the bike recently . I mentioned in a previous post that I'd had to raise the front of the fuel tank because I felt the need to fit a better fuel tank breather to the fuel cap under the dummy tank .Doing this required welding on another couple of short tubes which would allow me to use a pair of stock rubber mounts .
After a lot of searching I did manage to find a suitably compact breather made by Mocal , which is a nice albeit costly little piece  .
I managed to pick up a complete unused DYNOMAN 71.25 mm (1000) kit off someone off here for the right money, which has now been married up to my F1 block .
I've decided on reflection to go with the 1000 set up ,and relatively low comp/ratio of 10.25 in deference to the fact that I'm failing to see the sense in building an all out sohc motor in 2015 . I reckon that with the right head work , and with the right bottom end bits fitted I can end up with a potent ,yet reliable motor .




 
 
 
 

[Greg H]

Done a few things lately on the motor .
I spent ages cleaning out all the oil galleries , firstly I submerged the c/cases in hot soapy water and got stuck in with the brushes . Secondly I took them to work and gave them a good blast through with the pressure washer . Thirdly I used a combination of my own Karcher to blast through the galleries again ,the brushes again, petrol and airpressure to be finally be satisfied that I'd done all that I could do.
Thats definately the last time I ever have c/cases vapour blasted .

Some pics to show where we're at . 

[Greg H]

p.s . I've cleaned out the sludge traps on the crank by removing the balls and replacing them with M6 grubscrews . I'll be getting the crank re-balanced in the next few days .
I've also got a bunch of bottom end stuff coming over from cycle X .
I've painted the c/cases and cylinder block black so that they are  ready for when I start building up the bottom end .

[hotdog]

Looking good...

[BPellerine]

wow greg,it must feel good to have some thing going together!I cleaned my cases by hand because I did not trust myself to get all the media out,not as pretty but paint up ok..bill

[Greg H]

Yeh, things are moving on at a nice pace now  .
At one point I was starting to get a little frustrated with my slow progress with the motor, but I'm now getting real enjoyment out of getting it done at a pace which suits my lifestyle .
Like most on here ,I've got plenty going on just living a normal life , so doing this sort of thing is a hobby .
It's not the be all and end all , like it was back in the day 
Going back to what I previously said about not ever getting things vapour blasting again , yeh , the finish is superb , but the paranoia that I experienced  during the whole process of ensuring everything was surgicaly clean , I can do without  .
I suppose we'll only know if I've done a good enough job when it comes time to fire her up  .
Spec wise , I'm altering a couple of things I'd planned on doing to the motor  .Firstly, seeing as it is supposed to be a replica of the very first incarnation of a sohc 750 P/Stock bike ,ie basically a hotted up road bike . I'm doing away with the idea of using a remote starter , it's going to be kickstarted . And secondly,rather than fitting webbers or Mikunis etc I'd love to fit a set of bored out stock carbs  to  the motor to give it that real authentic early hotted up sohc 750 look . Greg "H".

[BPellerine]

I want to see this one kickstarted for sure!there always seems to be give and take when building a bike,things change as you go along,or like me you cant make up your mind!!haha bill

[Greg H]

I've got a couple of complete F1 transmissions on the bench .
I'm planning on experimenting at modifying one of the primary drive shock absorber/sprocket assemblies .
I have an uprated set of rubbers and rivets which I got a while back off Voxonda , but I've also read about a mod which was done by RC back in the day which involved precise alighnment of both sprockets and which also involved welding , so thats what I aim to have a go at .
I also had to move a few things around in my workshop today ( ah , the joys of having limited space in which to work  ) so I took a couple of pics of the rolling chassis while I had the chance  .

 

[MCRider]

I may have missed this, but where did you get the seat? DIY?

Great project BTW!

[Greg H]

I may have missed this, but where did you get the seat? DIY?

Great project BTW!

Thanks  .
The seatbase was a cheap copy of a "K" seatbase off ebay .
dito, the seat cover .
I had to braze spiked fittings to the underside of the base so that the person who fitted the cover had something to attach the cover to . She very cleverly  modified the replica cover  , managing to keep the quilted pattern in line( I hadn't realised that Honda had changed the seat pattern so many times between models) whilst still utilizing the original piping around the edge , when she put the step in the seat .

[BPellerine]

pics of the bike never get old!bill

[Greg H]

Cheers Bill  . It would look even better with a decent motor in it .
The crank is off being balanced and is having the journals micro-polished while it's there .
When it comes back I'll be getting one of my brothers to measure it up properly. He builds his engines in a temperature controlled enviroment , where as my workshops temp is usually all over the place . And also he's much better with  micrometers etc than I am as well
I've not had a chance to get started on the primary sprockets yet , hopefully I'll get down to doing it this next coming weekend .
I'll try and remember to take some pics  .

[Greg H]

Stripped and had a look inside a primary shock absorber set up on one of these motors for the first time today .
I have to say that welding up one of these to lock it doesn't look like rocket science , but seems pretty intuitive to me .
Obviously getting the two sprockets lined up spot on will be  imperative , but other than that "no big deal".I can't help thinking that it looks "too easy" and when set up like that in the motor there might be some "issues"with primary chains running sans any form of shock absorbtion. I have an uprate kit with stiffer rubbers which may be the way to go in the end .I think that I'll have to do a bit more research on this before I decide which set up to fit into the motor .I
cling film wrapped the c/cases and block for storage ,really just to minimise the chance of anything nasty getting inside them before the bits that I've ordered  arrive and the engine build begins .
I'll be going back into the workshop to have another look  in a bit  .  Greg "H"

[Greg H]

Ordered a couple of new needle roller bearing for the primary drive sprocket off David Silvers today .
I ended up having to destroy the old ones to get them out .
I've decided to go with the harder rubbers , I'm also scraping the idea of welding up the hub. So I'm going to replace the rivets  with Hi Tensile 6mm countersunk Allen screws , which I also had to order in today  .
However ,I did manage to get all the drilling and countersinking etc done today ,so now I'm just waiting for the screws to arrive then I can get the hub buttoned up again. Onwards and upwards  .
 

[BPellerine]

 

[dusterdude]

Rubbers?

[Greg H]

Got the primary hub finished off and buttoned up .
I've been really lucky with the gearbox internals . Apart from replacing a couple of bearings everything else. such as selector forks etc  measures up to well within manufacturers specs . And as I've got two complete transmissions to play with,it means that  I've got some spare parts if I need them .
I've got a couple of undercut gears on their way , so all I need to do is wash off all the gears etc , reassemble everything  and the gearbox will be done .
Clutch wise the basket I'm using shows no visible signs of missuse , so I'm just going to fit a set of uprated clutch plates/springs off either ape or cycle x . And then that will be sorted.
The crank isn't done yet , but when that comes back, and it can be measured up again after micro-polishing of the journals, I'll be able to start on building up the bottom end .Happy Days 

[BPellerine]

 

[Retro Rocket]

Nice 

[Greg H]

It's been a few weeks since I last posted anything about my project, mainly because there's been a long hold up getting the crank balanced and the journals polished .
Thankfully it's all been done , so all I've got to do now is find the time to go and pick it up .
Because of the exorbitant cost of getting anything shipped over to here from the US ,I've been trying ( without much success so far) to get things done over here ,which has also added to the delay in getting things done .
Hopefully when I finally get my hands on the crank ,I'll be able to make some significant steps forward with the motor build.   
 

[SBR-CB400F]

Hi Greg, how is the progress on the bottom end? Love the look of the bike  Adam

[Greg H]

Hi Adam . Sorry for the late response to your question regarding the progress of my project .
Thing have come to a stop at the moment , I'm afraid .
Due to cheap imports ,there have been  a huge number of redundancies in the steel industry over here  .
And as a consequence of this, the training company which a friend of mine and myself ran at a couple of the effected plants has had to fold .
So basically , for the time being at least ,it's a question of working for someone else and keeping a roof over our heads, meanwhile,  the bike is packed away in boxes at my new address .
I've not given up on the project , it's just a question of priorities at the moment .
Regards Greg "H".
 

[kmb69]

Got the primary hub finished off and buttoned up.
.....

Did you leave the stop pins out of your primary drive on purpose?

[Greg H]

Yes . I researched this and was told that if the stops came into contact with the hub I was in trouble . I fitted the uprated rubbers and figured that the pins would be redundant , so I left them out . Only time will tell if it was a wise decision  .

[johno]

Hi Greg,
 its been awhile since I read the thread and things are looking good.
I am curious about your primary hub journey !   When I modified and upgraded my hub same as you I ran into a big snag. I built the engine but when I was turning it over by hand it sounded like a broken or misaligned gear with a loud regular clunk.  I split the cases to discover it was from one of the needle roller bearings in the hub and I think it had a small piece of swarf in stuck in the needle roller.   It was so fine it was almost impossible to feel by hand but when it was assembled it sounded and felt bad, tried twice before I gave up and fitted another hub.  I asked my local honda dealer and he told me the needle roller bearings were unavailable so Im using the modified hub and rubber as a paper weight.
So reading your thread I got all excited when you said silvers could get the bearings.
Soooooooooooo Greg you dont have the part numbers by any chance

I can relate to your steel industry woes Greg, I'm in stainless fabrication game,  one of the largest in OZ , we have between 40 to 50 men and the best equipment available in the world and very efficient,  last 6 months has been scaringly tough as anything small enough to fit in a container now comes from China, the real issue is as efficient as we are and with an average sort of survivable margin say 20% profit, the importers are now selling at 50% less than us.......kind of wondering what we can do besides stop manufacturing and start retailing imported stuff ,  I am thinking of retiring and was looking forward to going out a winner but may have to roll out the door a loser, hard pill to swallow in this rapidly changing world, global econo.mies are good for people with nothing, bad for people with something
Maybe you will have to go international with your training company...........go global or sink baby 
johno