Honda-SOHC

Has anyone seen the current issue of "classic motrocycle mechanics" with 2 Suzuki 750 on the cover?

It's got a good bit inside about Honda RCB endurance racers. These were built from SOHC 750 base and represent the final most advanced research that Honda did on this motor I believe.

It was built with a DOHC top end but you can still see the origins of the crankcases etc in the photos, it even shows the conversion of the primary drive to gear type inside in one pic.

After this they were moved to CB900 basis as the race regs changed to allow only production based motors and this head / barrels etc had no street equal.

The nearest thing for the road that seems closest to this hybrid was the CBX750 that has gear primary, narrow angle 16 valve head, alternator on top of gearbox and even a slipper clutch as standard.

It's worth a look to see where the original 750-4 got to.

If you are confident of no underlying problems with oil etc then run it at about 2000rpm for about 15mins and it should dry the water out of the system and get it all hot enough. DON'T keep blipping the thottles though as the accelerator pump dumps enough fuel to make it go gltch free under max load and is far too much to burn properly without load.

Didn't some of the Honda pipes have a small hole at lowest point to let out moisture like this? don't know if F2 has one, I've got one stored so I'll have a look.

I ran Su's on SD1 V8 (think they are H1F from memory) Rover in rallying and got them to flow enough to give about 260bhp so one should easily be able to supply a bike at less than 130bhp.

Think they run with a fibre spacer on to the manifold to prevent heat soak into the carb, don't seem to have any problem with vibration, prefer the later type with built in float chamber for less components.

They can be run reasonably lean as the CV effect helps to make them richer during acceleration without altering basic cruising mixture, used thicker oil in damper tube to inrease this effect.

You often see them with bell-mouths on them, this is badly wrong as they need a small radius 6mm going into the venturi from a flat surface that extends 50mm away from the radius, then they flow properly to their maximum design spec. Used mine with pipercross foam filter fitted.

If you want any diags to explain these i'll try some scetches if you need them.

I remember now that we used to have gasket paper on rolls in the stores when I worked for the Gov of Her Maj, also as first year apprentice we made a small punch and die set with six different sized punches and this I still use for cutting stud holes in gaskets when I make them.

Don't know where you can buy gasket sheet now though.

Steve, I'll try and get a scan for you but don't have much in the way of kit to do it so it may take a while to get sorted.

Please remind me if I don't get it soon.

Looks really interesting, you'll have to tell us if you run it at an event so we could go and see/hear it.

Hello and welcome, as you've realised there are some good knowledgeable people on here to get advive from.

What bike do you have?

Thanks for that Steve, I looked at the photo again and you can see all the details looked authentic. It's just nice to some of that specially made stuff for real as some of the designs were really nice.

I used to be able to wander around the paddocks as a boy almost unchecked and was fascinated with all the details and engineering around, still like to go to festival of speed for the same reason.

For me, some of the design and production of these things is equally as good as art and with more function to boot.