Honda MG & MF 750

[Johno Senior]

The best flow I could get from the standard port angle was approx 70 cfm @10 inchs but the 18 degree head took the flow up to approx 90cfm @ 10 inchs sounds impressive but not up to the modern engines or that water bottle
ciao johno

[Johno Senior]

For the techno's out there just proving the numbers

[Johno Senior]

On the small 750cc engine I have some engine software and fed the info in and this is the printout.
Since this I have cracked onto a bigger cam , higher comp pistons and more head flow from a later 1978 F2 head, I'll use the pistons , cams etc I allready brought into the spare engine. The head is being done in the US for me and I wont receive it for a few months, many years ago I purchased a head from the states to see how mine compared and for me the port wer eto big and relied on massive revs , cam and compression to get the same result I was getting from my smaller ports and cams..............But this man doing it has a big reputation so cant wait to see how it stacks up

I'll post the big engine later on

Ciao johno

[Stayt`ie]

yeah, 90 cfm @10", very good numbers from a CB head, ,,

[Mossy]

Wow, your getting stuck into it, keep the pics coming.
Cheers Mossy

[ROSS BROWN]

Very interesting stuff Johno
Are you using, or will you be needing 900 boldor cranks ?
Ross

[Johno Senior]

The crud was so hard had to use a drill to get it out of the galleries.
cheers johno

[Johno Senior]

Hi Ross,
you must be an old Honda buff too ?

I looked at both the 900 boldor and 750 automatic but settled on the original crank.
I have drilled out the cross drilling and replaced the ball bearings with grub screws. I have lathed and milled the counter weights to about half the original size....ultra light

I need to get it balanced , I heard there is someone in Melbourne who is the man ??? the redline is 11,000 so need balancing to 12,000 rpm
If you know who or where please let me know

To run the original crank and roller chains I have purchased Da Bik German engineered chains at over $200 each, along with manual teflon primary and cam chain tensioners from Cycle X I spent big ( for me) last week ordered nearly $10,000 worth of parts for the engine and ignition.
I'll post some pics after I take the happy snaps, I have been slowly getting some parts together over the last couple of years and was planning to save a few bucks by doing the chassis myself but allready I'm thinking I need a heap of dosh....?
cheers Johno

[Greg Watters]

Whats the advantage/disadvantage of the 750 automatic crank ??
Kim picked up one in the US last yr for her outfit but not sure of its suitability , and i was messing around with MX 2 strokes in them days and have nfi

[Johno Senior]

Hi Greg,
The auto 750 honda has a hyvo primary chain with a roller camchain and are very popular with the US drag boys, its a reasonably simple conversion just need the old goldwing clutch drive as its also a hyvo to make it all work. The other high HP long life tip is to replace the cushion rubbers in the clutch hub drive with harder rubber units as they are old and crumble up badly with a few ponies. The boldors have a hyvo cam chain as well but is a bit more complicated to set up so most run the auto cranks.

The reason to do it is as soon as your making 90 plus HP the two roller primary chains have a very short lifespan ....with the Daytona Honda boys like M3 change their rollers every meeting until these german HD chains came on the market last year. The standard rollers at around 100hp in 750 class break on the throttle overun and pop up and out the cases. That Gets expensive where the hyvo chains last the boys a season.

These new german rollers are the ants pants but very expensive.....$440 compared to original $140.... the Hyvos are about the same as the original so good proposition.

I have been out of the race / bike scene for many years and the old age crisis got me fired up again, problem is all the machine / balance shops etc are all changed and I dont know who are the go to people. I need a couple of cranks balanced to 12,000.RPM so if anyone out there in cyber land has a good contact please let me know otherwise I have to send it to APE in the US and the freight is a killer.
Cheers Johno

[Johno Senior]

These are the Carillo con rods and the pistons I had for a while, trouble with winter it gets you thinking and thinking leads to changing ones mind The rods are cool but I changed my mind on the pistons, these are JE two ringed pistons 12.5 :1 ration at max allowable diam 62mm from 61mm std bore ( I hope I got that right) The trouble with pistons I had purchased 3 cams allready as a good start point now found out I can get an evan more radical cam but needs mega compression, lots of port flow and mega RPM to make power so I might end up with a sprocket the size of the rear wheel
Seriously though I am trying to get these pistons in blank top form to save some dosh and now chasing looking at 14:1........that will see how good the suneco race fuel is. The ignition is groovy one coil per cylinder with full programmable curves..........paid US $165. just for the cable to connect the lap top, I dont know what I'm doing yet with chasing stuff down on the internet , probably some computer guru is going to say I got shafted but hey.......I'm an old man
johno

[Johno Senior]

Back to the real world of cold and more cold.
This is the first coat of yellow and would improve second coat but it looks crappy compared to Mossy bike so I,m leaning on the poor bloke for his yellow thats what forums are for I hope !

[Johno Senior]

These are the bronze bushes I got for the swingarm to replace the stock type bushes.
johno

[Greg Watters]

Thanks Johno

thats some serious work on the old girl

the sunnoco will be fine, my compression effectively gets to 17:1 + at hi boost levels and not had any signs of detonation , you will need that real good ign to kick it off though ,

[Johno Senior]

These are my shed or transport wheels, dont want no flatspots on the good rubber.
Two std 750 fronts, one on front, one for the rear as the swingarm will be set up for a narrow front hub anyway.

Seeing as its just to look at I cant make my mind up, all yellow rim, spokes and hub or yellow hub and rim black spokes or yellow rim black hub and spokes ????? I'll have a beer and get a blood rush
cheers johno