Topic: Anyone interested in having their CB cylinder head ported?

[MRieck]

I will be able to port some CB heads starting in a couple of weeks. Stage 1, 2 or 3 are available.I can also offer other services such as bead blasting, guide removal/replacement, Serdi valve jobs, milling etc. I can forward pictures of previous work. I also port modern inline 4 heads as well. Please PM me for prices etc.

[eldar]

I would do a whole 836 conversion but the cash flow is not there right now.

[Terry in Australia]

C'Mon guys, pony up the doe-ray-me and get a "Mike the Magician" race head, and turn that wheezy old "touring" engine into a fire breathing ball-buster! Have a look at these pics of the head Mike built for me, these ports and combustion chambers ore "Oh so smooooootthhhh"! Cheers, Terry.

[amattel]

How much does it run to have a head ported?

[MRieck]

How much does it run to have a head ported?

It depends on what you want. Generally 200.00 to 375.00 for porting only. Later heads are a little cheaper as the chamber doesn't require as much work. The head I did for Terry has the works- new guides, Stage2 porting, milled, full radius Serdi valve job for oversize valves. That particular head should be good for almost 20 HP with an 836 kit and a cam with .375 to .400 lift on the intake side.

[MRieck]

Terry, thanks for the pics.

[Terry in Australia]

My pleasure Mike, work like this should be seen. It's almost a pity to think that my engine will look pretty much stock to the casual observer, that is of course, until I open it up, ha ha!

 Do you think 31mm Mikuni "Radial Flat Slide" carbs will work well with that head and your recommended cam? I've got a set off an early GSXR1100 race bike in a box, and now that my 29mm Mikuni round slide smooth bore carb dream is over, I thought they might be ok? Cheers, Terry. 

[cben750f0]

i want i want i want i want......... ... though whats the shipping cost like.... i am wanting to put an F2 head on my bike, it has the 836 kit, and the electronic ignition, and frer zaust..... , also what are your recommendtion on cams... makers etc... not really up with the performance stuff... though that head is bloody beautifull... you must be sad to see each of them go.... beautifull.....(am getting all emotional here)...peace..

[MRieck]

Thanks and yeah...it is a little hard to see them go but when you know it's going to a good home it takes the sting away. You look like you have a 76F1. I would NOT put an F2 head on that engine as the chambers are larger and you'll lose alot of compression. My CB is a 75F and the head on it moves ALOT of air. I'd stick with a head like a 75, 76 F or 75 thru 78K head. You can put in oversize valves easily. As for cams I like the Megacycle cams- the 125-65 and 125-75 are good cams with the 836 kit and a ported head. You will need valve springs but you have Wiseco pistons which have the deeper valve reliefs. I'm shipping Terry's head to him today or tomorrow so I can let you know the cost. Terry bought the head here(USA) for 10.00+ shipping which worked out well.

[MRieck]

i want i want i want i want......... ... though whats the shipping cost like.... i am wanting to put an F2 head on my bike, it has the 836 kit, and the electronic ignition, and frer zaust..... , also what are your recommendtion on cams... makers etc... not really up with the performance stuff... though that head is bloody beautifull... you must be sad to see each of them go.... beautifull.....(am getting all emotional here)...peace..

100.00 US dollars to ship air mail- 7 to 10 days delivery time.

[cben750f0]

thanks a bloody lot for that!!!!!!! .... ... now i really really want one!!!!!!!! and my missus said that if i spend anymore money on 'that' bike i will be permanently moved to a place frequented by our dog.... .... so thanks for the trouble, and yeah my bike is a 77F1..... that is interesting about the heads... i hadnt considered this....its just i managed to get a set of F2 carbs and i wanted to see if the accellerator pump would get the little flat spot out of the accelleration, but i need bigger head to carb rubbers, or i need to find a way to open up a set of standard rubbers to fit the carbs... Neway thanks again for the time....  and again.. brilliant work, i understand why terry keeps puting pic up of the head!!!! peace

[MRieck]

thanks a bloody lot for that!!!!!!! .... ... now i really really want one!!!!!!!! and my missus said that if i spend anymore money on 'that' bike i will be permanently moved to a place frequented by our dog.... .... so thanks for the trouble, and yeah my bike is a 77F1..... that is interesting about the heads... i hadnt considered this....its just i managed to get a set of F2 carbs and i wanted to see if the accellerator pump would get the little flat spot out of the accelleration, but i need bigger head to carb rubbers, or i need to find a way to open up a set of standard rubbers to fit the carbs... Neway thanks again for the time....  and again.. brilliant work, i understand why terry keeps puting pic up of the head!!!! peace

That's too bad- I would have enjoyed knowing 2 of my heads were kicking ass "Down Under".

[MRieck]

bump???   

I brought it back to life to have someone else look at it. Boy Cben, I'd do an extra special port job for you just based on your interest- you deserve it.

[Raul CB750K1]

C'mon cben, don't think about it anymore. I'm not interested in modifying my K1, but you can be sure that I will trust in Mike anytime. He has been a long time contributor in this forum and not only is he mechanically skilled, but a great person too.

Regarding the shipping charges, and besides the post open by Terry, it's true that sometimes I hate to pay high shipping when buying from abroad, but how much time and gasoline would I have to spend if I have to chase those articles in flea markets?. You pay the shipping and you have the article delivered to your door.


Raul.


P.S. Mike, please make the check payable to Raul Gallego. Thanks...

[Terry in Australia]

G'Day Mike, well I got home Friday night after a hard day avoiding work, and what was sitting there in the hallway, but a big box with both our names on it? Woohoo! I sneaked it out to the garage and carefully opened this incredibly well packed box, and "what did I spy with my little eye", but a beautifully crafted race head!

Man, the quality of your work is just impeccable Mike, honestly, I haven't seen work of this amazing high standard outside of the best performance shops here in Melbourne, of which there are precious few. The only guy who builds quality CB750 race engines here is a Rex Wolfenden (TRex Racing) and after looking at your work I reckon you'd give him a run for his money, ha ha! 

Geez, I better get my finger out over winter and put this bike together so I can tear up some roads come summer! Thanks again Mike, you really are a magician! Here's a pic of Mike's bike, as you can see, his talents don't just stop at brilliant engine work, his whole bike is immaculate! Cheers, Terry.

[MRieck]

Thanks Terry, I appreciate it!

[6pkrunner]

MRieck - great timing on the post. I am just starting to get back at a '78 750F that I started last summer. I dropped off the motorcycle scene after selling my '79CBX and did the wife- marriage- kids thing. Well the kids are mostly grown up and I got the 78 750 for a song. I've been porting automotive heads for over three decades, but know squat about the SOHC head. I was looking at the ports just today and see an awful neckdown in the transition area toward the bowl and the shortside radius looks to be a major flow inhibiter. For years the shortside radius on the automotive heads was taboo to touch, but now a little laying back is not only acceptable, it actually helps the flow instead of killing it off. This is with what I could equate to a street/strip head or possibly a Stage 1 or 2 in your area of expertise.
 So I guess my question is this.
The bike will remain pretty much stock - 3rd oversize (0.75) pistons and rings, barrels milled a few thousands, stock carbs (possibly rejetted and needle valve playing) stock 1978 cam (unless some one has a good recommendation) and a MAC exhaust system. The stock pipe was long gone when I got the basket case, and there is a Hindle system with it, but the collector has got a few dings in it and for the level or restoration the bike has got on it so far it would be a shame to install the dented system.
What level of headwork would you recommend for such a mild creature? Is the shortside blending a good idea with the Honda engine? Widening the transition area a good idea or will it kill flow in a low demand engine? Cam recommendatons - again for a basically stock engine?
 I don't want to pick your brain for free but any advice is welcome.
Thanks!

[MRieck]

 First off check the guide/stem clearence as the those guides are notorious for accelerated wear (secondery to valve angle and guide material). The F2/3 ports are approximately 2 mm larger diameter than K/early F and that's a good thing. The intake opening can be smoothed and not much work is necessary for the first 1 to 1.5 inches. Yes, definitely pull down, widen and flatten the intake short side especially where it meets the seat. Remove material and profile the guide boss- you want to add some height and length to the long side especially in the bowl. The bend on the long side is to sharp- by enlarging and extending the bowl behind the guide the mixture has a straighter shot at the back of the valve. I don't do car heads but the concept is the same in regard to bowl work.  Smooth the chamber and remove any sharp edges but DON't remove any real material. Don't remove material from the exhaust floor- a light smoothing only. You can Dykem and use an old exhaust gasket to maximize the exit sides and roof. You can remove/profile the exhuast guide boss a little though the exhuast on those engines work almost to well secondary to the very large valve diameter. If you email me your address I can send an old article done by Jerry Branch- it applies to early SOHC though but does have a nice diagram to show how the short and long side should be worked. I would consider this intake port a stage 1 and it will be much better with the work described especially at low lift which, as you know, happens twice. You are pretty much stuck with the stock cam becuse of very shallow valve reliefs. It would be nice to throw in something like a Megacycle 125-75 cam which has .400 IN/.375EX with added duration. The high lift gives nice acceleration as opposed to a cam which only offers alot more duration and with the improved port you can take advantage of the quick fill characteristics of the quick, high lift cam. It is a good idea to deck the cylinder to improve squish and raise compression a little- I'd take .005 off and mill the head .005 too. I'd run K&N individual filters or  cut up stock airbox with a K&N OEM type filter to take advantage of the headwork. To bad about the Hindle as that is what I run and it works well. Like I said earlier feel free to email your address and I can get that article out to you.

[zaidarms1]

where are you located

[MRieck]

where are you located

Massachusetts