Topic: 836 power

[Sam Green Racing]

Has anyone any dyno figures before and after 836 Wiseco conversion, with no other mods other than jetting.

[Jonesy]

For what it's worth, I remember seeing a website that had an old article on engine mods for the 750's (http://members.tripod.com/cb750k2/Technical/porting/Porting_the_Honda_Head.htm) that had comparisons of engine performance after various mods. The key thing I remember it saying was if you just drop an 836 kit in there, you won't really get a lot more out of it (or the standard 736cc, for that matter) until the head is ported and polished.

Hope this helps...

[cben750f0]

this is with jetting and 4-1... dont have a chart for just the motor...but it will give you an idea...peace

[Sam Green Racing]

Hi Ben,

Yes I already Have your input, but I was looking for more to get an average as dyno's can vary.
Did you notice the positions of the valve recesses on the pistons in relation to the valve positions in the head.

Sam.

[Geeto67]

for what it is worth a stock 750 will put out about 53 hp at the rear wheel.

[Clyde]

I have run both 810 and 836 kits , but no dyno figures. The 810 was in K2 with a 4:1 and the 836 was in an F1 with everything stock. From the bikes performance I would estimate that there is some good mid range increase but no difference at high revs.

[Sam Green Racing]

Thanks Geeto/Clyde

Any info is appreciated and is noted.
The motor we run at the moment is stock and high milage.
It breaths through 31mm CRs four into four open megas and runs total loss via a Boyer ignition system.
It kicks out 60 brake at the back end.
We have 836 Wiseco kit and Megacycle cam, and the head is to be re worked.
This is for next year as the stock motor is still strong enough to win.

Thanks Sam.

[6pkrunner]

In 1973 I had a K3 that I put a Yoshimura 812 kit in with their street/track cam and springs. Just main jet change at that time. Stock head/air box and exhaust. Not that impressive over stock. I put a Yoshimura track 4 into 1 on it and it was a bit better, but nowhere what I had hoped for. Maybe the head was holding it back but it wasn't really worth the money and time invested.

[Sam Green Racing]

6Pk,

The head is the main release of power, and is money well spent.
Thanks for your input.

Sam.

[MRieck]

The stock head and relatively low compressionreally holds you back. Larger intake valves are essential too. I've gotton 92 HP to the rear with 915cc which is only 80cc larger than the 836 kit.

[Sam Green Racing]

Thanks for that Mike, I had intended going up two mm on the inlets but dont want to go to high on the comp for reliability.
The 836 Wiseco pistons are 10.5, with a Megacycle cam that was designed to work well with these pistons.
Do you know anything about these particular pistons?  The valve cutaways in the piston crown dont look like they line up with the valves. They might be over engineered to fit any cylinder if you get my meaning.
I would be interested in your thoughts if you have come across this.

Regards  Sam.

[6pkrunner]

6Pk,

The head is the main release of power, and is money well spent.
Thanks for your input.

Sam.

Well aware of that now. I've been porting automotive heads for the last 30 years or so. Just getting back into the bikes now. But Pops said nothing about the headwork in 1973.

[Sam Green Racing]

6PK,

Have a look at the third post on this thread posted by Jonesdp. He lists a site on porting the heads of these big fours.
Also MRieck posting on this thread sounds to be a mean porting machine.

Thanks for coming back,

Regards  Sam.

[6pkrunner]

I bought a CBX in 1979 and sold it in 1980 to buy the lot that our house is now on. In 1991 I got a 1984 FJ1100 to use as a commuter to work and back to save on gas a bit. Still got it. But I always missed the CB I had. Fellow at work had a basket case '78 750F that I got for a song and snapped at it. With the great info from MRieck I hope to make her work a bit better. And on Saturday of this week I'm picking up up a K2 and a K5. Both are pretty much basketcases, but are intact. And the F3 isn't even finished yet. The CB bug came back hard.

[chippyfive50]

Hey Sam, i'm assuming that is  your bike in the pic??  My next project is a 72 750 I want to cafe, and yours is NICE... where did you obtain the tank and faring.... that is a good looking machine....

chris.

[Sam Green Racing]

6PK,  If you can port motors go for it.

Chip,  Thanks for the compliment, I will have to start telling people it is mine, but sadly it's not.
I just got to build paint and maintain it, but I do have the odd flirt down the quarter on it.

As regards a cafe racer useing CR parts you must be aware that all the fixing points are in different places.
The petrol tank has a well (sump) that hangs down under the rear of it, and we have a central oil tank.
These things all get in the way of the electrics ect, but it can be done. I have seen one on this site by a guy that builds cafe bikes but can't remember his name.

All the parts (tanks seat fairing brackets ect) came from Bartel Engineering in Northen Ireland UK. I am at work at the moment so don't have the address with me.  If you can get hold of Classic Racer (UK mag) it's in there, or you may find it on the net.

Good luck with your project Chris, Keep looking in as I may find Bartels address, but I won't be on again till next Saturday.

Regards Sam Green.

[Sam Green Racing]

Chris Chippy

The power of the net.

Bartel Engineering.  295  Killaughey Road,  Donaghadee,  County Down, Northern Ireland, BT21 OLY.

Tel 02891 820786.

The guys name that owns the bike is Chris.  His nickname is Chippy (wood worker) not quite the same as in the US.

[MRieck]

Thanks for that Mike, I had intended going up two mm on the inlets but dont want to go to high on the comp for reliability.
The 836 Wiseco pistons are 10.5, with a Megacycle cam that was designed to work well with these pistons.
Do you know anything about these particular pistons?  The valve cutaways in the piston crown dont look like they line up with the valves. They might be over engineered to fit any cylinder if you get my meaning.
I would be interested in your thoughts if you have come across this.

Regards  Sam.

Sam
 The valve reliefs are in line with the valves. They appear strange but that is because of the increased valve angle and wierd offset of the CB head (part of which is to accomodate the rocker arm design). I'll also tell you that the reliefs are plenty wide and deep- I have yet to see any valve to piston clearance problems even after some serious head milling and/or cylinder decking. Another thing to take in consideration along with the cam is getting an adjustable cam sprocket from Falicon- it is essential. You will never realize the potential of your engine- no matter how large it is or how much porting it has- unless you time the cam to your specific application. Many people overlook this 30.00 part. Cam timing is not that difficult and it feels great when you master it.

[Henry Dorset Case]

Thanks Geeto/Clyde

Any info is appreciated and is noted.
The motor we run at the moment is stock and high milage.
It breaths through 31mm CRs four into four open megas and runs total loss via a Boyer ignition system.
It kicks out 60 brake at the back end.
We have 836 Wiseco kit and Megacycle cam, and the head is to be re worked.
This is for next year as the stock motor is still strong enough to win.

Thanks Sam.

Hi Sam I have been looking at your pic (nice leathers!) is the seat/tank/fairing a genuine CR item?  does it fit a street CB750 frame?

Is it available anywhere?  if so where?


 Ive been looking at pictures of the 60's Honda GP racers, (and the Honda Dream 50 a Japan only 50cc 60's GP lookalike).  that look is the look I really like, and I need a project for next winter.....

[GroovieGhoulie]

I'm going to find out more about that other UK company for these CR parts.  You say they are top quality but not as expensive?  Hmm... That is a good thing.

For fitting the tank, it appears that you grind off the factory tank rubber mounting tabs and then weld a catch for the tank rubber on the bottom of the frame, is that correct?

Also, does the CR fuel tank work with the factory oil tank?  If not, I may have to buy the CR oil tank as well.  Does mounting the battery sideways and moving some of the electrics around work?  How hard is it?

I have no problem with some fabrication on the frame, but I don't want to have to use an expert.

For my cafe, I was planning on the CR tank and seat, possibly clip-ons, but maybe clubmans, an oil cooler (I'm in Texas and 100*+ summers are routine here), pods, 4:4 megas, the early points plate with the aggressive advance curve, upgraded suspension (but still "period").  There are other mods, but I'm probably forgetting.  Does this sound silly or reasonable? 

samCR750, a few questions:

I like the look of the CR 4:4 megas but I would prefer them a bit longer, like this bike: (click "view image" to see it bigger)





Does anyplace supply stuff like that or do I need to look custom for that?  Also, how loud are the open meggas and do you lose anything for them having no backpressure? Would a semi-muffled design, like thin glasspacks, work better? I don't like obnoxious pipes, but I want it to ROAR! LOL

Which would you go with, clip-ons or clubmans?  Apparently with clip-ons, I would have to modify the steering stops, but no big deal, since I'm modifying so much else anyway.

Would the semi-rearsets off the 400F work on the 750?  I ask because I want rearsets, but still want the function of the kickstarter and the 400F's still allow that, even though they're not very rearset.

What fuel tap do you use for the CR tank?  Mead said that the CR250R tap is compatible.  Isn't that a new-production dirtbike?  If so, the tap should be easy to get.

You seem to be the CR750 MAN and since I want to mold my cafe into a "partial" CR, I seek your guidance.

[Sam Green Racing]

I am not sure if Bartel engineering is cheaper, it's nearly 5 years since we bought off them, but you can ask.
Regarding the tank mounts, the front ones are stock with the round rubbers, when you have the tank in place you will see where you need to position the rear one.
The CR tank can be used with the stock oil tank but I think the sump would foul the electrics/battery.
Bartel can supply a factory oil cooler kit and also a oil presure guage that works off the oil sensor pick up.
The pipes come ready formed but the megas have to be shaped by you (nightmare) unless you can find a company that makes pre formed systems (posibly Gibson in the UK)
The factory race pipes terminated just before the rear axle to give access to it, and yes, they are very loud.
The steering stops have to be modded as you don't want the bars to hit your new tank.
Can't help much on the rear sets as our chasis was modded by a guy that had blueprint for the frame.
The rear footrest mounting bracket is totaly removed. If you go back to the 9th post on page one of this topic, you can just see where the foot rest is behind my left calf, it just shows as a white dot. (you may have to enlarge)
Our fuel tap came from Bartel, but if he CR250 fits, it will be much easier to get hold of one.
Good luck with you project if you go ahead, PM me if you need any further help.

Regards Sam.

[Big Jay]

Thanks for that Mike, I had intended going up two mm on the inlets but dont want to go to high on the comp for reliability.
The 836 Wiseco pistons are 10.5, with a Megacycle cam that was designed to work well with these pistons.
Do you know anything about these particular pistons?  The valve cutaways in the piston crown dont look like they line up with the valves. They might be over engineered to fit any cylinder if you get my meaning.
I would be interested in your thoughts if you have come across this.

Regards  Sam.

When we first started making 836 kits in about 1970, we did them with the wide valve pockets so they would fit any cylinder., as we could get away with this and still have 10.5:1 C.R.  When Wiseco started making four stroke pistons, we helped them with piston designs. They made their 836 Honda piston exactly like ours because it worked.

When we did the higher compressions ratios for drag bikes and alky 3/4 midgets, we had to make the pockets the right size and in the right place.

Jay

[Sam Green Racing]

Jay, thanks for the reply, but the problem is now sorted.
It came about because at the time of posting I had never seen inside of one of these motors.
Although we had raced the bike for three seasons we never had the need to take the motor apart.
The first time it got beaten, we deceided to build another motor.
We had a tuning article in an American magazine by RC, it showed handed pistons.
You can imagine my supprise when the Wiseco pistons turned up with the valve cutaways in line.
That was the reason for that post.
The motor is ready to be built now, when our engine builder decides to get his finger out.

Sam.

[Sam Green Racing]

             You know, I don't even have a SOHC 750 (mines' a DOHC) but, I got to reading this post on
       the 836 and then andynzl's part of this and then, groovieghoulie's AND the next thing I know,
       I'm being sucked in by this!!  I, myself, won't be able to do a project like this for sometime (if
       ever!) but, I'll be soaking it all in, I promise you. I've always been a fan of the Honda racer's look,
       the way they run and the way they sound! Well, I'll get out of here and give these guys room,
       so they can get back to what they're doing.

       And Sam, I don't mind telling you that I envy you riding that bike, I can only imagine how
       exhilarating it is. Later on,  Bill

Billy, it's not that nice to ride. I have only had a few rides on it and it is set up for Chris who is almost twice my weight.
It spins up like fcuk in the first three gears if I give it full whack, it's scary

Sam.

[MRieck]

I think this is what Jay was talking about when he mentioned high compression pistons having the reliefs in the right spots.

[Sam Green Racing]

don't let Terry hear you call that an Island. Fairly sensitive fella.
I'm not sure how that panned out, I'll check, although I have a source in Auckland already sorted.

Did you get any rims sorted Andy, how's the exhausts shaping up/or not

[Sam Green Racing]

Michael, I wasn't refering to your valves, it was the ones that let us down here, the ones that your valves replaced, silly you.

I know Sam....giving you a hard time. Still.....don't make me come over there sir.......Christ..the Island will never be the same.

Dont know WTF is going on, it may still not be together when you come for your holiday.

Your room looks very cool.

Sam.

[Sam Green Racing]

Chris Chippy

The power of the net.

Bartel Engineering.  295  Killaughey Road,  Donaghadee,  County Down, Northern Ireland, BT21 OLY.

Tel 02891 820786.

The guys name that owns the bike is Chris.  His nickname is Chippy (wood worker) not quite the same as in the US.

There ya go Stert.

Sam.

[Jim F]

I think there is a company in California Called Air Tech that sells the replica stuff also.
CR, Dunstall, quarter fairings, full race fairings, TZ stuff..........

[754]

Regardless of..

Whatever whoever said, online, in print or in a real conversation..


If you want to assemble engines that work, check your clearances.. or one day it will bite you..

Do-overs are never cheap and there is  always someone very PO'd when it happens.

Its not hard to check, and a lot less work than if something goes wrong..

[Sam Green Racing]

bump