Topic: 836 Kit or .25 Overbore"?

[Imago]

I see the 836 kits aren't available on eBay right now and even if they were I understand the vendor no longer ships to Canada.

Anyone have an extra set they'd care to sell me?

Here's what they'd be going in. 2 pistons seized when the head was removed.

Or does Hondaman recommend just going with a small overbore, say .25" instead? Those kits ARE available on eBay.

I suppose it depends on what you're after... in my case, I'd mostly just like to get it back on the road, however the thought of 8 more HP IS appealing.

Thoughts?

[ekpent]

  I thought I have read where Hondaman says a 10% increase in power is possible just getting a fresh one over overbore to get the old now heat treated cylinder bores nice and round again. Now if you want to make a nice noticeable difference pop in a Wiseco  836 kit with the 10.5/1 compression. Just the pistons can be run on stock rods and springs.

[Terry in Australia]

That's a nice old 750 mate, don't piss around with a first or second oversize rebore, do the 836 kit, clean up the ports and shove a nice street cam in there while you're at it, and enjoy some power that you can feel! Cheers, Terry.

[Imago]

OK, 836 it is then... anyone have an extra "cruzinimage_co" eBay set they would part with?

The Wiseco sets are a bit too expensive.. probably very good though...

[Davez134]

That's a nice old 750 mate, don't piss around with a first or second oversize rebore, do the 836 kit, clean up the ports and shove a nice street cam in there while you're at it, and enjoy some power that you can feel! Cheers, Terry.

I agree! The 836/cam/port option is great if you are looking for a bit more HP. Since you are used to stock, you will notice the difference. If you aren't going to do cam/port, you aren't taking full advantage of the extra cc's though.

[754]

If you want to go cam and headwork, even down the road, forget that low compression kit...
I doubt you would regret going to the high comp 836 kits..

[Terry in Australia]

If you want to go cam and headwork, even down the road, forget that low compression kit...
I doubt you would regret going to the high comp 836 kits..

Well I've got to say that my 836 has only got the Cruizinimage pistons, a mild street cam and JMR stage 3 head and it'll happily lift the front wheel Frank, so while it might not have the outright BHP it had with the RC pistons, Megacycle 125/75 cam and 29mm CR's that were on it before it's last tear down, it's probably got a tad more torque.

Torque = Acceleration, BHP = Top End speed, over here being able to do flat out speeds will land you in jail, whereas being able to accelerate away from modern bikes is legal(ish) fun.........    

[Stev-o]

+1....go 836, you won't regret it.  Try these and let us know how they work....


http://www.ebay.com/itm/Honda-CB750-750K-69-78-836cc-65mm-Big-Bore-Pistons-Kit-10-25-1-compression-ratio-/112021588836?hash=item1a1501cb64:g:2UsAAOSwu1VW4I0-&vxp=mtr

[Don R]

 I used the ebay kit and pocket ported the head with a 77F cam. It was a lot more torquey. Then I put in a big road race cam, down low not much difference. I suspect the power band is in the rpm's I don't go to often.

[Imago]

+1....go 836, you won't regret it.  Try these and let us know how they work....


http://www.ebay.com/itm/Honda-CB750-750K-69-78-836cc-65mm-Big-Bore-Pistons-Kit-10-25-1-compression-ratio-/112021588836?hash=item1a1501cb64:g:2UsAAOSwu1VW4I0-&vxp=mtr

Looks reasonably priced.
Anyone try these?
Doesn't ship to Canada either but perhaps there's a workaround.

[Jerry Rxman Griffin aka MuthaF'er]

If you want to go cam and headwork, even down the road, forget that low compression kit...
I doubt you would regret going to the high comp 836 kits..

Be careful here. I, and others I'd bet, don't think you should use high compression kits. These 10.25:1 kits are plenty with their slight bump in CR. My take on high compression is the 12.5:1 kits you can still get. While they would give you noticeably more power than the 10.25:1 they can be trickey to set up with valve clearance being one of the potential issues. They shoudl be reserved for builders that have gone down this road before. 

Check this out. The guy selling prefers the 10:00/10.25/10.5:1 set up.

http://forums.sohc4.net/index.php/topic,161378.0/topicseen.html

[PeWe]

If you can find a cheap bore job the cruzinimage 836 will not cost that much as total. 836 with higher CR will cost more.
Kit Stage1+ with DP315 cam will be more fun.
http://www.dynoman.net/bikepages/sohc/packages.html

Head to be fixed as written earlier. Hondaman show the chamber/valve job and light porting. Another possibility to find a used ported head collecting dust in someones garage for a good price.

Edit:
open the case might be a good idea too, new chains with tensioners. Cam chain of heavy duty type.... while in the crank bearings might need a check too....

[Imago]

If you want to go cam and headwork, even down the road, forget that low compression kit...
I doubt you would regret going to the high comp 836 kits..

Be careful here. I, and others I'd bet, don't think you should use high compression kits. These 10.25:1 kits are plenty with their slight bump in CR. My take on high compression is the 12.5:1 kits you can still get. While they would give you noticeably more power than the 10.25:1 they can be trickey to set up with valve clearance being one of the potential issues. They shoudl be reserved for builders that have gone down this road before. 

Check this out. The guy selling prefers the 10:00/10.25/10.5:1 set up.

http://forums.sohc4.net/index.php/topic,161378.0/topicseen.html

Hi Jerry, So you're suggesting a 836 kit with a maximum CR bump to 10.25:1? If so, I was thinking the same thing. That way I'll only have to get a cheap(ish) bore job to start with...
P.S. How are the Lesters? Notice the Henry Abes on this bike I'm diving into?

[Jerry Rxman Griffin aka MuthaF'er]

Standard 836 10.25:1. IMO don't go 12.5:1 unless it's for the track. Simple and effective. Cam definitely. Basic upgrade without going nuts. Head work is ALWAYS good but can get pricey.

Lesters are killers with the fresh gold powder coat and the silver band around them. Something to think about 

[FridgeRaider]

+1....go 836, you won't regret it.  Try these and let us know how they work....


http://www.ebay.com/itm/Honda-CB750-750K-69-78-836cc-65mm-Big-Bore-Pistons-Kit-10-25-1-compression-ratio-/112021588836?hash=item1a1501cb64:g:2UsAAOSwu1VW4I0-&vxp=mtr

I have a couple of questions for us inexperienced engine rebuilders:

Do you think these kits would work with the stock valves? just get an overbore of the cylinders and "plug and play"?

What is considered a mild street cam? Is there a plug and play upgrade option for that as well?

[Jerry Rxman Griffin aka MuthaF'er]

Stock valves are fine. That was easy. Mild street cam not as easy. Mine are not mild.

Anyone recommend a mild street cam? stock early K, late K, early or late F are the hottest stock cams. mid year K cams are dogs. Go from there?

[754]

I did mean 10.5 to one,vs the stock piston.

[Terry in Australia]

I did mean 105 to one,vs the stock piston.

Fcuking hell Frank, 105 to 1? That'd be no good on the street!

[Terry in Australia]

Stock valves are fine. That was easy. Mild street cam not as easy. Mine are not mild.

Anyone recommend a mild street cam? stock early K, late K, early or late F are the hottest stock cams. mid year K cams are dogs. Go from there?

Throw all those Honda cams in the bin Jerry, or send them off to Megacycle etc as cores, that's all they're good for. I had a nice Andrews cam in my first K1, it was "bolt in" cam with a little more lift and more duration, and no additional timing was required.

The Megacycle 125/75 cam I had in my 836 was a great "top speed" cam, but was no good on the street, it felt weaker off the line than a stocker. For street bikes, milder is usually better.

The cam in it now is a "no name" cam, it's pretty much the same profile as the stocker, but has around 2mm more lift, and really works well with the bigger valves in the JMR head. Cheers, Terry.

[754]

Terry, was it an Andrews A grind ? Got a brand new one here in the box..

[Terry in Australia]

Terry, was it an Andrews A grind ? Got a brand new one here in the box..

I honestly can't remember Frank, have you compared it to a stocker? Just a little more lift, and a bit more duration. It was a great cam, my K1 would happily pull away from my mate Davey's K2, and he was about half my body weight! Cheers, Terry.

[754]

Its not much more lift/duration than stock. Mild enough that one would wonder how much difference it would make
I suppose though, it would help wake the bike up.

[PeWe]

Andrews D cam should fit fine on my cam shelf in my garage!
From satanicmechanic
                        Durat
                Valve   ion
Cam    Timing   Lift    @.05"
                inches  degr   Description and Application
--------------------------------------------------------------
A      20/40    .345    240    Good bottom end torque
       40/20    .345    240
--------------------------------------------------------------
D      19/40    .385    244
       40/19    .360    244
--------------------------------------------------------------
K      35/63    .370    278
       63/35    .370    278
--------------------------------------------------------------
4      32/68    .400    280
       68/32    .400    280

[Imago]

Terry, was it an Andrews A grind ? Got a brand new one here in the box..

Frank, I'm sending you a PM about your cam.

[754]

 I dont want to let that A go right now.
Stock valves ok, but springs and triplecut seats are a must to make power . Hotter cam means more revs and most will use it. Rods recommended, but unless a total maniac, they hold up 98 % of the time. I dont know about extended time at 10,500 or plus but that possible where you live. However in dragracing especially 1/8 mile, between three of us we probably did 1000 runs on 836,s with stock rods with no failure.
 If you are not revving pst 10 K i wouldnt think about it.