Topic: 836 wiseco kit for a CB750 K7

[mazingerzeca]

Hello all.
I'm thinking on installing a 836 kit on my cb750 K7, but I don't know if this kit fits the K7. The pistons are not the same as earlier models. The same, I think, with the camshaft.
As I've seen here, it needs 3 mm more of bore, but, would a new sleeve be needed? If it can be installed, would I need any carb rejetting? Are 836 engines more prone to oil leaks?
Thank you.

[wannabridin]

come on, there's PLENTY of threads on this subject in which almost everything you could think of asking has already been addressed.  as far as i can say, which is very un-educated compared to the rest of the members on here, is that 836 kits, when installed with HD studs, won't leak.  these are great motors, one of the best ever IMO, and as long as everything is installed properly, there won't be any problems. 

any piston will fit as long as its bored properly, without sleeves on these motors.  with any change in engine parameters, especially displacement, a carb rejet WILL be needed.  but you won't notice much of a difference with JUST a kit if you don't install a new higher lift and duration cam and get some porting done.  this will really wake these old girls up, now this is all from what i've read in my countless hours spent on here perusing the threads.  well i hope this helps, and again, use that search feature!

[sangyo soichiro]

Hello all.
I'm thinking on installing a 836 kit on my cb750 K7, but I don't know if this kit fits the K7. The pistons are not the same as earlier models. The same, I think, with the camshaft.
As I've seen here, it needs 3 mm more of bore, but, would a new sleeve be needed? If it can be installed, would I need any carb rejetting? Are 836 engines more prone to oil leaks?
Thank you.

What is your motivation for going for an 836?  Is it just for more pep? 

I would encourage you to search through this forum for a long time before you do anything.  Start here:  http://forums.sohc4.net/index.php?topic=43915.msg456896#msg456896

[mazingerzeca]

Well... the motivation:
I'm rebuilding the engine right now. I wanted to keep it stock. The cylinders were ok, so I had them brushed and ordered new rings from David Silver. The rings they gave me don't fit on the pistons. They had a different number from the one I asked for, but I thought they were superseeded parts. So, the only place where I can get the rings from is CMSNL (hoping that they fit the pistons I have). The fact is that the price including shipping costs for the rings is almost the same price of a 836cc kit.
I had the chance of riding a F1 with a Henry Abe 900cc kit installed a week ago, and it was amazing. These are the motivations, but I wouldn't mind to keep it stock.

[sangyo soichiro]

Well... the motivation:
I'm rebuilding the engine right now. I wanted to keep it stock. The cylinders were ok, so I had them brushed and ordered new rings from David Silver. The rings they gave me don't fit on the pistons. They had a different number from the one I asked for, but I thought they were superseeded parts. So, the only place where I can get the rings from is CMSNL (hoping that they fit the pistons I have). The fact is that the price including shipping costs for the rings is almost the same price of a 836cc kit.
I had the chance of riding a F1 with a Henry Abe 900cc kit installed a week ago, and it was amazing. These are the motivations, but I wouldn't mind to keep it stock.

Well, the thing to pay extra attention to is this part of Hondaman's post that I linked to:

...consider at least a step overbore (.25mm) before a big-bore kit, as the latter will reduce life considerably compared to a step bore. The metals in the new cylinders usually warp out-of-round in about 5,000-10,000 miles, then finally cure. Boring round again brings back a lot of lost power. Boring to 836cc starts the cycle over: after 5,000-10,000 miles, they need a step overbore to make them round there, too....

I was also seriously considering the 836, but I think I'll do the 1st step overbore instead.  Thanks to Hondaman.

[MCRider]

Well... the motivation:
I'm rebuilding the engine right now. I wanted to keep it stock. The cylinders were ok, so I had them brushed and ordered new rings from David Silver. The rings they gave me don't fit on the pistons. They had a different number from the one I asked for, but I thought they were superseeded parts. So, the only place where I can get the rings from is CMSNL (hoping that they fit the pistons I have). The fact is that the price including shipping costs for the rings is almost the same price of a 836cc kit.
I had the chance of riding a F1 with a Henry Abe 900cc kit installed a week ago, and it was amazing. These are the motivations, but I wouldn't mind to keep it stock.

IMO the 836CC is the best compromise engine upgrade size. You can get top quality forged pistons, go with the lowest compression ratio for a street bike. Doesn't require new sleeves (the 900 likely would, my 888 did). Just bore out the stock sleeves.

Very reliable, no leaks especially if you use HD cylinder studs. Without HD studs, it will leak about as much as a stocker, more or less. (Frankly if I were building a stocker, I'd still put HD studs in it.) Caveat: removing the stock studs runs the risk of breaking one and doing what may be necessary to remove the broken piece.

No modification is completely as reliable as stock, so it depends on how much it will be ridden and how much it will be looked at.

You won't feel quite the punch of the 900, especially if the 900 had other work done. but it'll be significantly better than stock.

[HavocTurbo]

I was also seriously considering the 836, but I think I'll do the 1st step overbore instead.  Thanks to Hondaman.

Sissy.... 

Seriously though, the step overbore is the next best thing to keep it "stock".

And I'll agree with everyone on the HD studs. And add that bottom studs make an extra insurance step if you have the cash to spare. Just my $0.02.

As with any kind of engine rebuild there are going to be questions and problems. Nice thing is there are members here (myself included) who have built all different kinds of iterations of the CB750. Trick is to figure out what you want vs. what you can afford right now.

[wannabridin]

Sissy.... 

Trick is to figure out what you want vs. what you can afford right now.

screw it, go all out!!  i originally wanted to build a hopped up stocker, but Mreick and some others talked me into going a big bore kit, at least for what i want.  i want something that will handle pretty damn well and be able to pull itself around nicely on the road.  and i think the 836 would be the best for that!  and i'll throw gordon's frame kit in there so i can work on it easier if need be...

but if you can afford it, go all the way!  i don't think i'll regret that decision!

[mazingerzeca]

I've seen that 836 kits are very popular here, but maybe it would be useless without a head job, and I don't know who can do it here in Spain, even not in all Europe, and sending the head to USA and getting it back would be very expensive.

[MRieck]

I've seen that 836 kits are very popular here, but maybe it would be useless without a head job, and I don't know who can do it here in Spain, even not in all Europe, and sending the head to USA and getting it back would be very expensive.

It is about 100.00 dollars to ship a head to Europe from the USA. That is air mail

[eurban]

The heads on your K7 should flow fairly well stock.  Honda improved the flow characteristics on the later heads.  The 10.25-1 cr 836 kit combined with a mild performance camshaft should (assuming everything else is tuned well) get you between 60 and 70 rwhp with a noticeable improvement in low end torque.  Its a nice performance upgrade. . . .

[mazingerzeca]

By a mild cam you mean the stock one?