Author Topic: where to buy 836cc kit? (Read 6648 times)

Sam Green Racing · « **Reply #25 on:** June 19, 2007, 02:09:53 PM »

All Honda pistons that I have seen are cast but I'm not sure if modern day replacments are .

Sam

eurban · « **Reply #26 on:** June 19, 2007, 03:24:09 PM »

The cycle exchange kit actually gives you more like 850cc. This means that your cylinder walls will be thinner than those machined for the 836 kits. I can not say for sure whether or not this is an issue but I always understood that the 836 bore size was pushing the limits for the stock liners. Also keep in mind that these kits are running higher compression ratios than the stock setup increasing the stress on the pistons. Can't really say whether or not the cheaper Cylexchange product will hold up (it hasn't been offered for very long) but Wiesco has been offering their kit for years. . . . .

eengler2 · « **Reply #27 on:** June 19, 2007, 06:47:54 PM »

Cast pistons are also lighter which would be LESS stress on crank and rods. I believe the last time I checked Cyclexchange site they recommended a cam upgrade (more overlap) to "soften" the higher compression at lower rpms.

As stated in previous posts, Forged are better for forced induction and nitrous because of the better resistance to detonation, but you usually need to run a little looser tolerances for more expansion of the forged pistons.

So street motor, good tune, no turbo, supercharger, or nitrous...cast will be just fine!

seaweb11 · « **Reply #28 on:** June 19, 2007, 06:52:51 PM »

A new member! 1st post ......and he seems intelligent....can we keep him?

Welcome eengler2

fretso · « **Reply #29 on:** June 19, 2007, 06:59:58 PM »

cycle exchange has a "hillclimber" motor 130 horses at rear tire, for a mere 10 grand

Sam Green Racing · « **Reply #30 on:** June 19, 2007, 07:03:31 PM »

Sounds cheap enough for that amount of power

And welcome to our 2 new posters

Sam.

ksmith0034 · « **Reply #31 on:** June 19, 2007, 07:21:00 PM »

Is it necessary to replace the cam when going to an 836cc kit? Or will the stock work just fine?

seaweb11 · « **Reply #32 on:** June 19, 2007, 07:33:15 PM »

It was recomended by both cycle exchange and my builder to replace the cam .

I will also ad that I purchased a lightened fly wheel for the engine from CX. My mechanic recomended it with the increased HP.

I'm new to this engine build stuff so I tend to liisten here and also to my vendors and mechanics.

jaguar · « **Reply #33 on:** June 19, 2007, 08:13:41 PM »

i have a K and a F(78) motor and im not sure what motor to build up. heard the 78 has bigger vavles but there are soo many more parts listed for K motors. will cams interchange? what about other parts?

Hockers Choppers · « **Reply #34 on:** June 19, 2007, 08:35:30 PM »

The f has a better bottom end but the topend is better on the k. I used the f bottom and put a k top on my engine. Make sure you use a k cylinder with the head, the oil return was different with the f cylinder/head. You can't get high performance parts for the f topend, and it had low compression and weak valve retainers. The f bottom end had bigger rod bolts, stronger cam chain, and a lower 5th gear ratio. Call ken at cyclex, he has built an f hot rod, but I think he spent a lot of $ to get it right.

jaguar · « **Reply #35 on:** June 20, 2007, 03:42:51 AM »

so what was it that i heard about he 78 head bing the one to use? i found SS vavles for a F too.

KB02 · « **Reply #36 on:** June 20, 2007, 04:49:28 AM »

Another question I have is about carbs on a big bore kit. Obviously the larger displacement will call for more gas so jetting and needle adjustments will be called for, but is the bore of the stock carbs big enough to feed the extra 100 cc's (or 114 cc's if you do the 850 kit)?

tmht · « **Reply #37 on:** June 20, 2007, 05:18:20 AM »

Quote from: Hockers Choppers on June 19, 2007, 08:35:30 PM

The f has a better bottom end but the topend is better on the k. I used the f bottom and put a k top on my engine. Make sure you use a k cylinder with the head, the oil return was different with the f cylinder/head. You can't get high performance parts for the f topend, and it had low compression and weak valve retainers. The f bottom end had bigger rod bolts, stronger cam chain, and a lower 5th gear ratio. Call ken at cyclex, he has built an f hot rod, but I think he spent a lot of $ to get it right.

My understanding was that the F and the K were identical from the jugs down. What exactly is the difference?

Hockers Choppers · « **Reply #38 on:** June 20, 2007, 06:13:31 AM »

The head has 1 point lower compression, so if you do the 10.5-1 pistons you'll only have 9.5-1.

The f topend returns the oil down 4 of the cylinder studs instead of 8 like the k. If you use a f cylinder with a k head, 4 of the return drains will be blocked and the valve cover fills with oil!

I don't think rejetting is a big issue but bigger carbs never hurt.

mazingerzeca · « **Reply #39 on:** June 20, 2007, 10:04:40 AM »

Quote from: Hockers Choppers on June 20, 2007, 06:13:31 AM

The f topend returns the oil down 4 of the cylinder studs instead of 8 like the k. If you use a f cylinder with a k head, 4 of the return drains will be blocked and the valve cover fills with oil!

Why did Honda introduce that modification on F2-F3 heads? Instead of having an oil return hole for each spring they made a passage between the springs and all the oil comes through the outer springs holes, but why?

Hockers Choppers · « **Reply #40 on:** June 20, 2007, 11:30:10 AM »

I don't know, why did they drop the compression and increase the rpm? and weaken the spring retainers? Why did they stop using the sohc???

rupzuk · « **Reply #41 on:** June 22, 2007, 12:37:27 PM »

I to have a 78 f1 ( ? ) engine . I thought the heads were the ones to use due to the larger ports and valves .
Can a guy inprove the F head by installing aftermarket valves , springs,retainers ?
So with 12.5:1 pistons on this head it should come out to about 11.5:1 ?

jaguar · « **Reply #42 on:** June 22, 2007, 08:59:39 PM »

i know that i must sound like and idiot but the 78F motor is not the place to start?

mazingerzeca · « **Reply #43 on:** June 23, 2007, 02:08:36 AM »

As far as I know, a big bore kit can not be installed with a F2-F3 head. The wiseco kit pistons are like the k0-k8 pistons, they have a shape in which the F2-F3 valves would crush. I think that the F1 head can be used. Dynoman sells aftermarket valves for the F2 heads, and springs, guides and so on, but anyway, a big bore kit can not be used.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #44 on:** June 23, 2007, 09:30:26 AM »

75 is F0 ; 76 is F1 ; 77 is F2 ; 78 is F3 in the US.

75 F0 ; 76 F1 ; 77 K7 ; 78 K8 all use a 392 head which first originated with the 75 F0

77 F2 & 78 F3 use a head with larger valves which in theory is better since it allows more airflow. However it did not hold up as well apparently due to premature valve guide wear caused by changed valve angles to accommodate those larger valves.

You can install larger intake valves on any K head or the 392 head for increased flow, still have the better valve angle and use the 810/823/836/888/900/915/1000 etc kits. Stronger springs are a must if you're going to build a high performance engine. I dropped a valve due to valve float above 10K on a missed shift on my stock F0 engine. One expensive mess!

My thoughts on the F2/F3 head/bike are to replace the valves guides, change the cam & springs, Titanium retainers, stainless valves, port & polish the head but leave it as a 736.

eurban · « **Reply #45 on:** June 23, 2007, 10:54:02 AM »

Good info from Rxman . The 392 head seems to be a better flowing head than the earlier castings. One thing to add is that the K8 used different valves than the earlier Ks. These valves use different cotters that I believe are also used on the F3 and perhaps F2. They appear to be a lighter setup. The valves don't seem to be available from Honda any longer but the earlier style valves will work fine as long as you use the correct cotters. Aftermarket larger valves will use the earlier cotters. . . . .

Big Jay · « **Reply #46 on:** June 23, 2007, 11:47:12 AM »

Quote from: Rocking-M on June 18, 2007, 06:51:04 PM

I went to the CBR site and they list valve guides for the SOHC 750.
Would these work in the F head? I'd sure like to keep the ole F head.

Yes they fit all sohc 750s

Big Jay · « **Reply #47 on:** June 23, 2007, 12:01:51 PM »

Back in the day, we made titanium retainers for the shim on top Kawasaki Z1. Turned out that the keeper bore / taper, etc was same as the F2. So everyone put the Kawasaki retainers in the F2.

As for the valves, there was no problem with the oem, just can't get them anymore. Valves could be made from blanks and would need to run a lash cap.

A wiseco 836 kit would probably wind up a little low on compression. They used to make a kit for the F2 which was the same as the K with a little more dome. I used to sell those to the 3/4 midjet racers who ran their cars on akly with a K head and liked the additional compression.

I just had a set of JE 12.5:1s in here for a customer. That piston would probably be 11 :1 in an F2.

Jay

Hockers Choppers · « **Reply #48 on:** June 23, 2007, 03:06:02 PM »

When I pulled the f head off my 78 the exhaust guides had .010 of mic'd clearance!!! It was running and only had 12k miles. I can't imagine bronze guides lasting any longer?

mazingerzeca · « **Reply #49 on:** June 23, 2007, 05:48:12 PM »

Quote from: Hockers Choppers on June 23, 2007, 03:06:02 PM

When I pulled the f head off my 78 the exhaust guides had .010 of mic'd clearance!!! It was running and only had 12k miles. I can't imagine bronze guides lasting any longer?

which material were the original guides made of? I've read here that the original guides were superseeded by Honda after detecting the problem. Maybe the bronze guides you can buy now also would fix the problem.

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Author Topic: where to buy 836cc kit? (Read 6648 times)

fretso

tmht

rupzuk