Author Topic: 836 cc or 812 cc - Which Way To Go...(need rings too!) (Read 12832 times)

Bill/BentON Racing · « **on:** October 06, 2009, 06:50:31 PM »

Went over to shed @ old house,found cylinder w/Pop's 812 kit,also 836 RC? Venolia pistons? Getting ready to install in Calendar Girl,traded Drew 2009 my 2008 CBR600RR and 74 CB350F straight up for Calendar Girl and spares(picked up the CBR600RR for song and dance!).Wondering which to use? Also need rings.It's neat to see POP Y and 812 again(been too long).Have some NOS 29mm smoothbores and Raask rearsets to install also along w/braided oil and brake lines!Bill

bwaller · « **Reply #1 on:** October 06, 2009, 08:38:55 PM »

I used to race mine with the 812 option then ran it on the street for many miles afterward. It would be a good bump in power with a cam and those carbs. I always liked these. Although most lean to the 836 these days.

At least rings are easy.

mick7504 · « **Reply #2 on:** October 06, 2009, 09:01:03 PM »

It's great to find those goodies in the shed that have been there for years and forgotten about - that's if the kids haven't found them first.
I told 'em about a big brown snake that lives in there and so far it's worked.

Trouble is that they only believed in Santa for so long!!!!

Jerry Rxman Griffin aka MuthaF'er · « **Reply #3 on:** October 06, 2009, 10:55:14 PM »

I went 812 Pops when I blew mine. My reasoning at that time was the next time I blew it I could go 836 without new cylinders. 30 years later I now have a 900 kitted and ready, a 1000 at Big Jay's, and a 1080 sitting in a box in the basement. It's amazing what time and money will do for wisdom

If you need rings for the Pops 812 just order the rings for a 68 CB350 twin. Just be sure you get the right number for the 3 piece oil rings.

I could base your decision on the comparable weights as much as the extra 1mm.

Bill/BentON Racing · « **Reply #4 on:** October 07, 2009, 04:24:18 AM »

Thanks,yes weighing them was next,the 812s have the old style one pc. oil ring,will get some CB350 rings w/3 pc. oil rings.Thanks,Bill

bucky katt · « **Reply #5 on:** October 07, 2009, 08:13:55 AM »

you dont want that 812cc kit, thats no good for you. just send it to me! lol seriously though, i'd go with the 812 kit, then when the cylinders wear some you still have the 836cc kit to go to before having to replace cylinders

voxonda · « **Reply #6 on:** October 07, 2009, 08:42:52 AM »

Or after that go 850 before trowing anything away!

delay pedal · « **Reply #7 on:** October 07, 2009, 09:57:00 AM »

throw some pics up of the raasks after the install
im curious how they look compared to the tarozzis i have

Bill/BentON Racing · « **Reply #8 on:** October 09, 2009, 04:24:45 PM »

Geting ready to install Raasks if my mouth will quit hurting!,Had rt rear molar extracted Wed.@5:00 p.m.It hurts,(dry socket)?but not what Havoc and others going thru,anyway weighed the Yosh 812's 171.7 for 3,one weighs 172.2,Wiseco weighs 177.7,Venolia (RC),192.2,Yosh tapered pins weigh 31.2,RC 39.7,Length of pin,Yosh 57mm,RC 53,Go figure,? What does stock pin weigh and how long is it?Also weight of stock piston(K) model? I plan on using the Yosh,weight,can bore again to 836,and just to honor Pop!!Also looks like dome slightly higher.Bill

BLUE71TURBO · « **Reply #9 on:** October 09, 2009, 04:34:16 PM »

Hey Bill !! Get some " OIL OF CLOVES " to put on the sore area in yer mouth. It works really great !!

JON G.

Bill/BentON Racing · « **Reply #10 on:** October 09, 2009, 05:26:30 PM »

Thanks Jon,off to store I go,I was wrong earlier,the Venolia piston had the one pc.oil ring,Sorry Pop,turn back over,it's OK,I should have known better!!,Bill

cavebear · « **Reply #11 on:** November 01, 2009, 06:29:44 AM »

I like the 811cc kit. I have a nos Forged True kit that I'm going to install with a 6mm stroker crank for a capacity of 921 cc in a F2 top end. Also Kenny Harmon D grind cam,ported head, oversize stainless valves and a choice between nos Kerker, Winning Performance or Yoshimura headers.

Bill/BentON Racing · « **Reply #12 on:** November 01, 2009, 07:25:53 AM »

Nice candy to choose from there,post pics etc!,Good Luck,Bill

eurban · « **Reply #13 on:** November 01, 2009, 11:15:21 AM »

Quote from: cavebear on November 01, 2009, 06:29:44 AM

I like the 811cc kit. I have a nos Forged True kit that I'm going to install with a 6mm stroker crank for a capacity of 921 cc in a F2 top end. Also Kenny Harmon D grind cam,ported head, oversize stainless valves and a choice between nos Kerker, Winning Performance or Yoshimura headers.

Likely you are already aware, but the the F2/F3 head will give you a larger combustion chamber (18%?) This also results in a lower compression ratio than "advertised" when you use pistons designed for the K engines. For example a standard Wiesco 10.25-1 836 kit will give unsatisfactory results in F2/F3 engine with a compression ratio of around 8.5-1.

cavebear · « **Reply #14 on:** November 01, 2009, 07:43:02 PM »

Overlooked 2 items.

1-This engine will have a ported/polished K head.
2- I recommend Total Seal gapless rings. I used them on three different Turbo motors in my glory days and they never failed.

Also I'll post a list and photos of engine parts for mixing and matching shortly.

Mike

rokart · « **Reply #15 on:** January 04, 2010, 07:16:27 AM »

Hallo,

interesting how many different versions of big bore sets have been produced, further the possibilities of using piston rings from former models. I have opened my old engine CB 750 and inside was 812 cc, piston dia 64. On the piston is described (Honda, CB 810, D 64, Toho). The oil ring is 1 piece, and after my newest information, also here in forum mentioned, the piston rings from cb 350 twin will fit.

Before worn out the engine was running fine with that 812cc, from start to midrange, not at top end.

Does anybody know something about that piston or set? Will that 350 rings also fit, as they do on the Yosh 812cc pistons?
Thanks and regards
Klaus

andy750 · « **Reply #16 on:** January 04, 2010, 07:47:14 AM »

Quote from: rokart on January 04, 2010, 07:16:27 AM

Before worn out the engine was running fine with that 812cc, from start to midrange, not at top end.

Does anybody know something about that piston or set? Will that 350 rings also fit, as they do on the Yosh 812cc pistons?

Hi Klaus,

I am interested to know how much performance increase you saw over stock (736cc) with the 812cc. What do you mean there was no top end increase? Is that due to cam choice?

Perhaps a photo of your piston would help identification? I aquired a spare engine with a 812cc kit in it - currently getting rebuilt and 350 rings are being used with those pistons. Pretty sure they are not Yosh 812cc pistons - anyone know who else made the 812cc kit??

cheers
Andy

rokart · « **Reply #17 on:** January 04, 2010, 08:50:09 AM »

Hi Andy,

what i mean with "not at top end" , was that the engine was running fine upto 7000 rpm.
Cam and valves are original, no other modifications, engine K7.

Nearby the pics of the piston

Klaus

754 · « **Reply #18 on:** January 04, 2010, 09:03:52 AM »

Rocky Cycle sold one I think,

Forgedtrue.. used forged slugs...138.00 new I think!

andy750 · « **Reply #19 on:** January 04, 2010, 09:47:51 AM »

Thanks for the feedback Klaus. So you think its better in the midrange than stock?

Cheers
Andy

rokart · « **Reply #20 on:** January 04, 2010, 10:00:29 AM »

Hi Andy,

sure it is really better than stock, from bottom to midrange. Was fun to drive, even with two persons.
The type of carburator with acceleration pump is neccessary.
This is the reason while i am looking to use the pistons again, with hopefully new rings.

You see its not Yosh, its true Honda piston...(

)

Klaus

andy750 · « **Reply #21 on:** January 04, 2010, 10:09:13 AM »

Thanks Klaus good to know! I am looking forward to trying it out for myself. As for the carbs why do the accelerator carbs make such a big difference with the 812cc kit?

cheers
Andy

rokart · « **Reply #22 on:** January 04, 2010, 10:21:22 AM »

Hi Andy,

i have tried both carburators from the 750s on that 812cc, result was that
that the type with acc pump worked much better. Think that it gives more petrol on lower rpms.

Any thougts about rings for my piston??
Klaus

HB-1fan · « **Reply #23 on:** January 04, 2010, 03:11:42 PM »

Bill, keep looking in the shed, maybe there is some more POPS hard parts to go with the pistons. Rods and cam, maybe!!

HB

Jerry Rxman Griffin aka MuthaF'er · « **Reply #24 on:** January 04, 2010, 06:01:16 PM »

Klaus,

What are the ring and land measurements?

Very interesting pistons. I wouldn't believed it without seeing it. Anyone have ANY background info? Honda and CB810??! Honda experiment?

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Author Topic: 836 cc or 812 cc - Which Way To Go...(need rings too!) (Read 12832 times)

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