Author Topic: 1st over instead of 836 ? (Read 4055 times)

Bill K · « **on:** January 25, 2010, 04:33:03 PM »

I've tore down my motor this winter including splitting the cases to fix some oil leaks. Head gasket and counter shaft seal. The bike has good compression and runs fine. I just "wanted" to do a 836. Well that's snowballing into big bucks so now I'm reconsidering. After talking with Ken at Cycle X today (hell of a nice guy) I'm thinking of going with the 1st over piston kit they now offer. Cam, pistons, gasket set, 400.00 bucks. Just looking for opinions. What ya think ?

Thanks, Bill K

MCRider · « **Reply #1 on:** January 25, 2010, 04:43:03 PM »

Quote from: Bill K on January 25, 2010, 04:33:03 PM

I've tore down my motor this winter including splitting the cases to fix some oil leaks. Head gasket and counter shaft seal. The bike has good compression and runs fine. I just "wanted" to do a 836. Well that's snowballing into big bucks so now I'm reconsidering. After talking with Ken at Cycle X today (hell of a nice guy) I'm thinking of going with the 1st over piston kit they now offer. Cam, pistons, gasket set, 400.00 bucks. Just looking for opinions. What ya think ?

Thanks, Bill K

A good running stocker is still a handful. "First over" is just 1/4mm, though and that's nothing but a clean up. Are we talking about the same thing?

Nevertheless, a cleaned up stocker, with a street cam, pipe, can be really sweet and last forever. Spend some money on steering stem bearings, freshen up the suspension with oil and springs. Maybe take an MSF course.

I went to his site, hadn't seen it in a while. It is a .25mm 1st over cleanup kit. Not much more cc but it will be fresh and new and I think you'd like it.

Whaleman · « **Reply #2 on:** January 25, 2010, 04:53:10 PM »

I second MCRider's thoughts.Cam, pistons,rings and gasket set is a great deal for $400.00. Thing is your cam is most likley fine. Dan

Terry in Australia · « **Reply #3 on:** January 25, 2010, 04:55:34 PM »

400 bucks for a new set of pistons, rings, gaskets and a performance cam is a bloody bargain mate, go for it!

Bill K · « **Reply #4 on:** January 25, 2010, 04:56:58 PM »

Yea, its a 0.25 pston kit, I figured that would freshen it up nice. The kit comes with a 360 lift / 270 duration cam. Think I'll notice a differnce with that ? When it comes to cams the tech. end of that goes over my head pretty quick.

MCRider · « **Reply #5 on:** January 25, 2010, 05:00:09 PM »

Quote from: Bill K on January 25, 2010, 04:56:58 PM

Yea, its a 0.25 pston kit, I figured that would freshen it up nice. The kit comes with a 360 lift / 270 duration cam. Think I'll notice a differnce with that ? When it comes to cam the tech. end of that goes over my head pretty quick.

That sounds like the webcam 41 grind. I'll be using that in mine. I have some more cc, but I wanted to keep it mild.

Yes you'll notice a difference. You may need to tweak the jets a bit depending on your pipe. I'm sure Ken will help.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #6 on:** January 25, 2010, 05:13:54 PM »

From the other side, why even go 1st over? If you're going to go over, then go 4mm over ie 836?! You have to prep the cylinders either way and it can't be that much more expensive. Now, if you've got good compression etc stock, why not jut hone and rering stock size vs .25mm over and save the cost of pistons?

Cams are always good

wannabridin · « **Reply #7 on:** January 25, 2010, 05:25:18 PM »

the reason to not to an overbore and just a hone to known down the glaze is because of cost. if they have to bore, it's going to add cost to the build. you can still get away with a nice little motor with no overbore. i'm going this way, hopefully i don't have to bore at all to keep price down. i might consider this kit from Ken if i do though. otherwise, i'll use the money i save and get some HD springs. and if you do overbore, try and find a set of 4mm pistons. i believe this is a 752 cc size, at least this is what Terry has told me. good luck with the build! keep us posted!

Bill K · « **Reply #8 on:** January 25, 2010, 05:37:54 PM »

Thanks for the input guys. What ever I decide to do I'll post some pics of my rebuild when I get some parts in. I need to get at it. I wanna be riding when the weather warms up !

MCRider · « **Reply #9 on:** January 25, 2010, 05:40:09 PM »

Quote from: wannabridin on January 25, 2010, 05:25:18 PM

the reason to not to an overbore and just a hone to known down the glaze is because of cost. if they have to bore, it's going to add cost to the build. you can still get away with a nice little motor with no overbore. i'm going this way, hopefully i don't have to bore at all to keep price down. i might consider this kit from Ken if i do though. otherwise, i'll use the money i save and get some HD springs. and if you do overbore, try and find a set of 4mm pistons. i believe this is a 752 cc size, at least this is what Terry has told me. good luck with the build! keep us posted!

A little misunderstanding. 4mm over is an 836cc. "4th over" is 1 mm over (4 increments of .25mm each) and comes to 752cc, I think.

While we're talking, does Ken's 1st over (+,25mm) require boring. I expect it does so there's some cost that would be nearly (maybe not?) the same for a 1st over or an 836cc kit.

Fun with calculators:
http://www.nightrider.com/biketech/calc_displacement.htm

Actually it looks like a 4th over (62mm x 63mm bore) is 761cc.

HondaMan · « **Reply #10 on:** January 25, 2010, 05:43:32 PM »

Going to 1st over will net you about 10% more power than you had before, that's a fact. It's technical: check in the Thoughts of Hondaman for the reasons.

If you also port the head, deshroud the valves, polish the valves, and match the intakes, you can bump over 70 HP in a K1. In the K4, the rebore plus all of this stuff usually nets a good 8 HP more than before.

wannabridin · « **Reply #11 on:** January 25, 2010, 06:24:07 PM »

a 1st over good for that kinds of increases?? wow! i guess restoring the compression and stuff is good for some power. if i have to bore, i'm going to try for the 4th over, 1mm, should be good for some better power i'd imagine. plus i can still say it's "stock"

oops, i did misread what was typed there, 4mm, not 4th overbore! but i do agree that if you have to bore .5mm or 4mm, it'll be the same price...

MCRider · « **Reply #12 on:** January 25, 2010, 06:43:44 PM »

Quote from: wannabridin on January 25, 2010, 06:24:07 PM

a 1st over good for that kinds of increases?? wow! i guess restoring the compression and stuff is good for some power. if i have to bore, i'm going to try for the 4th over, 1mm, should be good for some better power i'd imagine. plus i can still say it's "stock"

oops, i did misread what was typed there, 4mm, not 4th overbore! but i do agree that if you have to bore .5mm or 4mm, it'll be the same price...

My shortlived roadracer was a mismatch of parts. The class was unlimited modifications except displacement which had to be 750cc or less. So I had Yoshimura 2nd over (61.5mm, 749cc) 2 ring high compression slipper pistons, a Yoshimura East cylinder head valves, springs. But I thought I was smarter than them and used an RC big bump drag race cam. I had 2 DCOE40 Weber carburetors with 32mm venturis and a RB Racing pipe, hyped to be a replica of the Honda Bol Dors pipe. Lightened and balanced crank...but I cheaped out on the rods. Hey, its still only a 750 right?

THing would scream. But still a 750, but I could pull many open class bikes down the straights...till it bent a rod. I was pretty proud of that, bending a rod with a "stocker".

754 · « **Reply #13 on:** January 25, 2010, 08:11:43 PM »

Which cam MC?

Just a warning, if you go .25 or up to 1mm.. over, DONT let anyone talk you into HONING it out to save money or for whatever reason. Better to bore, then finish hone, straighter hole.. It can be done on certain hones, and done badly on a lot more..

Doing the bore for 836 does cost more, more meat to remove..

Do yourself a favor if its possible..try to ride an 836, and see how you like it...its more money, but more power..

wannabridin · « **Reply #14 on:** January 25, 2010, 08:25:28 PM »

no way for me to ride an 836, there's nobody around here that really even has a cb, let alone an 836!! plus, the cost of the 836 and parts is about 400 or so more than i'd like to spend, then throw in there the fact that i'd like to make it even hotter than i would with a stock displacement... so basically it's $400 at least over what i wanna spend that i could throw into other places, and i just wanna get this dang thing back on the road!!!

plus, having a bit of a screamer "stock" bore sleeper is always cool!

Don R · « **Reply #15 on:** January 25, 2010, 10:15:38 PM »

More's law, If more is better, than too much is just right.

dave500 · « **Reply #16 on:** January 25, 2010, 10:41:57 PM »

stay with the 1st oversize!!itll have plenty power and pull,dont be tempted to thrash it ,break it in nice with frequent early oil and filter changes,youll sort out the jetting properly once its run in and you can climb the rev range.lug it slightly to bed in the rings ,about a minute then cruise then lug then cruise,a few times over,dont let it idle for long with a fresh rebore!!

Terry in Australia · « **Reply #17 on:** January 26, 2010, 02:20:43 AM »

FWIW, the difference in cost between a 1st oversize bore and a 4mm 836 big bore job here in Oz is substantial. My old Repco boring bar is only good for 20 thou passes max, so a 10 thou pass for a 1st oversize bore requiring one or two passes at the most, will be a heck of a lot cheaper than 16-20 passes per cylinder for an 836 kit. I imagine that modern boring bars can do bigger cuts than mine, but even so, the more cuts required, the more the labour cost. Cheers, Terry.

wannabridin · « **Reply #18 on:** January 26, 2010, 05:18:13 AM »

touche terry. i didn't think about the cylinders needing multiple passes, i just figured they took most of it off in one rough cut with a carbide insert or the like and then did a final pass or two to finish up the dimensions...

either way, wouldn't a 1st overbore be better in case you need to bore out again later? or is it true that with proper break in, you'll be just fine going straight to the 4th overbore (1mm) and having it last awhile with some decent high speed runs?

MCRider · « **Reply #19 on:** January 26, 2010, 05:58:10 AM »

Quote from: Terry in Australia on January 26, 2010, 02:20:43 AM

FWIW, the difference in cost between a 1st oversize bore and a 4mm 836 big bore job here in Oz is substantial. My old Repco boring bar is only good for 20 thou passes max, so a 10 thou pass for a 1st oversize bore requiring one or two passes at the most, will be a heck of a lot cheaper than 16-20 passes per cylinder for an 836 kit. I imagine that modern boring bars can do bigger cuts than mine, but even so, the more cuts required, the more the labour cost. Cheers, Terry.

Got it, thanks.

MCRider · « **Reply #20 on:** January 26, 2010, 06:03:32 AM »

Quote from: wannabridin on January 26, 2010, 05:18:13 AM

touche terry. i didn't think about the cylinders needing multiple passes, i just figured they took most of it off in one rough cut with a carbide insert or the like and then did a final pass or two to finish up the dimensions...

either way, wouldn't a 1st overbore be better in case you need to bore out again later? or is it true that with proper break in, you'll be just fine going straight to the 4th overbore (1mm) and having it last awhile with some decent high speed runs?

If you go straight to the 4th overbore, and wear it out, you still have lots of alternatives. Next up is the 810/811, then 836, then 850. Wear all those out I'll give you a cigar.

General FYI: The 1st thru 4th overbores are so named as they are the overhaul alternatives offered by Honda (or were). .25 mm at a time. After that, you enter the "aftermarket" territory. Many/most just skip the OEM alternatives and go straight for the throat with an 836. But as HondaMan and my seat of the pants indicates, a well prepared stocker with OEM size overbores can be plenty of fun and leaves more money better spent on suspension restoration, safety gear and training.

MCRider · « **Reply #21 on:** January 26, 2010, 06:05:45 AM »

Quote from: 754 on January 25, 2010, 08:11:43 PM

Which cam MC?

SNIP

I don't remember exactly, But in those days I was into the bigger the better and I remember the lobes being huge. The pistons, I still have them, had nick marks in the pockets from valve contact, probably over-revving.

MattFreeman · « **Reply #22 on:** January 26, 2010, 06:35:04 AM »

I was considering the cyclex first over pistons and decided against it because the pistons were cast, if I remember correctly, instead of forged.

It that really a big deal or not? Has anyone tried the "tinned" pistons from CX?

MCRider · « **Reply #23 on:** January 26, 2010, 06:59:01 AM »

Quote from: MattFreeman on January 26, 2010, 06:35:04 AM

I was considering the cyclex first over pistons and decided against it because the pistons were cast, if I remember correctly, instead of forged.

It that really a big deal or not? Has anyone tried the "tinned" pistons from CX?

At that size I doubt you'd find any forged pistons for general street use. Except in the mega-hi performance area. I see M3 (big time racer shop) has 62mm (4th over) piston kits for $695-$795. They are likely forged and high compression to boot.

That's usually reserved for the bigger pistons. It was fine for the factory, fine for replacement. It's all relative to cost and what you're trying to acheive.

Pistons have been coated with various things for many years. I've never tried any myself.

sangyo soichiro · « **Reply #24 on:** January 26, 2010, 07:50:55 AM »

I am torn on this issue myself. At first, I wanted to jump to the 836. And I had everything else, like which cam, etc., figured out to match the 836. But then I read a thread where HondaMan said, basically, that a first overbore may be better because of issues with the cylinders becoming out-of-round and non-parallel within 5-10k miles, and that the first overbore cures this, but the 836 starts the process over again. Plus, I kind of like the idea of increasing performance via finesse rather than brute force.

But then... seems like trying to find parts for a mild overbore is a pain in the butt. I, also (like MattFreeman), want to avoid cast pistons and would rather have forged ones. But I can't seem to find high-compression pistons for the first overbore, and the cost of the forth overbore pistons (the only thing I can find) seems more than the Wiseco 836 by about a couple hundred dollars. And if I go to F pistons, I'm going to struggle with making sure whichever cam I use that the valves don't hit the pistons. It seems like the cams are pretty much figured out for you if you go to the 836 because of the popularity of this bore size, but for the Wiseco forth over I'm no longer sure which cam would work best.

It's a lot to decide, and time's ticking away. I don't want the good weather to get here and still have my bike in pieces thinking about what to do.... $:-\$

Question for you old timers: Let's say I just wanted to do a first overbore. Let's also say that I wanted to use my stock pistons. (Forget for the moment that my Hemi'd head could use higher compression pistons.) For the first overbore, is it just a matter of buying the correct rings, or are new "first over" pistons required? Just curious.

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Author Topic: 1st over instead of 836 ? (Read 4055 times)