Author Topic: cylinder dowels (Read 9945 times)

oldk6guy · « **on:** July 03, 2011, 12:27:21 PM »

how important are these? how many am i supposed to have? where can i get some? i think i may be missing a few.

KingCustomCycles.com · « **Reply #1 on:** July 03, 2011, 12:44:25 PM »

Very important, are available new or used, will make assembly much more precise and aid with gasket location. 2 in the head, 2 in the block, and I believe 2 per stator cover. They are different sizes also.

zzpete · « **Reply #2 on:** July 03, 2011, 12:50:09 PM »

Z1 or CycleX has them.
http://www.z1enterprises.com/products01/APE-16-piece-Heavy-Duty-Cylinder-studs-Honda-CB750-SOHC.aspx
http://www.cyclexchange.net/Engine%20Parts%20Valve%20Trane.htm

oldk6guy · « **Reply #3 on:** July 03, 2011, 05:40:49 PM »

those are head studs. not at all what im talking about. i do have the APE set from cycleX BTW.

zzpete · « **Reply #4 on:** July 03, 2011, 06:28:54 PM »

Quote from: k5streetfighter on July 03, 2011, 05:40:49 PM

those are head studs. not at all what im talking about. i do have the APE set from cycleX BTW.

OH sorry you mean these!
http://cgi.ebay.com/ebaymotors/HONDA-CB750-KO-K5-CYLINDER-HEAD-DOWEL-2-/390243358062
or these
http://babbitts.motorsportdealers.com/pages/OemParts#/s/HOM/CB750/94301-12150/1

HondaMan · « **Reply #5 on:** July 03, 2011, 09:03:21 PM »

In the 750K5 engine, there are 3 different length dowels: 12x20 (or 22 in the last K6 engines), 12x18, and 12x15mm size. Check at www.kawasakipartsnation.com for your particular engine (in Honda parts) to see the right sizes and where they go. Their K5 fiche is correct: you can right-click on their pictures and print them for reference.

oldk6guy · « **Reply #6 on:** July 03, 2011, 09:47:15 PM »

awesome. thank you guys so much!!!

oldk6guy · « **Reply #7 on:** July 03, 2011, 11:07:29 PM »

hondaman, that link has nothing at all for my engine. how else could i find out the length of the missing dowels?

zzpete · « **Reply #8 on:** July 04, 2011, 05:17:35 AM »

This link will show pin dowels and size (the size is shown in the parts list) for the cylinder:
http://www.servicehondapsn.com/fiche_section_detail.asp?section=126222&category=MOTORCYCLES&make=HONDA&year=1975&fveh=3003
This link will show the pin dowels and size for the head:
http://www.servicehondapsn.com/fiche_section_detail.asp?section=126221&category=MOTORCYCLES&make=HONDA&year=1975&fveh=3003

HondaMan · « **Reply #9 on:** July 04, 2011, 09:37:02 PM »

Quote from: k5streetfighter on July 03, 2011, 11:07:29 PM

hondaman, that link has nothing at all for my engine. how else could i find out the length of the missing dowels?

I think they moved the 750 into the "All models with no year" section.

oldk6guy · « **Reply #10 on:** July 04, 2011, 11:54:17 PM »

here is where i'm talking about, the four holes in the middle. see how they have a seat machined for a dowel? yet no dowel. i have the two between the crank case and the cylinder block. i also have the two on the corners of the cylinder block. however, there are four more in between the cylinders and it appears that there are four missing.

MCRider · « **Reply #11 on:** July 05, 2011, 12:26:39 AM »

You have the later style cylinder than what's been talked about here, though its not real late, laike K3+ or so.

Anyway, those are for holding the ORings in place which was an attempt by Honda to reduce the chance of oil leaking out of the head gasket in those areas. those dowels are not the alignent dowels that have been discussed so ar, and which you indicate you have.

Yes you are missing 4 of the "special" knock pins and their ORings. They are available from Honda, the Fish calls for 12mm x 16mm. Sometimes these dowels are indicated on the fish (I use motogrid) but when actually ordered they get put on an infinte backorder. They are not crusial to alignment and possibly not crucial to oil control either. Those pasageways are not under pressure. Oil flows thru them from the cam area to the crankcase by gravity.

In discussions here it has been indicated that those can be left out under the logic that the early ones didn't have them at all.

But I don't know for sure.

I think if twere me, I'd find them and put them in.

MCRider · « **Reply #12 on:** July 05, 2011, 12:35:14 AM »

The two passages on the rear of the cylinder on either side of the cam chain tunnel are under pressure and require ORings, but not knock pins.

HondaMan · « **Reply #13 on:** July 05, 2011, 11:18:13 AM »

The dowels that go inside those 8 rubber seals ('donuts') are primarily there to prevent the collapse of the rubber seal when the head compresses them, on K3 and later engines. On the earlier engines, the head gasket had a sealant (clear) painted on it around those same holes, which glued the head shut to make the seal (and made it REAL hard to get apart later). When the 811cc and 836cc high-compression kits appeared, the increased crankcase pressure from the larger rings (especially 836) made the seal goo dissolve away with oil and internal pressures, making the [in]famouse K0/K1 front-of-engine oil leaks. Honda responded by making bigger crankcase vents at the back of the engine and installing the 8 little rubber donuts in these stud holes, to help keep the engines clean. This worked better: when the PCV system was installed on the F0 bikes (and some K6) to meet EPA rules, the extra suction was additionally routed to the crankcase in improve the situation even more.
In those days, Honda was very concerned about 'keeping face' with the appearance of their bikes, even if they were not stock.

oldk6guy · « **Reply #14 on:** July 05, 2011, 07:53:37 PM »

well, i have an 850cc kit that im about to install in the next few weeks. i believe it raises compression as well. although im not sure how much. the pistons are 65mm. i have all of the rubber doughnuts, brand new from cycleX. so do i need to try to find some of those dowels or would i be okay without them? what kind of sealant should i use?

oldk6guy · « **Reply #15 on:** July 07, 2011, 09:45:15 PM »

anybody know where i can get these?

Terry in Australia · « **Reply #16 on:** July 07, 2011, 10:04:00 PM »

They've long since disappeared from the Honda parts inventory mate, so you'll either have to ask someone here who's parting out an engine, or get an engineer to make some new ones up for you. Contrary to Ron's reply, (and no offence to Ron intended) I'd definitely use them as they prevent the rubber seals from just collapsing inwards. Cheers, Terry.

MCRider · « **Reply #17 on:** July 08, 2011, 05:41:19 AM »

Quote from: Terry in Australia on July 07, 2011, 10:04:00 PM

They've long since disappeared from the Honda parts inventory mate, so you'll either have to ask someone here who's parting out an engine, or get an engineer to make some new ones up for you. Contrary to Ron's reply, (and no offence to Ron intended) I'd definitely use them as they prevent the rubber seals from just collapsing inwards. Cheers, Terry.

If you'll see my post #11, I said if it were me I'd find them and use them. No offense taken.

Haven't heard from you in a while, job assignment?

If you're referring to my post #12, I think I'm right in saying that those ORings don't take dowels, couldn't put them in if you wanted too. Correct?

oldk6guy · « **Reply #18 on:** July 08, 2011, 08:32:18 AM »

oldk6guy · « **Reply #19 on:** July 08, 2011, 12:54:45 PM »

since the parts fische search returned nothing useful i figured i'd post this link to the one hondaman pointed me to
http://www.kawasakipartsnation.com/pages/oemparts?aribrand=HOM#/Honda/CB750K5_A__MOTORCYCLE%2c_JPN%2c_VIN%23_CB750-2500001/CYLINDER_%2b_PISTON/CB750K5-JPN-A/2Y143413E14341305B

thabx hondaman

oldk6guy · « **Reply #20 on:** July 08, 2011, 12:57:44 PM »

anyone know if these are still available?
http://www.cmsnl.com/products/pin-special-12mm_12116300000/

oldk6guy · « **Reply #21 on:** July 08, 2011, 01:08:11 PM »

would the m12 on this page work?
http://www.mcmaster.com/#dowels/=d39s6h

oldk6guy · « **Reply #22 on:** July 08, 2011, 01:30:06 PM »

or this
http://www.spirol.com/library/sub_catalogs/bush-GD100_Specifications_us.pdf

Terry in Australia · « **Reply #23 on:** July 08, 2011, 01:43:06 PM »

Quote from: MCRider on July 08, 2011, 05:41:19 AM

Quote from: Terry in Australia on July 07, 2011, 10:04:00 PM
They've long since disappeared from the Honda parts inventory mate, so you'll either have to ask someone here who's parting out an engine, or get an engineer to make some new ones up for you. Contrary to Ron's reply, (and no offence to Ron intended) I'd definitely use them as they prevent the rubber seals from just collapsing inwards. Cheers, Terry.
If you'll see my post #11, I said if it were me I'd find them and use them. No offense taken.

Haven't heard from you in a while, job assignment?

If you're referring to my post #12, I think I'm right in saying that those ORings don't take dowels, couldn't put them in if you wanted too. Correct?

G'Day Ron, yeah mate, I've been working in the country and interstate a lot recently, and with Army Reserve training on weekends, not a lot of time to goof off at the moment.

Those cylinders seals aren't "O Rings" as such, but rather, tubular shaped seals that need the dowels or knock pins or whatever we're gonna call them to stop them from collapsing under compression. Without the dowels they would provide no sealing purpose at all. Cheers, Terry.

MCRider · « **Reply #24 on:** July 08, 2011, 02:33:09 PM »

Thank you for your service, I appreciate it even though you're not a yank but an ally.

I switched the topic a bit in post 12, the ORIngs I'm talking about are the 2, 1 on either side of the cam tunnel and they don't take dowels.

The 8 , 4 of which the poster is missing, are the cylindrical type and I agree that they should be used, with the dowels.

THough its still some's position that one can get by without them, and I don't see why not.

I know the original poster is trying to score some before moving on.

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Author Topic: cylinder dowels (Read 9945 times)

KingCustomCycles.com