Author Topic: CB 750 Project 1 - Rides Well but a few tweaks needed (Read 114245 times)

timbo750 · « **Reply #350 on:** November 20, 2015, 08:36:03 PM »

Pulled the valves out of the head and noticed a considerable difference in the valve guides between the intake and exhaust. The exhaust have no seal on them which seams quite unusual. Is this normal, I am gathering not as the gasket kit comes with 8 valve seals.

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01Thomas · « **Reply #351 on:** November 20, 2015, 08:39:02 PM »

Hi. The exhaust valve guides on the early heads did indeed not have any valve stem seals. Unusual yes, but that's how Honda did it in the early days.

Regards
Thomas

timbo750 · « **Reply #352 on:** November 20, 2015, 10:12:39 PM »

Thanks Thomas. From memory this engine is supposed to be 75 or 76 but I am also certain it has been pulled apart a few times and some parts would of been swapped out.

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timbo750 · « **Reply #353 on:** November 22, 2015, 12:18:42 AM »

Pulled all the valves out this weekend. I removed some of the casting irregularities and lapped the valves. Should get the head reassembled during the week.

Now I need to get the shift mechanism right. It is shifting through gears when I use a screw driver on the shift drum but after installing the shaft that that the gear lever attaches to, the shift drum is not rotating when I move the shift shaft.

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timbo750 · « **Reply #354 on:** November 24, 2015, 01:23:13 AM »

Got the head back together and noticed a few dowels missing. Not sure why I didn't notice them missing before, I will have a look arounf for them and may to place another order to Yamiya, I think the Japanese post will end up knowing me as well as my local postie.

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Davez134 · « **Reply #355 on:** November 24, 2015, 01:49:38 AM »

Quote from: timbo750 on November 24, 2015, 01:23:13 AM

I think the Japanese post will end up knowing me as well as my local postie.

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I know the feeling. My mail carrier enjoyed following my build too!

edwardmorris · « **Reply #356 on:** November 24, 2015, 02:17:59 PM »

Be sure to order the correct length dowel pins, the parts manual has them listed incorrectly as 22mm long, they're really 18mm long.

http://forums.sohc4.net/index.php/topic,107040.msg1672454.html#msg1672454

timbo750 · « **Reply #357 on:** November 29, 2015, 08:33:42 PM »

I was making sure I had all the bits to assemble the heads and cylinders on the weekend and noticed the washer that I have for under the head nuts on the head studs are different thicknesses. I can't imagine this would be and issue and I think its another hang over from the PO but if anyone thinks an issue then please let me know.

Terry in Australia · « **Reply #358 on:** November 30, 2015, 03:26:42 AM »

Shouldn't be a problem Tim, Are they copper washers, or steel? From memory, the washers on the studs that go through the oilways need to be copper, or they'll leak. From memory again, the nuts for these should be captive, for the same reason. Sorry mate, I'm a bit rusty as I haven't pulled one apart for a couple of years. Cheers, Terry.

timbo750 · « **Reply #359 on:** November 30, 2015, 10:10:15 AM »

I have no captive nuts and no copper washers. So I better do some reading on the subject.

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timbo750 · « **Reply #360 on:** November 30, 2015, 07:43:38 PM »

Terry, I didn't read a lot, I usually follow the theory that a picture tells a thousand words. I have an electronic copy of the factory workshop manual and it doesn't mention much, however I did find a picture that shows not cap nuts. I also checked the Yamiya site and he mentions them being for the sandcast and shows them on the outside studs.

Terry in Australia · « **Reply #361 on:** November 30, 2015, 10:56:11 PM »

Yeah mate, the cap nuts were used on most big fours in the 1970's, probably just to stop the outside studs from rusting to the nuts. Suzuki GS1000 OEM gasket sets came with 16 copper washers for the cylinder studs. From memory, the theory about using captive nuts on the 750 head was to stop hot oil under the cam cover from seeping back down the studs, and dripping out thru the fins at the rear of the head/cylinder block? Cheers, Terry.

knottedknickers · « **Reply #362 on:** December 01, 2015, 07:40:57 AM »

Quote from: timbo750 on November 30, 2015, 07:43:38 PM

Terry, I didn't read a lot, I usually follow the theory that a picture tells a thousand words. I have an electronic copy of the factory workshop manual and it doesn't mention much, however I did find a picture that shows not cap nuts. I also checked the Yamiya site and he mentions them being for the sandcast and shows them on the outside studs.

Here's another picture (of my '76 top end):

You can see 'flange nuts', not 'cap nuts' (maybe they have a different meaning of 'cap nut' down under?) And I didn't have any copper washers--all steel. For what it's worth.

Oh, this might be worth something: do remember that the nuts and the bolts have different torques--15 lb/ft and 8 lb/ft respectively. I almost screwed that up... [pun intended]. Good luck! It's fun to see progress! ;-)

timbo750 · « **Reply #363 on:** December 01, 2015, 07:18:55 PM »

Here is a picture of the cap nuts and the suggested location by Yamiya, they also mention they are recommended for sandcast engines. not going worry about them but I would like to know how you torque the short bolts on the head, I cant get a socket on to them.

knottedknickers · « **Reply #364 on:** December 01, 2015, 08:33:17 PM »

Quote from: timbo750 on December 01, 2015, 07:18:55 PM

Here is a picture of the cap nuts and the suggested location by Yamiya, they also mention they are recommended for sandcast engines. not going worry about them but I would like to know how you torque the short bolts on the head, I cant get a socket on to them.

Oooh, funky. I've never seen that before; NOT that I've "seen it all"--not even close!--but just in my following other peoples' builds here, this is the first time. As for tightening the 6 short head bolts, I'm pretty sure I used a 1/4" drive socket and extension with a 3/8 x 1/4 reducer at my torque wrench.

timbo750 · « **Reply #365 on:** December 01, 2015, 09:57:27 PM »

Yeah funky describes it well. I still am not sure why you need it on the outer studs as I would think that there is not much oil passing through them. From memory I didn't have a socket that would get on those outside bolts. Ended up using a screwdriver and spanner combination to get them loose.

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Terry in Australia · « **Reply #366 on:** December 02, 2015, 01:19:45 AM »

Quote from: timbo750 on December 01, 2015, 07:18:55 PM

Here is a picture of the cap nuts and the suggested location by Yamiya, they also mention they are recommended for sandcast engines. not going worry about them but I would like to know how you torque the short bolts on the head, I cant get a socket on to them.

Yep, that proves that I'm not mad, ha ha! I know that I ditched the OEM 6mm bolts and replaced them with cap head screws (allen bolts) so I could torque them properly. It makes it way easier to get them in and out too. Looking good Tim, keep up the good work! Cheers, Terry.

timbo750 · « **Reply #367 on:** December 02, 2015, 01:33:11 AM »

Glad you mentioned that Terry, I will get some 6mm alan bolts tomorrow. My local bolt shop calls them 'socket head' screws.

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colined2 · « **Reply #368 on:** December 02, 2015, 03:14:11 AM »

Hello Timbo
Greetings from South Morang Melbourne.
I have been following your rebuild and thought you might be interested in some mods I am doing to a cylinder and cylinder head I am preparing for an 836 kit.
I have already replaced the 4 cam tower bolts with studs on my restored CB750 K4 so I know they work and I have replaced the bolts under the rubbers under the cam towers with studs and also the long bolt at the front of the head and the small one at the back.Easier to tighten down and less chance of stripping the thread in the cylinder head.
I have attached 2 pics. to show you what I mean.
Good luck with your rebuild.
Regards
Colin Edwards.

colined2 · « **Reply #369 on:** December 02, 2015, 03:19:08 AM »

Having trouble sending attachments

colined2 · « **Reply #370 on:** December 02, 2015, 03:20:44 AM »

cylinder head

timbo750 · « **Reply #371 on:** December 02, 2015, 01:06:14 PM »

Colin
Where did you get the studs from, I have been searching this morning and having no luck. I have used 'Small Parts' before but if they don't have it in stock they are pricey.

colined2 · « **Reply #372 on:** December 02, 2015, 01:42:19 PM »

Good morning Tim
I will take them out and measure them.
I used to be a spare parts manager at Peter Stevens Springvale and Geoff Taylor Motorcycles for many years in the past so I had a good idea that they were available. I went to my local Honda dealer (Moto GC in Thomastown) and gave them the part numbers and they got them in. They were only a couple of dollars each, but they had to go on back order which took a couple of weeks to get in. The only stud I had trouble with was the long one at the front of the cylinder. Jack the spare parts man at Evolution Motorcycles in Epping had a good secondhand one from his collection of old Honda parts. I also believe that a Kawasaki KV400 also has the same stud. I will get back to you with the length and part numbers later this morning.
Colin

timbo750 · « **Reply #373 on:** December 02, 2015, 01:47:00 PM »

Colin, thanks. I had a look on Yamiya and CMS and they dont have yhem listed so I figure they may be discontinued. I have also searching bolts supplier web sites and there is not much range in the 6mm available.

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timbo750 · « **Reply #374 on:** December 02, 2015, 01:50:16 PM »

Colin don't go out of your way removing them, I can measure thread depths and also depth through the head. I think will have to start ringing around to find them.

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Author Topic: CB 750 Project 1 - Rides Well but a few tweaks needed (Read 114245 times)