Topic: Converting to exhaust studs, cb750, what length

[markreimer]

I'm about to install a Hindle 4-2-1 system on my K4 cb750. I beliebe the stock exhaust bolts are m8x1.25 and 22mm long, but I don't know what length to choose to convert to a stud style mount like the F series.

Has anyone converted? I'm going to the hardware store after work and can't measure on my bike before. Nothing turns up in the search.


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[flybox1]

+100 for studs! (especially if you have to remove the headers to change oil filter)
soo much easier to work with.  you'll not run any risk in stripping out threads in the head.
A set of 8 studs will run you about $10.

http://www.partsnmore.com/parts/honda/cb750/?filters[category]=hardware&filters[page]=2

Exhaust Stud Pk/10
#49-0010
Exhaust Stud Pk/10 High Tensile Plated Size: 8mm x 56mm Threaded Ends: 15mm & 18mm

This stud stays in the head.  You only need eight M8 nuts to draw the headers down snug. 
Just remove the nuts if you need to pull the headers off.  Studs stay in place.

[markreimer]

Awesome. I had bought 40mm and figured it was way too short. Ill swing back and grab the 55's they had. I do need to remove the headers for oil changes, but the hindle has springs so it's easy


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[PeWe]

Also possible to use allen bolts. I did that with my old 4-1.

[markreimer]

Totally. I was thinking I'd use studs because it would negate the constant instal/removal of the bolts and preserve the head threads longer. But then I just remembered I have springs on the headers so I'll never need to remove the collar. So I guess both would work!



Now if only it wasn't -20C with almost a meter of snow on the ground 

[flybox1]

Set the studs with High temp Locktite, and use serrated flange nuts, or lock washers.
On my last day trip I developed this really rough exhaust sound.
Stopped for gas and a look-see.  Two studs had backed out, and the nuts had vibrated off.  WTF!   
Luckily we had just passed a hardware store.   15 min later we were back at it.   

[Chachi]

I just ordered F model parts (studs) for my K when I converted. I got them at my local Honda shop. Link for reference. Installed with the double-nut method.

http://www.cmsnl.com/honda-cb750f-750-super-sport-1976-usa_model490/bolt-stud-8x32_92900080320e/#.WHVU4FMrLIU

[markreimer]

Oh interesting, these say 8x32? So M8 by 32mm long I assume?  Does that sound right from what you remember? If so, the 40mm ones I have on hand would be just fine...

[whitjonw]

Oh interesting, these say 8x32? So M8 by 32mm long I assume?  Does that sound right from what you remember? If so, the 40mm ones I have on hand would be just fine...

I ordered studs and nuts from Southern Honda Powersports and was able to look at the different year exploded views of the parts diagrams and it appears the same stud was used on the CB750F models beginning in 1975, the CB750A models and the '77 & '78 CB750K models, so that is what I got. They are indeed 32mm in length.


The items you ordered:

Qty      Product      #      Price EA   
8   NUT, FLANGE (8MM)    94050-08000   $0.62
4   GASKET, EXHAUST PIPE    18291-MM5-860   $3.31
8   BOLT, STUD (8X32)    92900-08032-0E   $1.10

[Chachi]

Yeah, that's what I did. You can check all those bikes/parts on the CMSNL site. And I think one side of the stud has more threads than the other. The longer side goes into the head? I can't remember, but someone here advised me. And those 8mm flange nuts also work great on front brake rotor if you've got it apart and can't get tongue washers or opt not to.

[calj737]

Oh interesting, these say 8x32? So M8 by 32mm long I assume?  Does that sound right from what you remember? If so, the 40mm ones I have on hand would be just fine...

32mm may not be long enough for the exhausts if you are using the MotoGP exhaust. The spigot that mounts to the head is about 5-6mm longer than the stock flange (in my experience). I used ARP studs on a 500 motor and found that the end of the stud would barely expose enough threads to screw a nut on. Certainly no way with a lock washer beneath it. I had to shorten the spigot by about 1/4" for their flange to lock into place.

32mm for bolts is probably fine with stock flanges. Just be prepared for a surprise or two mixing fasteners and products from stock configuration. 

[markreimer]

Thanks for the tip! I'm using a Hindle system and I don't know how their spigots compare to the moto GP. But you know, it's easy enough to walk two blocks to the parts store today and pickup some 50mm studs just to be safe... I'll post the results on the weekend.

[Airborne 82nd]

You could use a depth gauge to see how deep the hole is and add the thickness of the flange and nut 

[drumstyx]

Set the studs with High temp Locktite, and use serrated flange nuts, or lock washers.
On my last day trip I developed this really rough exhaust sound.
Stopped for gas and a look-see.  Two studs had backed out, and the nuts had vibrated off.  WTF!   
Luckily we had just passed a hardware store.   15 min later we were back at it.   

Wow! Loctite on an exhaust stud eh? I've only ever had problems with them seizing on other bikes, so I use anti-seize.

Honestly I'd rather deal with a bit of maintenance attention than the hassle of a seized stud later. But then, I won't be taking great big trips on my CB...that's what my Concours is for.

[flybox1]

Set the studs with High temp Locktite, and use serrated flange nuts, or lock washers.
On my last day trip I developed this really rough exhaust sound.
Stopped for gas and a look-see.  Two studs had backed out, and the nuts had vibrated off.  WTF!   
Luckily we had just passed a hardware store.   15 min later we were back at it.   

Wow! Loctite on an exhaust stud eh? I've only ever had problems with them seizing on other bikes, so I use anti-seize.

Honestly I'd rather deal with a bit of maintenance attention than the hassle of a seized stud later. But then, I won't be taking great big trips on my CB...that's what my Concours is for.

Siezed stud?  Maintenance?  Once they're in, there's few reason to ever need to take them out again...but by no means is it permanent. 
Much easier to remove than a galled bolt, but they wont free up with vibration or header removals.  I still recommend it.

[Mr Freeze]

I ordered a set of these and installed them on my 1978 K model and I have to say they are excellent for the money.

http://www.ebay.com/itm/Honda-CB750K7-and-K8-Four-039-77-039-78-Stainless-Steel-Exhaust-Stud-Set-/332087488275?

[Don R]

 I prefer the studs also, some headers need a bit of wrestling to get lined up. Starting a bolt under duress might cause an issue. If everything lines up nicely I'd guess that would be the exception.

[whitjonw]

I ordered a set of these and installed them on my 1978 K model and I have to say they are excellent for the money.

http://www.ebay.com/itm/Honda-CB750K7-and-K8-Four-039-77-039-78-Stainless-Steel-Exhaust-Stud-Set-/332087488275?

That is good to know and thanks for the link. Are they at least the minimum of 32mm in length ?

[markreimer]

Looks like 40mm studs just squeak in. Not long enough if you're using washers though. I'm using the copper exhaust gaskets. Then it's have that serrated edge to lock to the spigot and I used a bit of blue loctite on the nut.


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[754]

There is a good reason to remove the studs, some of them..
If you dont have a frame kit,and you pull the motor, easier with some studs pulled out.

[markreimer]

I'm gonna have to get one of your kits soon. Stud conversion was a success


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[flybox1]

Nice work. Looks good 

[Mr Freeze]

I ordered a set of these and installed them on my 1978 K model and I have to say they are excellent for the money.

http://www.ebay.com/itm/Honda-CB750K7-and-K8-Four-039-77-039-78-Stainless-Steel-Exhaust-Stud-Set-/332087488275?

That is good to know and thanks for the link. Are they at least the minimum of 32mm in length ?

They are exactly the same length as what the later 76-78 bikes have except stainless.