Topic: 1978 CB750F - Metric Mayhem"

[scroggins5000]

thanks for the link scroggins thats perfect. I know how to use solid works and was looking for a good place to print out designs.

Have you priced your piece yet? Is the pricing reasonable?

Yeah it's fairly reasonable for custom designed stuff. To have a single badge printed in the white plastic material is $30 with free shipping. The most expensive material is the stainless steel and that would run about $190... Ouch!

[scroggins5000]

thanks for the link scroggins thats perfect. I know how to use solid works and was looking for a good place to print out designs.

Have you priced your piece yet? Is the pricing reasonable?

Yeah it's fairly reasonable for custom designed stuff. To have a single badge printed in the white plastic material is $30 with free shipping. The most expensive material is the stainless steel and that would run about $190... Ouch!

That's probably enough to create a new design.

[scroggins5000]

cycle x had the best prices on valves for the f motor that i could find.

Yeah, they are about $200 cheaper than Honda OEM. $159 (CycleX) vs $355 (OEM). I'll most likely go with these..

Here's pricing I've found of the rest of the stuff I need:
(4) .5 OS Pistons w/ rings, pins, and clips - about $460
Inner and outer valve springs and retainers - about $155

I think I've already got valve stem seals in my gasket set, If not then they're cheap. Like $10 or less. I think I can get nice valve guides through the shop too..

Well this is becoming a wash... Every place I call, or try to order pistons and rings from, doesn't have them. I was hoping to find one place that just had at least 4 of each, but now I'll take whatever I can find. I have found some pistons here and there, but I have only found two ring sets. Both on ebay. If I can't find two more sets, I am going to have to just go with the big bore kit form Dynoman.

[Flying J]

Rebuilding an F sounds frustrating. Thats 1 reason i havent taken on that task yet. I just keep collecting parts so that when i do i have it all. Your other option is to put a k top end on your F case. Not as high performance but more reliable and easy to find parts for.

[scroggins5000]

Rebuilding an F sounds frustrating. Thats 1 reason i havent taken on that task yet. I just keep collecting parts so that when i do i have it all. Your other option is to put a k top end on your F case. Not as high performance but more reliable and easy to find parts for.

Yeah, I think it's Terry from this forum that has an F with a K top end. It's a viable option, but I've already got all the other replacement parts I need to the top end.

Just need two more ring sets! Anyone got any? here's the part number 13011-410-601

[Flying J]

People have them. But getting them to part with them is another story.

[scroggins5000]

Well, I gave up on finding STD pistons and rings. I just went ahead and ordered the 836 piston kit for the F2 from Dynoman. Once these come in, we can finally finish rebuilding the motor. The shop already has the new valve guides I ordered (from Dynoman) and the new valves (from cyclexchange.net). I'm tired of looking and waiting, especially since it's spring. I've got the itch to ride.

Two of the spark plug holes in the motor have new threads in them now, because they were halfway gone.

Next I need to find a new gear for the transmission. One of them had some teeth snapped off. I think it's the first gear, but I can't remember right now. I guess the PO(s) of this bike gave it some hell on the street.

[afastman]

Looks great.  Maybe rethink leaving the front fender chrome, though.  It appears overlooked while there is so much attention to detail everywhere else.

[Frankenkit]

+1 on that and... the seat.  There's something about the seat.  It doesn't quite fit with the lines of the bike.  Other than that, the colors are beautiful. I love the whole stance of the bike, too.  It's like a long, lean cheetah or something.  Rawr!

[scroggins5000]

+1 on that and... the seat.  There's something about the seat.  It doesn't quite fit with the lines of the bike.  Other than that, the colors are beautiful. I love the whole stance of the bike, too.  It's like a long, lean cheetah or something.  Rawr!

The seat is a knock off of one of Carpy's designs. I just loved it when I saw it on his "Black Bandit." It's a little big because I used the original seat pan (which is a boat), but I wanted it to be able to easily seat two people. I am also going to have some passenger pegs on there too.
The hump on the back of the seat doesn't have as sharp of a drop off as I'd like, but it was a cheap job done by a friend so I can't complain.

-Inspiration Pic- Carpy's Black Bandit:

[Frankenkit]

silver wins.

[scroggins5000]

Ran into a problem with the flywheel bolt... Turns out it is stripped badly, and needs to be replaced! The hole it goes into on the crankshaft will probably be ok once tapped. This wouldn't be too difficult to replace except that this bolt isn't a standard bolt. It is a fine thread (m12-1.0), and not standard like 1.5 and up. Which is probably why it's stripped, and no one carries it... I tried fastenal and some of the normal places that carry old honda parts. Anyone have an extra lying around?

Here is the honda alternator diagram of where it is (#11 on the diagram; OEM part no. is 3888582-001):

[Flying J]

like this one? 

[scroggins5000]

like this one? 

Booyah! That's it. m12-1.0 x 60 with a 30mm thread length. Is that on you would part with, or are you just bragging?

[Flying J]

PMed you

[scroggins5000]

PMed you

PM'd back!

[scroggins5000]

Ok, the engine should be wrapped up sometime in the near future. Looking forward I am going to need some advice for re-jetting. Right now, I have a stock set of carbs for the '78 CB750F. I think it has 105 mains right now.

I will end up with an 836cc motor, with 4 into 1 Yoshimura replica exhaust, and K&N oval style pod filters for the carbs. What would be a good place to start with for some new jets?

[scroggins5000]

I sent an email to dynoman.net to see what they recommended and this is what they said.

"We would recommend that you order 115, 120, and 125 jets to get you started. We would start with the 120 jets and see how it runs. Then go 1 size smaller and one size larger to see what works the best. All engines are a little different, but if you start rich and you will be safer, as a lean mixture can damage your engine."

Unless anyone would see a problem with this, I think I'll go this route. Not sure If I want to order from them, but they are 4.50ea there. Not bad...

[Flying J]

That is what i would do. I have 125 in mine and it run ok. Still need to do some fine tuning. I would not pay 4.50 a jet. go here and pay 1.60.
http://www.z1enterprises.com/detail.aspx?ID=1924

[scroggins5000]

That is what i would do. I have 125 in mine and it run ok. Still need to do some fine tuning. I would not pay 4.50 a jet. go here and pay 1.60.
http://www.z1enterprises.com/detail.aspx?ID=1924

Thanks for the link. That's the lowest price I've seen so far. Elsewhere I haven't seen below $3 each...

You motor is still stock size right? I'm guessing you have high flow exhaust and air intake too? Since I've got an 836cc I'm wondering if maybe I should start with 125's instead of 120's. However, these jets are so cheap, I can just work my way up if it's still too lean, without wasting a ton of cash...

[Flying J]

buy as many as you think you might need and then one size larger. Youll pay more for shipping then you will for the jets if you keep going back for more. My motor is stock. I have run open headers, but now i have a mac. And i did have pods but now i have stock box so i think i need to re jet.

[scroggins5000]

I just call from my Dad at the shop. The motor is finished now! He got the tap I sent today, and the guy who bored out the cylinders came and dropped them off today as well. He was able to tap the hole in the crankshaft and the bolt you sold me fit perfect. Thanks ffjmoore...  Waiting on the powdercoaters for the frame and some other pieces. Exhaust is getting heat wrapped. Rims are being repainted. This bike should be going together pretty quick now... I'm stoked.

[tweakin]

Great update, I bet you can't wait to get the bike built and ride.  I look forward to the finished product.

[scroggins5000]

Anyone else want to add their share on where to start the jet sizing for the 836cc?

[tweakin]

Anyone else want to add their share on where to start the jet sizing for the 836cc?

I went with CR 29 carbs so I can't speak from axperience, but I have heard 128's are a good place to start for an 836 with stock carbs.  Hope this helps a bit.