DOHC CB750's

Rob5zat said:
Just getting started!

Been lurking for the last month or so trying to soak up as much knowledge as I can, there's a lot to be had here. Finally picked up my first bike last night, as 81 CB750K. Runs pretty strong but has only starts with a pretty good bump, battery is on tender now so we'll see. Not sure what direction I want to take it, kinda have to learn to ride first so i don't want to go cutting anything up just yet.

67296_490576717674544_974285427_n.jpg


I'm planning on swapping out the coils for a set from a CBR and going with a slightly hotter plug, along with a stronger battery I'm hoping this will help the starting issue, or maybe it's just too damn cold in Philly right now. I have the current exhaust, look and sound, so I'm gonna grab a 4 into 1, recommendations welcome, but leaning towards a Carpy. Decent pods and new jets should get round out the hop up, again, recommendations welcome.

I figure I'll ride for a little bit before sorting out the aesthetics, im leaning more towards a brat style, we'll see.

In the mean time I'll be learning as much as I can from all you guys and my local shops

Cheers!

R
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Pods on this bike will drastically decrease performance; you need to charge your battery. Coils and plugs don't need to be changed unless they're bad. :)

Charge the battery, clean your carbs, check your intake boots. Nice scoot.
 
Invest in carbs (FCR's or CR Specials) instead of all the pods and jets and coils and plugs and etc. FCR's and CR Specials are 10x the carb the stockers are, easier to tune and you can run them with velocity stacks and birdcatcher screens and they look trick. But eah, the stock carbs are not fans of pods. It won't kill your engine, but it sure won't make it run any better.
 
@rocketritch: it's a shorai battery strapped to the swing arm. I've gone a different direction with the bike in the last couple of weeks while getting itchy for spring.
syqenu4a.jpg
 
Rich Ard said:
Pods on this bike will drastically decrease performance; you need to charge your battery. Coils and plugs don't need to be changed unless they're bad. :)

Charge the battery, clean your carbs, check your intake boots. Nice scoot.
Click to expand...

Jewbacca said:
Invest in carbs (FCR's or CR Specials) instead of all the pods and jets and coils and plugs and etc. FCR's and CR Specials are 10x the carb the stockers are, easier to tune and you can run them with velocity stacks and birdcatcher screens and they look trick. But eah, the stock carbs are not fans of pods. It won't kill your engine, but it sure won't make it run any better.
Click to expand...

Thanks guys, this is the info I'm looking for, as really, I don't know shit yet
 
davidgwells said:
@rocketritch: it's a shorai battery strapped to the swing arm. I've gone a different direction with the bike in the last couple of weeks while getting itchy for spring.
Click to expand...

Same here. I have Clip-ons and rearsets on the way. I need anew battery and was thinking about maybe relocating it. How does the battery hold up?
 
That battery is awesome. You won't believe how small and light it is until you're holding one. It's held up really well with zero maintenance. I won't go back to lead acid I'm sure.
 
Ive been lurking for a while as well, this is what I purchased last September, 1979 750K 15000 mi, along with a field find 1972 cl350. The CL will be my second build on a bike and my first cafe, the first bike build is a 1979 shovelhead no engine work just modified bodywork and paint. The 750 is in such good condition that I am not sure how I want to go with it, so I will ride until I get the CL350 up and running.
 

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davidgwells said:
That battery is awesome. You won't believe how small and light it is until you're holding one. It's held up really well with zero maintenance. I won't go back to lead acid I'm sure.
Click to expand...

Don't ever let it discharge all the way, or you'll be truly fucked
.
 
Well this is what I started with over a year ago and below is what she is starting to look like.
I was hoping to do a build thread but right after I started the build I lost all of my earlier tear down pictures to a hacker and now that computer is a paperweight.

CB750-1.jpg


What the frame looks like now. That's Lolly Pop Candy Red. ;D
CopyofFrame11_zps320097e4.jpg


Here are the front and rear wheels.
CopyofWheels31_zps6e553638.jpg

CopyofWheels11_zpsdc21b0cb.jpg


And an engine cover teaser!
CopyofStarterCover-Finish_zpsbf0542e1.jpg
 
Rob5zat said:
Just getting started!

Been lurking for the last month or so trying to soak up as much knowledge as I can, there's a lot to be had here. Finally picked up my first bike last night, as 81 CB750K. Runs pretty strong but has only starts with a pretty good bump, battery is on tender now so we'll see. Not sure what direction I want to take it, kinda have to learn to ride first so i don't want to go cutting anything up just yet.

67296_490576717674544_974285427_n.jpg


I'm planning on swapping out the coils for a set from a CBR and going with a slightly hotter plug, along with a stronger battery I'm hoping this will help the starting issue, or maybe it's just too damn cold in Philly right now. I have the current exhaust, look and sound, so I'm gonna grab a 4 into 1, recommendations welcome, but leaning towards a Carpy. Decent pods and new jets should get round out the hop up, again, recommendations welcome.

I figure I'll ride for a little bit before sorting out the aesthetics, im leaning more towards a brat style, we'll see.

In the mean time I'll be learning as much as I can from all you guys and my local shops

Cheers!

R
Click to expand...

Before you do anything check the valve clearances are set 0.005 both inlet and exhaust, then do a compression check.
Once that is sorted you may find it starts easier. The best upgrade for the ignition is to fit 1990's CBR600 coils and put a direct 12v feed switched with a relay direct to to the coils.
Carbs are a how deep are your pockets or how long is your patience. Deep enough for FCr's or the like or patient enough to get GSXR carbs to work properly, which in the long run can cost nearly as much as the FCRs. The standard carbs run best with the airbox fitted.
Anything and everything that can be done to DOHC's is on the forums here http://www.cb1100f.net
 
Yeah I noticed that also Hoosier.
But where you have polished I will have Black and Carbon fiber.
I am at the point of getting it all back together but since I changed front end and wheels I hit a road block every so often.
Then I have to stop and wait for something to be shipped to me.
I did my home work and everything is compatible with all of the bikes except for that one little piece you didn't think about.

DUH!

But it is coming together and I hope to have it ready to have the engine installed in a month.
It is an actual rolling chasis now but I am holding off on the pictures for now.
 
notlob said:
Before you do anything check the valve clearances are set 0.005 both inlet and exhaust, then do a compression check.
Once that is sorted you may find it starts easier. The best upgrade for the ignition is to fit 1990's CBR600 coils and put a direct 12v feed switched with a relay direct to to the coils.
Carbs are a how deep are your pockets or how long is your patience. Deep enough for FCr's or the like or patient enough to get GSXR carbs to work properly, which in the long run can cost nearly as much as the FCRs. The standard carbs run best with the airbox fitted.
Anything and everything that can be done to DOHC's is on the forums here http://www.cb1100f.net
Click to expand...
notlob
Do you have access to a schematic that shows how to do this? (The best upgrade for the ignition is to fit 1990's CBR600 coils and put a direct 12v feed switched with a relay direct to to the coils.) I am trying to get logged in on the CB1100f forum but it is taking some time.
Thanks
 
[qoute]
young'n said:
notlob
Do you have access to a schematic that shows how to do this? (The best upgrade for the ignition is to fit 1990's CBR600 coils and put a direct 12v feed switched with a relay direct to to the coils.) I am trying to get logged in on the CB1100f forum but it is taking some time.
Thanks
Click to expand...

x2 on this one. Would really like to see this.
 
notlob said:
Before you do anything check the valve clearances are set 0.005 both inlet and exhaust, then do a compression check.
Once that is sorted you may find it starts easier. The best upgrade for the ignition is to fit 1990's CBR600 coils and put a direct 12v feed switched with a relay direct to to the coils.
Carbs are a how deep are your pockets or how long is your patience. Deep enough for FCr's or the like or patient enough to get GSXR carbs to work properly, which in the long run can cost nearly as much as the FCRs. The standard carbs run best with the airbox fitted.
Anything and everything that can be done to DOHC's is on the forums here http://www.cb1100f.net
Click to expand...

I have the coils already, but how do I set up the direct feed?
 
young'n said:
notlob
Do you have access to a schematic that shows how to do this? (The best upgrade for the ignition is to fit 1990's CBR600 coils and put a direct 12v feed switched with a relay direct to to the coils.) I am trying to get logged in on the CB1100f forum but it is taking some time.
Thanks
Click to expand...
I did find this link http://gstwins.com/gsboard/index.php?topic=62039.0 after doing a google search for coil relay mod.
 
young'n said:
I did find this link http://gstwins.com/gsboard/index.php?topic=62039.0 after doing a google search for coil relay mod.
Click to expand...

Just like in the link above. The Power to coils wire it the black/white which comes from the kill switch. So 86 is the black/white fro kil switch and 87 is the black/white to the coils. 30 is feed from battery side of the starter relay.

ign_coil_relay_upgrade_diagram.jpg


This just ensures you have maximum voltage to the coils with no voltage drop due to connections in ignition switch, kill switch and loom connectors.
 
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