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'80 CB750 F - boring build

64K views 426 replies 37 participants last post by  shinyribs 
#1 ·
Well, not even a build actually. But I don't have a thread on this bike so I thought I'd start one to keep track/ask advice as I make some changes to it.

All of this has been mentioned before elsewhere,but I'll say it again just to keep this all organized.

Chassis:
Forks- '91 CBR 1000F
Triples- '92 CBR 600 F2
Front calipers- ''92 CBR 600 F2
Front master cyl- '96 CBR 600 F3 (5/8 bore)
Rear caliper- '87 CBR 600 F1
Rear master cyl- '95 CBR 600 F3
Rims- '87 CBR 600 F1 Hurricane
Rear susp- stock raised 2''

Engine: 823cc
Case-'82 750F
Trans/clutch- 900F w/Barnett stuff
Rods- 900F
Pistons- Wiseco 10.5:1
Cams- stock 900F
Head- Ported 750F
Oil pump/pan-900F
Oil cooler- 900F
Exhaust- stock (why???)

Ok, now thats out of the way,here it is when I first got it.

Rims were all scratched and chipped. Stock 4-2 pipes choking the motor (wouldn't rev past 7k).It had stock VFR turn signals on it which were fookin' huge,so they got swapped out for some smaller el-cheapo bikemaster jobbies. And I just recently discovered the rear wheel was running 11.5 mm off center. :doh:

Oh,and how can you miss that CBR front fender. :puke:



As she sits now:

Rims are powdercoated and CENTERED! I relocated the horns('cuz they stuck out like a sore thumb before) and it has decent exhaust now. It's a V&H 4-1 which I'm mostly happy with. The megaphone tucks up nicely,but I'm afraid I'm gonna drag the primary tubes...fingers crossed on that.I also removed the rear turn signals and wired in a tail light integrator thiny-ma-bob that converts my two-bulb tail light into a tail-stop-turn unit. My throw-over bags had issues clearing the turn signals.

Oh,and the new exhaust system saved 14 lbs over the stock set up :thumbsup:

Pics:




So next on the list:

-lower headlight
-new clocks???
-new front fender- ideas,please
-foot peg mount modifications/possible rearsets.
-rims def need a strip or sumthin'
 
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4
#2 ·
You're going to need a front fender. I would either cut up the cbr one or try your hand fiberglass or make one out sheet metal.
 
#3 ·
I thought you were gonna go white with the wheels?? The newer cbr fenders are pretty nice...that's what I'm running on mine. I'm digging the exhaust...how does it sound??
 
#4 ·
Yeah,running fenderless sucks. I did that once before. It didn't last but a few days.

J,I really like the white wheelson your bike,but it just didn't look good on this bike. I painted them white the other day and didnt like it. I think it's the lighter colored paint. The white just washes out on it,if that makes nay sense. I have been meaning to ask you about your fender. I do like that. I guess if I wasn't so lazy I'd just read your thread....
 
#12 ·
Thanks Mike. And thanks for the fast shipping. It felt good to get that sorted out finally!

I went ahead and lowered the fender some. Looks better IMO. I'm kinda concerned about the (lack of) coverage on the back side of the fender,but I guess if it worked on the Ducati it'll work for me.

The adapter bracket shows a little at the bottom edge where it bolts to the axle pinch bolt,but once it all gets PC satin black you'll probably never notice it.

I'm glad my buddy is a packrat. This fender will run me $25. I'm pretty happy with it. Now I have to decide if I want to paint it body color or run it flat black. I will admit the idea of flat black came to me out of sheer laziness and not wanting to try to find paint that matches the rest of the bike.

And on lowering the headlight. A buddy on another forum mentioned that I can flip the headlight ears on this model. Seems like an easy solution,but not very fun or creative. We'll see what happens. I was kinda wantin' to make sumthin'...





Yes. My fork legs needs some attention.



 
#13 ·
Well,shit.

Like I feared,these pipes drag worse than shit.



I wasn't even trying hard. Seriously,I was just trying to get the tires warmed up so I could see if I could make them drag or not. I rode on some back roads for about 10 minutes then decided to let loose. I took a good left hander and the tires felt solid so I went for another... to the right....aaaaaand-BAM!!!! Unloaded the bike enough that the rear tire went in to a skid but it recovered easy enough. So,any body need an almost new set of pipes for a CB750F 900F or 1000F??? :D:D:D I can't use these things. I bet my peg was probably a good 5-6'' off the ground still.
 
#15 ·
Got the fender sorted out. Figured I'd post pics incase it would help someone with an idea one day.

Here's the brackets. It was a piece of 1" square stock I split into 1''x1'' angles.


Mounts to the forks like so. Between the fender and the brackets there are some spacers to get everything sitting just right.That top bolt is a biiiiitch to get to once the brackets are bolted to the fender. Gotta turn the allen wrench thru the holes in the rotors.:D



On the bike. I'm pretty happy with it. Not sure I'm crazy about the black after all,but we'll see.

 
#16 ·
Nice, simple but should be a good deal better than stock.

Definitely invert the headlight to start with at least. Zero money so it can't hurt.

Would the extra length in the forks help keep the exhaust up, teamed with maye another inch or two in the back? Those pipes look great it'd be rough to have to lose them.

Stock tyres on f1 rims are 110/80-17 and 130/80-17. A good resource to see what fits, what can be made to fit, and the total OD is this site: http://www.bridgestone.com/products/motorcycle_tires/products/battlax/bt45.html

Bt45 should be about right for this bike. You see the 110/80 is actually marginally taller than the 120/70 and that the 110 fits but the 120 should go on a 3.5" rim where you have a 2.5" rim.

Baffled by the brakes. Can't help thinking the 1000f calipers would be equal quality but fit in without adapters, or if you were going to make adapters why not use something bigger and better? Perhaps the calipers even fit to the forks and getting some 1000f discs (identical but 296 instead of 276 outer diameter) would give you bigger brakes without adapters.

Ps the early 600 calipers go with a 1/2" master and the f3 master isn't 5/8", although the f4 is.
 
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#17 ·
Cool bike shiny!!!

Ya, that headlamp has to come down a bit, looks weird that high. I would also send that chrome ring to the dark side!!

I like the front fender. I also liked the one that was on there when you got the bike. That one painted black would look cool.

I aint really feelin the blue frame.

I would do the "dremel fender eliminator kit" out back.

Looks like you can slide the forks down about an inch in the triples. May help your pipe clearance issue.

Anyway, cool bike, has tons of potentail!!!:D
 
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#19 ·
Amorti, as always, thanks for that info! I didn't build this bike so the parts list is just what was written down by the PO. IIRC, he was running some sort of vintage super bike class with this thing and was only allowed a certain maximum diameter rotor. But I'm not exactly sure about that.

I do have more fork leg I can use, and I've been strongly considering raising the bike more, but I was concerned about lifting the rear suspension even more than it is. Will the extra angle on the swingarm affect anything? I know the chain is close to rubbing the swing arm now, but I could run a slider type chain guide if needed.

On one hand I'd like to keep these pipes since I already own them, but bottom end power is down with the 4-1 vs. the 4-2 I just removed, so I'm not sure what I'm gonna do just yet. But I would like for the bike to sit higher either way. My knees are pretty bent while seated as it is.

Thanks for the kind words guys!
 
#23 ·
The seat height will be higher but the relationship of seat/pegs is the same so your bent knees issue will be the same.

As for other issues it can play havoc with chain slack as the chain only tightens on its way through the travel to straight alignment. Means as well as the obvious risk of chain rub you also need to run the chain slacker and make even more risk.
 
#25 ·
What happens when you ride a CBR600 without front brake lines hooked up and you bust your butt? I get to buy your wrecked bike and score cheap parts!

Thursday afternoon I picked up the following for $200: front end complete with rim,new tire,rotors,calipers and trees. Rear s-arm. Rear rim with new tire,cush drive and rotor. :rock: Both tires have date codes of Jan. 2013,but the rear has seen some burnout duty apparently.

When I got in last night i discovered my current trees were identical to these so i swapped the new FE on. I love it. This setup has no provision for a speedo drive though,so i gotta work something out there.

Comparo of new and old:

Mmmm...beef.


So first off this rear uses the same size axle so that was easy. I put it on the bike using the preexisting chain side spacer to see where my alignment was. 6mm off-center. Not too bad!

So I made a new chain side axle spacer and centered that up. Easy-peasy,on the money.

Then I checked the chain run and it was off by 3mm. My original plan was to shave 3mm off the sprocket mounting surface of the cush drive,but there was not enough tire-chain clearance for that. This tire is a 170 and I think it's only supposed to be a 160 on there. We'll see if it rubs or not.

I don't have a pic of this yet(cuz I haven't made the piece),but I can step the primary sprocket out the 3mm i need to align the chain. The splined portion of the sprocket is 14mm wide and it has a taper on those splines. There is ~2.5mm of unused spline on the outer edge due to the shape of the taper, so when I step the sprocket out I'll only be losing roughly 0.5mm of engaged spline. I'm comfortable with that.

New chain run mocked up with 3mm sprocket spacer.

Using the stock spacer between the brake side of the rim and the caliper mount was on the money, so I just reused that. Had to turn up a thinner spacer to finish up axle spacing and the rear rim was on!

There's about 5mm of clearance between the tire and the swingarm. We'll see if it rubs somehow,but it should be fine.

I still need to make the primary sprocket spacer and I'll need a new sprocket for this cush drive with the correct tooth count. I checked before I bought these parts and the sprockets available range from like...32-74 teeth in 1 tooth increments. Crazy.

This has raised the bike 1/2-3/4'',which I really needed. And I think it really helps the overly large rear fender look more in proportion. Super stoked about this set up now.

It's almost wider than the stock mud guard.:LolLolLolLol:




And compared to the already-wider-than-stock 140 that was on there. More beef!


But all that glitters is not gold, there is wee lil ding on the rear rim :doh:


I'm not sure if that's fixable or if I'll just need to replace that. Also,one of the fork cap preload thingy's in boogered up. Gonna need one of those. Oh,and a front fender. I think I'll just run a stock (to these forks) fender. I kinda like 'em.
 
#28 ·
Hell yea man!! This bikes ride like they are on rails with that fat rear tire. I'm running a 180 in the back and I believe either a 110 or 120 up front.
 
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