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Paul in NZ
17th December 2009, 18:30
Yes the fugly DOHC ones with the inclined engines and horrible comstar wheels.

I've work on one and ridden it a short distance (fuggin awful) but in general, what are they like powertrain wise?

RDjase
17th December 2009, 19:14
Yes the fugly DOHC ones with the inclined engines and horrible comstar wheels.

I've work on one and ridden it a short distance (fuggin awful) but in general, what are they like powertrain wise?

The ones like CB900's or that in between (K model) ?

The CB900 type had strong engines, but have a chain drive primary to gearbox that gets tired . My mate drag raced one. I think the 750's were the same. Not a honda expert tho. I just had a 900 with cams and carbs, It went really well

AllanB
17th December 2009, 19:17
Is it the CB750F? same as the CB900F but a 750.

1980 something?

I like them. Comstars look good blacked out if that helps!

If I remember they proved to be reliable. High km ones may get a camchain rattle.

Wiseco had a big bore kit once .......

madmal64
17th December 2009, 20:02
Similar to the CBX750F?
If so this is a good place to start Paul
http://www.teamrc17.net/
Viking and the rest of the group know thier stuff on these things
EDIT:
Just had a look at the above site and they do have some info on the CB

Paul in NZ
17th December 2009, 20:35
Nah - the later (1980 or so) one with the tipped forwards engine like the 900.

Just wondering, (at the moment)

F5 Dave
18th December 2009, 10:45
engine wise they should be fine unless if at some time in their life the oil was run low which will shag the crank & turn a oil light on to tell you it's ferked.

Probably a good thing, feck they were dreadful compared to the Suzuki of the same vintage.

HenryDorsetCase
18th December 2009, 12:49
Yes the fugly DOHC ones with the inclined engines and horrible comstar wheels.

I've work on one and ridden it a short distance (fuggin awful) but in general, what are they like powertrain wise?

For their time they weren't a bad bit of kit. Remember in the early 80's there was power (kindof) but not chassis or tyre technology to make it that usable.

Ive done a few miles on one and it rode very well at the time. I had a ZX750A3 at the time which was from about 84. I think they're very reliable. In the day we called them "Rolladoors" as hilarious parody of Bol D'Or.

F5 Dave
18th December 2009, 13:35
Rollerdoors were the full fairing version. Typical Honda trying to extend the life of an obsolete model by adding 30kg of weight to the front of the bike.

jellywrestler
18th December 2009, 16:31
Rollerdoors were the full fairing version. .
not so, the 1979 FZ had bol d or on the sidecover and the nickname started then

F5 Dave
18th December 2009, 16:43
Hey, every day's a school day. Quite often you learn stuff you'd rather forget, - but I have a plan involving beer.

Bonez
22nd December 2009, 15:57
Nah - the later (1980 or so) one with the tipped forwards engine like the 900.

Just wondering, (at the moment)Had one 23 years(Gerty the Integra). http://www.kiwibiker.co.nz/forums/showthread.php?t=6072 Absolutely shocking. Must get the carbs back in and the charging issue sorted. Collected a few bits n bobs over that time, as you do.

An excellent resource at http://www.cb1100f.net/

The CB70KZ was the first of that line of engine in production being Aus BOTY for '78 or '79 (damn memory) sharing it with the CX500. RollaDoors where the 900s but the later 750Fs inhereted that moniker by the uneducated(ell they looked the same so you can forgive them ;).

Of course Honda in there wisdom thought it was a great idea to have two cam chains in these brutes, what where they thinking? And as previously mentioned they have a chain primary drive.

Not as well balanced or powerfull as the later CBX750, which were a total redesign. Btw a later cb750s use an engine evovled from the cbx750 which was in production at least till 2008 in the Jap domestic market. Called Nighthawks in some markets only ever seen here as grey imports.http://en.wikipedia.org/wiki/Honda_CB750

I'd own another F at the right price if it is in reasonably good condition. Later ones, like Gerty, had bigger fork tubes, TRAC and wider rims with banana type comstars and twin pot brake calipers all round.

SPman
22nd December 2009, 16:46
Weren't they the last Hondas to have 4 pipes?

Bonez
22nd December 2009, 16:57
Weren't they the last Hondas to have 4 pipes?The Cb750KZ was. This could be what Paul is looking at. Fs had twin mufflers and are certainly nicer to look at. But Honda has made a few models in recent history for the jap retro market with 4 into 4 though.

Edit-No I was wrong the CB650(had one of these)/CB750/900 customs were 4 pipers too.

Paul in NZ
22nd December 2009, 17:57
Well I was attracted to the big DOHC tilted forwards donk and thinking hmmmm... that looks a bit (if you squint) like a 60's Honda factory racer engine and since they are CHEAP and other donors for a cafe racer are NOT cheap I went... hmmmm!

BMWST?
22nd December 2009, 18:02
For their time they weren't a bad bit of kit. Remember in the early 80's there was power (kindof) but not chassis or tyre technology to make it that usable.

Ive done a few miles on one and it rode very well at the time. I had a ZX750A3 at the time which was from about 84. I think they're very reliable. In the day we called them "Rolladoors" as hilarious parody of Bol D'Or.

at the time the honda 900 was on a par with the gs1000...and was prolly a better package than the gsx 1100.I has two a FZ and then the FA.I was gonna buy a gs100 but wheni passed about four on the hutt motorway i thought bugger that every man and his dog has got one.....

Bonez
22nd December 2009, 18:08
Well I was attracted to the big DOHC tilted forwards donk and thinking hmmmm... that looks a bit (if you squint) like a 60's Honda factory racer engine and since they are CHEAP and other donors for a cafe racer are NOT cheap I went... hmmmm!Cheap is good ;). Shit forgot all about the 750C. That would be a great basis for a cafe racer. http://stever.ca/other-stuff/cool-cb750-cafe-racer/

Pedrostt500
22nd December 2009, 22:14
I had a 1980 CB 750 K in the early 90s, it had a horible primary chain knock at idle, got a price from a mate to rebuild the motor, was cheaper to buy a new bike, doubt its got any cheaper to rebuild one of these motors.

pete376403
24th December 2009, 23:26
The "twin-cam-four-valve" thing was more of a marketing exercise than an attempt to make serious power. The angle between the inlet and exhaust valves was too wide, which made the combustion chamber too big, so the pistons had to have high domes to get decent compression. This resulted in a long thin chamber which didn't burn fuel as well as a more compact chamber. The previous single cam two valve 750s made more power.
Well that's what Kevin Cameron reckoned when they came out, anyway.

Howie
25th December 2009, 07:33
Shit that brings back Memories. I had a CB900F back in the very early eighties, as to reliability I only had a couple of problems with it. First one was that it developed a slight ticking noise in the engine when I was about 400km from home. I thought it was that it needed the valve clearances checked.(which are a shim type) Turned out the cam chain guide for the chain connecting the two cams had cracked and a little bit of it was rubbing on the chain and I got to within about 20km of home before it broke a little bit off, which broke the connecting chain. which dropped into the one connecting to the crank, which also broke. End result new chains, Temsioner’s, sprockets, and 8 bent valves.(warranty claim) Lesson learnt check out those strange noises. The other problem was after a medium speed drop on the right hand side,(black ice) which it turns out bent the crankshaft, end result of that was a broken crank. Other than that it was a great bike, and took me quite a few places around NZ.
I think I still have a Haynes manual in the shed for the CB750-900 from the late 70’s/ early eighties.

What?
28th December 2009, 08:29
I had a CB750FC - 1982. Great bike (in the day), albeit needing regular and carful maintenance (esp. cam chain tension). Traded it on a CB1100 that I still own (Yeah, yeah...)

I have got a rear wheel c/w disc and cush drive off another 750FC if anyone wants it.