Author Topic: cb750 "K" vs "F" Triple Tree (Read 11461 times)

brycegp · « **on:** October 06, 2010, 04:30:15 PM »

I bought a 1971 CB750 (cafe NOT stock)...assumed it was a "K"...they didn't make "F" models that early. Since it isn't original, its very possible any old triple tree was swapped on at some point and I'd never know the difference without closer inspection.

Well...I bought a spare TOP triple tree from a guy on here that was a 1976 CB750K top triple tree. Because I've always assumed I was riding a 1971 CB750K...I assumed his '76 should fit. I thought it was '76 and earlier that should be compatible.

Regardless...should a '76 CB750K fit on a '71 CB750K?

1. Should a '76 CB750K TOP Triple Tree fit on the LOWER triple tree of a '71 CB750K?

The bike was purchased with the Tank of an '76 cb750F...so maybe an "F" triple tree was used also. So...

2. Early CB750 "K" vs "F" Triple Tree: Is there a difference?

Thanks for reading!!

cobra2411 · « **Reply #1 on:** October 06, 2010, 04:36:34 PM »

The gauge mounts are different, that much I know. Just found out that I have at least 71 gauges and top clamp... It's funny that you might have an "F" front on your 71 and I have a 71 front on my F.... Maybe I have your front

No you can't have it back...

Oh here's the thread with a pic of my gauges/top clamp.
http://forums.sohc4.net/index.php?topic=77870.0

brycegp · « **Reply #2 on:** October 06, 2010, 04:54:52 PM »

Here is the gauge cluster as it was when I bought it....

Don R · « **Reply #3 on:** October 06, 2010, 10:25:27 PM »

The F trees have a different offset than K, the fork tube holes are not the same distance from the neck holes.

scottly · « **Reply #4 on:** October 06, 2010, 10:48:20 PM »

My K1 trees have more off-set than the K7 trees I recently fitted. The trees in your pic look closer to the K7 off-set, at least from that angle.

knowsnothing · « **Reply #5 on:** October 07, 2010, 06:39:51 AM »

The ignition switch and dummy lights are all k7-k8 so i would guess the triples are too.

cobra2411 · « **Reply #6 on:** October 07, 2010, 09:21:59 AM »

Quote from: scottly on October 06, 2010, 10:48:20 PM

My K1 trees have more off-set than the K7 trees I recently fitted. The trees in your pic look closer to the K7 off-set, at least from that angle.

Is it just the top clamp that's different or the bottom too?

Also do the forks interchange? I've got a pair of K7 forks that have been rebuilt and I was thinking of swapping them in. It would be nice to know if they'll fit before I take everything apart...

brycegp · « **Reply #7 on:** October 07, 2010, 02:51:16 PM »

Quote from: cobra2411 on October 07, 2010, 09:21:59 AM

Quote from: scottly on October 06, 2010, 10:48:20 PM
My K1 trees have more off-set than the K7 trees I recently fitted. The trees in your pic look closer to the K7 off-set, at least from that angle.

Is it just the top clamp that's different or the bottom too?

Also do the forks interchange? I've got a pair of K7 forks that have been rebuilt and I was thinking of swapping them in. It would be nice to know if they'll fit before I take everything apart...

Forks will interchange as long as you are using the same 35MM fork tubes.

but what I am learning is that you can't just swap an "F" top triple tree for a "K" top triple tree....sucks...waisted money.

Anyone want a 76 CB750K TOP Triple Tree Smoothed? Bar clamps and gauge mounts have been removed. See pics....

brycegp · « **Reply #8 on:** October 07, 2010, 05:11:39 PM »

A little clarification:
* K Model: 182mm spacing,with 60mm offset.

* F Model: 182mm spacing,with 50mm offset.

Ugggghhh...I have an "F" triple tree...not a bad thing...but good to know. This thing is a franken bike...

1971 CB750 K frame
19?? CB750 K/F?? Motor
1976 CB550 fork tubes and lowers
19?? CB750 F triple tree
1980 CB750 DOHC Swing Arm
1976 Harley Rims
1964 Ducati Oil Tank
Headlight / Speedo off some European Moped
And a slew of custom bits....

cobra2411 · « **Reply #9 on:** October 09, 2010, 08:21:57 AM »

Quote from: brycegp on October 07, 2010, 05:11:39 PM

A little clarification:
* K Model: 182mm spacing,with 60mm offset.

* F Model: 182mm spacing,with 50mm offset.

So is this how they changed the trail on the F bikes? If so by having K1 clamps do I also have the K trail?

754 · « **Reply #10 on:** October 09, 2010, 10:15:25 AM »

By Ducati oil tank?,
do you mean off a Cadet or Mountaineer.??

scottly · « **Reply #11 on:** October 09, 2010, 07:45:36 PM »

Quote from: brycegp on October 07, 2010, 05:11:39 PM

A little clarification:
* K Model: 182mm spacing,with 60mm offset.

K7 is 50mm offset; checked mine today.

Timrek · « **Reply #12 on:** October 10, 2010, 08:22:39 AM »

I have a franken bike too so don't feel bad.

I have a 76 CB750K6 from the steering tube back and the front end is off of a 79 CB750F SS. So it works ok and seems to ride nice.

Old pic. I have been cleaning it up and I got it painted. Not running roight now though due to electrical issues.

bollingball · « **Reply #13 on:** October 10, 2010, 08:35:21 AM »

Trees are 77 or 78. can not tell if K or F.

754 · « **Reply #14 on:** October 10, 2010, 08:54:17 AM »

If they are F's, the lower tree will have two studs or tapped holes in the center of front part of the tree.

sharpinski · « **Reply #15 on:** October 10, 2010, 09:24:00 AM »

I recently bought what I thought was a triple tree top for a 76 cb750k but got a triple tree top for cb750f. I was going to shave it down identical to what you have. If you are serious about getting rid of your shaved down triple tree top i would take it off your hands.
Let me know.
Thanks

brycegp · « **Reply #16 on:** October 10, 2010, 05:36:42 PM »

Quote from: sharpinski on October 10, 2010, 09:24:00 AM

I recently bought what I thought was a triple tree top for a 76 cb750k but got a triple tree top for cb750f. I was going to shave it down identical to what you have. If you are serious about getting rid of your shaved down triple tree top i would take it off your hands.
Let me know.
Thanks

I'd be interested. But still need the smoothed top of the "f". Smooth your "f" and we can swap even trade...my "k" for your "f"??

PM me...

brycegp · « **Reply #17 on:** October 10, 2010, 05:48:12 PM »

Quote from: brycegp on October 10, 2010, 05:36:42 PM

Quote from: sharpinski on October 10, 2010, 09:24:00 AM
I recently bought what I thought was a triple tree top for a 76 cb750k but got a triple tree top for cb750f. I was going to shave it down identical to what you have. If you are serious about getting rid of your shaved down triple tree top i would take it off your hands.
Let me know.
Thanks

I'd be interested. But still need the smoothed top of the "f". Smooth your "f" and we can swap even trade...my "k" for your "f"??

PM me...

oh BTW...I only have to TOP TRIPLE TREE...not the whole thing. So you'll have to score the bottom...but if buying only the bottom...its much cheaper on Feebay.

Anyway...let me know...

mcuozzo · « **Reply #18 on:** October 10, 2010, 09:35:40 PM »

I might be wrong about this, so double check the info...but I believe that you can not use the top triple tree from 76 or earlier with a bottom of a 77/78. Whether it's a K or F doesn't matter. So make sure you both have later triple trees before you swap. I'm pretty sure this is right since cycle x's website saw the top alone can only be used on 69-76's. Obviously if you by the complete triple tree, it works on any year bike.

So BryceGP, what exact top are you looking for? A 78K or F? I ask because from your gauge picture that looks like a 78 K, but you keep saying you are looking for an F. Can you snap a pic of the lower triple tree?

Sharpinkski, you're looking for the top to a 76K then right?

I have some triple trees in my shop, if your swap won't work, I might have a tree for both of you. I definitely have 77/78 K and F triple trees, not so sure about the earlier model, but I might.

icmock · « **Reply #19 on:** February 21, 2011, 01:05:08 PM »

Hey Mcuozzo, maybe you could help me with my triple tree/bracket problem...

I replaced my '77 cb750k top tree with a polished one that had lower bar risers. The dude I bought from on ebay isn't sure what year or model they come from (although listed as '78 750f). My problem is now my '77 gauge bracket will not fit due to the new top tree bracket holes are 3/8"-1/2" further apart (6" center to center to be exact). The tree fits perfectly on my forks and appeared identical to my '77 k, all for the gauge mounting holes.

SO, I figured I just need to figure out what year this top tree is in order to get a bracket that will fit.
ANY advice?

Ricky_Racer · « **Reply #20 on:** February 22, 2011, 09:45:22 AM »

Bryce, from what I've read it looks like no one is in line for the upper tree. I'm interested. If you want to PM with your price, I'd appreciate it. Thanks. RR

brycegp · « **Reply #21 on:** February 22, 2011, 10:33:51 AM »

Quote from: Ricky_Racer on February 22, 2011, 09:45:22 AM

Bryce, from what I've read it looks like no one is in line for the upper tree. I'm interested. If you want to PM with your price, I'd appreciate it. Thanks. RR

Email sent...

HondaMan · « **Reply #22 on:** February 22, 2011, 12:05:11 PM »

The 750K6 was the first Frankenbike, being composed of partly K5 and partly F0 parts. If you look at 2 K6 bikes side-by-side, one will often have a different wiring harness from the next one, very common. The triple trees: the last of the K5 and some of the K6 bikes had the top-mounted keyswitch that is a feature of the F0. Many folks liked the feature and swapped trees to get it: you have to also swap the front fender (or make spacers) to join things together.

Ricky_Racer · « **Reply #23 on:** February 22, 2011, 12:58:34 PM »

Thanks for the email, Bryce. I appreciate it! RR

Silverback · « **Reply #24 on:** February 22, 2011, 01:23:20 PM »

I have a bracket from a 78F somewhere, if that will help you out. I won't go looking for it in all my parts boxes unless you need it, so let me know.

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Author Topic: cb750 "K" vs "F" Triple Tree (Read 11461 times)

Timrek

bollingball