Author Topic: DOHC CB750 swingarm in a K1 (Read 19210 times)

Industrial Cafe · « **on:** February 13, 2009, 03:41:55 PM »

I cannot get the needle bearings out of my 80 dohc swingarm.
The plan is to cut about 0.5in out of the one side and reinstall them deeper in the swingarm, so I can put it on my k1.

help!

mattcb350f · « **Reply #1 on:** February 13, 2009, 04:02:39 PM »

I think if anything, you have to cut the same amount of each side. Otherwise, you through off yer alignment...which you'll find out rather quickly after it's back together.

Does it need to be narrower to fit in the frame?

Matt.

Industrial Cafe · « **Reply #2 on:** February 13, 2009, 05:20:18 PM »

yeah, one side is longer than the other.
gots ta be narrowed- it doesn't fit by about a half inch.
take a gander at this here link>

http://forums.sohc4.net/index.php?topic=34880.0
just scroll down to the pics

Industrial Cafe · « **Reply #3 on:** February 14, 2009, 07:49:33 AM »

moved!?
Its' a single cam cb750 with an attempted dohc swing arm!!
its not "other bike" subject matter.
did you not you see the part about the K1?
oh well, maybe someone in the "other bikes" section can help. maybe someone with extensive experience in Yamaha RD350s.
I guess I should be thanking this "SteveD" character.

thank you Steve, thank you for moving my post.

754 · « **Reply #4 on:** February 14, 2009, 08:38:06 AM »

I agree this should be a comon mod for the 750. I think more/all does come off the one side though.

After reading all on this earlier posted, i am thinking that Bronze bushings are far easier to live with and get made.

I dont think that the needles come out easily and could be reused, plus they are pricey. and must run on a hardened spacer.

If I had one in hand I could probably tell you a home method for removal.. will try to get over to 1080s to look at a 800 one he has.
754

bryanj · « **Reply #5 on:** February 14, 2009, 10:31:31 AM »

From Memory its a special puller that slides through then a pilot expands the far end that has a lip and you use a slide hammer to extract the bearing----This ALWAYS wrecks the bearing as the inner end is rounded whilst the outer is flat.

Industrial Cafe · « **Reply #6 on:** February 14, 2009, 11:05:11 AM »

I figured I would need a slide puller.
I'm not worried about effin' up the bearing... there's some bearings on ebay for $19.99.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=250365129276&fromMakeTrack=true

I also noticed the inner race(tube the bolt goes into) has a little over a half inch of space to move the bearing (on the cut side) in.

But I'm not yet sure if I can press the bearing a half inch further into the pivot tube without machining it inside...
methinks the end cap should fit fine after the cut.
$:-\$

754 · « **Reply #7 on:** February 14, 2009, 07:45:21 PM »

Cut a disc, just under the size of the bearing out of 1/8 or thicker metal.

slit down the centre, then nick the corners off...install in back of bearing.. wiggle in place.

Insert rod near bearing ID size.. and wail away...

MRieck · « **Reply #8 on:** February 15, 2009, 07:04:46 AM »

Quote from: bryanj on February 14, 2009, 10:31:31 AM

From Memory its a special puller that slides through then a pilot expands the far end that has a lip and you use a slide hammer to extract the bearing----This ALWAYS wrecks the bearing as the inner end is rounded whilst the outer is flat.

Exactly. I just removed the needle bearings in a JMC swingarm with the blind puller attachement on the slide hammer. Keep in mind the bearing housings have a "thick" end (the code is posted on it)....that's the side you push against when installing them

Industrial Cafe · « **Reply #9 on:** February 15, 2009, 03:57:15 PM »

uh... i Got it out

I felt like such a dumb hillbilly pounding away with a hammer 'n' chisel.

oops...

all better $:-\$

well after all that, it looks like I did ok.
Although I had to grind off the chisel burrs on the swingarm, it's only .001 out of round.
now I just need to press the new bearing in, when it gets here.

Industrial Cafe · « **Reply #10 on:** February 15, 2009, 03:59:38 PM »

MRieck's idea would have been great, if I read it yesterday

754 · « **Reply #11 on:** February 15, 2009, 09:01:01 PM »

Shoulda tried Mikes method or mine.. & saved scarring up the swingarm...

Industrial Cafe · « **Reply #12 on:** February 15, 2009, 09:35:30 PM »

Oh yeah, don't I know it.

Industrial Cafe · « **Reply #13 on:** February 18, 2009, 03:58:21 PM »

I had to drill out the holes at the pivot point on the frame to 41/64 inch to accommodate the 16mm bolt. I pressed in the new bearings and did a mockup.

I gotta turn down some axle shims, cause using the late model shims doesn't work. it makes the tire a half inch off center.
maybe a late model cush drive takes up the 3/8 inch needed on the chain side... I dunno, I don't have one yet.

Industrial Cafe · « **Reply #14 on:** February 18, 2009, 04:12:15 PM »

I must admit I didn't expect the shocks to be so far back, but I'll fix that with an additional shock mount welded in later.

Industrial Cafe · « **Reply #15 on:** February 24, 2009, 08:18:04 AM »

I should have cut a 1/4 inch off each end of the inner race.
but it works.

Industrial Cafe · « **Reply #16 on:** March 30, 2009, 09:43:18 PM »

K8 carrier because I got a k8 motor. wouldn't have needed it if I had the original K1 motor.
had to put an extra 1/4 inch spacer on the other side with the oem DOHC brake side spacer.

with the K1 motor and sprocket carrier-

Industrial Cafe · « **Reply #17 on:** April 14, 2009, 09:58:35 PM »

now that it's all done I like the way it turned out.

Magpie · « **Reply #18 on:** April 14, 2009, 10:11:34 PM »

Looks great, good work!!!!!!!!!!!
Cliff.

GoatBaSS · « **Reply #19 on:** August 20, 2009, 05:40:06 AM »

Looks great now I have to re read it all to understand!

Industrial Cafe · « **Reply #20 on:** August 20, 2009, 07:39:46 AM »

reading it all might screw you up

GoatBaSS · « **Reply #21 on:** August 20, 2009, 08:04:10 AM »

Nothing a hammer and a impact driver cant fix.

bill440cars · « **Reply #22 on:** August 20, 2009, 08:08:38 AM »

Nice job on that Swing Arm Conversion AND on the bike as well.

Something for others to keep in mind, that they might want to do.

Industrial Cafe · « **Reply #23 on:** August 20, 2009, 08:19:03 AM »

thanks, hopefully, someone can get the general idea from this thread.

bill440cars · « **Reply #24 on:** August 20, 2009, 09:27:07 AM »

Quote from: Industrial Cafe on August 20, 2009, 08:19:03 AM

thanks, hopefully, someone can get the general idea from this thread.

I hear ya, it just might get to be a "Common Conversion" that folks just get in on and DO!

THAT would be something.

Industrial Cafe · « **Reply #25 on:** August 20, 2009, 12:58:14 PM »

I really like it, it handles really well and it launches better than the short swingarm.
I think it has something to do with weight distribution, I sit -pretty much- right over the shocks. and my front end used to come up enough to get light under hard acceleration.

not anymore.

MCRider · « **Reply #26 on:** August 20, 2009, 01:17:51 PM »

Quote from: bill440cars on August 20, 2009, 09:27:07 AM

Quote from: Industrial Cafe on August 20, 2009, 08:19:03 AM
thanks, hopefully, someone can get the general idea from this thread.

I hear ya, it just might get to be a "Common Conversion" that folks just get in on and DO! THAT would be something.

What's the advantage of this arm over stock? It is tubular and longer, anything else?

Edit: I just read the last post from IC. Things attributed to length. I see.

brycegp · « **Reply #27 on:** September 30, 2009, 07:47:15 PM »

Quote from: Industrial Cafe on February 24, 2009, 08:18:04 AM

I should have cut a 1/4 inch off each end of the inner race.
but it works.

I am doing the same thing on my K2 now. And I have some additional questions on this swap, if you don't mind me asking.

1. What do you mean by "1/4" off each end of the inner race"....? Is this the metal tube that goes in the pivot tube??
2. Once you trimmed the length off the swingarm pivot point and removed the old bearings, did the new bearings just pushed right back in?? Or would you now recommend going with bronze bushings instead of needle bearings?
3. Did you use the late model sprocket or the K1 sprocket?
4. What length chain did you go with after the swap? Does the longer DOHC chain now work?

Here are the parts I am using.
1. '80 swingarm and pivot bolt. (all length trimmed .5" and pivot mount hole on the frame bored to fit 16mm pivot bolt)
2. K2 hub
3. K2 brake drum
4. K2 Sprocket
5. '80 axel, cush drive and spacers.

Thanks for reading...

Industrial Cafe · « **Reply #28 on:** September 30, 2009, 08:00:45 PM »

Quote from: brycegp on September 30, 2009, 07:47:15 PM

Quote from: Industrial Cafe on February 24, 2009, 08:18:04 AM
I should have cut a 1/4 inch off each end of the inner race.
but it works.

I am doing the same thing on my K2 now. And I have some additional questions on this swap, if you don't mind me asking.

1. What do you mean by "1/4" off each end of the inner race"....? Is this the metal tube that goes in the pivot tube??

yes, the one thats shiny on both ends and machined in the middle

Quote

2. Once you trimmed the length off the swingarm pivot point and removed the old bearings, did the new bearings just pushed right back in??

yeah, the inside of the swingarm is machined in quite a ways

Quote

Or would you now recommend going with bronze bushings instead of needle bearings?

I went with needle bearings cause they were readily available and they were a direct replacement (so it was just like stock)

Quote

3. Did you use the late model sprocket or the K1 sprocket?

I used my original K1 sprocket. the chain is easier to find in different lengths and colors

Quote

4. What length chain did you go with after the swap?

120 link, and cut out 6 links

Quote

Does the longer DOHC chain now work?

the DOHC chain is a 630. you'd have to change your drive sprocket as well as leave off your front sprocket cover for clearance

Quote

Here are the parts I am using.
1. '80 swingarm and pivot bolt. (all length trimmed .5" and pivot mount hole on the frame bored to fit 16mm pivot bolt)
2. K2 hub
3. K2 brake drum
4. K2 Sprocket
5. '80 axel, cush drive and spacers.

Thanks for reading...

be real REAL picky on your spacer lengths, you gotta line that chain up PERFECT. you might need to do some mods to the spacers.
you shouldn't have to stretch the swingarm apart or squeeze it together either.
do not hesitate to ask more questions.

brycegp · « **Reply #29 on:** October 13, 2009, 10:13:32 AM »

thanks for all the help...I've got the arm mounted up and the sprocket seems to be lining up perfect. but I don't have a chain yet so I'll have to wait to see for sure.

As far as the spacers go...I used the sprocket side spacer from the early model on the brake side. And I used the sprocket side spacer from the late model on the sprocket side. That made it mount up at the right over all width between the axel mounts.

Question: Did you have to modify the brake lever rigging? Now its seems to be hitting the new swing arm in a couple spots. Maybe in reinstalled the rigging wrong...

Industrial Cafe · « **Reply #30 on:** October 13, 2009, 10:53:59 AM »

Quote from: brycegp on October 13, 2009, 10:13:32 AM

Question: Did you have to modify the brake lever rigging? Now its seems to be hitting the new swing arm in a couple spots. Maybe in reinstalled the rigging wrong...

yeah, it's supposed to hit I think... it did on my original swing arm, stops the pedal from just hanging there and bouncing around.

I repositioned the foot pedal on the splines cause the pivot tube on the swingarm is larger and pushed the lever down about 1 spline tooth.

Industrial Cafe · « **Reply #31 on:** October 13, 2009, 10:55:16 AM »

Quote from: brycegp on October 13, 2009, 10:13:32 AM

thanks for all the help...I've got the arm mounted up and the sprocket seems to be lining up perfect. but I don't have a chain yet so I'll have to wait to see for sure.

you'll know when you go to ride it around and it starts leaving grease marks on one side of the rear sprocket

brycegp · « **Reply #32 on:** October 15, 2009, 08:12:59 AM »

Now I am noticing that the wheel is offset about .5" to the brake side of the bike. But the sprocket lines up! And the wheel is lining up in the center of the swingarm.

I think its because I used the late model cush drive (which is about .25" wider). But now I am thinking there is no reason I couldn't just use the original cush drive. Then the wheel will be back to original.

like you said...just find the right spacers to position the original wheel correctly within the new swingarm. (I thought I'd already done that.) Can you tell me how many inches of spacers you've used on each side?

thanks, man!

Industrial Cafe · « **Reply #33 on:** October 15, 2009, 09:55:05 AM »

heh, mine is offset about .25in or so to the brake side as well, I think it's because I used the inner spacer from the k1 on the k8 carrier. the reason I say this is because the carrier sits inside the hub a bit.

KRONUS0100 · « **Reply #34 on:** August 16, 2010, 08:49:54 AM »

no pictures yet. using 1981 cb900f swingarm into a 1976 cb750f.......stock 1978 cb750 rear wheel/brake....fits centered in swingarm just like it should. have trimmed the right side of the pivot 10mm......waiting on new bearings. having sleeve made for the stock pivot bolt so i dont have to bore the holes in the frame.

Industrial Cafe · « **Reply #35 on:** August 16, 2010, 11:30:32 AM »

good idea.

Free Booter · « **Reply #36 on:** March 14, 2012, 10:53:55 PM »

1997 HONDA CB250 NIGHTHAWK SWINGARM?//

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Author Topic: DOHC CB750 swingarm in a K1 (Read 19210 times)