Topic: Drag Bike / The Big 4 Express.

[Don R]

 With the crank sideways the torque should be front to back except the deflection from the chain drive not being in the center.
  I'm abandoning this engine case, The K5 case I got from a wrecked 10,000 mile bike also has bbbbb bearings and they look perfect. I got the F2 trans in the case with the k3 sprocket shaft, I need to pull the head studs from both motors.

[Don R]

 I got the studs out of the K5 case. Oh. My. Goodness, I do not enjoy that at all. I used PB blaster, beeswax, atf/acetone, freeze-off, electric heat gun, propane heat, oxy acetylene. I wore out several locking nuts, used all of my vice grips, small pipe wrenches and ratchet strapped the case to the lift.
 A couple of them did a half twist before coming out, I was pissing my pants and keeping the small pipe wrench as low as possible.
 Time for a late lunch break, then I'll clean the case up and begin moving the aftermarket studs to this case.
 Edit, it's the same fight with the rings. Same stuff.

[Don R]

  I pity the fool that assembles one of these without another one, or good pictures to look at. The manual wasn't much help.

  Assembling this without something to look at is a recipe for frustration. I wanted to see the F2 trans in a K5 case swap work. It does. Thank goodness.
  One tip, don't forget the neutral safety switch, just saying.
 
   Thanks to Per for the photos and advise. This trans swap deal has been stewing inside my brain for a long time. Others had explained the difference but not so much a solution. I hadn't considered the F clutch swap, but that's a reality too, I just need to strip the black off of that cover.

[Don R]

 This is why two 750's are minimum. One to work on, and one for riding and reference.

[PeWe]

This is why two 750's are minimum. One to work on, and one for riding and reference.

+3
And a stock CB750 to compare with.

I got very old memory flashbacks when I rode my stock K2 the first times.   The sound and bahavior.

[Don R]

  I have spent two full days moving and cleaning studs and threads, tapping the oil galley for 1/8" tapered pipe, cleaning and sorting parts. This crankcase is a K5 out of a wreck that I bought from the original owner, it had 10 oil changes in 10,000 miles and then was left in a barn with no carbs on it. The mice killed the cylinders, but they need bored 4mm now anyway.
  I've sorted out the valve train and cam gear and picked out the best of the other parts.
 
   I put the clutch in and had an outside snap ring left over. I think it holds the basket on the shaft, since it's an F2 trans and an F2 clutch. I had planned to do the clutch oil hole mod to the basket anyway. Time to check the clutch section, this time I need the F manual.

[Don R]

 It's crazy, the parts F2 had 9400 miles on it and that included the miles on the second engine that was in it. The parts K5 had right at 10K with 10 documented oil changes.
 The drag bike was parked in the late 70's or early 80's but I have a feeling its parts were used a little harder.
 I didn't find anything about the snap ring, but it has to be the one in the F clutch basket.
 
   Edit, I got the snap ring back on it, drilled and chamfered the oil holes in the clutch hub and got the clutch back together. I found an old K clutch hub in my stash that some goof went to town drilling holes in, they are everywhere, large and random, a couple even went into a rib on the underneath side.
 

[Don R]

 I emailed Ken at CycleX, he said we should talk on Monday. He might be interested in some of my stuff but probably the things I want to use.
  I'm not sure if any of my early cylinders that aren't earmarked for a particular engine are usable, something needs bored to 836 and something else needs sleeved for the 1124 motor. I have several late type, but the head gasket gets a little thin around the O rings.  The problem is, my best early cylinders are both sandcast type. 
  I think I might just sell a bike and send Ken the $$. L0L!

[Don R]

http://www.cyclexchange.net/Clutch%20Page/INSTRUCTIONS%204%20Friction%20Clutch%20System%20NEW%201.png

  I seem to have three late clutch baskets and only one late clutch center. (22120-300-050) The one slanted disc I have has peeled the friction on one side. I remember one F motor was full of water and the clutch frictions were disintegrated, maybe I junked it.

[PeWe]

Do you have the late clutch basket? 22100-392-010
https://www.cmsnl.com/honda-cb750k7-four-1977-usa_model495/outer-comp-clch_22100392010/

It is about 2mm deeper than same looking K6 that has same depth as the earlier.
22100-392-000
https://www.cmsnl.com/honda-cb750k6-four-usa_model14380/outer-clutch_22100392000/

Same difference in depth as the matching center hub.
Important measure or place side by side to compare when K6 and later K7, F2 look the same but different depth

Model after K6 that also have the outer slanted disc with wider ears. K6 and later use same clutch fibers.

I updated my clutch with an F2 clutch 2 years ago. I reused my K6 clutch fibers, EBC CK-1145 and same really hard springs Barnett 66 lb version as to CB500 and smaller CB.
Billet plate lifter as it got earlier.
http://good-bits.co.uk/product/cb750-sohc-clutch-actuating-hub/

http://forums.sohc4.net/index.php/topic,180468.msg2092617.html#msg2092617

[Don R]

  I do have three of those clutch baskets. I bought a complete F trans off of ebay and had APE back cut it.
  And I did finally spot another wide clutch center. The plates and frictions that were previously on it were a solid ball of rust so there's some cleaning needed.
  I parted out a few rust outs and wrecks and sorted according to the part. Now I've decided it's better to assemble into motors even if they are just test fitted.
  I noticed that cycle x drills a few more oil holes than Hondaman suggests. I drilled mine halfway between the two holes and single holes to get the oil to different plates.
  One of the folks selling the billet clutch hubs has an unfortunate history selling to me so no money will go that way again.
 Thanks for the information on the clutches, we might need a tips and tricks thread. 

[PeWe]

Drill more oil holes will not affect the grip at higher power?
I drilled the clutch with  extra holes when my K6 had 836 and 80whp.
I did not drill the F2 clutch since I thought extra oil flow could cause slips. Back then 93whp. Today 10 more.
Take offs work fine with smooth starts.
The heavy springs make left hand to remember a longer ride with many gear shifts afterwords

The metal discs got a glass bead treatment this winter. Not the double disc. Too risky to let the small glass beads to get trapped in there. Outer grinding only.

Don, your trans gears are undercutted for downshifts too?
I have heard about undercutting for acceleration only. Roadracing bikes for deceleration too.

[Don R]

 I believe big Jay just back-cut for acceleration. It was a trade deal as a favor to him and Jerry RXman. It was one of those deals you think back, and maybe it made dollar sense and helped someone out then, but today would rather have the parts I traded away.

[Don R]

  I sorted my trans parts today, one had been in a broken case and had tooth damage and aluminum extruded into the root of the teeth. I also turned up half of a super sport trans, main shaft but not the countershaft. A guy that ran mini sprints with Honda motors gave me a box of left-over parts one night, it must have come from there.
 I swapped gears on a countershaft that had damaged teeth. Halfway through I got lost but it looks like a correct one now. The transmission out of the turbo motor has some shaky dogs on it, I'll see if I can swap a few loose parts to make it look a little better.

  Clutch parts ordered off of ebay. I got an f2 clutch hub for $22.50, My good crankcase has the k6 basket so it has a home.

[Don R]

   I've spent the last week going through motors, I'm trying to remember what parts came from what, and were planned to go where.
  I labeled a K5 really nice top end from a "broken case" motor and I have a 75f crankcase that had 10,000 miles on it with 10 oil changes. There are 5 or 6 potential motors here, three of which have a home. 
  I found a few clutches and assembled the parts into complete units. The turbo motor will get all of the best stuff.

[Don R]

  I decided to run a 16" V twin type Drag bike rear tire.  Shinko sticky compound. The decision now is, do I make it drum brake or disc. If they all had a drum brake, I could swap tires bike to bike depending on where it is being used. I do have a cool disc option though, I have both F1 and F2 rear disc brake assemblies.

 I ordered a right control for #2 bike (the one that runs) so I can have the headlight switch, start button and kill switch in one place.

[Don R]

  The Lesters look a lot better, there were some small pitts on the bottom side that sanded out and polished pretty nicely. I'm looking at a 16x3  7-star Henry Abe rear and a 5-star Suzuki front wheel. This hinges on what I learn about the 16x150 Shinko V twin drag tire.
  The 18x3.5" DID rim's rusty spokes all came loose at least a couple turns. I have a good bearing retainer for it but the hub side threads are half gone.

[Don R]

 I got my 5 year old grandson loosening spoke nipples today. I had them all broken loose and we backed them out with 8mm wrenches so the screwdriver bit could get past the end of the spoke. He asked if his Grandma's XR70R can come to his garage and also be painted blue before he comes back again.

  It appears the spokes in the 3.5x18" DID are cut down 18"ers. I'm not sure what I'll use going back. I'd go stock but Buchanon stainless are so nice to look at, and yet this old dad's wallet is going drag racing soon. I ordered a Shinko 140X18 just for riding around and maybe the 1/2 mile top speed deal. 

[Don R]

 I went through my parts and rounded up a wide late model rear sprocket carrier and rebuilt a pair of F front calipers, one for the turbo project and one for the F1. The F'n K has a center outlet caliper too. I'd like to make double disc F brakes for the Hot Rod and maybe use a 550 rotor and forks on the turbo drag bike.
 
 

[Don R]

 The frame is raked 10* over stock, I'm wondering how short the forks can be, I have choices in my stash of stuff.
  The exhaust goes around the engine to the turbo and back out the left side, nothing under the bike.
  Frank would have liked it. 

[Don R]

 I began to re-lace the 3.5x18" DID rim with the best of my used stock and original spokes. I got the innies done. I'm still not sure what tire it will get but the rim needs to be on a hub whether I use it or not.
 This thread will just be the turbo drag bike, now it was getting too confused. The stroker motor is on the back burner for now. It needs sleeves and a cylinder.
 

[Medyo Bastos]

I began to re-lace the 3.5x18" DID rim with the best of my used stock and original spokes. I got the innies done. I'm still not sure what tire it will get but the rim needs to be on a hub whether I use it or not.
 This thread will just be the turbo drag bike, now it was getting too confused. The stroker motor is on the back burner for now. It needs sleeves and a cylinder.

What size tire was on it?


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[Don R]

 The tire said 3.50x18 but the tread was over 5" wide. Goodyear road race tire. It's a tire swing now. I laced it back up with the old shortened spokes and some nicer used ones and put it under the bed.  I'll probably call Buchanon's if I end up using it.

[Don R]

 I drug the "other egli" frame off the shelf tonight and began to mockup the turbo bike.  I want to see how the rake affects the ride height and how low I can get it since the exhaust doesn't go under it. Steve told me they added 10* to the neck but as it sits it's about 4 or 5* different than stock fork tube angle.
 I went with the +3" box tube swingarm and the 750A axle, the A spacers don't work out due to the inside width of the swingarm. The tire is a 16x5" M&H slick.  I'll likely cut off the wheelie bar mounts and weld on new ones that fit these bars. I think I can design in some adjustment.
 The front end has cb550 #341 forks right now, if I use them, I'll order some new tubes, maybe lower them a bit more and probably go with K double discs on my A front wheel.  It has a fork dampener and the front fender is fiberglass. 
  I made a fork brace for a cb900 once out of carbon fiber sheet and Kevlar composite from a funny car roll bar shield, I wish I had access to those scraps again.  I don't know how rigid it was but it looked cool as heck.

[Don R]

  The PO remembered cutting the rear peg loops off and was surprised to see them in place when we rolled it out of the barn. Apparently, he cut them off, then later got replacements and had his welder re-attach them. The welds are sweet, but the right one swings out a bit.
  The 750A axle bolt works perfectly, but the spacers don't due to the thickness of the box tubing. That leaves me wondering if the 76A rear hub, brake panel and sprocket carrier are standard.