Author Topic: Drag Bike / The Big 4 Express. (Read 66020 times)

Don R · « **Reply #450 on:** February 14, 2022, 04:32:26 PM »

Putting back what was gone! This is just a mock up first try. Welding will happen later. It's never easy dealing with all of these triangles when the center is from a different bike.
I haven't had them line up yet after fixing three of them, the top is still in a bind here and not welded in yet.

The 29's and the ignition switch bracket are making things close. I'll probably notch the ignition switch bracket, the original frame cutter left enough to connect to but just barely enough.
Thanks to Scottly for making these and selling me the last set.

Don R · « **Reply #451 on:** February 14, 2022, 09:13:39 PM »

So far, I've just put it back together enough to see what is here, that's why it looks a mess, but I felt like it was a good time to replace the frame section. The PO wasn't really sure why it got parked in 1987 except he got faster drag bikes. He took it apart and put the rolling carcass out in a barn. Wasn't really sure which engine it had in it. Turns out it's the one with the goodies in it.
I envision a new wiring harness and new controls, frame paint, its former K1 gauges and new radial tires on the Lester mags. For now, I want to make it run and ride to see what else it needs. It's a wee bit smokey but I did put some top end lube in the gas and MMO in the oil. The 29's may be jetted a little rich at idle too.

Don R · « **Reply #452 on:** February 16, 2022, 02:33:27 PM »

Dragbike #3, it's going to be the low rider.
I tightened down the frame tubes, My mig is loaded with stainless wire and C25 so I didn't weld the triangle to the top tube yet.
I tidied up the wiring a bit and put the coils back on. It needs plug wires but rotating the coils to stop the arcing to the new frame tubes worked for now. It started and ran. It's over 50*F so I did a couple block ride, it pulled good in first and second. I tried a burnout and it got a little hoppy, it needed more rpm. And I needed more balls.
I topped off the gas tank with some fresh no alky fuel and let it idle, it's windy and began to rain so it didn't overheat, popped it back in the shop to cool down.
The marvel mystery oil got circulated pretty good through the rings and oil system. I cranked it over every few days, at first with no plugs and later with plugs in.
The smoking may be valve seals. I'm in no hurry to judge it, there are other engines that need attention more. This quick turn throttle sucks and no stock right control sucks too.
I was careful shifting, the shift stud still needs a helicoil. Neutral is difficult to find but it hasn't jumped into gear again. Yet. It was good to get the oil up to temp, I think that may help a motor that sat over 30 years and was soft seized. The oil pressure gauge is re-assuring to have since I replaced the poly tubing.

Don R · « **Reply #453 on:** February 17, 2022, 06:27:29 PM »

I sent the PO a picture of the low rider's frame repair, I got a thumbs up. I asked, and he doesn't have any pics of this bike.
I'm hoping there's a picture of the turbo bike, we're due for a visit when it warms up and the roads are clean. Doing the license plate math, it hasn't been plated since 1987 that's a 35 year sleeper. It's not a surprise it smokes a little.

Don R · « **Reply #454 on:** February 18, 2022, 12:35:08 PM »

I checked out the best of the drilled brake rotors, I like the pattern on the "right side" speedometer modified disc and was going to duplicate it. 105 3/8" holes but the original driller had his drill bit walk and the holes wander a little. It's nothing you would notice walking past but my ocd says I can't duplicate an imperfect job. I tried looking for a patch of accuracy that I could transfer punch and then rotate but so far nothing I like.

Don R · « **Reply #455 on:** February 21, 2022, 07:31:21 PM »

They shot a rat that was sitting on the seat. True barn find. 22 cal through and through.

Terry in Australia · « **Reply #456 on:** February 21, 2022, 10:06:57 PM »

Quote from: Don R on February 18, 2022, 12:35:08 PM

I checked out the best of the drilled brake rotors, I like the pattern on the "right side" speedometer modified disc and was going to duplicate it. 105 3/8" holes but the original driller had his drill bit walk and the holes wander a little. It's nothing you would notice walking past but my ocd says I can't duplicate an imperfect job. I tried looking for a patch of accuracy that I could transfer punch and then rotate but so far nothing I like.

Just buy some new cast iron drilled discs like the ones I have on my K2 Don, they crap all over the slippery stainless OEM ones, drilled or not.

K2 Bitsa Wednesday 7 Jul 2021 3 by Terry Prendergast, on Flickr

Don R · « **Reply #457 on:** February 22, 2022, 09:01:59 AM »

Terry are those EBC?

Terry in Australia · « **Reply #458 on:** February 23, 2022, 03:25:05 AM »

No mate, they're stock CB750 carriers with new cast iron rotors bolted on by a really good engineer here in Oz. Around $130 USD each, on a core exchange deal. If you want some and need someone to do the postage for you, I'll help, I need to send my spare one back as I sent him a bent carrier and it was sending me cross-eyed watching it wobble at any speed.....

Don R · « **Reply #459 on:** February 23, 2022, 09:18:36 AM »

I think I found an ad for those rotors.

I'm thinking my plan of restoring the drag bike's engines to competition status may change to make something that runs and put it in. Three are too many for my budget right now.

Terry in Australia · « **Reply #460 on:** February 23, 2022, 10:04:46 PM »

Ha ha, well don't forget I'm sitting here patiently waiting for your scraps, maybe we can do some cross pond bartering....?

Don R · « **Reply #461 on:** February 24, 2022, 03:08:42 AM »

I swore I found a picture of my Webers today online, they had the same intake, hoses, brackets, rubber mounts and overstuffed air filters. Even the same crappy chrome finish on the top side. Mine came stock on a Ferrari. I can say that because someone polished off all of the numbers.

Don R · « **Reply #462 on:** February 24, 2022, 06:00:46 PM »

I took the turbo motor apart, all of the bearings are perfect, it's got a sweet set of MTC steel rods but 2 of the pistons are stuck tight in the bores. I tried various chemicals, hot air gun and torch heat, cold spray, pressure, tapping with wood, and finally went to the hydraulic press. At this point I'm just trying to save the rods. Pretty disappointing.
If only they had stuffed the ports with plastic bags.

Don R · « **Reply #463 on:** February 24, 2022, 08:53:31 PM »

Did I mention how much I despise mice? Little F'ers ruined some good RC engineering stuff.

Don R · « **Reply #464 on:** February 24, 2022, 08:57:03 PM »

Here is the bottom end which is beautiful. The trans has had some (ab)use, might have been backcut once but does not seem to work. I have a nice APE back cut trans from an F2, this has the big output bearing, so it should fit?
And what's up with those gauges?

PeWe · « **Reply #465 on:** February 24, 2022, 11:18:55 PM »

"I have a nice APE back cut transmission from an F2"
The later trans have different final shaft, longer.

I have a late transmission that is now in a shop for backcutting 2-4.
To be used in a K case. (K5)

I'll move the final gear from the late shaft that is longer to match the later case and mount it on the earlier shaft.

The teeth look a little bit different and must match the trans.

Don R · « **Reply #466 on:** February 25, 2022, 01:49:18 AM »

Thank you for that info, I'm going for a big tire on a long swingarm and the offset will be welcome. I also have a 77 sprocket carrier.
Somewhere in this thread I tried the F final drive shaft in an earlier trans and realized the F has different gears. I have lots of parts to choose from and worse case scenario, I can use an F engine case.
I got a text from the PO. He remembered buying this motor from a pair of Dragbike guys that switched to racing Suzuki's. The info comes in little tidbits. That explains the MTC steel rods, he was an RC guy.
I may try to remove the sleeves from the cylinder next. The two stuck pistons can't be as bad as the K6 engine I pressed apart, that one was solid rust top to bottom.

PeWe · « **Reply #467 on:** February 25, 2022, 04:44:32 AM »

I found a photo where I compare.
I have not changed the gear yet.
Remove later gear on the right, assemble it on the K2-K6 shaft to the left.
Then bearings. I have new.

I doubt the later shaft fit earlier case. See the double row bearing.

Don R · « **Reply #468 on:** February 25, 2022, 09:11:52 AM »

Aah, I see your point, thanks.
This just in, motor was bought from/built by two pro stock M/C racers that retired from racing around 2000.

Don R · « **Reply #469 on:** February 25, 2022, 02:44:12 PM »

PeWe, thanks for that explanation. That is exactly what I have to work with. My F2 trans is a low miler bought from a parted out lost title bike. I got all of the shift forks and associated parts. I traded APE a 900 kit for the backcut job to help out Jerry and Big Jay at APE after an engine parts problem.

I got the pistons out, they are forged flat tops, I think the cylinders are toast, a few chipped fins and rust rings that won't hone out. I'm sure I have a K4-6 cylinder here that needs bored. The 2 rusty pistons are soaking top down in some vinegar to see if the rust comes off.
A little penetrating oil and some encouragement and I got one set of rings off enough to measure them. They have one piece oil rings, the first time I've seen them on an 836.

Don R · « **Reply #470 on:** February 26, 2022, 04:26:39 PM »

I got the F final gear on the K big bearing shaft, it pressed off/on easily. Now the k transmission is in the former F trans shipping box so I don't mix anything. The K trans wasn't backcut and 2nd gear had a serious wear mark on the dogs, it couldn't fully engage.
The F trans does not have an F clutch basket, I assume the k basket will go on since it's a later model engine.
Edit, it's a K3 case so... K3 clutch basket on an F2 trans? I'll let you know. I'm washing the case halves now. I have a very clean K6 case but really don't want to get into guessing main bearing sizes.

Don R · « **Reply #471 on:** February 26, 2022, 06:21:38 PM »

Awww jeez. I was scrubbing off the black paint and rat pee residue and uncovered a weld on the case, it appears the entire rear motor mount was broken off and welded back on. It's a good weld, as far as case welds go but there's no reason to proceed since I have cleaner and unrepaired engine cases to choose from.
It appears I'm dealing with main bearing sizes after all.
This causes me to wonder when this damage happened and if my turbo bike's frame has an issue at the same motor mount.

PeWe · « **Reply #472 on:** February 27, 2022, 03:20:55 AM »

Find a later clutch with double metal disc. It is more rigid than earlier. I upgraded my K6 with that. It was spongy and rattled.

K6 and F2 same primary hub shaft with a groove for a circlip, K5 and earlier have not. The earlier have a wider washer there.

You only need the double riveted metal disc, K6, F1-3 clutch fibers,
- Later outer clutch steel basket
- Alu hub with grooves for clutch metal plates. Both these ca 2 mm deeper to give space for the double disc.

The other alu part with 4 towers for clutch springs and bolts same part. This make the spring force a litle bit harder so no additional washers under springs not needed to ensure grip.

The outer clutch cover need the flat bottom for a thread to avoid contact. My K6 had that model.
F2 cover look the same except for it is panted black which I noticed after assembly and I had fixed the F2 clutch cover by grinding the paint off , drill hole and thread for AN fitting creating addional ventilation.

I have also mounted the later final gear on an earlier shaft to ensure it fits before trans will be undercutted. My K2 engine with frame build.

It fits well except for gear contact with lower case. I had to grind a radius to avoid it.
Upper case no problems.

PeWe · « **Reply #473 on:** February 27, 2022, 03:32:31 AM »

Intereresting why the case is welded on right side. On left understandable if chain snapped hard.

I have a K1 case that also is welded on right side.
I have not taken that engine apart yet to inspect inside. I get other ideas with higher prio all the time

I have ideas to grind it smoother, fill with JB Weld and hopefully make it to look ok after painting it.
Rear side and drive chain side OK.
Like it has cracked only. A bike crash or engine drop in shop only?

My K2 build engine is welded on lower engine mount on right side. Lower thread for ign cover was bent up and cracked too. Fixed with JB weld. Possible bike drop.

dusterdude · « **Reply #474 on:** February 27, 2022, 01:03:49 PM »

Does the engine torque to the left when pulled on hard?perhaps the motor mount bolt was loose.

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Author Topic: Drag Bike / The Big 4 Express. (Read 66020 times)