(Not so) Budget drag bike project - DOHC 450, of course

Sorted through all the gears available between 2 sets of CB450 gears and shafts, as well as the 500T shafts and gears I bought a couple months ago. In the process I discovered something I haven't seen much in these engines, a bad bearing on the mainshaft of (of all engines) the 450 engine with the lowest mileage and the cleanest internally. Because the 17 tooth 1st gear I wanted to use is part of the mainshaft, fortunately the other mainshaft had a good ball bearing on the clutch end. It takes time to count the teeth on each gear to be sure of which is which, since one tooth doesn't visually change the gear size much.

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Also found some discrepancies in gear teeth listings at both CMSNL and Partzilla, as well as missing gear teeth information from some of the listings. Had to go to the Honda CB450K1-K5 parts book to find accurate entries for all gears. Also found out I could search the worded description for each gear to find the missing information (in most cases, but there were a couple that still couldn't be found) and discovered that Partzilla uses yet another supplier for some NOS transmission parts and the gear information is shown as supplied by them.

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So I arrived at the combination I plan to use, and as a last confirmation I assembled both shafts and then re-counted each gear's teeth, did the math, and took notes on both paper and the 50 year old crankcase.

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12ozPBR said:
Nice to see some action on this project Tom and your interesting change with respect to the bottom end. Even though the subject matter of racing gear ratios is outside of my wheelhouse I do find the fact you can mix and match gears from the 450 and 500T very fascinating. I’ll be following along with the progress and trying to grasp the concepts. Let me know if there are any specific 450 parts you are in need of and I’ll check my ever growing parts stash.
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Thanks Chris, I appreciate the offer and will if needed. Right now I think I have what I want to use for the transmission, though I do plan to see if any 4 speed gears will interchange and fit/function properly in an effort to try to get an even closer ratio gap between 3rd and 4th. Not holding my breath as at a glance it doesn't look like it will work, but it's worth looking into before this thing goes together for good because at this stage of the game, how it turns out this go-round is how it will be.
 
More progress this afternoon, it's been raining here nearly every day and we woke up to it this morning so no (much needed with the rain-fed growth) yard work yet.

Rinsed out and did a light cleanup on the upper case and have been soaking the lower case in the parts washer for days, scrubbing the crud off the lower half repeatedly and finally have it close to decent enough.

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Upper case came out super clean everywhere except the usual areas on the outside and even that is passable.


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Remember that oil filter cover that got roughed up by the cabin driveway a couple years ago?

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Well, it got a new lease on life. Filed and sanded and polished it up, got it as nice as it's gonna be for this rig.

Rechecked all the bearings, gears, thrust washers and circlips for usability and proper assembly. And I have a couple extra shift forks, though only one good center fork. Amazing how badly a bike was treated at such a low mileage number, that 3000 to 4000 mile CB450K6 the engine came from was clearly pounded from pillar to post in its short life.

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And because it will now be a 5 speed bottom end, the spare right crankcase cover from the nicer engine will get used. And would you look at that, it's already modified for @Jays100's oil pump. (y) (actually, it was the spare cover I used to make the modification for the oil pump installation pictures)

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The oil filter cover turned out really well. I guess the file is used to get the deepest scratches out, but I'm wondering how you do that given that the cover is rounded and the file is flat. Is the file held in a fixed position (as in a vise) or are you holding both the file and cover in your hands?
 
stl360+450 said:
The oil filter cover turned out really well. I guess the file is used to get the deepest scratches out, but I'm wondering how you do that given that the cover is rounded and the file is flat. Is the file held in a fixed position (as in a vise) or are you holding both the file and cover in your hands?
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Interesting question because I didn't think to clamp the file and move the cover over it. No, I held it in my hand and filed the roughest parts out, lightly wire brushed it with the wire wheel on the grinder, then sanded it with 180 followed by 320 and then the rag wheel with red polishing compound. I tried to keep the curvature but on the forward edges of it where the damage was the worst, it thinned the edge of the taper slightly. Plenty good enough for what it's going on, though overall at least the rolling chassis isn't ratty considering the pretty ugly condition some of it was in when I got it. But most of it was free and if some work was the only cost, fits by budget perfectly. Save the money for the good stuff like brand new carbs, fabulous cylinder head work and cams/pistons.

Oh, and even though I bought that 20 amp LiFePO battery about 9 months early, I've been exercising it fairly regularly (hook a 35w stock 350 sealed beam to it for about 15 minutes, then use the smart charger on it afterward) and after sitting for a day I checked it earlier - 13.86v at rest. Should make some serious spark with those knock-off Dyna coils and my modified, longer dwell advancer.
 
Slowly starting assembly and of course, found something I hadn't noticed while spending most of my time previously figuring out gear ratios. After putting the shift drum of choice in place with the shift forks in the right order (which took a couple tries, silly me thinking the wrong left because the engine is upside down), I laid the shafts in place and looked for the countershaft seal. Then I noticed the end of the shaft where the front sprocket resides was a bit grubby so I gave it a wipe with a rag and carb spray, at which point I finally noticed a scratch and a divot on the sealing surface of the shaft next to the output bearing. Some neanderthal must have previously used something that slightly gouged the shaft while replacing the seal, so to avoid a potential future leak I had to change all but one of the hand-picked gears to a different countershaft. Fortunately I had 2 extras to choose from. The outer race of the bearing had the look of it previously spinning in the crankcase too, despite the bearing itself checking out fine after dozens of rotations in both directions. Either way, better to do it now than later.

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Jays100 said:
Looks like the spline is pretty worn as well.
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Sure is, thanks Jay. At first glance I thought the splines might be tapered toward the inner end of the shaft, just went out and looked again. Probably the worst case of worn splines I've seen and it would have slipped by me. Another case of forest for the trees, I spent so much time staring at other stuff I just didn't see it. :oops:
 
Oof. I spent weeks planning then fabbing those pipes. I built a tube bender from plans then bought precision dies, some 15 years ago. I was thinking since exhaust is a limited option that I could build my own, yadda, yadda, blah, blah.

The reality has been a much more difficult to get right and pretty involved.

So here goes.
-The megaphones were off the shelf from Aliexpress, they were ~$35 each, 17” long to fit 1.5” OD tube. The easy part.
-Flanges were hand cut from .5” thick aluminum plate (SAE 6061), the ID’s were precision cut on a lathe.
-Pipe-to-port interface has taken longer. There are no standard sizes available in the US so I’ve tried several things. The first and best was bar stock machined exactly to dimension to the port, tube, keeper/insert(s). The second is a pair of thick washers with the ID cut to fit then welded to tube bungs. Both work, the first is just cleaner but most expensive.
-pipe/tube bends are something I’m confused about (at least for now that is). I bought a length of 1.5” from NAPA, $3.xx/ft. But it wouldn’t bend without buckling. I filled it with sand and had the same buckling issue even with the bending die. I then tried electrical conduit (1.530”OD) with excellent bend results but with a galvanized surface, paint is an issue. I sanded it all off so paint sticks but surface finish isn’t perfect. What my streettracker has is a mix of mandrel bends, die bends, emt tube and Napa tube to get the end shapes and routings needed. They’re quite light.

I recommend buying if you can find headers, in the long run is just simpler.

I haven’t talked to my local muffler shop if they could bend up something (assuming I’d provide the bungs) to my spec but I do intend on (eventually) doing that (did I mention it’s on my extended list?).

Failing that and this is an if all else fails, call me.
 
Jays100 said:
Oof. I spent weeks planning then fabbing those pipes. I built a tube bender from plans then bought precision dies, some 15 years ago. I was thinking since exhaust is a limited option that I could build my own, yadda, yadda, blah, blah.

The reality has been a much more difficult to get right and pretty involved.

So here goes.
-The megaphones were off the shelf from Aliexpress, they were ~$35 each, 17” long to fit 1.5” OD tube. The easy part.
-Flanges were hand cut from .5” thick aluminum plate (SAE 6061), the ID’s were precision cut on a lathe.
-Pipe-to-port interface has taken longer. There are no standard sizes available in the US so I’ve tried several things. The first and best was bar stock machined exactly to dimension to the port, tube, keeper/insert(s). The second is a pair of thick washers with the ID cut to fit then welded to tube bungs. Both work, the first is just cleaner but most expensive.
-pipe/tube bends are something I’m confused about (at least for now that is). I bought a length of 1.5” from NAPA, $3.xx/ft. But it wouldn’t bend without buckling. I filled it with sand and had the same buckling issue even with the bending die. I then tried electrical conduit (1.530”OD) with excellent bend results but with a galvanized surface, paint is an issue. I sanded it all off so paint sticks but surface finish isn’t perfect. What my streettracker has is a mix of mandrel bends, die bends, emt tube and Napa tube to get the end shapes and routings needed. They’re quite light.

I recommend buying if you can find headers, in the long run is just simpler.

I haven’t talked to my local muffler shop if they could bend up something (assuming I’d provide the bungs) to my spec but I do intend on (eventually) doing that (did I mention it’s on my extended list?).

Failing that and this is an if all else fails, call me.
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Yeah, that's a LOT more in-depth than I planned. I guess I should have been more detailed from the couch last night while watching TV with my wife, but I have a couple sets of header pipes now, both slightly different diameters, and the length of the megaphones was all I really meant. My first drag bike just had TT pipes on it, I was 19 and caught lightning in a bottle with the right combination of parts and porting, so this time I wanted to at least try a little bit more 'scientific' approach.
 
Used some paint remover (man has that stuff gone up in the last 6 months) on the front sprocket cover and right crankcase cover to get the remaining yellowed clear coat off today, and it also worked great on most of the goo inside the front sprocket cover. That low mileage engine may have gone through hell, but it was junked well before it lost much luster on some parts. It looks better than the left crankcase cover it sat next to.

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The other side of the engine must have gotten more exposure previously. More work to do there for sure. Since the flat aluminum replacement left crankcase cover from ElectrexWorld is plain aluminum finish, I decided I'll give these two a modest shine to go along with it instead of silver paint.

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And the 6 spring clutch from the 4 speed, without the oil pump pushrod because @Jays100's gear-type oil pump :giggle:

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And I picked up a fresh 5 gallons of solvent from Tractor Supply, shocked that it was on the shelf this time and the price was about the same as the last purchase at least a year ago.

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wentwest said:
That kind of solvent can't be sold in California - neither can Mineral Spirits or acetone.
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Not really surprised Bob, and I'm having to dispose of my old solvent in our burn barrel a little at a time because I'm certainly not pouring it on the ground. Our local landfill will take a lot of recyclable things like oil and antifreeze, but they don't accept solvents.
 
ancientdad said:
That low mileage engine may have gone through hell, but it was junked well before it lost much luster on some parts. It looks better than the left crankcase cover it sat next to.
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I'd say that cover cleaned up really well.

Regarding the six-spring clutch, do I understand correctly that it will grab better than the four-spring variety, allowing you to get more out of the motor without slipping the clutch?

But, on the flip side, you can still slip the clutch via the lever as you take off?
 
stl360+450 said:
I'd say that cover cleaned up really well.

Regarding the six-spring clutch, do I understand correctly that it will grab better than the four-spring variety, allowing you to get more out of the motor without slipping the clutch?

But, on the flip side, you can still slip the clutch via the lever as you take off?
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Yeah, it's not exotic, just two more springs to help prevent slippage. It should have similar lever pull tension, maybe a little more but it's been decades since I pulled the clutch lever of a 6 spring version. They are hard to come by, popular for road racing too. Chris found it with a bunch of 4 speed engine parts he gathered for me, all of which he will now get back.
 
Well, at this rate if it doesn't run as well as I'd hoped once it's done, at least it will look pretty good. It's hard for me to make something look "okay" once I get started on it. Corrosion kept things from turning out as nice as most of the parts on my red bike, but for what this thing will be doing - and the low light environment it will be doing it in - it's more than decent enough.

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But an up-close look in the right light reveals that I could have spent a LOT more time getting rid of the corrosion scars.

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And the much nicer looking front sprocket cover, trimmed down like the previous one

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Even if you have no feeling left in your hands, it looks like it was worth it.

With your first 450 drag bike, did you trailer it to the strip or just ride it over? I assume this one will go by trailer or on the back of your truck?
 
stl360+450 said:
Even if you have no feeling left in your hands, it looks like it was worth it.
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LOL thanks... but no, this wasn't overly brutal today, though my hands were getting pretty tired after lots of filing, wire brushing and sanding so at one point I figured it was enough. The upper case from the K6 engine is in nice shape, so all that's left are the cam bearing covers and they'll just get a little rub.
 
stl360+450 said:
With your first 450 drag bike, did you trailer it to the strip or just ride it over?
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LOL... tiny tank, no lights or tag. This picture of the later version of the bike was taken at Lakeland Dragway (now closed), which was about 35 miles from Tampa. Nope, it went in the back of my then-new '72 Chevy LUV, and later in my raggedy '55 Chevy pickup.

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stl360+450 said:
I assume this one will go by trailer or on the back of your truck?
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Yep, on the carrier on the back of my truck. If the fairly new local 1/8 mile track in Masaryktown FL at the run-like-a-theme park facility only 20 miles from me turns out to be a good one (I haven't even been as a spectator yet), then it will save me hauling it further south to Clearwater where the longstanding (and more professionally run) Showtime Dragstrip is located (70 miles from me). The 1/4 mile nearest me is Gainesville Raceway, but almost 90 miles away.
 
ancientdad said:
Nope, it went in the back of my then-new '72 Chevy LUV, and later in my raggedy '55 Chevy pickup.
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I should have realized from the title of your other build thread (street legal this time), which suggests that your OG drag bike was not street legal.

I didn't really have any sense about how far away things were for you, so that is helpful, too.
 
stl360+450 said:
I should have realized from the title of your other build thread (street legal this time), which suggests that your OG drag bike was not street legal.

I didn't really have any sense about how far away things were for you, so that is helpful, too.
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Back then, the nearest track was about 35 miles away too, none were ever really nearby. And one Friday night I loaded up the bike and drove all the way there before I realized I'd left my helmet at home, did the drive twice that time.
 
Hi Tom,
You probably already have a source for sprockets but, if not, these guys make really good stuff.

REBEL GEARS CUSTOM MADE MOTORCYCLE SPROCKETS ANY SIZE

Rebel Gears Inc. makes the highest quality American made custom motorcycle sprockets for all makes, most models. We have a wide selection of front sprockets available. We stock EK, and RK chains. Our sprockets are made from 7075-T6 Aluminum purchased from smelters right here in the U.S.A. Don’t...
rebelgears.com

I learned about them from another club member and they helped me out with my road race project.
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Emlupi said:
Hi Tom,
You probably already have a source for sprockets but, if not, these guys make really good stuff.

I learned about them from another club member and they helped me out with my road race project.
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Thanks, I'll keep them in mind for ratio changes after this thing comes together. It's very possible I'll need to go a bit lower for the 1/8 mile and a 14 tooth front is the smallest I'd put on it, so I might have to go a couple-three teeth larger on the rear. And it will save a little weight too.
 
To dispose of solvent, I usually mix that into the old/used oil from my oil change container. Our local AutoZone will dispose accordingly. I suspect any US based auto parts store will have the same option. I don’t know in the EU or Asia.
 
Jays100 said:
To dispose of solvent, I usually mix that into the old/used oil from my oil change container. Our local AutoZone will dispose accordingly. I suspect any US based auto parts store will have the same option. I don’t know in the EU or Asia.
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Yeah, that's probably what I'll have to do. My local Advance Auto has oil collection bins too.
 
Been spending an hour here, couple hours there when I can lately (this place has gotten busier for sure). Lots of cleaning parts, still gathering parts since it's like a basket case without the basket, and discovering more oddities between what seemed to be a low mileage but abused engine and another left to get trashed by the environment, overall condition largely unknown.

Washed up the oil filter cup and cover, then found the cover wouldn't fit it properly. No matter what I did the cover got bound in the upper area of the cup, wouldn't go in easily. Ended up going back to the frozen engine and removing that one thinking the cup was the problem since the cover looked fine and unscathed. Nope, turned out to be the cover, but I still can't see anything wrong with it. Fortunately I have the two so I'm good. In the process, hoped the spanner nut lock tab might be better in frozen engine as the one from the nicer engine had two missing tabs... hmmm, so parts of that low mileage engine had been apart previously, possibly more than once or twice... yet the one from the frozen engine looks to have only been bent once total. Go figure.


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Used my 55 year old spanner socket that has been hobbling along on 3 legs since it was about 3 years old. We cut the t-handle off and welded a socket on it before that even happened, and it's managed to hold up all this time so I still haven't bought a new one.

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Since Jay's oil pump is going in this engine, I figured I'd better do the oil filter valve mod to help take better advantage of the extra flow. Modestly though, because on the 450 version the circlip needs enough meat left on the valve so it won't get past. And of course, made sure those damn little legs got into the casting holes they're supposed to fit in during assembly.

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Took the time to (sloppily) drill 3 oil passage holes behind the oil pump location into the sump under the crankshaft as Jay suggested, just missed the mark a bit on the right-hand hole. Couldn't use my drill press because the platform wouldn't lower enough to get the crankcase half in there sideways. Pretty sure the oil won't know.

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Spent so much time trying to clean up the front sprocket area and the underside of it, I just noticed even more gratuitous factory sealant, this time all over the front motor mount.

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There was a stubborn blackish stain on the bottom of the sump under the transmission and solvent wouldn't cut it even after days of soaking. Used a little bit of the phosphoric acid I bought on it and it cleaned up nicely, as well as took a little rust off the windage tray.

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Getting close to start assembly, gotta find the continuous time to start and finish the crankshaft flush before that happens.
 
Good to see you making so much progress Tom!
When you get down to the nitty gritty of cleaning, examining, and fitting parts for a rebuild, having spare parts to compare with is so valuable. Without them you would undoubtably end up using some sub par components. At this point I can’t imagine doing a full rebuild of a bike without a parts bike and motor to pick from. It is a luxury that some can’t afford I realize. Fortunately for us Hondas are not so exotic and expensive to make it impossible to find donors. I am glad you had spares to pick from to make it as best as it can be. Keep up the good work! 👍
 
12ozPBR said:
Good to see you making so much progress Tom!
When you get down to the nitty gritty of cleaning, examining, and fitting parts for a rebuild, having spare parts to compare with is so valuable. Without them you would undoubtably end up using some sub par components. At this point I can’t imagine doing a full rebuild of a bike without a parts bike and motor to pick from. It is a luxury that some can’t afford I realize. Fortunately for us Hondas are not so exotic and expensive to make it impossible to find donors. I am glad you had spares to pick from to make it as best as it can be. Keep up the good work! 👍
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Thanks Chris, it's slow going right now in part because everything is apart and still being gathered, but it's starting to pick up speed. And yes, having that frozen spare engine my local riding buddy Ray brought down from Wisconsin a few years ago for me for $50 was huge for the very reasons you point out. If the crankcases of the low mileage engine weren't so obviously untouched, I would swear it had a crankshaft replacement in its short life just because the rods are as snug as any I've ever touched yet some parts of that poor engine looked to have been so badly treated (including the horribly cross-threaded right spark plug).

And since reassembly is starting to pick up speed a bit, it won't be long until I need that right intake cam bearing and drain plug we talked about. :giggle: I have much to offer as trading material.
 
ancientdad said:
And since reassembly is starting to pick up speed a bit, it won't be long until I need that right intake cam bearing and drain plug we talked about. :giggle: I have much to offer as trading material.
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Thanks for the reminder! That one had fallen through the cracks lately. I’ll get back on that hunt ASAP.
 
Tackled the crankshaft cleaning today. I zip-tied the alternator side main bearing so it wouldn't drop all the rollers out of it, left the primary drive gear on the other end to hold that set of rollers and put it in the cleanest oil drain pan I have. Not much came out, though there was a little gritty stuff in the WD40 afterward but nothing shiny. Used probably half the can through both crankpins and flushed the outer races of the outer bearings too, then squirted some motor oil/Lucas oil stabilizer mix into them to prevent rust while it waits to get installed. I'm still amazed at how tight the rods are in this engine considering how badly beaten up some areas of it were.

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Also realized today that I now need four 10x90 motor mount bolts for the narrower 5 speed width front motor mount... yet another trip to the local hardware store, LOL
 
And spent some time over the last week or so polishing up the 3 cam bearings I do have, and the somewhat pitted points cover too. In hindsight, it's great that machinist Russ did two left exhaust cam bearings with the bronze bushing because, as mentioned earlier in this thread, the left bearing journal on the exhaust cam from the pair I sent to Terry Naughtin to get modified was undersized, likely had been cleaned up/repaired at some point in its life and needed to be fitted to the extra bronze-bushed bearing.

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So, if this thing doesn't run as well as I've hoped for during this long journey, at least it will look decent. :giggle:
 
Don't forget you also need some form of spacers to go around the long bolts, between the mounting plates and the motor mount. I found what I needed at the hardware store - the hard part was getting the length of the spacers correct.
 
wentwest said:
Don't forget you also need some form of spacers to go around the long bolts, between the mounting plates and the motor mount. I found what I needed at the hardware store - the hard part was getting the length of the spacers correct.
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I know what you mean Bob, and machinist Russ made the spacers I needed for me - but that was when I planned to use the 4 speed bottom end in the 5 speed frame, the wider 4 speed motor mount on the lower case meant the spacers would be needed to fit the narrower front mount area of the 5 speed frame. But now I'll be using a 5 speed bottom end in a 5 speed frame, so I won't need the spacers or the long 10mm bolts I found to go with that extra width. And because this thing is being put together out of so many loose pieces, I didn't have the four 10x90 bolts for the 5 speed width at all. My local Ace had made a bit of money from all my hardware purchases.
 
Back at it this afternoon. In order to clean the sludge traps, I had to pull the outer races away from the inner crank throws and of course, all the rollers fall out. That gave me the chance to look closely at them and I did find a few that had some dark spots on them. They would probably have been okay but because I have spares I looked through them all and replaced probably 8 rollers. Learned this rubber band trick back when we were still at HT, from Bill Lane I believe (though I can't recall for sure) and as our friends across the pond say, it works a treat.

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Once all the rollers were back in both inner bearings, I happened to notice something I'd never noticed before - all of the main bearings have slightly different oil feed and locating pin hole locations.

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AND, I'd found a different locating pin laying on the lift that I initially thought was from the 4 speed engine, but because it's been forever since I've put one together from a "basket case" I wasn't convinced of where it belonged so I put it in the tray with the other loose 5 speed bottom end parts. Turns out it was the primary drive end bearing's locating pin, realized once I washed and blew out the upper case and saw the larger hole on the clutch side. Put all the pins in place and slipped the crankshaft into place.

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Broke out the brand new torque wrench and put the center main bearing cap on, only to realize the torque for those 4 bolts is roughly 12 to 15 ft lbs and the new torque wrench.... only goes down to 20. :ROFLMAO:

AND, yet another moment of proof that when you order something that might not get used right away, it might be a good idea to check it. Yep, in a first for me, twowheelsfrank in Germany sent me the endless version of the DID 219T-128 cam chain... so I had to drag out the below-average chain tool, grind the heads off the pins and break the chain.
 
That's the chain he sent me, along with the master link. Report back how you did flaring the pins. I finally got up the nerve to put the engine into the frame, but I can't until I'm confident about the master link. Might just buy one with hollow pins, from 4into1.
 
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