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

[ancientdad]

I don't know, maybe... actually, the only bike I've ever had any wobble problems with (other than weirdly worn front tires causing a 35 to 40 mph deceleration shake with hands off the bars) was my two Gold Wings and that was alleviated by simply using a lighter grip on the bars at speeds over 70 to 80. The tighter you gripped the bars on both of my GWs, the more it wanted to shake. None of my other bikes, including both my 450 and my father's 175 drag bikes, ever gave me any wobbles at speed. Maybe I've just been lucky.

 

[ballbearian]

I don't know, maybe... actually, the only bike I've ever had any wobble problems with (other than weirdly worn front tires causing a 35 to 40 mph deceleration shake with hands off the bars) was my two Gold Wings and that was alleviated by simply using a lighter grip on the bars at speeds over 70 to 80. The tighter you gripped the bars on both of my GWs, the more it wanted to shake. None of my other bikes, including both my 450 and my father's 175 drag bikes, ever gave me any wobbles at speed. Maybe I've just been lucky.

Me too, but only on a bicycle over 60mph on a mountain decent (guy in a Porche clocked us), I guess adrenalin can make you shake too.

 

[ancientdad]

Price shopping is hit and miss, but when you hit on a good one it's satisfying in these times of inflated prices for practically everything. I've been waiting to order the drive chain only because I won't actually need it for a few months or so, but checked on the 110 link DID 530 chain I'll need for the added swingarm length and it was still in stock and still $40. I decided to look at the other lengths Amazon had just out of curiosity, and it turned out the 114 link length was only $25 today for whatever reason so I snagged it.

I got a text this afternoon from my local riding buddy Ray, he was on his way over with the new Kenda tires he so graciously ordered and is donating to the cause. They have a very similar tread pattern to the Shinkos I put on the red 450, hopefully the rubber compound will be as soft too. They look good.

And finally, another sticker was added courtesy Dale (VHT member 1969 CL350) and it was put in its proper place.

Thanks Dale!

 

[1969 CL350]

And finally, another sticker was added courtesy Dale (VHT member 1969 CL350) and it was put in its proper place.

Thanks Dale!

You’re welcome!…LOL. It looks great on there. A fitting thing for those you pass on the drag strip to see and remember. :lol:

 

[ancientdad]

My parts from CMSNL came in yesterday and like the idiot I am, I accidentally looked at the entry above the single JIS screw I needed that can't be bought locally - a 6x75 for the longest spot in the right crankcase cover of the 4 speed bottom end - and ended up buying one I already had (6x60, part #22 instead of #23 in the fiche). Grrrr.

However, everything else was fine, including the new hoses for the CB900F airbox, a 16 tooth front sprocket for the drag bike and a 10mm flange bolt for the front motor mount, also not available locally, to match the other 3 I already had from the hardware lot bought a couple years ago from a SOHC CB400.

For the first time, in addition to the little green key chain guy holding the wrench (I already have a couple of them, didn't really need another) they also sent a poster. Might have been smarter of them to put it under a layer of thin cardboard to prevent the front sprocket from bouncing off it repeatedly during its trek to the US which left dents in the poster, some almost all the way through in places. But, in the end it doesn't really matter much to me because in their infinite and gratuitous wisdom they gave me a poster of a Kawasaki 175. Despite me not buying one part EVER from them for any Kawasaki.

I guess it was supposed to be the thought that counted. And what's up with the girl holding a baseball bat??

 

[12ozPBR]

I’ve got a 6mm x 80mm bolt I can clean up and donate to the cause. I can cut it to 75mm length and even cut a few extra threads on it.

 

[12ozPBR]

Too bad the poster wasn’t of this D kit 450 with an old factory electrical tester sitting beside it. Sweet!
It is cool however that they send some swag with the order.

 

[ancientdad]

Too bad the poster wasn’t of this D kit 450 with an old factory electrical tester sitting beside it. Sweet!
It is cool however that they send some swag with the order.

Yeah, that would have been much more appropriate for sure. As to your question above, did you mean "bolt" or 6x80 screw? I literally have all the other screws necessary for all the covers at this point, that's the only one I don't have and I should have paid more attention to the one I was buying when I placed that CMSNL order.

 

[12ozPBR]

Yeah, that would have been much more appropriate for sure. As to your question above, did you mean "bolt" or 6x80 screw? I literally have all the other screws necessary for all the covers at this point, that's the only one I don't have and I should have paid more attention to the one I was buying when I placed that CMSNL order.

I did mean bolt but now realize you need a screw. I’ll check what I have and see if I can come up with one.

 

[ancientdad]

I did mean bolt but now realize you need a screw. I’ll check what I have and see if I can come up with one.

Yep, the fact that it's a screw is why I'm having difficulties locally. My best option was during that CMSNL order and I screwed up that opportunity. Most places locally have sizes up to 6x60 but nothing longer in a JIS or phillips head. And it would look a bit silly with one hex head right there at the top of the right crankcase cover. And you know I'm not using an allen head there, or really anywhere on it. Thanks for checking into it for me.

 

[Flyin900]

My parts from CMSNL came in yesterday and like the idiot I am, I accidentally looked at the entry above the single JIS screw I needed that can't be bought locally - a 6x75 for the longest spot in the right crankcase cover of the 4 speed bottom end - and ended up buying one I already had (6x60, part #22 instead of #23 in the fiche). Grrrr.
I guess it was supposed to be the thought that counted. And what's up with the girl holding a baseball bat??

AD I have a 6X78mm as a used JIS screw, since 40+ bikes leaves you with a few parts in the stash. Honda normally cuts the holes deeper, so a few extra mm's should fit, or trim as needed.

Send me a PM if you interested with your address and I can ship Canada Post N/C.

Its all packed up and ready to ship.

 

[ancientdad]

AD I have a 6X78mm as a used JIS screw, since 40+ bikes leaves you with a few parts in the stash. Send me a PM if you interested with your address and I can ship Canada Post N/C.

Its all packed up and ready to ship.

Thanks, very generous of you. PM sent

 

[ballbearian]

I guess she's holding the 'pay attention' bat.

 

[ancientdad]

I guess she's holding the 'pay attention' bat.

THAT'S what it is! Thanks :lol:

 

[12ozPBR]

Looks like Flyin900 and his stash beat me to it. I had found a 6x70 that looks as if it would work. In this process I discovered that this is one of the subtle differences in a K0 450 right side cover. All the other 450 models do not have this long screw. Learned something new today.

 

[ancientdad]

Looks like Flyin900 and his stash beat me to it. I had found a 6x70 that looks as if it would work. In this process I discovered that this is one of the subtle differences in a K0 450 right side cover. All the other 450 models do not have this long screw. Learned something new today.

Me too, never really paid any attention to that area even though I had a 4 speed bottom end in my first drag bike engine. If I ever pulled that cover back in the day I never noticed the difference and I owned a new CL450K4 prior to then so it just never stood out to me. These bikes just keep on giving us interesting and fun surprises. I think a 6x70 would do okay, that area of the cover is unlikely to leak with the rest of the screws tightened up well.

 

[ancientdad]

Price shopping is hit and miss, but when you hit on a good one it's satisfying in these times of inflated prices for practically everything. I've been waiting to order the drive chain only because I won't actually need it for a few months or so, but checked on the 110 link DID 530 chain I'll need for the added swingarm length and it was still in stock and still $40. I decided to look at the other lengths Amazon had just out of curiosity, and it turned out the 114 link length was only $25 today for whatever reason so I snagged it.

Well, once again the likely combination of below-average employees and Amazon's well-publicized habit of overworking them reared its ugly head. I ordered the chain, came in yesterday and I just put the box in the garage without even thinking about it. I mean, a DID chain of a certain size and length is a pretty simple order, right?

So, it will go back and we'll try it again. Except that now my luck will be that price is no longer available.

 

[ancientdad]

I'm sure all of us have some stories of frustration with customer service at most retailers, possibly Amazon in particular, and this sure isn't my first rodeo with them. The worst one was the a/c compressor that they stupidly put some pillows in the box next to the original box the compressor came in, then when it got thrown around on the way the power plug socket on the end of it was absolutely destroyed. That one was really fun to explain.

This time it took 2 phone calls, some serious audio-translation for the accents of all but one person involved, and a re-purchase of the same chain for $46 with tax while returning the wrong chain at their cost (except for the fuel to go to the UPS dropoff 15 miles away, of course). I'm told all I have to do is call them when I receive the replacement and I'll be refunded roughly $20.

Not gonna hold my breath on that one. It's no wonder Bezos is almost universally vilified.

 

[Troy]

Price shopping is hit and miss, but when you hit on a good one it's satisfying in these times of inflated prices for practically everything. I've been waiting to order the drive chain only because I won't actually need it for a few months or so, but checked on the 110 link DID 530 chain I'll need for the added swingarm length and it was still in stock and still $40. I decided to look at the other lengths Amazon had just out of curiosity, and it turned out the 114 link length was only $25 today for whatever reason so I snagged it.

I got a text this afternoon from my local riding buddy Ray, he was on his way over with the new Kenda tires he so graciously ordered and is donating to the cause. They have a very similar tread pattern to the Shinkos I put on the red 450, hopefully the rubber compound will be as soft too. They look good.

And finally, another sticker was added courtesy Dale (VHT member 1969 CL350) and it was put in its proper place.

Thanks Dale!

Is "Ichiban Moto" one of us?! He's my hero.

 

[stl360+450]

Anything new with the drag bike, Tom? What are the next steps?

 

[ancientdad]

Anything new with the drag bike, Tom? What are the next steps?

Nothing since the 900F went on the lift a couple months ago, and since then it's been life getting in the way for the most part. I have to get the 900 running before taking it off the lift and starting on the engine for this bike.

 

[stl360+450]

Discovered a nice spot for the shift relay, attached to one of the CM250C gauge mount points on the top bridge very near the main power switch. Since the starter button I'll be using for the shifting kill is a later model 4 cylinder piece, the starter button sends 12v from the button through the yellow/red wire (not ground like most of the twins) so it will open the relay to break power to the coils. The yellow/red, as well as the black/white power output to the coils (through the kill switch on top of the assembly) are both fed by the single incoming black wire, so having the relay in close proximity will make the wiring short and compact.

What type of relay is that? Am I understanding correctly that the unpowered position of the relay is closed, unlike the OEM starter relay for the CB450. I was wondering this morning if there is a reasonable way to perform this ignition interrupt function using the OEM starter relay. Seemed like it would be a waste of power if it is even possible.

 

[ancientdad]

What type of relay is that? Am I understanding correctly that the unpowered position of the relay is closed, unlike the OEM starter relay for the CB450. I was wondering this morning if there is a reasonable way to perform this ignition interrupt function using the OEM starter relay. Seemed like it would be a waste of power if it is even possible.

It's a standard 5 pin relay, one path closed when off and the other path closes when powered up. I've never used the word relay for a solenoid, though I suppose it qualifies. The level of amperage a solenoid is capable of isn't nearly necessary for the coils, a standard relay like one used in today's electric fuel pumps or one for driving lights is more than enough for the draw of the coils. I was mostly concerned with the relay's durability when on for an extended time, as opposed to the short bursts of disconnect I used when I temporarily added a shift relay to my red 450's ground-completion starter button to interrupt the power to the coils for a couple trips to the track. Because the right handlebar switch I'm using is a power disconnect (for the headlight during cranking), in this situation the relay will be on when the main power toggle is on, closing the relay contacts to provide the coils 12v. Hitting the red starter button will take power away from the relay which will then disconnect the 12v to the coils. Even starter solenoids are designed to be used for short bursts, which was the reason for my concern about getting a fuel pump relay which is designed to be on all the time while driving. I was told a standard Potter & Brumfield relay would not overheat the internal coil when used for the few minutes the engine will be running each time the bike is used.

 

[stl360+450]

Thanks for the detailed explanation, Tom.

So, the five-pin relay could perform this function with either a momentary contact switch or a momentary interrupt switch, right? You would just wire it a little differently depending on what you have.

 

[ancientdad]

Thanks for the detailed explanation, Tom.

So, the five-pin relay could perform this function with either a momentary contact switch or a momentary interrupt switch, right? You would just wire it a little differently depending on what you have.

Yes, on the red 450 I wired the power through the normally-closed pair of internal contacts so when I hit the starter button it energized the relay's coil and drew the contact away, opening the through circuit and taking 12v away from the coils. This one is energized when the 'key' is on, closing the normally-open pair of contacts to provide the coils' 12v and when the starter buttton is pressed, breaks the 12v going to the relay's coil thus opening the closed pair and dropping the 12v to the coils.

 

[stl360+450]

How difficult would you say it is to shift using the ignition interrupt?

I once had a clutch cable break on my 360 and limped it a short distance home by shifting with no clutch action. The hardest part was starting from a stop, but, here, you still get to use the clutch on takeoff.

 

[ancientdad]

How difficult would you say it is to shift using the ignition interrupt?

I once had a clutch cable break on my 360 once and limped it a shirt distance home by shifting with no clutch action. The hardest part was starting from a stop, but, here, you still get to use the clutch on takeoff.

As quick as you can push the button, you can shift. All it takes is a momentary interruption of power, even at WOT, and it shifts pretty much like any other time. Listen to the engine interruptions in this video, I was using it then. Without a clutch cable, you have to gently roll off the throttle with a little preload on the shift lever and make the shift quickly before deceleration begins, or the transmission is under load again.

 

[LongDistanceRider]

How difficult would you say it is to shift using the ignition interrupt?

I once had a clutch cable break on my 360 once and limped it a shirt distance home by shifting with no clutch action. The hardest part was starting from a stop, but, here, you still get to use the clutch on takeoff.

The interrupt system is purely to unload the transmission momentarily, similar to pulling the clutch but measured in milliseconds. It's how all the electronic shifters in race cars/trucks/bikes work. Clutch is used for starting off the line and even those have gone electronic.

 

[stl360+450]

As quick as you can push the button, you can shift. All it takes is a momentary interruption of power, even at WOT, and it shifts pretty much like any other time. Listen to the engine interruptions in this video, I was using it then. Without a clutch cable, you have to gently roll off the throttle with a little preload on the shift lever and make the shift quickly before deceleration begins, or the transmission is under load again.

Sounds seamless in the video. Good excuse to watch that run a couple more times. You're well over a thousand views on that one.

 

[ancientdad]

You're well over a thousand views on that one.

It is pretty much seamless, and frankly I was surprised it didn't result in a few pops and bangs from the exhaust due to the ignition interruptions but I guess with straight pipes there isn't a lot of unburned gases collecting in that short a span. I kinda thought it would take less than 4 years to get to 1000 views though... but then again, my other ride videos aren't very exciting, the YT crowd likes to see people carving up twisties at record speeds. Mine are yawners by comparison. Never gonna be a YT star, that's for sure. :lol:

 

[ancientdad]

After seeing the mounting plate that came with @Emlupi's crankshaft ignition for his 350 road racer, I looked into buying it separately. Turns out Electrex does sell them separately so I bought one for my drag bike engine. Russ did a nice job on the plate he made for me but I failed to mention (and he didn't ask) the thickness of the metal he planned to use, and he used a piece of flat stock that could have been half the thickness to save weight. He made it in between my visits so I was a little surprised when I saw it. And it would have required me to do something for a crankshaft seal. This plate from Electrex is ready to go and weighs an ounce or two less than the plat plate Russ made. And for my purposes it's still a bit thicker than necessary, but their ignition is mounted on it so I get the reasoning.

 

[Emlupi]

Just have to plug up the two 6mm holes for mounting the stator.

 

[ancientdad]

Just have to plug up the two 6mm holes for mounting the stator.

And since they're threaded, I would imagine something like a bolt with fiber washer would do.

 

[Emlupi]

Maybe a little thread sealer, too.

 

[ancientdad]

Got back to this in the last couple weeks with a different perspective. As much as I'd love to replicate the great top-end pull the 4 speed bottom end offers for the 1/4 mile with a much closer ratio between 3rd and 4th, the realization that this bike will spend most of its limited use on the 1/8 mile tracks in my 'general area', combined with the advantage of having a low mileage 5 speed bottom end plus a second 5 speed spare engine to work with has caused me to change course.

After a short exchange with @1969 CL350 and @rotorwrinch about the combination of gears used in RJ and Graham's 450 road racer, I found a pair of CB500T transmission shafts and gears on eBay to start the mix and match effort for the closest ratio 5 speed I can assemble to go the approximately 80 mph top speed in the 1/8 mile.

Of the two engines, the $75 nearly complete engine was the nicest in many ways but clearly I'm just the lucky recipient of its early demise. Despite the quite shiny condition of the left crankcase cover, the fact that the bottom end had never been apart and the cleanliness of the interior of the bottom end that proved it was low mileage, it led a very hard life. One plug hole ruined, spark plug run in at so much of an angle it only went about halfway and feels like it will break off if turned, a shift fork with a small gouge in it already and a horrible non-factory drain plug cross-threaded into the lower case. So, parts of it are beautiful, yet parts of it are as ugly as it gets.

On the plus side, the low mileage crankshaft is in excellent condition, barely any collection of debris in the sludge traps at all. Rods are the tightest of any used engine I've touched in a while. The upper case will barely need to be cleaned, pictures below are just as it came apart. Aside from the one nicked shift fork the transmission is in above average condition.

Amazingly, the grommet around the alternator wiring is still soft too.

But this, ugh.

Then there's the other engine, a $50 lump that came down from Wisconsin with my local riding buddy Ray who saw it in his travels a few summers ago while spending time there to escape the Florida heat. Both cylinders rusted and stuck, nasty inside overall but the lower case in good usable condition. The shift shaft, one of those things getting harder to find these days (I have two 4 speed shift shafts but they are different), was bent from a crash badly enough that the big flat washer behind the still-seated circlip was slightly concave from the impact. Had to clamp the lower case in the vise at the front motor mount and use a cheater pipe on the shaft to get it just straight enough to slide out of the case. And of course, the splines are fairly worn on it too.

But, at least this

 

[ancientdad]

 

[boddy]

Sludge traps look very clean. With both engines you'll have plenty to work with to make one engine with some nice NLA parts left over.

 

[ballbearian]

Sludge traps look very clean. With both engines you'll have plenty to work with to make one engine with some nice NLA parts left over.

Forcing some flow through the crank pins and out around the big end rods is as good as it gets. Looks great, thanks for the pics.

 

[stl360+450]

It's nice to see some activity on this project and I'm curious to follow the development of your gearing.

Once you have an inventory of the gears available, it would be interesting to see what recommendation you could get from one of the AI tools. (allowing for revisions to correct mistakes and careful prompting about the goals of your project)

 

[ancientdad]

It's nice to see some activity on this project and I'm curious to follow the development of your gearing.

Once you have an inventory of the gears available, it would be interesting to see what recommendation you could get from one of the AI tools. (allowing for revisions to correct mistakes and careful prompting about the goals of your project)

I've already chosen the combo of ratios I plan to use, actually intended to mention them in the previous post. Here are the ratios for the two different engines. I'll be using 1st gear from the 450, 2nd and 3rd from the 500T and their shared 4th gear as well as 5th, which is really irrelevant in this case. The idea is that, like the 4 speed 450, the largest rpm drop will be during the lowest wheel speed as well as the lowest overall gearing so the engine will more easily overcome the wider gap early in the run. I opted for the lower ratio 1st gear of the 450 to help get the bike moving with (hopefully) less wheelspin. In only 660 feet of track, I'm guessing I'll be just going into 4th gear near the traps.



Here's the custom gearing laid out in Gearing Commander with a 14 tooth front/39 tooth rear (stock CB650) combination of sprockets. I do have some room to potentially go larger on the rear sprocket if necessary but it will likely be a custom sprocket. There will be a roughly 4000 rpm drop between 1st and 2nd, very similar to my first drag bike with the 4 speed bottom end, then roughly 2000 rpm drop between 2nd and 3rd and between 3rd and 4th with a less relevant roughly 1500 rpm drop 4th to 5th. I haven't tried it yet, but I suppose there is a possibility that the 4 speed 4th gears might work for an even small;er gap, I'll be checking that next.

 

[stl360+450]

Very cool. I misunderstood when you mentioned mixing and matching — I was thinking you meant seeing what would be best from a gearing point of view, rather than choosing the best parts from the multiple donor motors.

Does the gearing commander allow you to modify the rpm columns? Seems like you might want to focus more on the high rpm range with smaller gaps between the columns.

I guess I can imagine why the largest rpm drop should occur on the first shift. Are these "drops" typical for drag setups?

 

[wentwest]

My work through the years when I was being a lawyer taught me (slowly) that finding the right answer is often easier than asking the right question. With AI it's even more common. Putting all the thoughts in your head about a subject into a form that can be understood and solved can take a long time. I used to start writing it all down and then editing and rearranging the words until what I had in writing matched the mess of related ideas floating around in my mind. Lots of times the answer got clearer just by doing this process.

 

[ancientdad]

Very cool. I misunderstood when you mentioned mixing and matching — I was thinking you meant seeing what would be best from a gearing point of view, rather than choosing the best parts from the multiple donor motors.

Does the gearing commander allow you to modify the rpm columns? Seems like you might want to focus more on the high rpm range with smaller gaps between the columns.

That format is standard on all readouts offered. I only care about the shift points, and it's easy to roughly calculate the rpm drop between gears by looking at the max speed in the previous gear and then finding the closest equivalent speed in the next gear up - which shows the rpm range the engine will be in after that shift.

I guess I can imagine why the largest rpm drop should occur on the first shift.

Yes, wind resistance is lowest and overall gearing is lowest then as well, making it easier for the engine to accelerate back into the higher rpm range where max power will be. This also assumes a similar power peak (10,500) to the current cams I'm running in the red bike, but it might be different with these .414" lift camshafts as I've never used them previously.

Are these "drops" typical for drag setups?

The lowest possible drop is best of course, since it keeps the engine closest to its powerband.

 

[ballbearian]

This seems to be right at the heart of the whole strategy. Fun for the imagination.

 

[ancientdad]

This seems to be right at the heart of the whole strategy. Fun for the imagination.

Yes, and if things work out as I hope, it will probably mean the bike will be in mid-4th gear at the finish line. Which means I might have to go lower overall gearing with a bigger rear sprocket than the existing 39 tooth on the CB650 rear wheel.

 

[ballbearian]

Yes, and if things work out as I hope, it will probably mean the bike will be in mid-4th gear at the finish line. Which means I might have to go lower overall gearing with a bigger rear sprocket than the existing 39 tooth on the CB650 rear wheel.

Hmmm. Could you save the 39T, in case you get a crack at the quarter?

 

[ancientdad]

Hmmm. Could you save the 39T, in case you get a crack at the quarter?

Oh yeah, it's actually in good shape. It's about 85 miles to the nearest 1/4 mile (Gainesville) so if I do take it there it will probably only be once just to find out how it does. If it needs lower gearing after running the 1/8 mile a time or two I might try it at Gainesville first before changing the rear sprocket. And maybe the GoPro will cooperate this time, the only time I took my red 450 to Gainesville I was pulling out of the staging lanes when the camera shut off due to a corrupted SD card, at the time I'd never saved any videos from it and erased/formatted it ever so the files were corrupt. All I got were a couple of screenshots from before Ray and I pulled onto the track.

 

[ballbearian]

Would the 39t and 5th gear be long enough for the 1/4 ?

 

[ancientdad]

Would the 39t and 5th gear be long enough for the 1/4 ?

I think so based on the max speed showing in Gearing Commander for 5th gear (101 mph), might even come up just a bit short with the 14 tooth front. On my old one I ran stock gearing (15/35) and it was turning about 10,200 rpm (the tach was much newer and properly functional then, so hopefully more accurate) through the traps at 105 mph on the time ticket (well, best of 104.77).

 

[12ozPBR]

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.