HondaCB+Hatz Scrambler project

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Haha. I'm all about the loud! Can't wait to get weird looks.

[alexanderfoti]

Haha. I'm all about the loud! Can't wait to get weird looks.

Heheh

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Alright!

So I have a cardboard mockup I made last week, but I didn't see it around the shop this morning when I came back, so I hope it's still around. It's not that accurate, so we'll see how much help it actually ends up being. Maybe the shop guys threw it away out of pity? Hahaha.

Better news is I've got a comet 94c clutch on the way (found what I hope was a pretty good deal), and I'm trying to finish bargaining on a matching 90d driven pulley as well. So hopefully they'll be arriving sometime next week. I got some good conversation in with (a rather skeptical) ATV shop owner around here, so I think i'll be able to bore out the 94c to fit on the weird Hatz crankshaft taper. And Tappy here at the forum has been giving me some good advice and resources for the Hatz 2g40! All in all, I'm feeling pretty good, with a healthy dose of skepticism that this will all get off the ground.

In the meantime, it looks like i'll be starting to figure out what the subframe is going to have to look like. Before I go rummaging around this forum again - any good info on center distances for the two cvt pulleys?

Hope to get more photos up soon, as interesting things start happening.

-Alex

[tappy]

Somewhere around 266mm by my calculations

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Well, not much more progress to report, but I did get the bike moved in to the shop. Started taking off extraneous pieces (That was a big clunky air intake!), and the hatz is starting to look like a respectable motorcycle engine!

Got the bike propped up a bit, and the motor tilted on its frame, and it almost looks finished! Seems like there's going to be plenty of room - the subframe is really only going to have to lower the engine an inch or two for everything to fit nicely. Glad I found this donor!

gonna be a close fit!

And here's a power-side view. Won't know exactly where this engine is going until I can get my hands on the CVT, but it looks like there'll be plenty of room.

power-side view

-Alex

[gilburton]

Can I give you a word of advice.
Before you mount the engine get your rear pulley mounted and make sure it clears everything in the fully open position.
Include any brackets and footpegs.
The reasoning is that the rear pulley will determine alignment of the engine.
I fitted a cvt to mine and it was only after mounting the engine I found that the rear pulley fouled the stand spring when fully open.
Obviously you'll be using a jackshaft so it can be slid in/out until correct.
The engine is mounted on its feet so all you need is a basic flat plate and the engine can be moved about until you are happy before actually drilling/cutting "hard" mounts.
If you have to cut the front down tubes just make sure that you compress the forks and the front wheel clears the engine/brackets.

[sideshow]

Can I give you a word of advice.
Before you mount the engine get your rear pulley mounted and make sure it clears everything in the fully open position.
Include any brackets and footpegs.
The reasoning is that the rear pulley will determine alignment of the engine.
I fitted a cvt to mine and it was only after mounting the engine I found that the rear pulley fouled the stand spring when fully open.
Obviously you'll be using a jackshaft so it can be slid in/out until correct.
The engine is mounted on its feet so all you need is a basic flat plate and the engine can be moved about until you are happy before actually drilling/cutting "hard" mounts.
If you have to cut the front down tubes just make sure that you compress the forks and the front wheel clears the engine/brackets.

Thanks! I've been thinking about a few of these things too. I've got some chain and turnbuckles that I can use to maneuver the engine in to place, but definitely going to need to wait for the CVT to come in. Do you know - when the driven pulley slides, which face is fixed?

Thanks!

[gilburton]

It's usually the inner so you have to allow extra room for it to open up.
First time I ran mine up with no drive chain to test it it promtly hit the stand spring and threw it off lol.
I then had to realign my engine mounts.
However mine was a CV Tech so you'll need to check that out on your Comet as I don't know a lot about them.
I believe some of the smaller units with asymmetric belts means both outer halves move.

[garbs]

Gilburton is correct. The driven pulley will always open toward the side with the spring. Most cvts have the drive pulley sheave furthest from the engine move towards the engine, the driven pulley has to open in the same direction in order to maintain belt alignment. Like gilburton said the asymetric versions open the towards the same side as the belt never moves side to side (viewed from above) as one side rides on a flat face. The comet 94c is not asymetric so your driven pulley will be expanding towards your frame.

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Thanks guys! Also just watched a good youtube video on CVT clearance issues.

Some good news and bad news to report

I've got the engine hung in the frame by using some chain and turnbuckles. Almost looks like a motorcycle! It immediately became obvious that I'm definitely going to have to do more of a complete subframe build - I thought I was going to get away using most of the original CB750 frame, but the engine doesn't have quite enough room to get its center of gravity to the center of the bike. I guess that's not too much of a surprise with this 2g40.

Thankfully though, I'm looking at some pretty simple stuff, already scoped some good spots/techniques for mounting the jackshaft pillow-block bearings. At this point, I think it's just time to bite my fingernails and obsessively check email/ebay for updates on the CVT pulley shipments! Hope they come next week.

While I'm at it though, wondering if anyone has advice on removing the foot-plates on the engine. There's some recessed bolts that have super tight clearance - only a couple millimeters of space around the bolt head - I don't think I have the tools to get them out! Anyone have any tips?

Thanks as always - you guys have been great!
Alex

[gilburton]

Don't get too hung up about the CofG.
Wait until you get the rear pulley mounted and then see where the engine sits to align it.
After all old Vespas have the engine off to one side and it works

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Good to know. I do have enough weight that I want it to be pretty centered, but if it turns out it's a centimeter one way or the other, I'll try not to worry too much
Looks like the CVT stuff is coming early next week, so I'm pretty stoked for next week/weekend!

[gilburton]

The heavy flywheels on these engines tends to make the C of G off to one side anyway.

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Yeah, thankfully the engine has a nice eyebolt up top at the CofG for moving purposes, so the engine is both easy to move, and the CofG is very obvious. It's definitely a lot closer to the flywheel side than the power out side. Heading home from a nice weekend up in the Olympic mountains in Washington, looking forward to coming home to see my CVT pulleys! (Should have arrived this week!)

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Alright - life has been busy, but I've got a couple hours on the train to update you all on where I'm at. Internet isn't good to upload pics - but those'll come soon. Life got derailed this week with my main ride (BMW f650) busting its radiator. Right after I put on new tires, of course! New radiator is on its way. Sometimes I hate german engineering.

The diesel bike is continuing, slowly but surely. I've got all the jackshaft material here - shaft, pillowblock bearings, shaft collars, so I'm looking forward to installing that - still got some clearance issues to work out there with the CVT driven pulley movement, but there's enough extra material on the frame in that location that I think I've got plenty of room to keep chopping out bits

The engine mounting plate is in location, and leveled. It's just got some tack welds, but it's already feeling pretty solid. I'm really thankful for whatever luck I had when I found the donor bike - the engine's got plenty of room, and I only had to drop it down a couple inches. It's got a nice forward lean too (within specs) - so that'll give it a nice look I think. I've got bolt holes more or less located, although I'm sure i'll have to mess with them a bit to get the engine true to the frame. I'm going to wait on that until I can figure out more about cvt belt length availability so I can judge center-center distances between the pulleys better. I've found a nice equation to calculate center-center distance from a golf-cart modding forum:
http://www.buggiesgonewild.com/big-bloc ... ource.html

L= ((2*a*D2+2*a*D1)*Pi+D2^2-2*D1*D2+D1^2+8*a^2)/(4*a)

a=the center to center distance (distance between the center of the bolt holding on the drive and the bolt holding on the driven.)

Pi= if you don't know what this is, where in trouble.

D1=The Diameter of the drive clutch with the belt wrapped around it. Measure with a cheap dial caliper.(the belt is important because all belts are measured by the outside circumference not the inside)

D2= The diameter of the Driven Clutch with the belt wrapped around it. An easy way to measure this is to take it off the cart lay it on the concrete and mark it's diameter (with the belt on it) with a pencil then measure the distance between the marks with a tape.

But - this doesn't tell me what's actually available. Anyone have a good idea on how to figure out what's available? Messaged people at Gates Belts but they didn't get back to me. Anyone? I'm hoping to use a Gates G-force or that new kevlar C-12 thing they have.

As always, thanks for all the help!!
Alex

[garbs]

I used the info on the pages below while buildig my bike. The site has a lot of good info regarding comet cvts. Unfortuneately the belt sizing charts only go up to the comet 40/44 series and I do not see any for ther 94c. A good point I read on a golf cart forum was: If you can find any application that used the same primary and secondary clutch as you plan to use, and can also find the center to center distance and belt length from that application, you can use those numbers to find your desired belt length. For instance if the application had a 12" c to c distance and 30" circumference. Add 2 inches for every inch that you increase the c to c distance, or subtract 2 inches for every inch that you decrease the c to c distance.

https://www.gokartsupply.com/tcbelts.htm


http://www.gokartsupply.com/beltchart.htm

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Alright - here's the progress with pics so far!

I got the engine baseplate tacked on before - it still needs some adjusting to get the motor in place and lined up correctly. It's just tacked on for now while I figure that out (currently working on that). You can also see what I did just this past weekend - mounted the jackshaft and secondary CVT pulley. Everything is just tacked together right now - I still need to work on the bottom frame mount of the jackshaft a bit - it's just got a throughbolt through the original engine mounts holding it in place.

Here's a side view of the jackshaft. As you can see, it's not finished, but it's all where it needs to go!

[coachgeo]

Alright - here's the progress with pics so far!....

P3210932.jpg

Here's a side view of the jackshaft. As you can see, it's not finished, but it's all where it needs to go!

Maybe Im not seeing it...... but how are you adjusting Jack shaft distance from Primary Pulley on engine for purpose of CVT belt remove/replace, along with tension adjustment?

[gilburton]

There is no adjustment for the belt as the distance is fixed.
Don't forget the pulleys are not fixed pulleys so the belt self adjusts as it wears.
What happens is that as it wears it starts to sit lower in the pulley and it also starts to affect the gearing but it doesn't slip.
These larger size CVT/belts do not wear as quickly as the smaller Comet types. The Aixam car belt changes were scheduled at 11000 mls so on a much lighter bike they should go on much longer.

Not sure about this type of system but in the workshop with the proper tools you can split the front pulley to change a belt but in an emergency how do you do it??

You change belts by opening the rear pulley causing the belt to go slack.
On the later CV Tech ones they had a threaded hole on the outer pulley half. You threaded in a bolt and this pushed the inner pulley open.
In practice it is possible to lift the belt on the pulley up to the edge and then twist it off the edge as you turn the engine/pulley by hand.
This has the effect of pulling the rear pulley open as the belt acts as a wedge on the rear pulley.
Think along the lines of tyre replacement or putting a slipped chain back on a cycle.
Many years ago I had a Daf car and it was possible to lie underneath and pull on the bottom run of the belt and rock it back and forward which worked it in to the rear pulley,opening it up,you could then have enough slack to take it off the front or rear pulley.
The official method was wooden wedges lol

[gilburton]

Your pics reminded me very much of how I mounted mine although I was struggling a bit with the MZ frame room wise lol

One thing I did do was weld the mounting plate on to the upright jackshaft plate in an "L" type configuration as I felt that it would tie the 2 elements together in a sort of old Brit bike unit/pre unit sort of way and be stronger.
If I've any criticism your jackshaft plating looks a little thin? I used 6mm or 1/4" on mine and that was only an 8hp single

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Yup! plating seems a bit thin to me as well, but it's what I got lying around the shop. I'm going to get everything in place first, and then add bracing wherever possible. FWIW, the guru who's advising me seems to be totally unworried about it. We'll see what happens!

Just finished up releveling and adding a bit of bracing to the engine mount plate, so I'll be remounting the engine to adjust the hole pattern next! Moving along!

Thanks again for everybody's advice - everything is very much a learning experience for me right now!

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Actually, if anyone is interested, the plating is all scrap from various other cool projects around here - engine plate is from an old wheelchair lift for some sort of bus or car I think, and the jack shaft plating is from some huge old custom gas tanks from an old Willys, which has since had its gas tanks sized down from its own diesel conversion. This is truly going to be a frankenbike!

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Alright. Chugging along!

Had some difficulty with the different duster clutch models, but I finally got that sorted out, and the correct (I hope) adjustable one is in my possession.

Right now I'm working on the jackshaft and engine mount welds, which are somewhat daunting for a newish welder like myself. I'm pretty satisfied with the penetration I'm getting, so I know I'm safe, but there's a long way between safe and pretty for me!

The plates are already constructed and aligned, so we're just solidifying the welds right now.

Here we are with the bike upside down to finish up the welds more easily. Unfortunately about 2 min after I took this picture, the MIG wire spool ran out. Gotta go pick one up tomorrow!

After that it's time to remount the engine and check the CVT placement, so I can order a belt and get the crankshaft adapter made up. The taper at the end of the crankshaft is a large 1:5, so I've got to turn down something to fit into the more regular 1:20 taper on the duster clutch. Not sure, but I'm probably going to farm that out to a local machine shop. Not quite confident in my ability with the lathe to get that spot on, and I'd like to get this thing moving sooner rather than later.

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Alright - long delay, but I've been busy. All the major pieces are in place - here's proof!

https://www.youtube.com/watch?v=BjNT1qur1U4X

Hope y'all enjoy! Didn't quite get to the video before dark - I'll have to get a better video in a bit in the daylight.

Still plenty of plenty of work to do. Found a small oil leak that needs to be tracked down now, plus plenty of big stuff left - exhaust, air filters (just arrived!), CVT tuning, and a lot of beautification/cleaning up from the last owner. But it does feel super nice to get to this point!

One thing I noticed - the fuel shutoff solenoid takes a lot of power draw. I'm guessing people here have moved to a mechanical fuel switch? I'd be interested to hear what people have come up with - my first thought is some kind of cable-activated latch that i can wire to the now-unused clutch lever.

-Alex

[alexanderfoti]

Yes they do indeed, I measured mine at 2amps,

Depending on local laws you can have a mechanical tap, this will stop the engine quickly enough.

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Thankfully the laws are pretty lax here if i've got it all right. I do understand the appeal of the tap, but I'd definitely like to rig something up to a handlebar control. The solenoid shuts down the engine very nicely, so I figure with my luck, it'd be nice to keep that shutoff capability within arms reach.

[Nanko]

You can minimize the current with a resistor in serie with the solenoid.
The holding voltage/current when the valve is already open is much lower.
Check with a variable voltage powersupply at which voltage the solenoid closes.
To be sure it stays open even if the the batteryvoltage is a bit lower, add 1 Volt.
Calculate resistor value.
Solder a 1000 MicroFarad electrolitical capacitor across the resistor.
Initially the capacitor is not charged and full battery voltage is supplied to the
solenoid coil

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You can minimize the current with a resistor in serie with the solenoid.
The holding voltage/current when the valve is already open is much lower.
Check with a variable voltage powersupply at which voltage the solenoid closes.
To be sure it stays open even if the the batteryvoltage is a bit lower, add 1 Volt.
Calculate resistor value.
Solder a 1000 MicroFarad electrolitical capacitor across the resistor.
Initially the capacitor is not charged and full battery voltage is supplied to the
solenoid coil

Whoa! great idea! definitely will try this going forward. Have you gotten it to work in practice before? Thanks!

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Alright. Minor setback - vibrated the jackshaft out of its bearings! whoops! Gotta tighten those down. Good news is I think the oil leak is fixed (loose oil pressure switch), and she starts up great! The current major issue is that fuel solenoid - all the crappy batteries I have lying around just aren't cutting it - the fuel solenoid just has too much current draw. It starts great when I'm holding down the switch manually, but obviously that won't do in the long run. Re-thinking implementing the resistor/capacitor trick - I think it's going to have to be a manual cable latch of some sort.

Unfortunately - i'm in the midst of a shakeup - regular work is getting weird, and I'm moving to a new house to boot, so the diesel bike has taken a back burner for now. Hoping to get most of the move done this week, so back to diesel fumes the next!