HondaCB+Hatz Scrambler project

[sideshow]

Hey Everyone! New builder here - My name is Alex, working from the Eugene, Oregon area in the US.

After (pipe)dreaming around for a bit, I've decided to go for it!
I've purchased a somewhat beat up 1980 Honda CB750 on the cheap, and plan to put a Hatz 2g40 in, paired with some sort of 4-5 speed ultima or older gearbox (Depending on frame space and budget).
Final product will be a scrambler type bike - something like that beautiful sommer bike that was up on bikeexif.com awhile ago.

As it stands, I've got the bike waiting for me to pull the old engine out, and hopefully the hatz will be on its way within the next couple of days.

I'm currently on vacation for another week or so, but I hope to start as soon as I get back in august - I'll post some pictures then too!

[henneberg]

Hi,

Nice choice of engine, although it weights in at approx 100 kg .

[ckhenshaw4]

Interested, can't wait to see more. I am going to look at a 1973 Honda CB750 donor bike right now.

[tappy]

The engines aren't that heavy - with no flywheel, no startermotor, no exhaust, no air filter, and the ducting removed, my 2G40 weighs 54Kg.
The fan-flywheel can be replaced with something lighter, the starter motor is over-sized, and the exhaust and air inlet can be a lot lighter than what's fitted as standard..

[sideshow]

Nice choice of engine, although it weights in at approx 100 kg .

Yeah - I'll definitely be trimming it down a bit, we'll see what's possible. after researching a bit, this seemed like a good combo of power/weight/quality, but I'd be interested to hear if you had a different, lighter option in mind.

As of now - engine is purchased, but I'm still working out the shipping over to my place here in Oregon. Spent a bit out of budget for it, but I figured the Hatz 2G40 will make for a (hopefully) more reliable end product than the punsun or another similarly powered china clone.

[sideshow]

Engine has arrived!! Whoa it's big.

Gonna get the bike and engine moved down to the project space this friday - so stay tuned for pics!

[coachgeo]

You could consider dry sumping it and drop the size in height a good bit. My old (1973) Yamaha XT550 is dry sump. Part of the frame up by the triple tree and down under the tank also holds the oil.

[pietenpol2002]

Nothing to be gained by dry sumping as the crankcase is the oil reservoir. You need 23 inches for the Hatz and your DOHC frame comes close. Repositioning the air filter and muffler will help. But, the engine mounting will still need to be dropped below the lower tubes. And even though that frame has the removeable lower tube section, both sides will need to be cut away. The height isn't as much the problem as the length fore and aft. Just no way you're going to squeeze that engine and an Ultima into the avialble space. Perhaps you can cut the down tubes and move it up against the front wheel.

For the record Alex, the motor mounts at the rear of the engine opening can easily be removed to gain a bit of space. Just cut the stamping off while leaving a bit of margin, and then grind the weld away. Much like this SOHC frame.

https://www.dieselbikeforum.com/down ... &mode=view

[sideshow]

Thanks everyone for the advice! I'm gonna need it.

Haven't checked spacing yet, so I'm gonna wait on deciding on a transmission. Seems like it'll make more sense to go with a smaller pre-unit transmission.

It's been a bit crazy getting back from travel, but I hope to have the bike and engine moved into the shop early next week!

[sideshow]

Alright! Bike and Engine are moved into the shop!

It's nice to have everything in one location finally. I feel like I'm finally wrapping my head around what needs to happen. Still deciding on transmission options - the frontrunner is probably a bsa/norton/enfield style transmission and clutch, with a CVT being the next option. Ultima is probably going to end up being too big and too pricey, and the bottom end of a 2-stroke bike is probably more than I want to attempt right now. More research and skulking around the forums to come!

Anyway - here are the first set of pics:
Here's the donor bike! I'll be ripping out the old engine soon.


And here's the Hatz 2G40 that's going in!

It's looking a bit rough and tumble, but we'll get it looking great in a bit. It turns over like a champ, so it shouldn't need too much mechanically to be ready.

And here are my 2 beautiful assitants who live here at my friend's shop: Gromit and Kaylee! I'll let you figure out which is which

[sideshow]

I think I'm actually going to go with a 2-stroke tranny+clutch combo - I've got the tools and the expert advice on hand to do the job, and this seems like it'll be the longest-lasting solution out there - I was getting worried with everyone's talk on the quality of the enfield boxes, and the age of the bsa/triumph stuff.

After seeing sbrumby and other's success with the 2-stroke solution, it looks a lot less intimidating as well!

Gonna try and pick up a 2-stroke bottom end and get the old engine out next week!

[alexanderfoti]

Sounds good, just got to make sure the ratios needed can be accomplished.

The Villiers box I use is pretty small and cam handle more than the power I put through it. It's just not that oil tight that's all lol

[sideshow]

Sourced a bottom end of an old 2stroke 3wheeler - something off a 250- at $25 the price is right! Figure I'll at least use it to get a feel for spacing, and if it's not quite right, I'm not in the hole too much.

As for ratios - I was assuming I'd mess with them mostly with the pulley sizes on the crankshaft and outside the tranny/clutch, and possibly the final as well? I guess if the ratios there are still not good, that means I just have to get a differently geared transmission?

Engine is almost out - hope to have pics up on friday! I can already tell I'm going to have to chop up the frame a bit. I guess I'm going to be learning some welding!

[alexanderfoti]

Sounds like a good plan, how are you going to keep the gearbox /bottom end oil tight.

You should be able to get the ratios you seek by adjusting the pulley sizes.

Driving the box faster is easier on the gearbox and better for the feel of the clutch.

I will be interested to see pictures when you get started.

[sideshow]

how are you going to keep the gearbox /bottom end oil tight.

Since it's a 2-stroke engine, the clutch/transmission has a separate oil compartment from the gas/oil mixture in the rest of the engine. I should just be able to chop it off from the rest of the engine and use it with minimal patching up. We'll see though! I haven't actually set eyes on the 2-stroke yet.

Thanks for the advice - I hope to have more pics this friday!

[alexanderfoti]

Of course! I wasn't even thinking. Should be pretty simple to just chop off the engine portion!

[sideshow]

Ahhh! Just got word the engine I bought (through a friend) is a 4stroke. Oh well - it's only $20, so I'll chop it up anyway for practice/fun/knowledge.

PS - alexanderfoti - just saw that test drive video on youtube from earlier this month - looking good!!!

[alexanderfoti]

Ah thats a shame.

I always thought that the bikes that have the nice gearboxes would be a shame to cutup (nsr 125 springs to mind), but if you can get them cheap enough with worn out pistons and barrels then why not.

Thanks! I have been riding it daily since then with no issues! Happy days!

[sideshow]

This is a totally busted up scrap engine, with what appears to be a good working bottom end, but we'll see if it's usable. I started taking it apart, but I haven't got too far. I'm worried though - I think I see some big oil gaps - not just small holes to plug up. Probably going to have to go get an actual 2stroke engine to cut up.

[coachgeo]

This is a totally busted up scrap engine, with what appears to be a good working bottom end, but we'll see if it's usable. I started taking it apart, but I haven't got too far. I'm worried though - I think I see some big oil gaps - not just small holes to plug up. Probably going to have to go get an actual 2stroke engine to cut up.

Just lob off one side, take it to a machine shop/welder and have them weld on an aluminium? plate.

Another user here did it that way.

[sideshow]

Another user here did it that way.

any chance you know which one? I'd like to hear the detailS!

[alexanderfoti]

I think it's this one

https://www.dieselbikeforum.com/viewtopic.php?t=1775

[sideshow]

Ok - last update for a bit. Unfortunately I'm away for most of the month for work, so this baby had to get hidden away under a tarp til I get back.

But before I left, I did get to take some more photos. Here we go!
Got the old gas engine out! Good to see it go. Haven't sold it yet, but I'm sure it'll keep until I find someone that wants it.


Here's the old 4 stroke engine I'm tearing apart now.

It's an old yamaha 250. It was going to be scrapped, so they busted up the right side cover. But if I end up using it, I'll be making my own cover/shaft support to (hopefully to accommodate a wet clutch), so we didn't need it anyway. I'm in the midst of taking off the cylinder, and that will probably be it - I'll take out everything I can for weight savings, but probably won't chop it up that much more. That is, if it seems like it'll work. There's a good chance I'll end up scrounging around for an actual 2 stroke to (hopefully) make this process a bit easier. But I figure this'll be good practice in the long run.

And that's about it! I've got some help with planning out all this transmission confusion, so I'm pretty stoked to get back at it when I get back.

[Nortwestrider]

Maybe a stupid noob question here.
How do you get power from the diesel engine to the 2 stroke tranny/clutch combo??.

[alexanderfoti]

You would have a find a way to attach either a sprocket, or a chain to the crank shaft, or interface with the clutch directy?

[sideshow]

Alright - it's been a year! Holy crap.

A year of slow/not much going, but I do have some news to report. The project isn't dead - not by a long shot, but it still has a way to go.

Currently working with the bottom end of a 1974 suzuki ts185 as the chosen transmission. Got a newer kawasaki 250 waiting in the wings in case this one doesn't work out. Originally was going to fact of the separate 2-stroke tranny oil bath to make a new side cover and bring in a shaft to drive the clutch directly. This proved an interesting challenge - since I'm just learning machining, this ended up being pretty intimidating.

My machining mentor (a bit of an old mazada fan) found a cool link -
http://www.rx7club.com/megasquirt-forum ... ra-884641/ - It's not a diesel, but in the end, the wankel he puts in the bike runs into the same issues re: transmissions. He's using another small tranny - but instead of coming through the side cover, he took out the camshaft to run a jackshaft through, and put a gear where the old alternator was to get power from the wankel.

This seemed like a much more do-able solution. So - tranny is split, the old camshaft is out, and the jackshaft is mostly done. Not going to run a chain to the engine - seems like the alternatives on this site are much better. Going to be hitting up some junkyards for some pulleys, and run a 6v grooved belt with a tensioner.

It's been so long - I've got to figure out how to put some progress pictures up again. Too late to figure out right now. Catch y'all later!

[sideshow]

Hey everyone! (If anyone is still here)

Life's been getting in the way a bit, as I see tends to happen to projects on here quite a bit.

After taking a step back from the project, my plans for modifying the engine of a small 2-stroke to utilize it's gearbox/clutch have proved to be a bit more daunting than expected. I think it's still totally doable, but probably needs someone with more machining/tinkering skills than I have (This may be me, in a couple years, hopefully!!).

So for now - I'm switching gears (literally! ) and moving to looking in to a CVT system instead. I think there's going to still be plenty of challenges, but they seem a bit more conquerable right now for me. Thankfully I'm only out about ~$75 in old 2-stroke engines, so it's not too bad. I still love the idea of a gearbox, so hopefully I'll come back to it, but right now, I really want to get rolling on a diesel bike!

-Alex

[Stuart]

We are still here. Keep up the good work

[sideshow]

Alright. Not a lot of progress to report, but a video from tonight's festivities!

Decided to actually get the motor out and start it up. I had turned it over when I first got it, but I realized I needed some motivation right about now. I figured some diesel fumes and engine noises would do the trick. And I was right! Just posting this, and then I'm headed back out to the shop to get some more work done.

http://youtu.be/LCEqeoU6WP0

I hope that link works. Anyone know if there is a way to just embed the youtube video directly?

It seemed like there were some air leaks in the fuel lines we jerry-rigged up for the test run, but it sure sounded good! We were pleasantly surprised with how the engine settled down after startup - looks like vibrations won't be as bad as we thought!

[alexanderfoti]

Sounds good! I much prefer the sound of a water cooled diesel, the air cooled one I have is so loud and I get lots of looks when riding it about!