BLACKPIPES

Keep steppin’ yo game up

So last year I ran the PHBG 21, which was a great carb. I don’t understand anyone’s issue with PHBGs: I didn’t have to rejet constantly for temperature swings, it was pretty easy to tune, and it was easy to work on. That being said, a 21mm carb is good for 10-12 horsepower, so it was time to make the move to the TM24 to see where that took me.

The primary issue with getting the TM24 on there is that I don’t run a chopped frame, custom-built subframe, or a top-tank frame swap ala a Magnit or a Batavit or whatever, so there isn’t a lot of room for 24mm of intake due to where the case opening is and how the frame and subframe come together. Also, the stock Hobbit intake can be bored out to about 20mm (not even 21, really), so I needed to figure out a way to get 24mm of capacity into a low-profile intake. The nice big tall Dio reed setups that some people run on non-top-tank converted Hobbits require either too-tall shocks or metal rods in the place of shocks altogether, and that wasn’t really an option for me due to my being obstinate and also not wanting big stupid euro shocks.

My first plan was to get Julian to weld extra material to an extra stock intake, so I could grind it out to 24mm, and then use that big exhaust header treats sells, cut down to essentially be like a larger version of the 21mm intake I already was running. Before I bought the big header, though, I heard rumors of MLM making 21mm and 24mm intakes for the stock reed block, ones that would be sized to fit on a stock Hobbit. So I was patient for a few months, and the 24mm intake from MLM became a reality, and I snagged one the other week in preparation for this seasons upgrades.

The issue with the MLM 24mm intake is that it technically works with a stock Hobbit, but you pretty much need to run 300mm shocks or you risk hitting it with your frame as your shocks bottom out. Additionally, I didn’t like where the path of the intake made the carb come out - it sits perpendicular to the bike and I couldn’t imagine any way to run an air filter due to pedal clearance issues. And the floor boards wouldn’t really work anymore, which I think looks really ugly on Hobbits. Ryan posted some good photos of the intake on his bike on MA, and I realized that I could cut it down to act like my 21mm solution, then run a big rubber tube out from it to connect to the TM24. So I measured a whole bunch, then took an angle grinder to my brand new $50+ intake.

The first line I marked was what I thought would work, but after mounting it up and checking it more closely, I had to circumcise even more. And no offense to MLM, and maybe mine was messed up, but I had to grind the upper mounting holes on the intake like 2mm down to make it fit correctly - not what I imagined having to do for an expensive, custom-made, intake. Here’s how it looks with the hose:

Man, the bike is getting pretty grungy and some surface rust is forming. Whatever. Then I ate a burger from Kuma’s in my new city of Chicago. It was absurdly good.

I’m also working on a new seat idea to replace the gramma seat, which I have realized looks pretty cornball with the rest of my bike. Chopped up a PA-2 seatpan (thanks, Cap’n) and cut the foam in half. I’m going to have a local guy weld up the back and then I’ll recover it with the stock cover for some OG looks. Hopefully it works out. Right now it looks like meatloaf on a pan, according to Taco.

My TM24 is still in Ann Arbor, so my new local buddy Seb let me bum a TM24 from him while he does his casematch and engine build on his Puch. I went to his garage last night and got it fitted to the hose, got the throttle cable sized up right, put the air filter on, and everything fits better than I could have imagined.

So of course I had to start it…..

- ShaneB

pullstart, 2 months l8r

This post is an update to this post.  

The opposite of what I thought would happen happened.  Instead of the washer being bent by the force of the teeth yanking on it, the teeth were the ones that succomed to mortality.  

poor ‘lil teeth, I hardly knew ya.  Realistically, I should’ve expected this; the teeth are aluminum and the washer is steel.  oh well, time to try something else.  

I must have been drunk when I made the first version of this.  As you may or may not recall, I used a puch flywheel cover as a spacer over top of the hobbit flywheel cover to get the needed clearance.  Well, that was dumb and unnecessary.  

Not sure if that really describes what I did, but the spacer I needed between the recoil and the flywheel cover was under my nose the whole dang time…

keep it simple keep it simple keep it simple…

-DW

The consequences of power

I haven’t posted much about Black Butte in a while, but it’s been going well. Devin of Motion Left Mopeds recently provided me with 4 prototype pipes to compare with the St-Ripper, which has proven a little too rev-crazy for my build. I haven’t tested it again with the HPI and lightened weights, so maybe I should soon. I’ll avoid posting a photo of them in order to not reveal too many of Devin’s new designs, but they are all pretty different and give me a lot of options.

A reminder of current setup (the important things at least):

• Athena with about 172 degrees of exhaust duration and opened up transfers (not widened)
• Stock reed block with boyesen dual-stage mod reeds (more on these later)
• Stock intake ground out to about 20mm (this will soon be replaced with a new intake with material added, ground out to 21mm+ and a smoother entry into the reed block
• Puch magnum exhaust header to radiator hose intake hose deal
• 21mm PHBG with velocity stack
• Malossi MHR Delta clutch springs, the blue middle strength set (still ridiculously strong)
• Derbi 6 roller variator with 15g of weight
• 1977 house brand BX5 belt
• HPI ignition, set to 2mm BTDC
• Terry Dean Cain edition lightened and re-angled clutch bell, matches the angle of the derbi driven face
• Starter clutch pulled, rope-start thingy attached to HPI rotor

I have been running the prototype pipe with the largest chamber, and it’s a real winner. Lots of torque all over the place, and it revs out nicely to the low 60s. I can get to 50 in about 10 seconds and just cruising around and then throttling on around 30mph is a blast. It’s a real winner and I think it could be finalized and sold as is as a competitor to the MMM Destroyer. Note that I haven’t run the Destroyer in a long time so I am not directly comparing them at the moment. I put about 60 miles on the bike during the Toledo rally and the bike performed perfectly, besides being somewhat tricky to start with the rope starter. The crank spins up incredibly quickly due to the HPI, which is great, as it makes the clutch grab much more firmly and with less slip, which puts power to the wheels more reliably and quickly. It also allows me to cruise around 30 with no big effort, as the clutch can stick at that speed. The torque is great, because I can throttle on to pass slower bikes or just have fun blasting down an open road, or slow down to take a corner and then throttle on through it.

Ryan cooked this rope start up for me. The pull-start setup simply won’t work with the HPI rotor, and I know Julian had been using a similar disc on his bike with good results, so I gave it a try. It does add 5oz of weight to the rotor, but it’s still laughably light compared to the nearly 2lb stock flywheel. I’m still figuring out how to reliably start it; it’s usually a combination of a hard pull and a quick blip of the throttle.

So since coming back from Toledo, I’ve wanted to test out the other 3 prototype pipes, and went down to the shop to do so. One of them seemed similar but not as fast as the pipe I was running, but that isn’t conclusive, as at the end of the night I noticed the freewheel on the rear wheel was rubbing against the pipe and ground a nice big groove into the inside. Slowing me down? Maybe. I pulled the pipe and installed another one, which looked to be designed for higher RPMs. Initial tests seemed interesting, but when riding back to the shop I noticed a strange sound, and when I stopped the bike stalled out and wouldn’t start back up. After checking for blown seals and any obvious leaks, I pulled the frame off the subframe, pulled the carb, and found this:

My bike ate my reed. :( This bike has maybe… 300 miles on it? I guess I blasted too hard… but I can’t be replacing these dual-stagers every few hundred miles, so I’ve ordered the .4mm carbon reeds and will see how those perform. I ran carbons once before on my yellow bike (which is a drastically different setup) and they just didn’t seem right AT ALL, but I’m hoping that they will be a good match for this setup.

Since I had pulled the clutch to check the seal, anyway, I decided to give it a quick sanding to get some fresh pad material against the clutch bell. Check out what strong springs do to a stock clutch:

What you are seeing here is that the arms of the clutch are bending and only the dark parts of the clutch pads are engaging the bell. This isn’t terrible, but I’m interested to see how long this clutch lasts. I should probably get a backup clutch on deck, and remove the black MHR springs from that other clutch I have to avoid premature stress. The real key is to sand down the pads and clean off the inside of the bell every 50-100 miles to avoid slipping. It’s a pain, but it’s the price you pay for running a setup like this. You can honestly do it in under 5 minutes if you are fast, though.

So probably no more pipe tests until this weekend. I’m sending Christian two of the MLM protos for testing on his new build (which I hope he posts about soon), but keeping the torquey pipe and a higher RPM pipe for my own use for now.

Oh, I also opened up my variator to check the weights. After 250-300 miles (estimated) they were beginning to flat spot a bit, but nothing terrible. I ordered 5g Dr. Pulley sliders and tossed 3 of them in there. I also compared the TJT ramp plate to the stock Derbi 6 roller plate. The difference was fairly obvious: the TJT ramp plate features an aggressive flat angled ramp surface that begins in the middle of the plate and continues to the edge. The Derbi plate is a smooth curved surface to the edge. The edges are exactly the same at the end, but I’m not sure if the flat surface would cause the variator to more fully open or not, resulting in a higher final “gear”. It appears to me that the Dr. Pulley sliders would match very well with the shape of the ramps on the TJT ramp plate, while only a small portion of the sliders would be pressing against the Derbi ramp plate. I put the Derbi plate back on, but am going to be testing the TJT plate as soon as the bike is back together and I am able to do some good testing, instead of changing like 4 things at once.

More to come later, of course.

-ShaneB

HPI yeh

Whatever. Picked up a used HPI and put it on the Hobbit today, finally. I was going to write up a how-to but it was seriously beyond easy. Still dialing it in perfecto, but I hit 65mph on a slight down-slope… my previous highest speed on those same roads was like 61.5.

February 2012 edit for clarity: That 65mph wasn’t GPS’ed and I later realized my bike speedo was off by a few mph.

Will post more later once this thing is done… for now I guess.

I realized I’ve never shown the full intake/hose/carb setup on this. Next steps: Julian is adding some material to the top of a spare intake I have so I can grind it out suuuuuper big and smooth. I’m going to modify a spare reed block to open up the holes a bit, thin the bridge, and cut a carbon reed out of some reed material. Experiments.

HPI. This was so ridiculously easy to get installed and running… I’m not even going to bother talking about it. Flywheel cover doesn’t fit. Going to mod it to make it, though. I have some neat ideas for a pull-start mechanism, involving a thick disc mounted into the threaded puller holes and grinding a negative image of the pull-start cog into it. You’ll see.

Messy but functional, and it hardly matters under a side cover.

Put the light coil on, too, and installed a spider LED headlight from superbrightLEDs that the previous owner included with the setup. I already run a LED taillight, and they definitely light up. We’ll see how they look in the dark. I don’t ride this bike in the dark, really, so as long as I’m visible to cars I’m happy.

-ShaneB

…and another wild Magnit was born…

CTH

A cheap, effective pull start for hobbits

One thing that sucks about hobbit engines is the starter clutch. Here’s what I did to get around this problem.  

The only way to fix this problem is to remove the starter clutch completely.  If you do that, you have to figure out another way to start the bike.  There is a kickstart available for pa50s but they’re expensive and you have to order them from the Netherlands.  I really couldn’t be bothered with that.  I decided that a pull start would be the cheapest way to go, so I started researching.  

I used this guide to get a basic idea of what I was looking for.  Unfortunately, with that design, there is no way for pedals to clear.  Also, with this new MMM Destroyer that I’m running, I wouldn’t be able to keep my pedals parallel to the ground.  Not cool.  s’anyway, here’s what I came up with.  

First, I took off the starter clutch and threw it away.  

Then I bought this pull starter (it’s an ebay auction, if the link is broken, email me and I’ll help ya out.)  actually, now that I look at it I think it’s the exact same one from the guide above.  okay cool, moving on.  

Next step was to make something for the recoil to grab onto.  

I removed the stock washer and replaced it with a more manly one.  I cut four slices into the edge and bent it up.  With this and a notched variator you can have a blender on either side of your moped, how fun!

before & after:

oh, make sure all four “arms” are bent evenly, so the recoil doesn’t just grab one of them.  I’m not sure if this is going to work in the long run.  I may or may not need to weld in little supports.  I’ll update this post if I find that to be the case.  

Next step: mount the recoil to something.  I chose to use the stock flywheel cover because it already bolts to the dang moped.  I used a puch flywheel cover on top of the honda one for more clearance and some washers in between the two covers until it was all spaced properly.  Peep dis:  http://blackpipes.tumblr.com/post/7401903847/pullstart-2-months-l8r

So here it is.

The pedals clear by about 1mm.  <$20 spent.  I’m happy.

-DW

Ohhhh yeahhhh

After a little extra waiting, my MLM St-Ripper is finally here. Devin really knocked these out of the park, to be honest. Great looking welds, top-notch powdercoating, nice custom elements… I’m happy to have one in my hands. He was kind enough to send me one with a welded-on logo instead of just the MLM text on the stinger. Cool touch.

Should be getting this bolted up tonight. The weather looks like it might cooperate! HYPED.

-ShaneB

Closer

So last time I posted I had hardwired the bike but things were still pretty messy. Since then I trimmed the wiring down and got things a lot cleaner. It’s not 100% perfect yet but it’s good enough for now. Everything routes under the fuel tank or is the right length for where it needs to go. The CDI box is zip tied to one of the little tabs on the subframe and I think it’s pretty secure. I think I might replace the visible wires that go up front to the headlight with black wiring for stealth ninja powers. I’ll tell you what’s a valuable tool - a good wire stripper and crimper. Do your wiring right: spend $10 on a stripper and $5 on some proper connectors (for a hobbit use bullet connectors because you will need to be able to remove the frame from the subframe) and don’t just twist stuff together.

I spent a few hours at the shop the other day simply trimming up and re-routing the brake cables and decomp cable. It’s not that hard of a job. You will need to get some knarps from autozone/etc or from treats, for one. Then basically take your double-ended brake cable and cut off one of the knarp ends. I chose to cut off the control end, because Hobbit brake cables are fancy and weird on their hub ends. I then took the cable and held it up to the control and figured out how much to trim off. Remember that you want your cables to sweep in fluid directions, no hard angles. I erred on the side of caution at first, better too long than too short. You then pull out the cable inner (the metal cable) and use some decent pliers with a cable cutting section (or some proper cable cutters) on the cable housing. Bear down and cut through that stuff. You can also use a dremel with a cutting wheel, but for lined cables the cable lining can melt and gum up the works. So your cable housing is probably a good length now, so run the inner back through it and then figure out where the knarp needs to go. This is a lot less critical than the housing because you have adjusters to work with, usually on both ends, and you can just relocate the knarp if it’s all off. The only one that caused me any issues was the decomp cable, because there are no adjusters on it, and the knarp has to be precisely placed to provide the right amount of tension.

I had also previously trimmed a little bit of housing off of the Motion pro throttle cable, to allow me to run it through a 90-degree bendy and not shoot straight up out of the carb and look absurd. This was a pain in the ass, as I didn’t have a throttle knarp at the time and just decided to cut the housing while the cable inner was running through it. This is dumb and takes forever, and could have potentially cost me a trip to the bike shop for a new throttle cable inner. You have to cut through a bunch of spiraly rings in the cable housing and pull them off one by one with needle nose pliers. I should have just waited for the right knarp that would have fit in the throttle control body. But whatever, it’s done, and looks a ton better.

With the cables resized and routed under the tank where possible, things were looking really good. I then put the side covers and foot panels back on. To get the left-hand foot panel on, I had to trim it to fit around the carb that shoots out from under the frame. I also trimmed a little notch out for the throttle cable to route through on its way under the fuel tank and up to the throttle.

So here’s how things stand now. I’m thinking of trying some other seat options, particularly the PA50-II seat, with the foam cut down and the seat post moved forward. Rear rack will be painted (probably just powdercoated cheaply), and the rear fender will be chopped a little and put back on. I will have to look closely at front fender options, maybe some photoshop will be my friend to see how and where I will chop it. New MLM pipe (the St-Ripper) will come at the end of the month, along with some porting by Devin himself. But for early January I’m pretty pleased where things are.

-ShaneB

Yes yes yesss

Hey bro I heard you like bad cable and wire management

I took advantage of the warm temps and clear skies and went down to the shop to wire the bike up. It’s an easy hardwire once you figure it all out, and sketching it out in advance made it easier. Right now everything is pretty hilariously janky, a lot of stuff needs to get shortened, re-routed, etc. But the important thing is… it runs. And runs pretty damn well for a guess on the main jet and needle settings. Check out this rats nest of crap:

I rode around for a few miles and did a top-end run on a long straight 45mph road, and my phone GPS gave me a top speed of 56mph. Not too bad for a mid-range pipe and no tuning whatsoever. It’s variating too early, I think, and the RPMs are dipping too low for the pipe to be generating a lot of power at certain areas.

However, there was a moment of total zen that I have to share. On the second run of a few miles, I turned out onto the wide, long road, totally clear of other vehicles. The sun had just begun to set, and the sky was fading from blue to orange. With clouds in the sky, a flock of hundreds of birds flew over the road, their animated silhouettes creating patterns in the expanse before me. I accelerated beneath them and just watched as each continued their flight to god knows where.

And then opened up the throttle.

-ShaneB

New bars, controls, lights

I ordered a bunch of new parts with Christmas money and have spent a few hours in the shop getting everything on there. Some stuff has been frustrating but mostly everything has been pretty smooth.

Tossed on a set of 1977 batmin bars, which are basically black powdercoated m-bars. I love the treats m-bars on my Magnum, so I’m hoping they work nicely for this build. Also got new Domino controls, a kill button, and a motion pro long-pull throttle (from Tom) and throttle cable. Got all those on the batmins today. The left side of the bars aren’t uncoated like the right hand side, so I had to do a LOT of sanding wheel action on the inside of the brake lever to get it over the bar end.

I also got the EBR headlight brackets on, using some cut innertube to line the insides against the forks. The guia headlight fits in there perfectly, and is nice and shallow. Sticks out a lot less than those goofier bigger ones treats sells. Here’s how it looks from the drivers seat. You can see the decomp cable is pretty long, I’m hoping that after it routes under the fuel tank it is cleaner looking. Also the Magura grip doesn’t cover the Motion Pro throttle enough… looks kinda dumb:

And the front:

As you can see, I got a yellow 78-style rear rack from a buddy. It’s going to get painted black, but for now it’s a placeholder. What’s great is the LED light I snagged at O’Reilly’s fits perfectly under it, and the rack mounting bolts line up nearly perfectly with the light mounting holes, so a few angle brackets makes a perfect light mount. I’ll probably raise it up to the top holes and cut off the bottom part, or paint the brackets black when I do the rack:

So yeah. Cabling is still ugly, wiring needs to get done, use my new angle grinder to get the seat down and back, put the tank back on, start it up again, ride it, tune it. Maybe I’ll get some nicer weather in a few weeks to actually tune this thing. I’m planning on ordering my own exhaust come February after I get paid again.

-ShaneB