Tag Archives: smallframe

Re-snaking an expansion chamber

Unfortunately, the images to this post were lost in a server crash.  i’m preserving the text in case it is of any help to anyone.

Here is the Ape 50.

There aren’t any really high-end exausts available to fit this, so we are going to modify and re-snake a Hammerzombie pipe to fit it.

First thing i did was get access to snake the exhaust.

As i currently do not have the fuel tank installed or any fluids in the engine, it was a simple matter of removing the battery and tipping it on it’s side.

This is the Hammerzombie, in it’s unaltered state. A great smallframe pipe.But, when put on an Ape,  the truck bed got in the way of the header, and the differential got in the way of the main body of the pipe and the axle got in the way of the muffler.

so, we’re going to fix that.

First, we had to cut the header along the seam in it and rotate it to get it away from the truck bed.  we used this cut off saw, but found out later the band saw would have gotten us a better cut.

Here we are, cutting the second cut.

It looked good, so we tacked the header together at the first pipe with a TIG setup.

And then did a test fit.

This went well. So we did the next cut.

We tried the band saw, but on this large section of the pipe it was deflecting to much, giving us not a straight cut.

So we got it most of the way with the thinwheel, then switched back to the bandsaw to finish off the cut.

And then a test-fit. and then tacked together.

we were worried a little about the pipe coming too low, and killing the ground clearance.

We tried another test fit. We ended up going with a slightly different routing on the final weld, though.

And here is the pipe fully welded and good to go, except for the bracket modifications.

And here we go. the final picture. looks a bit different than the standard Hammerzombie.

All in all, i’m happy with it. we just need a piece of  1″ angle stock and an exhaust clamp to make the bracket and it’s good to go.

Reinstalling the Ape 50 engine

Unfortunately, the images to this post were lost in a server crash.  i’m preserving the text in case it is of any help to anyone.

Here’s a write up on reinstalling the Ape 50 engine.

it’s going to be more write up than photodocumentation, as i didn’t take too many good pictures of this step.

So, in this picture I have the front engine mount bolt in place, and both axle shafts removed. i’ve also removed both the rear shocks as I planned to replace them anyway and this seemed like a good time to do it.

Of note, you’d typically want to have the cooling shroud on the cylinder, but I left it off since I have to modify an exhaust and figured that would make it easier.

Next, swing the engine up into place and bolt up the engine cradle.

Then, I replaced the rear shocks.

Here’s a shot of the old shock and spring next to the new shock. These shocks were pretty reasonable. I’d recommend replacing them if you have an ape 50.

To get the shocks out, there’s two covers held in place by two screws each in the truck bed. remove these  to get access the top shock mount. remove these nuts top and bottom to get the shocks out.

Then you install the half shafts. These slide in, and then there is a thrust washer that goes against them. Of note is that this washer has a tab on it. This tab has to line up with a corresponding notch in the differential.

Then you install the circlip.

At this point, you’d probably hook up all the electrical and the control cables. I have other things to do first so i didn’t.

Assembling the ape 50 engine and differential

Unfortunately, the images to this post were lost in a server crash.  i’m preserving the text in case it is of any help to anyone.

Alright. sorry this has been a few weeks late but here it is; assembling the differential and engine on an Ape 50. It’s been a busy spring here at Hodgespeed.

So, here you have the four engine case bits for an Ape 50 and the differential. First you’ll have to swap the cylinder studs for the longer 125 studs if you’re upgrading displacement as we are.  you’l also need to install the Christmas tree in the flywheel side case and the clutch basket in the other main engine case along with all bearings and seals.

Now, attach the inner differential case to the clutch side case.

Here you’ll see the first mistake i made. You need to insert the three differential cover bolts on the left hand side in this picture into the case, before bolting the two pieces together. otherwise, there’s no way to get them in the holes, similar to those two annoying case bolts on a handlebar bike engine. save yourself the do-over and put them in before you bolt these case bits together. you need to use gasket goo (witch i personally dislike) on this joint. there is no paper gasket.

Now, insert what is the rear axle on the scooter, but is the output shaft to the transmission on the Ape. make sure to line up the shifter with the shifting fork, and get the gears lined up with the christmas tree. some people like to install this shaft and then put the gears on, as it is slightly easier that way.

Next, we’ve got to put the differential together.

Here you see how all the internal bits go together. it’s pretty straightforward. three gears and a shifting fork for the reversing gear. gasket goo again here, no paper gasket.

Now, back to the other side. from here it’s like a regular smallframe except way simpler because there is no kickstart mechanism. i never realized just how much work that added getting that lined up, but this thing just flew together in no time compared to a scooter smallframe case because of this omission. no runner biffers to install, not spring to fiddle with, no quadrant to line up. just set the parts in the engine and bolt together.

First you install the crankshaft, then grease the gasket surface.

Then you put the gasket on.

Then you grease the gasket

Then you install the flyside case.

If you’re using 50cc-style ball bearings, you’ll have to tap into place. if using the needle style bearings used in all other displacements, it’ll just slide right on.

Notice these two case bolts:

Leave those out for now, because you need to use them to install the engine mount.


Now, install the crank gear. to get good speed you need to go way higher than you’d think, as there is a 1.68:1 reduction in the differential. as a result, the gearing i went with was so tall i needed to clearance the case a little to fit it.

now install the clutch.

Then install the clutch push plate and cover, repeating the grease-gasket-grease from earlier.

Install the top end.

And here’s the issue i found. Most scooter carb setups do not work with the Ape because of the T-shaped engine mount. The reed block will not go together here. the solution? Polini makes a reinforced performance engine mount. here they are side-by side.

the mounting points are the same, but it is Y-shaped to clear whatever carb you want to run.

See? the carb manifold now fits. Here’s another shot of it.

And now to resolve one of those weird little things. there’s a hose that goes from the stock carb to the intake tract, and i didn’t bother to look too hard at it to figure out what it did. needless to say, the 25mm carb doesn’t have this bit, and I’m just going to close it off for my build.

I used a bit of stainless rod in some vynil tubing, and then put that over the nipple on the case.

now, install the stator and flywheel. And here we have another issue. the electric start gear interferes with the malossi 136. score the cylinder fin with a cutoff wheel and then grab it with pliers and break it off. use a grinder to clean it up and to clearance it so it doesn’t rub.

install the flywheel cover and cooling shroud and it’s pretty much ready to go in the bike.

next installment we put it in place and possibly wrestle an exaust snaking.

Ape 50 top end and gearing comparison

Unfortunately, the images to this post were lost in a server crash.  i’m preserving the text in case it is of any help to anyone.

Most of the parts for our shop truck have arrived; I wanted to take this chance to illistrate the difference between the stock parts and what i’m going to.

First up: the cylinder and piston

As you can see, it’s bigger. much bigger. It’s also going to have a longer stroke. this takes displacement from 50cc to 136cc. In addition, it has a much improved set of transfer ports inside the barrel walls, improving the changeover from burnt gasses to fresh fuel and air. It is also set up for a cylinder inducted reed valve and larger carb, giving it much more power overall and a much wider spread of power.

Next, to take advantage of the power-

This is the old primary gear next to the new one. the old one is the one with the wee tiny separate gear and is a 14/69 tooth count, ratio 4.93.  the new set is a 29/68 tooth count, so 2.34 is the ratio.  If you’re coming from the Vespa smallframe world and are familiar with their gearboxes, you might think i’d lost my mind. when put in a smallframe scooter, this ratio gives you about 85mph @ just over 8,000 rpm. Fear not; there are other factors at play.  first off, the gearbox on this ape is different from the typical 4-speed scooter gearbox.  Actually, it’s more of a scooter 3-speed with a higher fourth gear added. (Remember the zirri short 4th gear kits? they use a modified ape 50 3rd gear as a 4th gear). it’s a 26/42 1.62 ratio 4th gear instead of a 22/46 2.09 like the scooter uses. But wait- that means if this combination was in the scooter, it’d get 105mph @ 8000 rpm. How does this work with the Ape 50? It’s the differential. there is a 34/52 1.53 ratio reduction in the differential. This drops the gearing considerably, to get us a ratio that gives 68mph @ 8000 rpm. in addition, this specific kit gives us some leeway to adjust the gearing easily later. there are 26,27,28, and 30 gears available separately that can be swapped without removing the engine from the frame. This gives us a range of steps from 62mph @ 8000 rpm to 71mph @ 8000 rpm. This should work well if we need to later fine tune the gearing once this is in service.

Stay tuned; i’ve already modified the cases for the new top end and expect to post that article next week. Feel free to ask any questions you might have in the comments; i’ve enabled using facebook to authenticate users so you shouldn’t even need to sign up for an account or anything,

UPDATE: This kit turned out to be a hair too high, even with the 26/42 combo. it might be right if used with the DRT short 3rd/4th christmass tree.

Rebuilding the rear brakes on the Ape 50 – Part 2

Unfortunately, the images to this post were lost in a server crash.  i’m preserving the text in case it is of any help to anyone.

So, when we last left off we had removed the half-shafts from the Ape, and had removed the brake backplate and drum on one side.

Yesterday the parts arrived, so last night I finished this up. so. here’s how you take apart and rebuild the backplate and brakes. First, remove the brake slave cylinder.

This removes via two screws that hold it to the backplate.

For comparison, here’s my old cylinder and the new one next to it. for some reason the bleeders were pretty much completely corroded away and would have been completely unserviceable. the other wheel’s cylinder  was actually WORSE than this side.

The next item you have to address is these little springs that pull the brake shoes towards the backplate.

Just grab them with a pair of needlenose pliers and unhook them. Next, push the brake shoes off the pivot rest. they should slide right off. Like this-

One important note – notice how the spring’s hooks are offset to one side on that bottom spring? remember that. you need to have that orientation correct when you re-assemble them or the spring will want to pull the shoes off their rests and out of the alignment they need to have.

Once the shoes are off the backplate, unhook the bottom spring. you can push the shoes together to take the tension off of the spring.

Then pull the shoes apart at the bottom to remove the bar the cable brake uses. remember which side goes towards the backplate, as it is different.

Reassembly is pretty much the reverse of these steps, with a few exceptions. of note is the replacement RMS brake shoes. in stock form, the hole for the smaller spring was not big enough for the spring to fit in so I had to enlarge it with a drill. I recommend making sure all the springs fit in all the holes before attempting reasembly.

For reassembly, install the bigger spring and the e-brake bar. make sure you get the bar in properly as it is different front to back and left to right.

once that is on, it should look like this:

next, i installed the master cylinder into the space in between the shoes. Then i installed the smaller spring opposite the brake cylinder.be sure you have it on right. Here’s the correct and incorrect way, shown against the backplate for reference.

Before putting the shoes onto the backplate, put the brake cylinder in place on between the shoes. then put the shoes into place.

One huge thing to point out- see those two bolts to hold the backplate to the bearing holder? put those in now, because these two ones can’t be installed into their holes if the brake shoes are on the backplate.

You’ll need to get the brake shoes onto the piece opposite the brake cylinder. it’s not easy, but with a little careful levering they pop into place.

Once you get the shoes seated in place, bolt in the brake cylinder.

Re-install these two springs:

And the brakes are back together.

Rebuilding the rear brakes on the Ape 50 – Part 1

Unfortunately, the images to this post were lost in a server crash.  i’m preserving the text in case it is of any help to anyone.

Last week, we started rebuilding our Ape 50’s engine. While we wait for parts to arrive, we’re going to rebuild the rear brakes.

So, when we got this thing it wouldn’t roll. after we removed the engine it became clear this wasn’t in the differential, it was in the rear hub/brake drums.

And there’s the rub; the brake shoes were stuck to the drum. a pain-in-the-ass situation to say the least, not even taking into account the fact that i hadn’t ever had one of these apart.

In the spirit of  “in for a penny, in for a pound”, I decided that as long as i had to take the rear wheels apart, i’d get new brake shoes, cables, and hydraulic slave cylinders.  The slave cylinders ended up costing $15 a piece, so it really was a n0-brainer.

But how to get it apart?

I ended up removing the wheel bearing housing from the A-arm.

 The brake line, two bolts, and the nut that holds the shock on the bottom is all that held it on.

I managed to get the four bolts out of the bearing holder that held it to the brake backplate; once I removed these and the nut on the shaft, the half-shaft and wheel bearing housing  just lifted off the assembly.

This is definitely not the preferred disassembly order; but, it did make the shoes and the hub easier to separate by making the assembly less cumbersome.

From here, I had to tap, beat, and pry ever so carefully. If one is VERY careful not to overtighten them by mistake, the rest stops for the brake shoes can be adjusted to their relaxed position. these are the two hex head bolts at approximately 12:00 and 6:00 on the picture above.  I managed to walk it free and get them separated.

I’ve also decided the wheel bearing holders will get all new seals since i have them apart.

Watch the website for part two, witch will detail the re-assembly of the rear hubs and bearing holders, to be written when the parts arrive.

Inside the Ape 50 engine.

Unfortunately, the images to this post were lost in a server crash.  i’m preserving the text in case it is of any help to anyone.

Hello World!

Just last week Hodgespeed acquired something not often seen in the United States. a 1998 Piaggio Ape 50.

This is the ‘smallframe’ Ape, and is even smaller than the main line of full size Apes. In some european countries, these qualify as a moped, and get much more lenient registration and driver licensing requirements.

It’s powered by a variation of the Vespa smallframe 50 engine.

See it back in there?

Because it is fundamentally a Vespa smallframe scooter engine, there’s tons of tuning parts available to fix the 23mph stock top speed. Yep. 23 mph top speed. takes four gears to get there, too. Piaggio did make a 125cc version of this vehicle starting in 1969, but stopped production in 1974 after only 1700 or so were made. The lenient laws regarding 50’s made the 50 the king in sales, but not in performance. The ape 50 has been in continuous production since 1969, till the current day.

When this project is done, this will become our shop truck; we hope to have it be the chase vehicle on rides and rallies in the Seattle area before Seattle Scooter Insanity this July. It should be able to haul a single scooter when we’re done with it.

Because this engine is not too common, yet familiar, I think there might be some interest in seeing what it’s like on the inside of these. So, I’ve documented the tear down for the rebuild on it.

Unfortunately, i didn’t document actually removing the engine from the frame. That was a real bear.  Suffice to say, if you have to remove an engine from an Ape 50, the thing is light enough to use milk crates as jack stands. You have to unbolt one of the A-arms from the frame and the shock and remove a circlip from underneath the boots on the differential to remove the half shafts.

Anyway, here it is, in all it’s glory. the Ape 50 engine.

This is the engine, propped up by a brass hammer on my work bench. if you’ve ever had or worked on a smallframe i’d imagine these angles look a bit familiar to you.

Here’s a shot looking from the side of the engine the rear wheel and rear shock would mount if it were a scooter. because this is an ape engine, this is actually the front; the cylinder faces to the rear on the Ape 50. On the Ape 50, the differential bolts to the engine case where the brake backplate bolts to the scooter version of the engine. that’s what that lump hanging off the back of the engine is. you can also see where the gear cables attach to the top of the engine, and where the reverse-selecting cable attaches to the differential.

Opposite the flywheel. for context, you can just see the starter poking out from behind the exhaust. just to the right of the exhaust is the differential.

Here’s the bottom.Note the stamped steel bolt-on cradle where you’d expect the swingarm to be. Also, the clutch cable on these is routed a bit differently than on the scooter. The cable stop is cast into the differential case just out of frame at 12:00 in this picture. Notice also- if this were a scooter engine this would be the bottom of the engine where the cables attached. However, on the Ape the offset linkage inside the case is omitted and the cables are attached to the top of the engine.

And here you can really see that stamped steel ‘swingarm’. Polini actually makes an aftermarket version of that  piece. I’m tempted to order one. You can also see the exaust. Becasue the engine faces the opposite direction in the ape as in the scooter, mounting a scooter pipe wold result in a forward facing tailpipe. In addition, one would need to come up with a bracket to mount the pipe to since there is no swingarn. neither is insurmountable; i expect to mount a hammerzombie pipe on this before i’m done.

And here you can see the differential with it’s cover removed. The big bit on the right hand side sticking up is the Planetary Gear System there are two freewheling planet gears inside there, and the sun gears are on the end of the axle half shafts.

The other two gears are doing something clever- first, the lower left hand gear. this is a single piece with thre gears on it. the lowest you cannot see in this picture, but it is always engaged with the ring gear on the planetary set. Above that, is a larger gear. and on the end, A helical Gear to drive the speedometer cable.

the upper left gear is freesliding on the splined shaft normally, as in this picture, it drives the ring gear from the shaft, propelling the Ape forward. now look at this picture-

In this shot, my grubby fingers are simulating what happens when you pul lthe lever in the cab to shift into reverse; the gear is lifted away from the ring gear, and drives that gear with the speedometer drive on the end. thus adding a reduction and driving the vehicle in reverse.

This shot shows that gear inside it’s shifting fork in the other side of the differential case. This gear is dormally held in the forward position by a spring outside the case.

And here we find what i find the cleverest bit in the engine. there is a sleeve cast into the differential case that holds a needle bearing and seal that is exactly the same outside diameter as the normal smallframe rear hub bearing. this keeps the differential oil and gearbox oil separate.

And here’s what that mates up to on the other side. the end of the axle is this club-like splined shaft that that sliding gear in the differential slides on. notice the five large studs here instead of the two the smallframe scotoer engine normally has.

And surprise- a P-style stator. even more interesting, it is actually wired and color coded the same as an american market 70’s P200 stator. the crankshaft is one of those 20/20 mm types. not the ETS / P-style 24mm i had been expecting. This is one of a few things where developments on the scooter side of things did not make it back over to the Ape side of the family.

And here we get into the clutch cover area. notice that this clutch has six springs in it, not one large one. this late PK style clutch is kind of like the ‘cosa’ clutch of the smallframe.

Here you can see how low this thing is geared. look how tiny that crank gear is! More on gearing later, however.

and the clutch cover. it’s gear driven, not lever driven. and the button isn’t brass, either. on this engine, believe it or not the pressure plate has a ball bearing in it.  Curriously, the oil passages that feed oil into the center of the clutch and the backplate do not exist in this case or the clutch cover. perhaps Piaggio thought the ball berating didn’t need as much lubrication as the brass bit they used on earlier engines did.

Here’s a side by side of a early 2000’s LML smallframe case for comparison. notice how much rounder the Ape case on the left is at the bottom. since the shifter cables attach to the top of the engine rahter than the bottom like on a smallframe. also notice that the holes the stamped steel swingarm thingamajig are in exactly the same place as the cast swingarm is attached to.

look at all the meat on that 50 jug! anyone got a 75th oversize piston? In all seriousness, you can see from this the potential to increase the displacement. in addition, the 50 has a shorter stroke than the 90/100/125 small frames. so longer stroke plus cylinder kit would give a massive improvement on this engine.

Wee tiny piston!

Here is another interesting thing; when i saw the manifold had three studs, I immediately thought it was like a 3-stud PK manifold  (on the left) . Not so! the spacing is different. upon closer inspection i realized Piaggio had just added a third stud to the earlier 2-stud smallframe pattern. look at this picture:

See? a stock 90 manifold fits, leaving one stud out in the cold, unused.

and here’s the christmas tree. notice, there are no notches for a kickstart ratchet. early ape’s had a hand-start that used the scooter kickstart mechanism. Sadly, that feature has been dropped from this model.

And here you can see the strange axle that also serves as the input shaft for the differential. And while we’re on the gears; looking at this gearbox, something didn’t look normal to me so i started counting ratios. this has a very wide ratio gearbox, with very high 4th gear and very low 1st gear. at first, this confused the heck out of me, until i realized what they had done. On smallframe scooters, the three speed top and bottom gears are roughly equivalent to the top and bottom gears of the 4- speed with 2nd  on the 3-speed splitting the 2-3 gap on the 4. However, on this gearbox, 1-3 are roughly equivalent to 1-3 on the 3-speed scooter gearbox, but with one higher gear added.

Here you get a shot of the inside of the case. Very small frame-like.


And here’s a side-by side of the clutch side case. there are definitely differences; the Ape lacks the reinforcing webs the scooter motor has  the swing arm, as the Ape engine is not loadbearing.  The ape also has a few reinforcing ribs added, most notably on the edge next to the bearing the clutch basket primary rides on.

Well, that’s it. my tour of the inside of an Ape 50 engine. Keep watching here, as once business picks up enough for us to spend the money we’ll be building a real screamer of an engine out of this.