103 Polini cases fitment issue

I am building up a 103 and am having an issue fitting the polini case engine mounts to the frame. The engine mounts are too wide to fit in the space provided and I'm not sure which direction I should go in trying to sort this out.

I can either shave off a bit of the variator side plastic bushing or try and widen the mount space. The swingarm mounts have a bit of extra room with the swingarm mounted so I could "squeeze" them a bit closer together. The amount of space needed is just shy of 2mm.

Has anyone run into this before?

The frame is a late model 103. Its an interesting frame because it uses the long swingarm but doesnt have a removable tool box/ seat mount.

Here are some pics of the cases and the swingarm

Here is a pic of the engine.

I'm using the Giraudo 50cc kit fully casematched to the polini cases.

A pic during case matching. The transfers were tiny compared to the case transfers.

Re: 103 Polini cases fitment issue

id go whatever way to line up the variator with the pulley.

Re: 103 Polini cases fitment issue

Yeah. That's what I want but I have no way of knowing how anything will line up until I get those cases in the frame. I have the pulley and pedal shaft mounted already. I've got plenty of pedal shaft to space the pulley away from the subframe but anything less than 2.5mm from the subframe and the outside of the pulley gets really close to the bends in the subframe for the rear wheels.

I'm thinking the easiest way would be to cut some of the bushing. It's only 2mm and I can always press a replacement in If I needed to.

It's been a lot of fun so far having to come up with creative ways to make things work together. Gotta love how nothing fits without work, sometimes a little but most times a lot

Here's a pic of the subframe where the pedal shaft enters. The bushings on both sides went in smooth and snug but the pedal shaft kept binding as soon as I pushed it through all the way. I couldn't figure out the problem. I tried new bushings, oilite flanged bushings, I even got me a nos pedal shaft thinking the one I had was slightly bent. It kept binding. Finally I looked and saw a big huge seam along the pedal shaft tube. I ground it down flush with the tube and problem solved.

Re: 103 Polini cases fitment issue

Had some time today and I got the motor mounted. I went ahead and took a sander the the left bushing and slowly ground it down, checking frequently till I was able to squeeze it in there. The variator lines up almost perfectly with the rear pulley.

I also got the pedal shaft all sorted. The swingarm I'm using must be wider than stock because I couldn't get the pedal crank to attach to two separate 103 pedal shafts. I tried the treats one and a nos one from Dos and they both are a few mm too short on the pulley side. I spaced the pulley as close as possible to the subframe and it just wont fit. I put a magnum shaft on there for now and cut a spacer to take up the lateral slack. The magnum shaft is smaller in diameter than the 103 ones though. I think it was around .1mm smaller. If that causes any problems I can always cut down the pedal crank some to free up some room on the og 103 shaft or get rid of pedals and put pegs on.

I also had a chance to mock up the Doppler pipe. The Simonini fit perfectly with no clearance problems but the Doppler will need work. I think I will make a larger version of the included clamp bracket or weld on something to attach part of what it came with.

Tuesday I will try to get my chains and cables cut and start getting the electrical stuff in order.

Re: 103 Polini cases fitment issue

It took a little longer than expected to get some more done to the 103. Lots of rain in the desert this week .

I did manage to get everything wired up. It is pretty messy right now but everything is wired up and grounded to bare metal on the frame. The engine has a ground running from a case bolt to the frame. I will worry about lights after I get the engine running.

I have a $2 ebay kill switch temporarily mounted to the frame and wired in. I got the drive chain cut and installed. I got it spaced correctly on the left but need to get a spacer for the right side. I also have working rear brakes. I had to shorten a universal cable housing and put a new cable end on. The 19mm phbg clears but I wish I had the version with the adjustment on the right side. I had to cut the idle speed screw down some to clear when the engine moves. Oh well. At least i can pull it off and out with no problems.

I tested for spark, turning the flywheel by hand with the plug against the heads fins and get a big blue one every turn.

I like being able to work at my own leisure, working on whatever I feel like at the time. I'm in no rush and will eventually get this thing done.

I have a bracket on the way that should allow me to install the polini spring directly to the round brace next to the rear pulley on the swingarm. Theres no provision for mounting a polini spring so I'm trying to come up with an easy solution. I still need to do a leak down test, time it, and change the main jet in the carb to something safe. I hope to at least start it up next weekend before getting it roadworthy. I cant wait to hear the engine

Re: 103 Polini cases fitment issue

Make sure when you line up the variator and the rear pulley that they are lined up when it's fully variated. If not it will sling the belt off under high RPMs.

Re: 103 Polini cases fitment issue

Thanksfor the tip. I Think it should be okay. The engine is at rest with the belt at the bottom of the variator and it is slightly misaligned with the rear pulley. When it variates it should climb and move closer to the engine and line up with the rear pulley. The pedal shaft has a spring washer on it too so the pulley can move a bit too.

I have been slowly figuring everything out and am super excited to fire this up.

I am gonna do a leak down test and start it for the first time this weekend.

I found some really cool clamps that should allow me to get the engine spring mounted in a perfect spot .

Re: 103 Polini cases fitment issue

Ilia Edouardovich /

What type of nut are you using on the cdi side of the crank? Is that a large taper Peugeot crank?

Re: 103 Polini cases fitment issue

Francois Labat /

Damn, nice build.

Re: 103 Polini cases fitment issue

Ilia, I originally bought a Puch flywheel nut and tried that. It fit the crank and I was able to hand tighten it down but after lapping the flywheel and crank and trying to tighten it with a wrench I realized it was too short. The end was just barely sticking out of the flywheel before it was fully tightened. I went ahead and forked over $9 for the polini water pump nut


It seems like I have enough threads engaged on the crank . next time I put it back on I will count how many turns it threads on.

My spring bracket came and I was able to begin fitting it. It is a p shaped tube clamp meant for mounting led lights to roll bars and such. It's gonna work perfectly. I may have to make a new rod for the spring that's longer. Maybe try threading an 8mm rod or using set screws to adjust it. I will post pictures when it is mounted up.

In a month or two I will be buying me a gas mig welder and wont have to dick around trying to find clamps and other bolt on solutions for solving little problems.

Unrelated but still moped related Awhile ago my girlfriend and I were drinking and watching netflix and we saw Highway To Heaven on there and started watching. Both of us used to watch it with our parents back when we were kids. During one episode I saw the coolest thing

Some spoiled kid was revving the heck out of a hobbit on the stand in a hotel room! I wish that was me when I was ten

Re: 103 Polini cases fitment issue

Forgot to add that I'm using an Artek k1 large taper crank. It is really nice.

Centered in the cases it leaves maybe 1mm on each side of the lobes and spins so smooth with skf bearings

Re: 103 Polini cases fitment issue

I like this build

Re: 103 Polini cases fitment issue

Thanks Cheetah. That means a lot coming from you. Your write-ups and posts about 103's have been invaluable. This is my first time doing anything other than riding peds so I'm learning as I go. I am trying to do things properly(whatever that means)

When I get off work today I gotta pick up an npt fitting for my leak down tester and see if the motor is sealed up good enough.

I also need to get my cylinder spacing and squish set again. The piston covers the exhaust and transfers at bdc. I raised the cylinder enough to clear the ports but the squish was huge. I couldnt even get a measurement without twisting a couple bof solder pieces together. I compromised and raised it almost enough to clear and get around 1mm squish. Should run fine but I really should just do it right and get those ports cleared completely and deck the cylinder down to .8 or .9mm squish. This is on the Giraudo cylinder. The Malossi 70 is perfect outta the box but I dont want to mess with that until I have some more experience

I wish I had more free time.

Re: 103 Polini cases fitment issue

Today was fairly productive. I was able to get my engine spring mounted up.

he clamp wasn't an exact fit to the pedal shaft tube but it came with some toothed rubber shims to fit it to different sized sized bars and after tightening it down i couldn't get it to budge. It came with 2 clamps so if I need to I can use both and connect them at the bottom with some flat stock. I like that i can rotate the clamp forward if I have to to make the belt tighter. As it sits I can turn the rear wheel and get the variator to start turning instantly and engage the clutch bell and flywheel almost immediately after. I also have a couple extra springs I found at ace to fit inside the polini spring if needed to add more tension.

I also tried out my leak down tester. After getting it all together the intake plug with hose would not seal the intake properly. I used an expanding plug for the exhaust and a rubber stopper with hose barb jb welded into the center for the intake. No matter how far i got it pushed in it still wouldnt seal. I was able to pump and spray soapy water and only got bubbles from that damn spot. I have an expanding plug for the intake but I will need to drill through the center bolt and epoxy a hose barb into it and go from there. I forgot to take pictures of the tester. Here is the expanding plug for the exhaust

These things are so cool because you can test your exhaust flange and intake for leaks. With a block off plate you are only testing the plate and could introduce leaks when you put the flanges back on.

I also modded a valve holder spark plug adapter to fit a cheap digital dial indicator to use for timing my engine

The hole going through the adapter was too small so I drilled it out to accept the indicators rod. It seems to work. The rod rises as the piston approaches tdc and falls when the piston changes direction

I wanted to get my cylinder spacing and squish set today too but I couldnt find any large sheets of sandpaper fine enough to deck down the cylinder so I just ramped the piston. I only went down just enough to uncover all the ports completely at bdc. The ramps are pretty small and leave plenty of space on the piston above the ring. I rechecked the squish after torquing it all down fully and was a bit larger than I thought at 1.18mm so I am going to make a head gasket from a disposable cookie sheet or something similar. The metal one I have is .5mm so I can use a soda can and get to around .7 or so. Sorry for the bad picture

At least the to do list is getting shorter.

Also, I was looking for an old style tool box cover so I can try to hide the electrics and start trying to make it look pretty and someone graciously offered me one for the cost of shipping. That level of kindness is just amazing to still see in the world.

Its alive!

I had some free time today and was able to get some stuff done.

I never cared for the look of the plastic tool box covers that go with this frame and wanted to see if the old style would fit.

I got this green cover from cheetahchrome and it fits without having to remove the seat post mount from the frame.

All I had to cut off were the tabs that the plastic cover fit to. I will have to cut the shock mount holes on the tool box or enlarge them because my frame has tubes welded to the frame for the shock bolt. I think the green and black go together nicely.

I got the launch lever linkage done

I had to make a couple different ones to get it right. I don't have a welder (yet) so I used some threaded rod. I heated it with mapp and bent it in a couple spots till I was able to secure it to a bracket I made from aluminum plate. The bracket also keeps the polini spring mount from rotating.

The threaded rod is grade 10.9 so it should be strong enough for now.

I did a leak down test with my new plug and got it up to 7 psi and after ten minutes had lost less than 1 psi so I figured it was good to go. I had problems before withthe tester so I jb welded up all the fittings before hand just to be sure and checked the tester first and then the engine.

I made a new timing tool from a cut up spark plug filled with jb weld. Rather than epoxy the dial indicator into it I drilled out the jb to just under the size of the immovable part of the stem and slowly dremeled it out until I could twist the gauge in to where it would not move

I also drilled a small hole in the side so the compression from the engine could escape and not affect the reading

I got the timing set to 1.2mm btdc.

I already changed out the main jet to a 96 and set the screws out to spec after ensuring the float was set correctly. I mixed up some gas and filled the tank.It was getting late and i was determined to get this thing running today.

I have serious spacing issues with the pedal sprockets and I havent figured out a workaround on that so I tried spinning the rear wheel up on the stand. It wanted to start but I wasnt able to get that flywheel moving fast enough so on to the drill. The flywheel nut I'm using has the water pump pulley part on the end and no way to attach a socket so I cut some flats on it and fit a socket to it. Sure enough, it fired right up after a few seconds of spinning.

I let it idle for a few minutes then I slowly gave it gas and got it to start revving up and engage the clutch and rear wheel. I watched all the spinning bits to make sure everything looked okay.Seemed to idle fine. I was so happy and excited to hear it running. I wanted to get the camera and shoot a video of it running but saw it was after 8 and realized I still have to get ready for work in the morning and feed the little ones so I shut it down.

I took the few pics later on.

I will have to wait till the weekend to start messing with it some more

Hopefully ride it soon

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