ZA50 Big Port Metra Kit Redux

Before I left for Japan, I was in the middle of building my black Magnum. I built a ZA50 big port MetraKit for it. But in the rush of moving, I just slapped this motor together in order to mount it on the bike for storage. I never ran it. It sat at my wife's grandmother's house for the past 5 years. Now I can correct some of the mistakes I made. This is the Redux of my ZA50 Big Port MetraKit for my Magnum...

Giant!! But it wants more!!

Case Match Porting Redux:

I had the sides weld built up by the "Yard's" finest before I left for Japan. I also match ported it to the big port 80cc MetraKit cylinder. After careful inspection, I think I could do a better job.

I marked the case and went to town. I corrected some mistakes and defects I didn't catch on the first pass. While I was porting, I accidentally "puka"-ed (holed) through my the case. I forgot to weld build up the magneto side pockets that run opposite of one of the transfer chamber. No biggie. Nothing that JB weld can't fix.

In too deep

Tape off and lay down the form work to pour the JB weld in the voids. If you get JB weld on places you don't want, no problem. Just go back and grind it out when it dries. I also filled the void opposite the front sprocket. I plan to put a 21 tooth front gear on this set up. I did a How To here.

Ready for pour

Oozing out goodness

Dried

After the JB weld dried, I continued the match porting process. Check out my post on my E50 Dio Build for some basic tips on how to match port. I used similar procedures here. Here are the finish product:

ZA50 BIG PORT!!

Lube hole

JB weld fixes

MetraKit Cylinder Clean Up Redux:

Intake

Cleaned up the imperfections of this kit. I also roughened up the intake and transfer ports a bit to match the transfer ports on the case. The good thing about this kit is the ports are huge so your able to get a Dremel in there. Also, polished up the exhaust port. Note: Always finish up with mini files and hand sanding. Don't rely solely on the Dremel.

Exhaust

Exhaust inside view

Chambers

Exhaust

Right chamber

Left chamber

Transmission Redux:

Roller bearing time!

 I initially had my stock crank's conrod pressed out and replaced with the MetraKit roller bearing from TreatsHq. One of my friends did it for me but didn't true or balance it. So, I sent it to Chris at Moped Crankworks to correct it. He did it no problem. He even sent me a video on what he did. The best thing is he did it for free!! What service!! Turn around time was a bit longer than usual since he was out of town. But I would definitely recommend his services.

I think change out the pucks on this tranny before. It was still pretty stiff. Not sure which pucks I used. For the clutches, I decided to try out the Treats ZA50 clutches I had lying around. Before they where dubbed "Treats" clutches, I bought a set from the original Puch guru Rigid76. If you check out his (site), he had parts way before anyone in the states had them. Fortunately for me, he is a friend of mine and lives down the street. Not sure if he is still in the Puch game but I know he still have tons of parts. Rare ones too!! Anyway, I ran these clutches briefly before on a polini set up and didn't like them. They didn't stall enough. The springs it came with were too soft. I searched Moped Army for information on alternative springs. Most people recommended these Malossi springs. But I never found any feed back on their performance. I probably test them out in the future but I wasn't willing to fork over $25.00 at this time. I even reached out to Chris at PuchShop.de if he had any recommendations. He had none. I had a bunch of Honda Dio clutch springs lying around. I decided to try and shorten them and test it out. I only changed out the second gear springs. For the first gear, I left the stiffest blue springs on. Here are the results:





The Build Redux:

Stock gasket

Primary gear

Allen head bolts

Torqued to specs

"Treats clutch"

More allen head bolts

Bottom end done

Roller bearing in

Monster piston on

Cylinder studs and fresh cut gasket on

Cylinder mated

Head mated

Custom intake on

Powerdynamo base plate

Powerdynamo ignition

Almost there!!

Mounted Redux:

Magneto mounted

Mounted

Carb mounted

Mounted!

Mounted!!

Pipe mounted

Mounted!!!

Almost done...

...Just the seat left...

Test runs coming soon...

ZA50 Big Port MetraKit Redux

Top:

80cc MetraKit cylinder (big port version)

Custom manifold

PHBG 21mm Dellorto carburetor

Homoet 6p exhaust

Bottom:

ZA50 case with weld build up

Treats ZA50 clutch set

Honda Dio clutch springs (shortened)

Stock crank with MetraKit roller bearing conrod

Powerdynamo Ignition

Gearing:

21 tooth front
36 tooth back

I'll update with section with a video and overall tuning and review later.

Happy Tuning!!