Puch AJH/Athena 45mm reed kit and its clones

There is a lot of disparate info floating around out there about the puch Athena 45 reed cylinder, small reed, AJH, and the AJH clones ‘DMP/single exhaust’ vs. ‘1977/Dos house brand dual exhaust’. I’m trying to offer a countersunk head setup to make these work, but the information on these things is confusing and incomplete. I’d like to do a blog/wiki writeup on all these but I don’t have the kits handy and I only have some of the information, if anyone can help fact check me or add anything they know/remember it would be great to get all this knowledge in one place. I’d just start with a wiki entry but this seems to get more attention on the forum, so lets discuss and I’ll put it all together into an article.

The ‘real’ AJH/ athenas have been around a long time, mopedwarehouse and heeters and the shops supplying the moped scene back before 1977 used to sell them with the Amal carb in a kit. Quality was top notch, really nice fit and finish. Probably selling dead stock from the 90’s. Sometime around 2005 they went out of production or became unavailable and the only kit you could get from Athena was the ‘small reed’ 70cc kit. The old ones had this weird AJH marking cast into the fins:

ajhcasting.JPG

Then at some point, maybe around 2008 or so, they came back on the market but they were noticeably lower quality. Packaging was different. This might have been because AJH was making the old ones and Athena bought them out? I don’t know. I would hazard a guess that they went from European manufacture to Taiwan.

athena-ajh.JPG

The small reed athena’s have never been too popular AFAIK, I don’t know much about them. Perhaps this was a kit that Athena was making historically and when AJH went out of business they bought that tooling for the ‘big reed’ kit? For the time that the AJH was off the market, the small reeds were the only ‘athena reed kit’ being sold. These are using the same reed block as the 80cc athena sachs. The big reed athena uses MB5 reeds, but there are only 2 petals in the reed block so flow area may or may not actually be bigger than the 'athena' style reed.

athenasmallreed.JPG

Then we skip a few years to 2015 ish when the clones showed up on the market. I don’t exactly remember how or when they showed up but around the same time there was a DMP branded cylinder coming in a kit with reeds, intake, piston, cylinder and no gaskets, and a ‘1977 house brand’ split exhaust version of the kit. A good thread came out around this time <LINK> and a few sources international and domestic were providing similar versions of the same kit.

Both DMP and ‘House Brand’ (lets call them ‘Single exhaust clone’ and ‘split exhaust clone’ for clarity) are characterized by these really poorly formed ports, spacing issues, a ridiculously too big exhaust, poor finish, etc.

They appear to have very similar reeds, intake, piston to the genuine Athena. The Single port clone/DMP kit that I got has no bolts, studs, crappy circlips, no gaskets.

The porting on the ‘single port clone’ I have is 46.5 mm from bottom of exhaust to top of cylinder (aka, stroke) the transfers are a bit higher. Transfers are pretty ok size and shape but they have some gnarly casting boogers… the exhaust is a really crummy shape, way too tall with too much blow down, but with aux ex. Ports it could be made to work and a lot of clean up on the intake.

Anyhow, that’s where I’m at, I’m probably not going to run this cylinder, just picked it up to prototype a sunk head to make these workable. I’m going to return it and grab a split exhaust kit which I am going to build on to an A55 bottom end. I’ve cut a handful of heads for these for people over the years with really good results, but its been really tough to get something that works across the board. I’m looking forward to be able to put out a head that can take care of the port spacing issue and make this a really gnarly little budget blaster. Getting it for <$150 with the intake and reeds and everything is a pretty rippin deal if you can make it work.

Re: Puch AJH/Athena 45mm reed kit and its clones

MEANT TO SAY~>

post up your experiences or if you've been around and remember some of the history on these, have you ran them, where did you buy them, what was the timing/shimming needed and how did they run?

Re: Puch AJH/Athena 45mm reed kit and its clones

Here's the most comprehensive thread on them so far. Feel free to shoot me a message with any questions, I'll try to remember...

https://www.mopedarmy.com/forums/read.php?7,3076297,page=1

Re: Puch AJH/Athena 45mm reed kit and its clones

You don't need a countersunk head, all you need to do is the switch out the piston they give you with a treats kit piston. Its 3mm shorter!

Re: Puch AJH/Athena 45mm reed kit and its clones

> Rocco Taco Wrote:

> -------------------------------------------------------

> You don't need a countersunk head, all you need to do is the switch out

> the piston they give you with a treats kit piston. Its 3mm shorter!

that wouldn't fix it. you have to space it out to clear the exhaust. If you get a piston thats shorter pin to crown you don't need to space it from the cases but you still have equivalent distance from crown to squish at tdc. that's why you need the countersunk head. (edited)

Re: Puch AJH/Athena 45mm reed kit and its clones

> Dave & Bummerzz Wrote:

> -------------------------------------------------------

> > Rocco Taco Wrote:

>

> > -------------------------------------------------------

>

> > You don't need a countersunk head, all you need to do is the switch

> out

>

> > the piston they give you with a treats kit piston. Its 3mm shorter!

>

> that wouldn't fix it. you have to space it out to clear the exhaust. If

> you get a piston thats shorter pin to crown you don't need to space it

> from the cases but you still have equivalent distance from crown to

> squish at tdc. that's why you need the countersunk head.

Yep.....

Re: Puch AJH/Athena 45mm reed kit and its clones

Jake, awesome, i remembered that thread but couldn't find it! Thanks

I got the DMP measured last night, i forgot my SD card at home so i cant upload photos.

the total stroke to the bottom of the exhaust port is ~46.5, but the casting is rough and uneven. The transfers are more accurate at 46 mm from deck. On a puch the piston is nearly dead even to the top of the cylinder and getting the transfers squared up would require 3mm total shim with a head counter sunk ~1.8 mm with a 1.2 mm squish.

On the tomos (measured off a ca. 2010 A55), the deck is about .8 mm higher than the puch. I've measured several of these and seen them be between .8 and 1.2 mm above puch deck height. This one, at .8 is actually the least-raised, that i've measured.

This one looks like it would take about 2.6 total base shim to line up to the bottom of the exhaust, or 2.2 to line up with the transfers. Stroke being the same it would use the same countersink.

Rocco i'm not sure what you're trying to say... the stroke on the kit is wrong, you cant fix that with a different height piston. The piston that came with my kit came almost dead nuts to the top of the cylinder, but all else being equal the ports are 'lower' relative to the zero deck position.

At some point i want to try making my own 45 mm crankshaft. Its a far off project but the timing on these would actually work really well if you did that.

Re: Puch AJH/Athena 45mm reed kit and its clones

Most of the kits on the market for puch will have the edge of the piston crown even with the deck of the cylinder at TDC with a thin base gasket. I usually set squish with the cut of the head along with the thickness of head gasket.

45mm stroke crank would be sweet with this kit but in the meantime try it out with either:

A) a shorter piston and countersunk head

B) a base spacer and countersunk head

You will be surprised with these kits out of the box with a slight cleanup. I really miss my split port cylinder sometimes.

Re: Puch AJH/Athena 45mm reed kit and its clones

Fuck I hate this supid kit

Re: Puch AJH/Athena 45mm reed kit and its clones

Relevant to my interests

Re: Puch AJH/Athena 45mm reed kit and its clones

I really though a shorter piston would fix my issue, now it looks like I going to the machine shop to get a head countersunk. The other problem is we all are getting different readings for measurements.

Re: Puch AJH/Athena 45mm reed kit and its clones

> Rocco Taco Wrote:

> -------------------------------------------------------

> I really though a shorter piston would fix my issue, now it looks like

> I going to the machine shop to get a head countersunk. The other problem

> is we all are getting different readings for measurements.

you gotta use your head, guy.

Re: Puch AJH/Athena 45mm reed kit and its clones

Yeah i'm trying to make a spacer/head combo to make these kits workable. wondering if they are consistently off, or if they are inconsistently off.

Looks like good news so far, everyone seems to be reporting roughly the same issue.

Re: Puch AJH/Athena 45mm reed kit and its clones

> Dave & Bummerzz Wrote:

> -------------------------------------------------------

> > Rocco Taco Wrote:

>

> > -------------------------------------------------------

>

> > I really though a shorter piston would fix my issue, now it looks

> like

>

> > I going to the machine shop to get a head countersunk. The other

> problem

>

> > is we all are getting different readings for measurements.

>

> you gotta use your head, guy.

I do lol I just miss those small fine details, at least you ditch the base spacer.

Treats reed piston + counter sunk head

Or

Big base spacer + countersunk head

Re: Puch AJH/Athena 45mm reed kit and its clones

i got mad heads for this stuff

lots of different squish profiles

Re: Puch AJH/Athena 45mm reed kit and its clones

I have the split exhaust port cylinder, had the deck of the cylinder milled down 3mm and using a piston from an Athena small reed. Piston crown was even with the bottom of exhaust port and with the cylinder deck. I had a countersunk treats reed kit airsal head I was using with a base spacer, then the spark plug threads shot out...used a 70cc high comp head after that with thinner spacer? I'd have to check n see what thicknesses the spacers we're. I'm also running like 2/3 of a skirt on it, cut a third transfer in it and on one of the times swapping spacers there was a hairline crack in the skirt and I just knocked it off rest of the way. Skirts are pretty thin

I widened the exhaust and the ring gap on the treats reed kit piston is too close to the transfers, the ring gap needs to ride between the booster port and secondary transfer. The timing is fairly extreme, I think it was 196? Exhaust and 132 transfer. Ripped! Til I blew up like 2 clutches within a couple months and harvested the HPI off of it for something else. It's sitting for a bit. Once I get that stuff again I wanna try with a longer pipe...

Here's a thread with some of my struggles with it. Pics of cylinder n stuff https://mopedarmy.com/forums/read.php?7,4140468

Re: Puch AJH/Athena 45mm reed kit and its clones

> jordan * Wrote:

> -------------------------------------------------------

> Ripped! Til I blew up like 2

> clutches...

>

>

> It's sitting for a bit.

that seems to be the recurring theme with these, hahaha

Re: Puch AJH/Athena 45mm reed kit and its clones

> Graham Motzing Wrote:

> -------------------------------------------------------

> > jordan * Wrote:

>

> > -------------------------------------------------------

>

> > Ripped! Til I blew up like 2

>

> > clutches...

>

> >

>

> >

>

> > It's sitting for a bit.

>

> that seems to be the recurring theme with these, hahaha

That makes me happy to hear though, because it's been a battle for me to strap to my e50. ( all I wanna see this thing do right now is rip & destroy some trannys blasting up hills

Re: Puch AJH/Athena 45mm reed kit and its clones

You read my old build thread, but i like this kit so much i'm'a gonna bump this. I took 3mm off the top of my DMP and raised it about the same to clear the bottom of the exhaust port, ended up over 190 degrees duration (and it's great). What id like to see in a kit is a 3mm countersunk head and matching base spacer, that's probably a safe minimum and one can adjust gasket thickness from there. Also could be used to raise the timing on other 45mm kits, turn anything in to a screamer, no? (edited)

Re: Puch AJH/Athena 45mm reed kit and its clones

timothy rendall /

Athena 50cc reed cylinder large read was really poor quality i had to work on the ports as there were badly finished. also the exhaust pot mating surface was not finish off so yet more work. I got it from Puch Shop it was one of their PSR ones !

Re: Puch AJH/Athena 45mm reed kit and its clones

I'm running this kit right now and it's horrible. Bottom end is no-where to found, hauls ass but getting there is slow even with low gearing.

Buy the treats reed kit with the 4 petal reed block a don't look back

Re: Puch AJH/Athena 45mm reed kit and its clones

Re: Puch AJH/Athena 45mm reed kit and its clones

Kevin Bishop /

^^^ this

Re: Puch AJH/Athena 45mm reed kit and its clones

Overpriced Parts /

> Kevin Bishop Wrote:

> -------------------------------------------------------

> ^^^ this

That crank only gains .5 mm @ bds of base spacing

Re: Puch AJH/Athena 45mm reed kit and its clones

yeah ken its not about the spacing, its about the fact that the port map is too tall. spacing is easy to fix but you can't port the exhaust floor up higher.

i think 45 would be better, the port map is closer to 46, but anything closer has got to make a big difference.

Re: Puch AJH/Athena 45mm reed kit and its clones

Alex Hedrick /

So what you guys are saying is, dont buy one unless you want to do a bunch more work to it just to get it to run properly?? I really want a 70cc reed kit that is reliable and gets it..

Re: Puch AJH/Athena 45mm reed kit and its clones

yeah i mean, the real winners for reliability IMO are the Gila and Polini in the reed world. Treat kits or tomos a35 parmakits can be made to rip hard AF but you gotta put some work into those porting wise.

its kind of the old adage- cheap, reliable or powerful, you get 2/3

cheap/reliable- keep your kstar or a treats reed

cheap/powerful- ported treats reed

powerful/reliable - big boy gila or polini build

Re: Puch AJH/Athena 45mm reed kit and its clones

Now they have a dio reed block adapter for piston port Puchs. It is great, chop a hole in your piston or pick up a reed kit piston and rip rip rip.

Re: Puch AJH/Athena 45mm reed kit and its clones

yeah ever since seeing naz's reed valved tccd i have wanted to build one, ought to be pretty good

Re: Puch AJH/Athena 45mm reed kit and its clones

Charles Cole (OFMC) /

I always wonder how any of these kits would run if auxiliary exhaust ports were added to an already dialed in motor. And had a weld wizard pipe!

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