pipe

[firko]

I've still got one of those awful Aaen up pipes that I'd bought for my 440 from Blair Harley back in 1974 after flattening my down pipe for the umpteenth time. I hazily remember it being a bitch to rejet the bike to suit the pipe.(36mm Mikuni at the time) .
I've still got it and briefly ran it on a 400 Maico radial I built out of left over shit during the early vintage years. It burned the shitter out of my leg causing me to remember why I'd taken off my bike back in 1974. Having said that, I'm going to use it on my upcoming 250 squarie powered Micro Metisse in a bid for period integrity.

At the same time Wheelsmith made an up pipe conversion that was far better in design but it had a severe design flaw. In a bid to route the pipe more cleanly and avoid the leg burner situation of the Aaen pipe, Wheelsmith routed the pipe through the airbox (mucho cutting and shutting was required unless you bought the Wheelsmith airbox).This cause the heating of the inlet air causing all sorts of jetting anf breathing problems. My mate Chris Ellis wrapped his pipe in asbestos matting and aluminium tape in the area that passed through the airbox and that eased the situation a bit but it was never very successful for motocross. The pipe was sold to another mate who fitted it to his Elstar Maico slider without an airbox and it produced some admirable improvements all through the range.

That pipe of yours Firko looks quite short, like it would be a bit of a top end screamer

Geoff, the pipe was originally built for my 250 Maico that was used purely for dirt track and on that bike it definitely produced a radical charge from mid to top. I fitted it to the 350 to see what would happen and we were pleasantly surprised to find that it improved the charge from bottom to top, not quite the abrupt charge as the 250 did when it came 'on the pipe' but more a fluid smooth flow with a very noticable top end rush. I'm not very up on expansion chamber theory but I'm sure Lozza can explain why the different characteristics occured. My 350 has the same stroke as a 250 with a 400 top end so in essense it's an over bored 250. The 350 Maico is the only short stroke Maico they ever made which explains why they are so 'un Maico' in their power charecteristics. They even sound different to other Maicos, as Tony T pointed out to me at the Coffs Nats. The pipe really made that bike into the good performer it is though. The old girls very rooted right now after 16 years without a major rebuild so she'll enjoy a freshen up over the break and hopefully have another go at the pre 70 class at next years Nats.
 

[paul]

KEITH STACKER(AFTER NUMERIOS TRIPS TO THE FACTORY) TOLD ME THERE WAS NOTHING SPECIAL ABOUT THE BIKES THE FACTOY KEEPT TO RACE ,THEY WOULD BUILD 10 OR SO A DAY AND WACK THEM ON THE DYNO THE ONE THAT PROFORMED THE BEST WAS THE FACTORY RACER OR GIVEN TO WHO WAS THERE AT THE TIME AND PUT IN WITH THERE ORDER,  ALL THE OTHERS WERE SHIPPED . SIMPLE AS THAT ,WHO EVER ADDED THE MAICO WORKS BIKE HYPE MUST OFF DONE IT IN OTHER COUNTRYS AFTER THEY ARRIVED , HE SAID THEY WERE BASICLY ALL THE SAME FROM A ITENERANT WORK FORCE WHO WOULD JUST GRAB ANYTHING AND BOLT IT TOGETHER THAT WHY THE NUMBERS ARE ALL OVER THE JOINT FROM COUNTRY TO COUNTRY,SO IM LED TO BELIEVE .

[firko]

THERE WAS NOTHING SPECIAL ABOUT THE BIKES THE FACTOY KEEPT TO RACE

WHY ARE YOU SHOUTING PAUL? 
That's true but each GP rider had their own setups and tuning tricks. The ex Adolf Weil 250 squarie that Per Klitland and later Chris Ellis rode is a good example. The crank was radically lightened and it was ported but other than that it was pretty standard. It was just the little things that each individual rider and his mechanic did to the individual bikes that made a difference. The Americans were a little different and they tricked their bikes up quite a bit. That's how the LTR frame came about. Steve Meridijan, the Wheelsmith shop manager told me that the Maico team were based at Wheelsmith Motorcycles during the '73 Trans-AMA series and when they saw the rear frame mod that Wheelsmith had been developing for local SoCal racers, the Euro boys had to have it done to their bikes. The factory heads weren't impressed but once Willi Bauer, Adolph Weil and Gaylon Mosier and Steve Stackable started dominating it wasn't long before the factory conveniently forgot the "no external mods team rules' and went with it. The LTR frame quickly went in to production not long after.

[paul]

 sorry if i was too loud but i carnt find my reading glasses mark  

[YUMASTEPSIDE]

Firko, is the 350 just a 250 with a 400 barrel or are they different cases and everything?

                Roger

[firko]

a 350 is a 360

Errr!, I don't think so Paul. Check your facts again.

[firko]

Nope...Someones thrown you a dummy.
350 mk1, 350 mk2, 360 and 400 are all different.

[paul]

ok then fill us in 

[firko]

Paul, The same bloke who told you a 350 and a 360 are the same engine reckons my 350 is a 400 so I guess I've been wrong all along and don't know what I've owned for the last 40 years   

[paul]

mmmm   well im interested just the same in the specs

[firko]

Maicos:
250... 67x70=247cc
350....77x74=345cc  (77x70=326cc (a small number of 326cc 350s were released at the end of the 350 run in 1970/1)
360....77x76=354cc
400....77x83=386cc
440....82x83=438cc
501....91x76=494cc
Paul, note the difference between the 350 and 360. They're very different bikes in both configuration and performance.

Firko, is the 350 just a 250 with a 400 barrel or are they different cases and everything?

Roger, all of the Maicos share the same basic crankcase casting but the size of the cylinder opening naturally differs between the 250, 400, 440 and 501. The 350/360/400 cases are identical.

[paul]

thanks firko /so performance difference is ?

[Lozza]

OOps forot all about this thread

Whoa the AAEN pipe that really was their salad days fortunately(for them) they went on to BIGGER AND BETTER THINGS in the sled world.

Firko I suspect by looking at that pipe that it is simply a better pipe,especialy the design. Maico port timing seems very similar from the cylinders I have measured. I would agree with Geoff that your pipe looks it's a fraction to short.For instance I make my tuned length for an air cooled 125 road race bike around 900-950mm with peak power @ 12,000 rpm.

[firko]

All I know is that the pipe works Loz. That's all I need to know. I leave the theory and braniac diagnosis to you blokes who understand such stuff. It was worth nearly 5 hp over a Wheelsmith pipe* on the dyno so that'll do me.
*On the '73 250 radial it was originally built for. It feels better on the 350 as well but we haven't dynoed her.

thanks firko /so performance difference is ?

That's a subjective question that's very hard to answer Paul. The 350 and 326 are revier and to me much easier to ride and faster than the 400, especially on dirt track. I can't theorise why, it's just my feeling and that of many dirt trackers of the day where the 350 was a big sjuccess. The 350 works well in motocross as well but some would prefer the bigger bottom punch of the 400 and bigger again 440. I haven't ridden a 360 in years but assume it's somewhere in between, sorta like a slower 400. The power characteristics between the 350 and 400 are very different as Stacker will tell you.

[Lozza]

I wouldn't doubt it would outperform a period pipe.
I forgot to type previously that why would anyone save that AAEN pipe from the happy scrappy and then (what appears to be) advertise it for sale  
James smart operators in the US would see Jerry Hall in Pheonix and in Canada Darcy Rosintreter is the go to man.