pipe

[YUMASTEPSIDE]

Can anyone tell from this picture if this pipe would give more top end or bottom end ?

     

              Roger

[paul]

did you buy it rodger

[vandy010]

it's a wild guess without more info but i'd reckon good tourque with trailbike style design.
tourque-not sheer horspower.
if that makes sense.
ride it and let us know

[YUMASTEPSIDE]

........sorry to get you all excited for nothing!    It's just a pic I found on the net ,and it looks like a well tucked in,properly silenced,and very neat exhaust .If the pipe gave good bottom and midrange in that configuration, I would get Geoff to make a copy for my GS250.

                   Roger   

   I can never remember if a longer header pipe is for top end or bottom ?

[Lozza]

What itwould make would sound that's all.There isn't anything really to copy and poor owner should demand a refund.It's common to see a pipe to fat but rare to see one to thin.
Longer headers are for bottom end.

[albrid-3]

Maico`s original pipes had stingers, not fat pipes, most pre 75 bike have stingers.

[FDR]

Pipe brand is Circle F made in the USA
Have one on my 73 - 400, works very well

[YUMASTEPSIDE]

The stinger would be inside the muffler just like a Frontera pipe ........thanks pigmy,good to know.

              Roger

  and yes, it does appear to be a small pipe for a 501!

[Maicojames]

Yes a Circle F pipe-if you look at the last weld near the tip-it has a stinger under and the silncer assembly welded on over that. The power is very nice and smooth, IMO kills some bottom from the 4spd and 5spd 400-440 engines. These pipes can be crushed more easly than a stocker or a M.O. pipe. ...and personally I think the stock, M.O. or GMC pipe looks way better. Kevin Felle is to be commended though for producing these pipes which make great power at a great price. We see a lot of them here in Texas, since he is in Houston.
Were I in Oz-I would likely have a GMC pipe-or have him make one to suit.

[Lozza]

The design is shit not the construction, there is not even a bare minimum of thought gone into that. All expansion chambers have 'stingers' as I think there is confusion with a 'silencer'. Works well compared to..........................?

[Maicojames]

Ok, but I challenge that the construction is light-as I smashed mine about a half dozen times-finally to the point that it could not be repaired. Again-an inexpensive pipe that happens to make smooth power. Yes, it is obvious that all the Circle F downpipes show a very similar design. I understand the up pipes he makes are quite good, though.

Lozza, I agree with the simplicity of the design-and also my M.O. pipe was beaten up way worse-and never dented or crushed. I'm not up on the current exchange rate, but the GMC pipes look to be the goods. Also available are the New "Canuck power Pipe" from Caldwell at Candian Maico.

[firko]

Methinks the Circle F Maico pipe is so close to stock there'd be little if any increase in overall performance . That pipe however appears to be a 400/440 pipe and think he may have it to spread the power of the 501 further up the rev range. The last thing you want on a 501 is more bottom end. I have a Circle F TM250 pipe that Kevin Felle claimed to be 'similar' to RH dimensions and while it's a nicely made pipe that works just fine, it's nothing like my genuine NOS RH74 pipe. The thing with any American made vintage MX pipe is that the AHRMA doesn't allow tapered headers in pre 75 classes in a bid to keep the technology 'old school'. I don't agree as tapered headers were around back then but rules is rules I guess so it's no good making modern designed pipes if they're not legal to use. I can see where they're coming from though. If there weren't restrictions we'd probably see a lot more "Poison 'Lil" atrocities in AHRMA ranks. Having said that, I reckon you can build a pipe using new age theories without damaging the asthetics of the bike.

Below is the Professor Pete pipe on my old squarie. Peter Reynolds built it for me in the early 90s using his own computer program developed using theories from A. Graham Bell and Eric Gorr and it immediately transposed my old bike into a rocket with  increases all through the range. Note the tapered header, fat belly and how neatly it tucks in. It's completely different to that Circle F thing shown on the above 501. My old 350's been used for motocross and dirt track with some pretty aggressive riders as well as fat old me on board her and there's hardly a dent in the pipe. My 'Professor Pete' pipe might not be as pretty as that on the 501 Yuma posted but I'd be my goolies it works a shitload better and it doesn't look totally wrong for the era.
                   
                   

[GMC]

I was going to say it looks very much like a stock pipe.
The end cone running inside the muffler tube is a common way to build them for strength. My very early pipes used to run the last cone down to the stinger tube & then add the muffler like Firko's but I found it too flimsy as the mufflers would often break off.

Small chambers tucked away aren't very good...








for business as I get less repair jobs


The early GS pipes were down pipes but the 74 GS was an up / side pipe.



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

[YUMASTEPSIDE]

.........looks like I've stirred up something here ,so how about this one?    The ad comes from " Motocross " September 1976

                                            Roger

                     

[YUMASTEPSIDE]

The bloke I got the pipe from never had it fitted to his AW400.........and by the way , thats not an AW replica, he actually has one of Adolph Weil's 1974 bikes.

                  Roger