Maxi+Proma Circuit=minimal gains?

Brandon Bakke /

Here's my setup: (on a '78 Maxi Luxe)

Stock high torque cylinder

Proma Circuit

Stock Bing 12mm Carb (upjetted from 60 that was in it to 64)

I was expecting a slightly better speed/power improvement than I got when I added the circuit pipe. I have the bike running pretty rich right now, a quite a bit darker than that "toasted marshmallow" look on the plug chop, but not dark black either. My question is:

Is running on the rich side killing my performance gains, or is the stock carb holding me back more than I thought it would? Or what is holding me back now? I have been running around 32:1 premix, which my Hobbit tolerates just fine, but is the extra oil bogging down the Puch?

Basically, is there something still keeping me at 35mph, or am I just spoiled by the Hobbit and expecting too much?

(Note:the bike is NOT four stroking except when it is first driven and still cold)

Re: Maxi+Proma Circuit=minimal gains?

Too much oil. Makes it run too lean. Run 50:1. 35 is pretty good, check your timing too

Re: Maxi+Proma Circuit=minimal gains?

Run 50:1, it is not killing your performance that much, but not doing you any good either.

Yes Hobbits spoil you.

Yes running rich robs you of power (but is safer)

35mph is pretty good.

You have have to up your gearing to get more.

Re: Maxi+Proma Circuit=minimal gains?

also if you haven't put a highflow air filter on, that will help with the current jet you are using. trust me

Re: Maxi+Proma Circuit=minimal gains?

That pipe is not so good for a stock set up. I think the tecno is better for stock.

Re: Maxi+Proma Circuit=minimal gains?

Brandon Bakke /

As I figured, my Hobbit spoils me.

I'm going to go ahead and gear up a little higher, I'm 135lbs so I doubt it'll hurt me on the hills much. The powerband seems to be around 25mph right now, so I imagine gearing up should help.

@Nick: I'm not currently running an air filter at all, that should be as "high flow" as I can get, yes?

recomendations on a front sproket size?

Re: Maxi+Proma Circuit=minimal gains?

I've put a proma on an otherwise (but 35mph) stock maxi before and had zero increase in top speed.

Re: Maxi+Proma Circuit=minimal gains?

I would say your current speed is due to the tuning. I saw 36mph from my za50 when it was pretty much stock with a modified cigar exhaust. That being said I would imagine that a e50 (taller gearing then za50) with a proper exhaust should see more then my 36mph.

Re: Maxi+Proma Circuit=minimal gains?

i had a promo circuit pipe on my stock e 50, it made go . , i jetted 62 with a small home made filter and it ran about 34/36 but had sick low end , which was fun for in town light to light traffic but the top end tok forever to increase. gearing 16 - 45 . using a del 14/12

i ported out an old stock head to match the transfers in a 62 malossi kit , exhaust port widened , transferes , ect.. put the pipe back on , running a 72 with no air filter and it goes 39, stick a 16 del on it and it will do low 40's , thats with a case stud leak due to being stripped ..

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