20 MPH, what next?

Ok, I have done everything thinkable except change the exhaust and the gears on my 1978 puch maxi with no results. I still run no faster than 20 mph. It runs beautifully, but I just can't break that limit. Here is the setup:

1978 maxi e50 engine 1 HP stock with the intake drilled out to match my 14mm carb and manifold. 68 jet on the carb, stock air filter. I have cleaned the engine, the carb, the exhaust, the gas tank, and replaced the fuel switch and filters. I get great gas flow and good compression. I have 14 tooth front and 45 tooth back (I think 45, the count is off a little each time. I haven't actually taken it off to count it)

What do I do next. I don't need 50 mph, but 25 to 30 would be nice.

Thanks in advance, you guys have been very helpful in getting it running this far!

Re: 20 MPH, what next?

Do you run the stock exhaust? Try cleaning it out, it might be clogged on carbon build-up.

Just take it off and take it apart and see how bad it is. If its badly clogged you can burn it out.

You do that by putting a lil gasoline in (wihtout 2-stroke oil ;)) and setting fire to it. After burning a while, tap the outside gently with a rubber hammer.

Re: 20 MPH, what next?

clean the exhaust pipe def.

Re: 20 MPH, what next?

he has a 1hp model, isnt' there a restrictor in the exhaust? just get a performance pipe. a bullet will do just fine for stock engine, and with that huge rear sprocket, you won't loose too much acceleration when you get a bullet, which is a top end pipe

Re: 20 MPH, what next?

The stock pipe is clean. i drilled bigger holes in the baffle and derestricted the exhaust just like the article said to. Do you really thing a new exhaust will lead to increasded speed?

Re: 20 MPH, what next?

hell yes it will. thats what they do :-)

Re: 20 MPH, what next?

change that front sprocket to a 16.

Re: 20 MPH, what next?

you need a highflow air filter and to upjet your carb again.

your stock air box and your filter are restricting your flow.

if you want around 30-35mph do this. i did this to a 1982 murray puch 20mph version

bing highflow filter (looks like k&N) $15

biturbo exhaust for puch e50 $77.77

upjet 3 jets for new filter and 2-3 more for exhaust $22.??

give or take since i dont know what your stock jet was. i went from a #52 to a #72

your gearing is the same as mine

depending on how much you weigh my set up can get to 40mph with a 140lb rider, or to 35mph with a 170lb rider.

also do some plug chops freds guide

e-mail me if you need help...... vegamew2394@yahoo.com

Re: 20 MPH, what next?

plug chop looks great as it is! if i replace the exhaust will i need to do the air filter and upjet too, or will the exhaust do it for me?

Re: 20 MPH, what next?

Unless you live in a really hilly area, I would switch to a 16 tooth front sprocket and rig up a less restrictive air filter.

Re: 20 MPH, what next?

you got 40 mph with the 1 hp model? did you mess with the gear ratio, or just the exhaust, air filter and jets?

Re: 20 MPH, what next?

Update... I have the high flow filer and after further review realized I have a 12mm not 14mm and the jet was 58 not 68. I up jetted to 64 and switched to a NGK b6hs plug. I also messed with the back sprocket and am running 14 x 38 now. Top speed is 24 mph. What gives? Shouldn't I be tearing it up with those improvements?

Re: 20 MPH, what next?

isn't a 45 rear sprocket kind of big? i think if you get a 41 tooth rear sprocket that might help your top end . . . that's what i've got on mine, which otherwise matches yours, except that i've got a bullet exhaust, and i top out around 30, 32

Re: 20 MPH, what next?

ok i think 1hp models had a 12mm intake . take off intake and look at hole in the cylinder. i think puch put a restricter in there. so 14mm carb and 14mm intake but cylinder is only 12. not sure how you take it out.

Re: 20 MPH, what next?

forgot to tell you take off head gasket. do you have thick one or very thin.

Re: 20 MPH, what next?

one more thing. stock exhast did you take out the two pins in exhust pipe.

Re: 20 MPH, what next?

seals? do you eat ATF or mysteriously gain it?

Re: 20 MPH, what next?

J - yeah a 45 is big. My ped was 12 x 45 stock. I changed to 14 x 45 and wasn't happy so I went to 14 x 38. My acceleration is not bad, but it really doesn't feel like it is winding up all the way. Do you have a 1 HP? I would love to get 30 - 35 mph on a flat.

Tim - I dropped the head gasket and de-restricted my exhaust as the first 2 steps after she was running. You are correct, there was a nasty steel ring that chocked the intake to about 10 mm. With enough force, I popped that ring out and bored it clean to about 14 mm. It came with and I still am running the 12mm carb and intake although I am toying with buying a 15mm carb (I have a 15mm intake already, that was the cheap part.).

Graham - ATF is good, no leaks that I can tell. Is 24 mph really all you can get out of the stock e50? I have the #2 with the open ports. I am 6'2" and 210 lbs. but it doesn't seem to go any faster for my 150 lb wife....

Re: 20 MPH, what next?

I just went thru the routine you have with similar results. What will get you the extra MPH is a pipe. I got one at the mopedwarehouse and now it will top out at right about 30. I also switched out the stock 1 hp cylinder with a 1.5 #2 type. I've owned a lot of Puchs and every stock one that I have ever had has been a dog. I know that they can run strong as I've seen them at rallys keeping up with my Peugeot U-3 TSM. Gotta keep tweeking it.

Re: 20 MPH, what next?

Is the #2 the open port or the closed port? I know I have the open port one, but can't remember which number was on it. Also, will I need a bigger jet for the performance exhaust?

Re: 20 MPH, what next?

I'm not sure what you mean by the open port. I kept the ofiginal #3 piston and just shortened up the intake side piston skirt to match the original number 2 piston. I bought 3 extra jets with my pipe but they were all too big. I drilled out the original jet and got lucky as it runs spot on perfectly thruout the rpm range.

Re: 20 MPH, what next?

http://www.mopedarmy.com/wiki/Puch_Maxi_Cylinder_Information

look at the first 2 engines. The first one is open right into the cylinder. the second one is closed or cut off from the cylinder and has 2 holes further down.

Re: 20 MPH, what next?

Switch to 16x45 gearing. That's what most of the bikes came with. If yours has 14x45, that was to keep it slow.

Re: 20 MPH, what next?

Ok I see what you mean. Mine is the open type. I think I could add a tooth or two to the front sprocket and get away with it probably add 2-4 MPH more at this point. When I first got my 1 hp running 17 MPH was about it and it would struggle to go faster. I removed the restrictor and rejetted, it would go maybe 21. I added the pipe and sprocket and it would cruise easily at 20 and top at about 25, I changed the cylinder and now it goes about 30. Here is a photo of mine, under 100 original miles

1195169775_maxi_sport_field_right.jpg

Re: 20 MPH, what next?

So here is what I have in my possession:

12, 13, 14 tooth front and 38, 45 tooth rear.

The 12 x 45 got me to 18 mph

The 13 x 45 got me to 20

The 14 x 45 got me to 21

The 13 x 38 got me to 23

The 14 x 38 also got me to 23

The 14 x 38 should get me 2 mph faster, but it just doesn't. I have used GPS to confirm it. That leads me to the conclusion that I lack the muscle to get the stupid thing going any faster. Is that correct? How do I get more power without changing cylinders? Will the pipe really make the difference? I have the high flow filter and 12mm carb and intake running a 64 jet and it runs great with no weight on it.

Re: 20 MPH, what next?

A performance exhaust will REALLY REALLY make a difference. As we say over and over again, it's the single best thing you can do to your bike. A 14mm carb and intake wouldn't hurt either. Also, you should be able to find a 16th front sprocket for super cheap.

Re: 20 MPH, what next?

Is it 4 stroking? Mine wouldn't sing with a 64 jet even with a pipe on it.

Re: 20 MPH, what next?

I should add that I am using the stock airbox to keep it quiet.

Re: 20 MPH, what next?

I also wonder if you're over-jetted. If I remember right, I have a 64 on my Newport and it has a high-flow filter and a pipe. Most stock Puchs I've seen come with a 56.

They are awfully loud without the airbox, but the stock airbox will slow you down considerably.

Re: 20 MPH, what next?

I was running a 56 with the stock air box. I have a high flow air filter now. I tried a 62 and it wouldn't run at WOT with that filter on. Will a 16 sprocket on the front do any good if the 14 x 38 didn't improve? Basically it seems like it will kill my acceleration and leave my top speed alone. When I run the ped on it's stand it screams, but the second I put a rider on it, it hums along smooth but doesn't wind up to (just guessing here) even 1/2 the RPM s. I really feel that if I can get the ped to wind up like it does on the stand I'll be ok. Bigger carb and intake? and I am definitely getting the pipe!

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