Speed question

I know that this moped being only a 1.5 HP machine, will not go very fast..it topped out at 27 MPH. I really would like to be able to keep up with the city traffic. 40 MPH would be really nice...but even an extra 5-7 MPH would be great. I know that the gains from modifications are a subject of great debate and I've read many of the old posts. Would some of the experts summarize the speed gain for me for the following mod's and if there is downside why it shouldn't be done Thanks!!

Rejetting the Carb: Speed Gain?

Changing the sprocket: Speed Gain?

Biturbo Exhaust: Speedo Gain? Do I need to rejet the carb or do anything else to make this work well?

Modifying the Air filter: Speed gain? My air box is 'permanently' sealed up..so I don't even know the internal construction. Can you clean them out? Do they need to be?

60 cc Speed Kit: Speed Gain? Will stock brakes give me a death wish? How reliable? What other mods are necessary to make this work?

70 cc Speed Kit: same as above

I have a 1986 Puch Maxi Sport 1.5 HP

Thanks guys!

Re: Speed question

Reeperette /

>>Rejetting the Carb: Speed Gain?<<

Unlikely unless you increase airflow.

>>Changing the sprocket: Speed Gain?<<

Yes, very minor..can go for power takeoff at the cost of top speed, or top speed at the cost of takeoff power.

>>.Biturbo Exhaust: Speedo Gain? Do I need to rejet the carb or do anything else to make this work well?<<

Very much gain, and it does tend to lean out the mix so jetting richer is reccommended.

Combined with the sprocket, it should get you that 40Mph you're hoping for.

>>Modifying the Air filter: Speed gain? My air box is 'permanently' sealed up..so I don't even know the internal construction. Can you clean them out? Do they need to be?<<

Best ask someone else on that, imma Tomos expert, mostly...tho I like Puch too.

Never did an airbox mod on one, however.

>>Speed Kit<<

Not reccommended, especially for beginners...ask around, you'll see.

>>1986 Puch Maxi Sport 1.5 HP<<

Now, I don't recall offhand how it is done, but I know some of the forum members do - but there's a "Conversion" procedure for changing the 1.5HP Puch models into 2.0HP models, which isn't all that hard, far as I understand it.

My suggestion would be to go with the BiTurbo pipe and a richer carb jet, and the sprocket, along with the 2.0HP conversion, realistically you'd get anywhere from 40-45mph out of it, and that's all you really dare to grab for on a ped, especially as a novice owner.

-R

Re: Speed question

thanks for the excellent info!

What size larger of a jet do I need to use with the bi-turbo? Is it like one size up?

Is the biturbo pipe the best in terms of price and performance?

If I want more top end speed, how many teeth should the sprocket have? How bad will this kill me on acceleration?

Thanks again

Re: Speed question

order the pipe from <www.mopedwarehouse.com>

i got my biturbo pipe for $70 and they knew exactly what jet i needed. An hour of install time and it's a total difference.

as far as the sprocket goes. I would say try the exhaust first. And then if you still aren't happy, go with the new gear.

Re: Speed question

Reeperette /

>>What size larger of a jet do I need to use with the bi-turbo? Is it like one size up?<<

Usually one or two.

Best bet is to do some "Plug chops" as described in Freds Guide, and figure out where to go from there.

>>Is the biturbo pipe the best in terms of price and performance?<<

As a general rule, yes - tho some folks here have ordered other models and are quite pleased with them, so ask around and make sure.

>>If I want more top end speed, how many teeth should the sprocket have? How bad will this kill me on acceleration?<<

I dunno about Puch...for Tomos it's 27...basically more teeth on the front = more top end, less acceleration.

With the BiTurbo pipe, you tend to get an improvement all the way across, power and top end, which is why I reccommend both mods, what you lose to the sprocket in acceleration, the pipe will give you back.

So you don't really lose any acceleration, all-in-all.

Some folks say best one mod at a time, but I am of the opinion that the Pipe and Sprocket works better as a combo than individually.

-R

Re: Speed question

I have a 1980 yamaha qt50. I can get it up to 28 ish. I have the same question Phil had. Is there any specific things i can do to speed up my moped. or would i do the basic same things. Where would i take this stuff to be done because i am not an experienced mechanic. Is it easy to do?

Re: Speed question

Ben, from what I can tell, there isn't much to increase power or speed, I'm looking, but nothing for the QT-50

Re: Speed question

I've decided to get the proma pipe for $85 from www.themopedwarehouse.com

I took a look at the jet # in the carb last night #56, damn that thing is tiny...could that be right? everywhere I see people mentioning jets in the sixties

Re: Speed question

Ron Brown /

Phil,

The only way to know if the jet is correct is with a plug chop.

Ron

Re: Speed question

Phil,seems I remember Puch always using a higher than average jet number. I remember something like average numbers being 62 or more. Maybe Ike or some Puch expert will answer you.

Re: Speed question

I've got two puchs that came stock with 56 jets and one that came with a 64 stock.

http://www.mopedarmy.com/resources/articles/4/

This will tell you if it's the correct stock jet. Ron is right, though, the only way to tell if your jet is right is to do a plug chop.

Re: Speed question

Sounds like maybe the #56 is for 1,5 hp and the #64 is for a 2 HP? I am pulling over 3hp,I'm sure now with a #64 jet. But that's on an Italian engine kitted to 60cc., X-Brand.(The specs say it's a 4.2 hp kit.

Re: Speed question

What I find kind of strange, the 2hp base model maxi takes a #64 and the Newport, Sport, and MKII 2hp maxis, which are all higher performance bikes than the base model maxi, all take #56 jets. You'd think the higher performance bikes would require more fuel.

I wonder what the difference is in the base model maxi, maybe the bigger jet is to restrict it by richening the mixture? Or maybe it's just built cheaper and less efficiently for some reason?

Re: Speed question

Ron Brown /

Brandon,

Fuel, to a ped, is a mixture of gas and oil. The main jet regulates the flow of gas into the air stream passing through the carburetor at full throttle, but it is only one factor. Some others are the level of fuel in the float bowl, the pressure differential between the float bowl and the carb venturi and the design of the emulsifier (how much air is mixed with the fuel in the emultion tube).

I don't know about Puchs specifically, but all of the above and I'm sure, some other factors can change the required main jet size.

Hope this helps,

Ron

Re: Speed question

Yeah,Brandon, it's like when I had to open my emulsion tube holes slightly for better mid-speed performance on my 60cc kit. The carb has a lot to do with it as far as design and throat size, and I'd agree with Ron. Puch also has that funny needle adjustment, right? My carb size is a little small,but the #64 main jet seems to be ideal with the Polini exhaust. My air filter is the larger type Dellorto with extra holes drilled in it for the bigger, reed valve type kit. Ike has all kinds of main jets if you need to order one.

Re: Speed question

Hey guys thanks for all the great help!

Do you think that I will have to monkey with the air box (drill extra holes or replace) in addition to the rejetting after I put on the proma circuit pipe? The existing air box only has 540 miles wear on it.

What would be the symptom of the engine needing more air?

How many holes do you make if any?

I checked the archives and found the info to do the plug chop to check the jets. Might be hard in my neighborhood, I get to a stop sign before I get to top speed, in any direction I head.

Re: Speed question

Ron Brown /

Phil,

You started this thread wanting to do 40 mph. Where?

Get out more. Explore the country.

Take a plug wrench with you and do plug chops, it is the only way.

Ron

Re: Speed question

35-40 MPH to and from work and tooling around...I am in the city...not much room to roam

Hey about about this for the plug chops: since I'll never get to top speed before hitting a stop sign, do them in my garage with the door open. I'll have someone I really trust hold the back of the bike off the ground (legs spread wide), as I stand to the side of the bike to work the throttle, kill switch and brakes? This way I can get to top speed for each jet and do it faster as well. Is this risky and dumb? Does the moped have to be under a load (my fat ass, friction etc..) to test the jet accurately? Sounds like a ridiculous question, but with such a small engine, I dunno.

Re: Speed question

Ron Brown /

Phil,

Yes, you need the engine load. You would have discovered immediately that you could hit max rpm with a very small throttle opening. This is not like real life.

Ron

Re: Speed question

thanks, yeah that makes perfect sense.

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