I was just wondering how many people have mod kits on their mopeds? I have a friend that swears that they are the worst thing you can do to a moped and that with out doing a complete modification (carb, cylinder, exhaust, whatever else there can be) they are pretty much useless. Then I see these sights advertising the kits that say they go anywhere from 55 to 125mph with a 50cc engine. With all these crazy looking hand made parts I have to wonder, is it true, or is it all hype to sell a product?


-Moped Army-

RE: kits

Reeperette /

It's mostly hype, and it's not for amateurs to try installing, more often than not, it frags the 'ped...sometimes even on a professional installation.

The general consensus seems to be that stock is better and more reliable.

You can improve performance quite a bit without resorting to the speedkit, via other, simpler mods that are less risky.

On the other hand, a fully-modded Tomos A5, with every concievable option and flawless tuning, and the 70cc kit, you could technically hit 70Mph, but the question is - are you crazy enough to try ?

Moped brakes are rated for a top of 30mph, even on some 'peds that hit 32-35mph stock (the Golden Bullet, in perfect tune, wound full out, could do that)....and you want to run that puppy up to 70mph and then try to STOP ? good luck.

Add to this, that most 'peds are single chain drive and when the speed starts to exceed factory limitations, it causes the bike to 'crab' (wander/jerk left, cause that's the side the chain is on) which gets progressively worse as the drive chain loosens due to wear.

For most folks, the risk isn't worth it, too much chance of fragging your precious 'ped, and at high speeds, it becomes VERY difficult to control the 'ped, you really have to know what you are doing, or you'll hurt your 'ped and possibly yourself in the process.

I reccommend sticking with the simpler mods, really.


(I may be nutz enough to try, but I been doin this for 15+ years..)

RE: kits

Yeah.. those speed claims you've been seeing are probably all for European spec bikes.. and Jan was right, their bikes are way cooler stuff than what we get (you can thank government controls for that... don't vote for GORE)... the ones that do those speeds probably all have gearbox's.

We are stuck with the slower, speed limited stuff with belt drives and restricted HP, and they are not really made to go fast.. so if you do make them go fast, you are overstressing them.. and quite often overrevving them...want to see my PA-50 that I modified to go 35 mph? (from the stock 21mph).. the crankshaft end broke right off from revving too high.. I was getting ready to shim the pulley to gear it higher and lower the revs.... but... snap!... and as Ree said.. the brakes are pretty wimpy too.

Or buy an old small motorcycle if you want to do 70 with reliability and safety.

RE: kits

If you own one of those pedal and chain mopeds don't waste your time with a bore kit, but if you own a honda elite-s, yamaha jog or a newer derbi and install a quality bore kit made by polini or malossi its no hype, if you want to see an engine almost identical to mine go to and click on project 1 moped pics. Remember with skill speed is unavoidable.....

RE: kits

i recently put a 700cc kit on my tomos. i absolutely LOVE the new speed and acceleration that i now have. it accelerates twice as fast, and tops out around 60 mph. However, the brakes do kinda suck and i have to really squeeze the handles to stop from 60. also, i recently had to lay down $260 for new lock ring, a seal, a spring, a gasket, and all the labor. Not to mention i needed 6 new clutch shoes, since the were worn down to bare metal, and the odometer reads on 3548! In spite of this, the incredable performance that i get is much worth the maintainance, and money

i ment 70cc!


RE: kits

In your post you said

"You can improve performance quite a bit without resorting to the speedkit, via other, simpler mods that are less risky."

Can you give some examples? I don

RE: kits

Reeperette /

Dave, get a larger carb, the extra teeth drive sprocket, and a Bi-Turbo performance exhaust.

As for how much larger, ask around about size/jets/etc and see what combos have worked for other people...myself, I pulled the DelLorto and used an Encarwi(sp?) carb of a different design which seemed to work a whole lot better.

All of those are relatively simple to install (tho you'll do a bit of cussin trying to get the drive sprocket off to change it, I'm sure..) and do not require any change to the factory fuel/oil mix that I know of.

It's relatively inexpensive as well, and you will see a slight performance increase, mostly in top end, rather than accelleration, but it's probably your best bet for that kind of upgrade.


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