Planet Minis

findmycar

Here's the deal, I have a 74 Honda ST90. My little brother has an Elite with a 120cc big bore kit that hauls the mail. His scoot is very fast, I mean very fast! The guy across the street has a 110 pit bike that my brother walked all over. Hands down this is the fastest scooter I have seen and ridden. The front end comes right up without any hesitation what so ever. I need to figure out a way to beat him but I would prefer vintage style. Does anyone have any ideas what I should do? His build cost around $600 in parts so I would like to stay under that budget to be fair. I was looking at this:

150cc PIT BIKE ENGINE MOTOR CRF50 G2Moto GPX Lifan:eBay Motors (item 320414555658 end time Sep-19-09 17:30:48 PDT)

My fear is that it will not be fast enough because the elite is a 2 stroke. I would appreciate any direction. Thank you for checking out my post.

nielspbr

A lifan 150 is strong, but not fast (my personal experience)
It is not going to stand up to a 120 2-smoke.
Better have a look at the YX160 types with the 09A carters. (or a tak 138+R if you have a big wallet)

mexicanyella

The Elite is a two-stroke? I had a buddy with a Elite 80 that was a four-stroke fan-cooled OHC single, and college dorm neighbor with an Elite 125 or 150 that was all Tron-looking and it was a four-stroke too. I guess I assumed the whole line was four-stroke.

But whether the scooter's a two or four-stroke, a big issue that will have you at an acceleration disadvantage is that the scooter has a CVT transmisison. If that's set up right, it will let the engine reach and stay up near its torque or hp peak rpm, while you'll be rowing the gearbox trying to do the same. If you stay with the ST's motor, you'll have three speeds, which is an acceleration disadvantage of its own. I've heard rumors that the ST has a weak gearbox, too, but no experience of my own to support this.

I think you're going to need a displacement advantage to and the torque that involves to have any hope of winning this particular drag race. Doopsx3 has a thread on this board about putting a larger China motor in a ST frame; I think he talks about the frame mods required in the motor mount area. With your limited number of transmission ratios you are bound to be spending too much time off your power peak, and the more you tune the motor the peakier it'll get, so the problem will compound itself. Unless you have a bunch more displacement and enough torque to snort through having fewer ratios.

But for what it's worth, and at the risk of pissing you off, look at it from this angle. As it sits, a stock ST90 is a) fairly rare; b) equipped (some on this board might say cursed, but I say blessed) with a durable, torquey, tractor-like engine capable of reasonable commuting speeds or easy-going trail performance; c) durable and d) heavy.

Also e) it's got a lot of vintage character mojo; more than one a them Devo-lookin Elite scooters, no matter how quick the scooter is (no dis on the scooter intended; I like riding them as much as anything else). So I say who gives a rip which one's quicker? The two bikes are apples and oranges, and if you want to whip hopped-up scooters an ST90's the wrong tool to pick up.

The ST could be a really cool thing to commute to class on or to work and will last a long time doing that. A hopped-up scooter being used to drag race on a regular basis will be (in comparison to anything powered by a healthy stock Honda 90) a short-lived, maintenance-intensive time bomb. If you want to whip him, why not buy an old beater early 90s 250cc MX bike; something old enough to not be competitive at MX anymore but still a knob-shredding wheely monster. Something with a top end that's just about shot but still runs okay so you can get it cheap. Totally humble your borther, get your drag on a few times, blow it up, and part it out. Make your brother scrub parts before taking photos of them for your ebay or Craigslist ad. Then continue commuting sensibly on your quirky and likeable old ST90 while your scooter-destroyin' brother watches with envy, since your main bike still runs and he has a big hole in his crankcase plus Honda's out of stock for two months on drive clutch shoes and variator belts.

Just a thought, just havin' some fun typin' and no offense intended.

CrawlerD

I agree. A scooter drag race would get old in about 2 seconds. Classic style never gets old.

z50 chopper

A better base to build a tire shredder would be a ct70 or z50 as you will have more engine options than an ST90 as the engine mounts for an ST90 are different than the z50 and ct70 engines. Though with a little effort a 50 based engine will fit but you have to modify the engine mounts which will IMHO weaken said mounts unless you have the proper experience and tools to do so.
A CRF50 engine is basically a direct swap into a z50 or ct70 but not so with a st90.

doopsx3

yep MAJOR engine mount changes required to put a CRF50 based engine in a ST90....the ST90 is a different base...largest OE displacement I seen for those is 110cc...I had originally was going to use a ATC 125M engine in my ST but the engine did not align up and it was heavy...I went with a Lifan 138cc...you could go with a big YX ...maybe one of Firepowers 192cc motors but you need to be raedy for some fabricating and bracing...the pressed steel frame of the ST is not gonna take the stress for too long....what ya can do tho is get a hi-compression piston from Firepower and a hi-lift cam from DRATV..maybe even slide a 110cc jug on it...send your head to Firepower and let Terry play with it and maybe open it u abit...manufacture a free flow exhaust....but ya may have transmission probs like 'yella said....look in my profile and check out some of my pics in my ST90 'Tard album

findmycar

Wow, great info! Thank you for the responses. I agree, vintage has it's own unique style and they typically are cruisers. I need to convey what my situation is a little bit better for everyone to understand. The situation stands as this, I am the big brother who really digs the old school stuff. Old cars, bikes, anything with wheels thats pre 80's I get excited about. Very strong appreciation for the old school stuff because it was built better in my opinion. Nothing beats jumping on an old school CT or ST where everything is cast and steel. The new stuff that is created is better powertrain wise but the components typically suck. Everything pretty much is created out of plastic and low grade metals.

Now, my little bro is the polar opposite. Constantly is making wise cracks about vintage and thinks its junk. We constantly are competing who is better and trying to one up each other. Since he built this 120cc he thinks he's the cats ass, which right now he is. Everyone is aware that he is the big dog in town for right now and waiting for me to create something. That is why I need to formulate a plan to whip his ass.

The ST that I have there is no way that I will fab mounts etc. to this bike. It's in very good shape and all original, so that idea is scrapped. I thought that I could just swap motors and convert it back to original without an issue. So, what I need is a 2 stroke scoot of some sort that will blow out an elite with a 120cc big bore on it. PLEASE GIVE ME ANY IDEAS! I think a CT with something harry bolted to it should do the trick. FYI it needs to be vintage as well.

doopsx3

if you can find one

schofell84

build an old honda CR up?

doopsx3

I assume you want something street legal

dsrt4

Find a ct70 and slap a Lifan 200cc upright onto it....

Like this fellow did.

Dax 200cc de MeHDi (Moto Quad Honda Monkey Gorilla CY CRF Dirt Pit) [PART2]#

doopsx3

I still like this

nielspbr

Yes, but slow. Can't beat the sound though.

doopsx3

yep slow but it is sooo darn kewl

50rider340

i wish the guy who built that showed how he got the power to go to the tranny with that. I still dont understand how he made it possible.

id leave the st alone. My buddy has a ducati scoot with a 75 kit in it and same thing it rips and hits close to 70mph. Your best bet is get your hands on a beat old ct70 and get the motor you were looking at. I think a 150 should be right up to part with it. My buddy has a passport 70 with a GPX 140 in it and it is down right silly how fast it is. I think a 150 or a yx160 would be more than enough to beat your brother.

doopsx3

He probably split the original 50 crank, removed the rod, and replaced the rod with a sprocket and he is using a chain to take power off the 4cy crank from the center...probably next to the chain /sprocket combo that he is using to drive the cam....just my guess

mexicanyella

Okay, I'm going to try and channel Carolyn Hax's syndicated newspaper column here:

With all due respect, trying to win this contest will be short-lived, expensive, futile glory at best and will not get you laid. If your little brother is as you describe, he is wrong and has chosen the path of immediate gratification, and for this he shall soon suffer. Try to keep him from hitting anything solid and stationary and injuring himself while he gets his head around this basic, essential truth, and don't be sucked into this superficial comptetition. You are better than this.

And if you choose to ignore this essentially inarguable advice, may I also offer a tidbit of discouraging spirit-dampening advice about the Suzuki GT185 twin in the picture?

That is a cute little two-stroke bike with a snappy little powerband, but this comes at the utter expense of any low-end power. It's literally zero hp until it gets into the upper midrange, then there's a pretty steep little climb; enough for a few grins, but probably not enough to beat something that weighs as little as a 120cc CVT-driven Honda Elite.

You will also get the full vintage experience trying to find parts for a GT185, probably.

Get an old Kawasaki triple. Also hard to find a steady parts supply, and you might need one, but on the occasions where it runs right it will be a) vintage; b) fast and c) smoky and non-politically correct, plus d) it might actually qualify as an investment.

Makotosun is a member here and has put in some old Kawasaki triple miles and can probably tell you if I'm exaggerating their quirks and faults and strengths or not. Closest I came was a Suzuki GT380 triple, which was slower than a Kawasaki and tougher/more reliable than the GT185 twin. Might beat a scooter, but...see, I can't take that criteria seriously. I keep thinking who gives a crap if it can beat the scooter, which won't be around in six months? Look at the long term...get something you really like and don't worry about your bro!

doopsx3

Well put 'yella......I had just about all of the GT's and a couple of Mach bikes...even had A7 Avenger....and a few other rotary valve 2smokers......yes none of them really were over abundant with low end (I wish they had power valves then) but once they were on the pipe...HOLD ON FOR YOUR LIFE....and hope no turns were coming up in your future.....yep, they go fast in a straight line but do not stop or turn well...kind of like my old '79 CR250 Elsinore

mexicanyella

Well, I mighta gotten a little out of line there. I was having fun at the expense of giving useful info, and for that I sort of apologize.

But seriously, I do know a bit about GT185s and 380s. The thing in my avatar is a GT380 that is modified and is jumping, kind of, on a MX track. Dumb as that sounds, it was pretty fun, and inspired one of my riding buddies to take a MINT GT185 and do similar "dirt" mods to it. I shudder to think of this now; the 380 I started with was pretty trashed and not that old at the time. The 185 went from being a neat little rarely-seen streetbike with just enough power to seem cooler than most commuter bikes to being an narrow-powerband, heavy utter failure of a dirt bike.

Anyway, the GT185 ran great but one night after a long unlicensed (maybe helmetless?) wide-open blast on a long straightaway, the 185 holed a piston. It made it home on one cylinder, slowly, for about 12 miles. This was in about 1987, and it was hard to find a piston for it even back then. I doubt it's gotten any easier. I also seem to remember the clutch pushrod and maybe shift shaft were very vulnerable to the chain coming off, which happened at one point and pretty much made the thing a lost cause to fix on our budget at the time.

The 380 was pretty beefy and understressed and held up pretty well, but the 185 might as well have been a couple cylinders from a small-bore MX bike...that is, kind of spectacular but short-lived and requiring a lot of wrenching if you pushed it. That's all well and good if it's a current or common model, but on something this rare and unsupported in the aftermarket, it's a better choice to display in your collection than to rely on for regular use. You will be sitting and waiting on parts a lot if you buy something like that and run it hard. That's the downside of vintage bikes. Owners of Honda Zs and CTs have it pretty easy; so many of those were made and Honda supported them so well for so long that you can still get a lot of factory parts (although these are drying up) and there are so many bikes being parted out, plus the various interchangeable clone parts, that keeping them running is no big deal. PLUS they come from the factory as understressed and durable as any bike out there. But they are not a way to win races with two-strokes or more modern four-strokes. That's not what's cool about them. What's cool about them is how they are sometimes 40+ years old and still work; not unlike vintage agricultural machinery.

Once you branch off into the world of Yamaha/Kawasaki/Suzuki I think you will find those factories bailed out on parts support much earlier and you will be working harder to keep them running, especially if you're dealing with a hi-rev time bomb of a model.

So my advice is, if you want fast + vintage, expand your horizons beyond beating your brother's scooter, and look toward "what can I afford that I can find parts for fairly easily and looks cool to me and has enough hump to it to give me the willies when I crack the throttle? Does it have to be street-legal? Do I plan to keep it, ride it long distances or just around town, etc. etc." And as a general rule of thumb you'll get longer, more trouble-free service by getting your acceleration from size than state of tune. You know, find a scruffy but mechanically sound Honda CB550 or 750 rather than a Suzuki X-6 Hustler if you want to actually put some miles on the thing. The X-6 will be cool but won't run all the time and when it doesn't you'll be scrambling to find parts for it.

Also, can you post up a secret spy photo of your brother's scoot motor? I'd like to see how it's set up; never seen a two-stroke Elite motor before.

Good luck. Stay away from the dark side. Carry the torch of vintage integrity and whatever.

dirtbkr188

Here's my take on the whole situation...

Take the ST90 and restore/rebuild/restomod it however you want, and when its completed, then challenge the youngster to aforesaid Drag Race for Bill of Sale. Once at the starting line, proceed to fire it up, put down the kickstand, knock him clean off the scooter and then kick the livin' s**t out of him on the spot. Then get on the ST and ride off into the sunset.
Race over, pride regained, pecking order re-established. Big Brothers do NOT take any lip from any little brothers...