Planet Minis

dirtbkr188 · 09-07-2009, 04:44 PM

All kidding aside, how about some pics of this tire-burning, neck-snapping little Japanese conveyance you're so intimidated by? Some nice 8x10 glossy closeups of that super-secret stealth engine would be great, too. Where did he get the big bore goodies, I'm kicking it around to get a scooter for some track action at a local kart track.

micromachine · 09-07-2009, 05:08 PM

this thread has no derection! it goes from a st90 build to abunch of nonsense about old two strokes
what ru trying to do? My $.02, build that st90 to the best of your ability if its faster cool, if not chalenge your bro to build a st90 faster then yours!

if all you whanna do is beat a scooter then stop messin around and use somthing like this. this is what i use to stomp scooters and rc51's

mexicanyella · 09-07-2009, 05:14 PM

I beg your pardon? No direction? To me, the direction is quite clear: it focuses on the original poster's specifying that he wants to build something vintage to whip his brother's scooter. The direction here is this: an ST90 is the wrong tool for the job. And trying to whip the scooter in the first place might be the wrong job. I think this thread stays pretty focused on trying to save him some frustration and expense, and maybe refocus on how to get some enjoyment from what he already has.

I was the one who led us into old two-strokes, since those are the bikes that were fast in those days. But I don't think anything I said about old two-strokes was nonsense.

So you're into whipping both scooters and RC51s? That's a diverse hobby, right there. I like your bike, however fast it is. It looks great, and I bet it sounds pretty cool too.

doopsx3 · 09-07-2009, 05:23 PM

Quote:

Originally Posted by 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.

ya hit that right on the nose bruddah....I had a 2smoke Elite but it was a 50...........also had a GT500 left hand kick start

dirtbkr188 · 09-07-2009, 05:29 PM

So I guess the new direction to take is to post more pics of Sportsters on Steroids...?

micromachine · 09-07-2009, 05:30 PM

meant no offense by the two stroke "nonsense" comment but my point is just like you said, to get enjoyment out of what he already has!
anyone can go by a faster bike but a fast st90 is a derection i think i would be aiming for weather its faster then the scoot or not! if he just went and bought a kawi tripple, his bros just gonna go buy a rc51 ect. ect. ect...

btw. yep scooters, rc51, geo metros, i dont descriminate! ill whoop on them if they know thier racing or not, im not picky

doopsx3 · 09-07-2009, 05:35 PM

or you could use anyone of these to spank that mean scooter

but seriously, I would keep the ST90 looking as much as stock as possible....ya can warm up the innards with parts n affectionate luv from Firepower and still have a cool machine...I only hacked up my ST90 cuz all I started with was a frame......and it has been a pain....there are lots of cool vintage bikes that can spank that scooter and you do not need 600+ cc's to do it....an SL or XL 70-100 with a warmed over motor (or transplant a 150R engine) and you got a vintage bike that will scoot pretty darn good..that will be street legal

findmycar · 09-07-2009, 08:09 PM

I will get pics of his scoot in the next few days. The kit was bought on ebay and then it went to the machinist because the tolerance was too high. They had to bore it out because it was at .01 when it was delivered. He figured that out after sticking 2 of them. I agree with the other posts about finding other bikes etc. But, that is not the point of this post! I was hoping to find something that was vintage and can haul the mail!

My thought was to do a CT with a 160cc on it, street legal, and call it a day. Do not get me wrong, I like the other responses on this post, I JUST WANT THE VINTAGE RECIPE to put a smack down. I may just have to suck it up and go with a KYMCO Super 8 with a big bore on it. Whatever it is, I need something in that class.

makotosun · 09-07-2009, 10:11 PM

As Yella said earlier, one of these babies would certainly whip the tires off of your brothers bike and would be vintage, cool, and did I say COOL?

I rode one of these from Portland, OR to Tijuana, Mexico and back over a 6 day period, so can vouch for EVERY comment about the bike that Yella made.

Evil bikes. But pure fun.

cdoublejj · 09-07-2009, 10:19 PM

well i skipped over most of what was said in this thread simply because i'm to lazy to read it all. If ya can mod it for the regular honda style mounts then get a nice big engine like z155 or yx160 then if ya want make it a 177 or even a 184 then ease on the gas so you don't flip the bike over then hold on tight and haul balls.

Or if ya can bore outthe st90 engine any where around 150 then ya might wanna too that looks some others are saying to keep it stock but it looks alot like a ct 70 too so i don't see the big deal unless the bike means something sent-ament-aly.

i'm currently waiting for the ups truck to drop off my donnor frame so i can stretch my z50 out to make some room for the oil cooler and then maybe rake it out some to make it more stable at high speeds at which i hope to be at least 60 if i don't fly out of control on stock knobbys and 8inch wheels

schofell84 · 09-08-2009, 12:51 AM

unless your sportster can turn 8k rpms, stay away. i want to see a picture of this 120 two stroke scooter by the way. dang.

MakeshiftPatriot · 09-08-2009, 02:37 AM

You are going to want something a little better than an ST90 to work with if you want to go a higher cc. You might as well get a Suzuki GT-185 like previously suggested. I bought one for my first motorcycle at $450 with only 5,500 miles on it. In fact I found one just like mine in my city, they aren't as rare as one would think. With how much you are going to spend on an engine you can pretty much have a whole motorcycle.

My Z50 with GPX150 is much scarier than the RD350 my buddy and I have been building, and thats with reed valves, 30mm carbs and expansion chambers. Your going to want a better platform or vertical engine design to beat his 120.

I have only been riding for a year and my garage is already full. After I could afford parts for my Z50 as a kid and got older it evolved into this. Vintage bikes are what I love.

mexicanyella · 09-08-2009, 05:01 PM

Wow, cool garage-full. What's that scrambler in the foreground?

I have experienced how even a stock early RD350 is a wheelie machine. I should have mentioned one of those earlier in this thread; those things are a blast. I bet with the expansion chambers and stuff like in your picture they are pretty wild once dialed in.

Your GT is pretty cute too, with the clip-ons. Probably makes more sense that way than as a dirt bike or a dragster. Easier on the driveline and more realistic.

z50 chopper · 09-08-2009, 06:21 PM

I m guessing you want somthing in about the same weight catagory as your brothers scooter. Sure you could go get one of the bikes some of these guys have mentioned but that I am sure would be out of your stated price range. So here are some options keeping with the vintage theme 1) build up a warmed over st90 engine, 2) find a CT70 or Z50 and build it into the street terror you envision, CT70 being the preference.

mexicanyella · 09-08-2009, 07:06 PM

Sure you could go get one of the bikes some of these guys have mentioned but that I am sure would be out of your stated price range.

I think I agree here. Any of those old two-stroke hotrods from the early-mid 70s, if priced at $600 or below, would probably either not run well or at all, or would be pretty ratty. It would not be a cheap way to beat your brother, I guess.

So here are some options keeping with the vintage theme 1) build up a warmed over st90 engine, 2) find a CT70 or Z50 and build it into the street terror you envision, CT70 being the preference.[/quote]

If you decide to build a hopped-up 90, do some research on transmission options. My own 90 experience is from being around several friends' ATC90s and 110s, back in the 1980s. These things had four-speeds with a high/low range, and as I recall there were a few high/low crunches that happened with these. The CT90/110 (sometimes called "Trail 90/110," or "postie bike" if you're Australian) had the high/low too. But I think there were some four-speed NOT hi/lo ones early on; maybe the S90 or C90 or CL/SL90. Although these will be fairly rare. Some of these might have had manual clutches too. Worth a look. If you could come across a parts motor with a complete tranny...

It won't be a tire-burner, but it might be fun enough to be worth it. I've had a dim recollection since posting yesterday of an old motorcycle magazine article from the early 70s where the editors built up a CL or SL90 with a big cam, locked-out centrifugal advance mechanism (always advanced, I think), bigger carb, tuned pipe...they didn't have a hopped-up Honda Elite to drag against but they mentioned it gained some sudden wheelie ability that it had not had before and was pretty fun.

dsrt4 · 09-08-2009, 10:28 PM

What does this scooter top out at?

My 1972 LT2 yamaha 100cc is a freaking rocket and with the front and rear gear change, mx100 carb, and the debaffled pipe it can sit at a easy 60-65 mph with my fat ass on it. And its pretty Damn quick out of the hole as well...

This is what mine looks like below, Down to the tee.
These guys are right about the small 2 smokers get one and he will be seeing your tail lights.....

MakeshiftPatriot · 09-09-2009, 12:51 AM

Quote:

Originally Posted by mexicanyella

Wow, cool garage-full. What's that scrambler in the foreground?

Its a '65 Suzuki T11, Picked up for $350 at Mid Ohio's Vintage days, its an 80cc two stroke, 4 Down shifting. Pretty neat sport moped but with rough clutch in it now its only doing 35mph, I guess they allegedly do 50.

FindMyCar, in all honesty you should get yourself an older smaller displacement two stroke bike or just save for a full motorcycle, you can easily get a $600 bike in rather good condition. A lot of people get old Japanese motorcycles from inheritance and sell them cheap simply because they don't know a darn thing about it, or only want that "old thing" out of their garage.
My friend bought a '77 Yamaha XS360 for $300 in unbelievable condition, 4,500 miles on it. Dreams come true man, just need to set yourself to it.

09-07-2009, 04:44 PM	#21 (permalink)
dirtbkr188 3rd Gear Member Join Date: May 2004 Location: New Jersey Posts: 2,970	Re: Need HELP ST90 build THAT NEEDS TO BE FAST!!!!!!!!!! All kidding aside, how about some pics of this tire-burning, neck-snapping little Japanese conveyance you're so intimidated by? Some nice 8x10 glossy closeups of that super-secret stealth engine would be great, too. Where did he get the big bore goodies, I'm kicking it around to get a scooter for some track action at a local kart track.

09-07-2009, 05:08 PM	#22 (permalink)
micromachine 1st Gear Member Join Date: Oct 2008 Location: san pedro ca, Posts: 100 My Mood:	Re: Need HELP ST90 build THAT NEEDS TO BE FAST!!!!!!!!!! this thread has no derection! it goes from a st90 build to abunch of nonsense about old two strokes what ru trying to do? My $.02, build that st90 to the best of your ability if its faster cool, if not chalenge your bro to build a st90 faster then yours! if all you whanna do is beat a scooter then stop messin around and use somthing like this. this is what i use to stomp scooters and rc51's

09-07-2009, 05:14 PM	#23 (permalink)
mexicanyella El rey de los puntos Join Date: Aug 2008 Location: Troy, MO Posts: 973	Re: Need HELP ST90 build THAT NEEDS TO BE FAST!!!!!!!!!! I beg your pardon? No direction? To me, the direction is quite clear: it focuses on the original poster's specifying that he wants to build something vintage to whip his brother's scooter. The direction here is this: an ST90 is the wrong tool for the job. And trying to whip the scooter in the first place might be the wrong job. I think this thread stays pretty focused on trying to save him some frustration and expense, and maybe refocus on how to get some enjoyment from what he already has. I was the one who led us into old two-strokes, since those are the bikes that were fast in those days. But I don't think anything I said about old two-strokes was nonsense. So you're into whipping both scooters and RC51s? That's a diverse hobby, right there. I like your bike, however fast it is. It looks great, and I bet it sounds pretty cool too.

09-07-2009, 05:29 PM	#25 (permalink)
dirtbkr188 3rd Gear Member Join Date: May 2004 Location: New Jersey Posts: 2,970	Re: Need HELP ST90 build THAT NEEDS TO BE FAST!!!!!!!!!! So I guess the new direction to take is to post more pics of Sportsters on Steroids...?

09-07-2009, 05:30 PM	#26 (permalink)
micromachine 1st Gear Member Join Date: Oct 2008 Location: san pedro ca, Posts: 100 My Mood:	Re: Need HELP ST90 build THAT NEEDS TO BE FAST!!!!!!!!!! meant no offense by the two stroke "nonsense" comment but my point is just like you said, to get enjoyment out of what he already has! anyone can go by a faster bike but a fast st90 is a derection i think i would be aiming for weather its faster then the scoot or not! if he just went and bought a kawi tripple, his bros just gonna go buy a rc51 ect. ect. ect... btw. yep scooters, rc51, geo metros, i dont descriminate! ill whoop on them if they know thier racing or not, im not picky

09-07-2009, 05:35 PM	#27 (permalink)
doopsx3 3rd Gear Member Join Date: Aug 2008 Location: San Diego Posts: 3,926 My Mood:	Re: Need HELP ST90 build THAT NEEDS TO BE FAST!!!!!!!!!! or you could use anyone of these to spank that mean scooter but seriously, I would keep the ST90 looking as much as stock as possible....ya can warm up the innards with parts n affectionate luv from Firepower and still have a cool machine...I only hacked up my ST90 cuz all I started with was a frame......and it has been a pain....there are lots of cool vintage bikes that can spank that scooter and you do not need 600+ cc's to do it....an SL or XL 70-100 with a warmed over motor (or transplant a 150R engine) and you got a vintage bike that will scoot pretty darn good..that will be street legal

09-07-2009, 08:09 PM	#28 (permalink)
findmycar PM Newbie Join Date: Sep 2009 Posts: 3	Re: Need HELP ST90 build THAT NEEDS TO BE FAST!!!!!!!!!! I will get pics of his scoot in the next few days. The kit was bought on ebay and then it went to the machinist because the tolerance was too high. They had to bore it out because it was at .01 when it was delivered. He figured that out after sticking 2 of them. I agree with the other posts about finding other bikes etc. But, that is not the point of this post! I was hoping to find something that was vintage and can haul the mail! My thought was to do a CT with a 160cc on it, street legal, and call it a day. Do not get me wrong, I like the other responses on this post, I JUST WANT THE VINTAGE RECIPE to put a smack down. I may just have to suck it up and go with a KYMCO Super 8 with a big bore on it. Whatever it is, I need something in that class.

09-07-2009, 10:11 PM	#29 (permalink)
makotosun 2nd Gear Member Join Date: Apr 2005 Location: Washington (southwest) Posts: 510 My Mood:	Re: Need HELP ST90 build THAT NEEDS TO BE FAST!!!!!!!!!! As Yella said earlier, one of these babies would certainly whip the tires off of your brothers bike and would be vintage, cool, and did I say COOL? I rode one of these from Portland, OR to Tijuana, Mexico and back over a 6 day period, so can vouch for EVERY comment about the bike that Yella made. Evil bikes. But pure fun.

09-07-2009, 10:19 PM	#30 (permalink)
cdoublejj 3rd Gear Member Join Date: Oct 2008 Location: St.Joe MO Posts: 1,367 My Mood:	Re: Need HELP ST90 build THAT NEEDS TO BE FAST!!!!!!!!!! well i skipped over most of what was said in this thread simply because i'm to lazy to read it all. If ya can mod it for the regular honda style mounts then get a nice big engine like z155 or yx160 then if ya want make it a 177 or even a 184 then ease on the gas so you don't flip the bike over then hold on tight and haul balls. Or if ya can bore outthe st90 engine any where around 150 then ya might wanna too that looks some others are saying to keep it stock but it looks alot like a ct 70 too so i don't see the big deal unless the bike means something sent-ament-aly. i'm currently waiting for the ups truck to drop off my donnor frame so i can stretch my z50 out to make some room for the oil cooler and then maybe rake it out some to make it more stable at high speeds at which i hope to be at least 60 if i don't fly out of control on stock knobbys and 8inch wheels Last edited by cdoublejj; 09-07-2009 at 10:23 PM.

09-08-2009, 12:51 AM	#31 (permalink)
schofell84 2nd Gear Member Join Date: Feb 2007 Location: Ogdensburg Posts: 277	Re: Need HELP ST90 build THAT NEEDS TO BE FAST!!!!!!!!!! unless your sportster can turn 8k rpms, stay away. i want to see a picture of this 120 two stroke scooter by the way. dang.

09-08-2009, 02:37 AM	#32 (permalink)
MakeshiftPatriot PM Newbie Join Date: Apr 2007 Posts: 42	Re: Need HELP ST90 build THAT NEEDS TO BE FAST!!!!!!!!!! You are going to want something a little better than an ST90 to work with if you want to go a higher cc. You might as well get a Suzuki GT-185 like previously suggested. I bought one for my first motorcycle at $450 with only 5,500 miles on it. In fact I found one just like mine in my city, they aren't as rare as one would think. With how much you are going to spend on an engine you can pretty much have a whole motorcycle. My Z50 with GPX150 is much scarier than the RD350 my buddy and I have been building, and thats with reed valves, 30mm carbs and expansion chambers. Your going to want a better platform or vertical engine design to beat his 120. I have only been riding for a year and my garage is already full. After I could afford parts for my Z50 as a kid and got older it evolved into this. Vintage bikes are what I love. Last edited by MakeshiftPatriot; 09-08-2009 at 02:48 AM.

09-08-2009, 05:01 PM	#33 (permalink)
mexicanyella El rey de los puntos Join Date: Aug 2008 Location: Troy, MO Posts: 973	Re: Need HELP ST90 build THAT NEEDS TO BE FAST!!!!!!!!!! Wow, cool garage-full. What's that scrambler in the foreground? I have experienced how even a stock early RD350 is a wheelie machine. I should have mentioned one of those earlier in this thread; those things are a blast. I bet with the expansion chambers and stuff like in your picture they are pretty wild once dialed in. Your GT is pretty cute too, with the clip-ons. Probably makes more sense that way than as a dirt bike or a dragster. Easier on the driveline and more realistic.

09-08-2009, 06:21 PM	#34 (permalink)
z50 chopper 2nd Gear Member Join Date: Jun 2009 Location: Nanaimo, BC, Canada Posts: 504 My Mood:	Re: Need HELP ST90 build THAT NEEDS TO BE FAST!!!!!!!!!! I m guessing you want somthing in about the same weight catagory as your brothers scooter. Sure you could go get one of the bikes some of these guys have mentioned but that I am sure would be out of your stated price range. So here are some options keeping with the vintage theme 1) build up a warmed over st90 engine, 2) find a CT70 or Z50 and build it into the street terror you envision, CT70 being the preference.

09-08-2009, 07:06 PM	#35 (permalink)
mexicanyella El rey de los puntos Join Date: Aug 2008 Location: Troy, MO Posts: 973	Re: Need HELP ST90 build THAT NEEDS TO BE FAST!!!!!!!!!! Sure you could go get one of the bikes some of these guys have mentioned but that I am sure would be out of your stated price range. I think I agree here. Any of those old two-stroke hotrods from the early-mid 70s, if priced at $600 or below, would probably either not run well or at all, or would be pretty ratty. It would not be a cheap way to beat your brother, I guess. So here are some options keeping with the vintage theme 1) build up a warmed over st90 engine, 2) find a CT70 or Z50 and build it into the street terror you envision, CT70 being the preference.[/quote] If you decide to build a hopped-up 90, do some research on transmission options. My own 90 experience is from being around several friends' ATC90s and 110s, back in the 1980s. These things had four-speeds with a high/low range, and as I recall there were a few high/low crunches that happened with these. The CT90/110 (sometimes called "Trail 90/110," or "postie bike" if you're Australian) had the high/low too. But I think there were some four-speed NOT hi/lo ones early on; maybe the S90 or C90 or CL/SL90. Although these will be fairly rare. Some of these might have had manual clutches too. Worth a look. If you could come across a parts motor with a complete tranny... It won't be a tire-burner, but it might be fun enough to be worth it. I've had a dim recollection since posting yesterday of an old motorcycle magazine article from the early 70s where the editors built up a CL or SL90 with a big cam, locked-out centrifugal advance mechanism (always advanced, I think), bigger carb, tuned pipe...they didn't have a hopped-up Honda Elite to drag against but they mentioned it gained some sudden wheelie ability that it had not had before and was pretty fun.

09-08-2009, 10:28 PM	#36 (permalink)
dsrt4 1st Gear Member Join Date: Oct 2008 Location: St Louis Mo Posts: 181 My Mood:	Re: Need HELP ST90 build THAT NEEDS TO BE FAST!!!!!!!!!! What does this scooter top out at? My 1972 LT2 yamaha 100cc is a freaking rocket and with the front and rear gear change, mx100 carb, and the debaffled pipe it can sit at a easy 60-65 mph with my fat ass on it. And its pretty Damn quick out of the hole as well... This is what mine looks like below, Down to the tee. These guys are right about the small 2 smokers get one and he will be seeing your tail lights.....

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