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Post by rallyrrr on Apr 16, 2009 22:52:33 GMT -5
Cool. I'm getting my Atlantis running with the original (now modded) iron 50cc cylinder. I cut a window in my piston to help the boost ports. My kick starter exterior shaft retaining ring slipped out of it's groove and allowed the fan-shaped gear to get against my plastic variator fan so I'm having to get a new one of those. I was getting 55 mph(tucked) with this unmodded cylinder and with the original 17.5 carb and unmodded NextR pipe. I now have the 21mm carb and modded (shorter) pipe. I'm hoping for 60 mph which won't be bad for a fifty.
Can you believe I rethreaded a 6mm mj to a 5 mm mj? The 105 from the 74cc kit was way too fat. I had some spare 85mm jets but they were the larger thread ones. It seems to want to rev out now. I'll be getting it off the bench soon to see what I got. Lard is the best threading oil. No kidding.
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Post by rallyrrr on Apr 16, 2009 23:11:34 GMT -5
Mods to my engine etc. include:
Exh. port: Widened at top by 3-4 mm, raised approximately 1 mm and arched top slightly to help rings. Smoothed port out to flange.
Mods to engine etc. include:
Boost port: Noticed ridge at upper exit of port. Ground off and raised port to open 1/2 mm before other xfers. At bottom of port widened and lengthened to match base gasket and also ground out on barrel side to remove a flange that was there. Also cut out a shallow channel from boost port cutout on bottom of cyl. skirt to lower entrance of boost port (where I had ground off that flange there). Smoothed inner channel of port.
All of this work at the lower end of the boost port was in thoughts of working with that window (approx. 12 mm wide X 18 mm tall) I cut in the piston skirt to provide a much shorter path for the compressed mixture as the piston descends. It was in a thin area of the skirt that left reinforced areas intact. The upper reaches of it was level with the bottom edge of the pin boss reenforcement relief. I hope the 3 mm left at the bottom of the skirt below the window will be sufficient. Bits of piston in my crankcase would not be good. A lot of this might have been wasted time and potential damage but who knows.
Aux. & main xfers: Matched to base gasket and tapered dividing partition to a broad point. Smoothed inner channels of ports.
Pipe: Noticed the inside diameter of my NextR flange was much larger than that on my stock cyl. The stock pipe had a tapered bead fit and of course was a perfect match. Therefore to maintain my gas velocities I sectioned, in two pieces, the stock header pipe to the NextR (about 2 1/2 " altogether). Whew. It cleared the frame by a few thou. after it was bolted up.
Bad stuff: Had forgotten I had bungeed the rear brake lever down for stability on my work bench and when I started it by kick starter by hand (battery weak but have tweaked that now with acid, water and charge and it spins like a champ) I revved it and became fascinated by the smoke and smell of 9 month old oil and fuel and forgot to note that the rear wheel was not turning so I may have glazed my clutch shoes.
I've painted a floor board and belly pan I got used from an individual in Miami Beach on eBay. That scooter must have sat in the sun and salty air for a long time from the looks of the parts. But Krylon Fusion sure sticks good to them though and they are at least undamaged otherwise... unlike the cellophane tape held together bits they replaced. LOL.
One other tid bit: While cleaning and flushing out the cyl. after working on it I noticed that you can get a good idea of how your transfer ports are flowing (direction and spread) by observing the water as it emerges into the cylinder while it is held upside down under a heavy running faucet.
Also I am running sans a head gasket for a little extra punch. I think the gasket was like 0.7 mm thick. Sorry I don't have all of this documented nicely in pictures like you always do 90GT.
Going back to 50cc was not by choice. New rings, pin retainers and base gasket was about $38.00 shipped. A new cyl. kit would have been 3 - 6 times that. A sum I did not have. But the riding bug is biting me hard!
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Post by rallyrrr on Apr 16, 2009 23:14:05 GMT -5
Rode my scoot for the first time since early last June. Seems awfully weak off the bottom but I may be used to that 50% more displacement. I've only ridden it a couple of miles and gotten to about 45. Have 85 main jet and started with needle full rich. I dropped it down next to leanest position(only four grooves in needle) and it ran a little better I think. I can close the air screw all the way down and the rpms seem greatest there. I don't like the way it picks up the throttle from idle. The plug showed a light ruddy brown. I mixed 50:1 Amsoil Saber, the same you use, and added a little cheaper mineral oil (Havoline) to make about 40:1. There is very little smoke. Thinking about making my clutch shoes a little tighter for better take off.
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Post by rallyrrr on Apr 16, 2009 23:47:48 GMT -5
Well, I drilled the jet out to around 89-90 and she will rev out. Took Derb out on hwy. and saw right at 60 mph and around 10,200 rpm but I had to tuck down to get it and had a 5-10 mph tailwind. Before I never saw over 9,600 rpm in a similar situation with this displacement. The bad news is she is a dog until the pipe hits at around 7,700. I kind of wish I had not raised the exh. port. I think I will go with 3.0 g. rollers and tighter clutch springs to try to bring back my in town zip. Will have to see if that affects my top speed. I chopped the plug at around 10k after around 2 mi. at full throttle and quickly braked to a stop. It showed a nice medium brown. I've been listening for the detonation devil but it's hard to hear anything over that pipe and K&N filter. When the pipe hits it's like a different engine. It smooths out and quietens down and pulls noticeably better.
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Post by rallyrrr on Apr 16, 2009 23:58:57 GMT -5
Cool. I guess I should have broken in my rings more carefully. My scoot wouldn't start today. The compression wouldn't blow my finger off. I thought it was running alright when I shut it down. Oh well, tear down coming, live and learn. Shudda knowed better.
A day or two later...
Had the Derb back on the road today. Kicked it three times and it started. Sometimes when your compression is borderline you can make one start with the kick start. Gives more of a "spike" in the compression... often enough to start .
Just went out and it started right up on the button after it had cooled completely. Didn't have to use the choke. I'm thinking I've got my pilot jet too big. I made it a little bigger since I could close my air screw all the way down and it seemed to idle best then. Maybe I need to take my carb apart and clean it better. Think I'll order the 3 g. rollers and go from there. Acceleration is terrible 30 - 42 mph
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Post by 90GTVert on Apr 17, 2009 4:31:28 GMT -5
Glad to see you doing this. I had thought of making a thread for you, but didn't wanna step on any toes. Most of your posts have been in my Triton 2.0 thread. It seemed like a shame to me for you to be burying the info about a 60MPH 50cc in with all the stuff about my 50-55MPH 99cc.  |
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Post by 2strokd on Apr 17, 2009 5:08:57 GMT -5
Congrats on getting the Mighty Mite Red Bullet going rally! 60mph with 50cc! Thats great to hear man. I always say it would be great to get a mile per hour out of every cc, looks like you did even better. +1 for all the interesting port work and getting her back on the road.
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Post by 90GTVert on Apr 17, 2009 5:20:28 GMT -5
I always say it would be great to get a mile per hour out of every cc, looks like you did even better. rally really needs a 100cc.  |
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Post by rallyrrr on Apr 17, 2009 11:50:38 GMT -5
Thanks guys. I'm not trying to brag or put anybody's ride or mods down. Tuning is just a hobby and I just like to experiment and, out of necessity, do it as cheaply as possible and maybe help others so interested.
Yes, 90GT, it would be fun to start with a Genuine Rattler Buck Ten and try to get about 85 out of it and live to tell about it. LOL.
Along the larger displacement lines, I have won a 70 Top Performance iron kit on eBay for $121.00 shipped. That's why I have not bought lighter rollers etc. to aid my acceleration.
I guess I just got used to that extra torque and want to use the scoot for longer trips and don't want to be impeded by hills so much.
I am thinking about playing a little more with the 50 though and try running w/o a base gasket (0.5 mm) to boot the comp. ratio a bit and drop the ports that much to see if it would help my mid range at all.
Anyway, to bring the saga up to date:
I don't know why old rojo would not start after that first high speed run??? She starts right up now. I've played a little more with the mj thinking that 90 was a little fat and holding me back on the top end and knowing with the weather warming up it would just get worse. I filled the original 105 with electronics solder and wound up settling for about 87 (#61 drill). I took her out for an extended high speed run a couple of days ago. Ran with the throttle pinned/near pinned for about 6-7 miles and chopped plug. It was about the color of corrugated cardboard on the tip and darker below with no signs of cement boil at the center electrode.
Someone please tell me if my pilot jet is still too small. I am running about 52 right now and the idle still seems smoothest with the air screw all the way in. I hate the way it takes so much throttle to come off of idle. It seems to me that I have to turn the idle speed screw too far in to get an acceptable idle and I wonder how much I am getting fueled through the idle circuit. I have taken the carb completely apart and have sprayed it out throughly. Doesn't that pilot jet seem big enough to you guys or do you think I need to go bigger?
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Post by rallyrrr on Apr 17, 2009 11:56:13 GMT -5
Brent,
I'm going to delete all my posts in your Triton etc. thread. Hope this doesn't cause too much trouble with your commenting on my comments there. I should have started my own thread on this subject and I apologize for cluttering yours up.
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Post by 2strokd on Apr 17, 2009 12:30:23 GMT -5
52 is the size of your pilot? That sounds plenty big enough to me. If your jet #s are around the same as mikunis, that would be to much in my scoot, im running a 32 pilot with the idle-air set at 1-1/4 turn out for now
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Post by 90GTVert on Apr 17, 2009 13:12:04 GMT -5
Someone please tell me if my pilot jet is still too small. I am running about 52 right now and the idle still seems smoothest with the air screw all the way in. I hate the way it takes so much throttle to come off of idle. It seems to me that I have to turn the idle speed screw too far in to get an acceptable idle and I wonder how much I am getting fueled through the idle circuit. I have taken the carb completely apart and have sprayed it out throughly. Doesn't that pilot jet seem big enough to you guys or do you think I need to go bigger? 52 sounds big enough, but it's hard to judge by numbers. My 25mm has a 70 pilot and my 19mm had only a 20 pilot IIRC. I would think that anytime you have to turn the mixture screw all the way in you should consider the next step up in pilot jets. If you are going to install that Top Performance 70cc kit, maybe you should hold off on the jetting if it's good enough for now. Not sure how great of an effect the additional vacuum of a larger bore will have on the pilot circuit? |
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Post by 90GTVert on Apr 17, 2009 13:15:15 GMT -5
Brent, I'm going to delete all my posts in your Triton etc. thread. Hope this doesn't cause too much trouble with your commenting on my comments there. I should have started my own thread on this subject and I apologize for cluttering yours up. It doesn't bother me either way. Do whatever you would like. If you delete them and it looks weird I can go back and delete anything I replied with. Don't apologize for adding great information Reg. That's one thing we can always use more of. |
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Post by rallyrrr on Apr 22, 2009 23:08:32 GMT -5
I started to ride my scoot downtown on an errand and it would not start. I decided to pop off the cyl. and check out my options on possibly running w/o a base gasket. After cleverly putting the bike up on my banquet table somehow by myself. I said to myself, "I bet the SOB will start now." I pushed the button and sure enough... it did.  Isn't it amazing what 30" change in elevation will do? ;D Anyway I decided to go ahead and take it down. After getting the cyl. and base gasket off I measured the thickness of the base gasket. It was 1.0 mm thick. I was thinking that 1.0 mm would be a pretty drastic change in the comp. ratio and remembered that I had ordered a new base gasket with my rings. It measured 0.2 mm so I enlarged the stud holes in it so my larger (from a scrap Mineralli clone) cylinder studs would pass through it, used it and reassembled the top end. My sorry intake was cracked open again (Gorilla Glue was the last thing I had tried. I know nothing will take it off your hands. ::)Only it dries brittle so I guess this is why it didn't hold) I'm trying 3M brown gasket adhesive and possibly something on top of that. So that is curing overnight. My iron Top Performance Trophy Series 70 cc kit came in today. I was pretty impressed with the quality. I would say that it is a little better than the aluminum AIRSAL T6 that flaked (literally) out on me in the quality respect although it is not as performance designed (butterfly bridged exh. port and squish type head) as the AIRSAL. The TP kit has a single trapezoidal-like single exh. port and a combustion chamber like the stock head. The underside of the head is anodized with a black oxide that is supposed to aid heat xfer. The inside of the ports seem to be powder coated or painted with glyptol to assure smoothness. The exh. flange is a taper fit like my pipe.  The piston has two real pretty 'eyes' in the skirt on the boost port side that lean outwards from bottom to top for cooling the pin bosses and underside of the piston. Also the upper ring is chrome plated and the rings are semi-trapezoidal in cross section and are guaranteed not to stick. I laughed when I read a description of the kit in the assembly instructions. Quote: "designed and developed by us for agonistic purposes only". I had to look up agonistic. It basically means competition. Also after the assembly instructions I read, "You will have a lot of fun and a great many emotions with your scooter thus tuned up, etc." I chamfered all the port edges and inner skirt edges at the bottom as they were pretty sharp. I used a ceramic stone. I filed a chamfer on the bottom of the piston skirt for oil trapping. I will still have to drill out (enlarge) the cyl. stud holes for my thicker cyl. studs. I'm pretty satisfied since American Scooter Center, Austin TX normally sells this kit for $150.00 + s&h. No one bid against me and I won it on eBay for $99.00 + $22.00 s&h (I guess they gotta make a little money somehow). |
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Post by 90GTVert on Apr 23, 2009 5:09:02 GMT -5
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Post by 2strokd on Apr 23, 2009 6:50:50 GMT -5
Thats a good deal on the 70cc Top kit. Glad to hear you got it. That should give you the low and mid range you were starving for. Hope you cant get that intake sealed up before you start running a new cylinder. Cant wait to here the results, have fun rally.
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Post by rallyrrr on Apr 23, 2009 22:41:40 GMT -5
Hey maybe I could put about a dozen condoms on it. ;D Go down to the public health clinic and get some free ones you know.  Wouldn't have to worry about STDs then (scooter transmitted disease). ;D |
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Post by 90GTVert on Apr 24, 2009 5:22:38 GMT -5
At least that's better than waiting until it's married. That would require too much Sta-Bil.
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Post by 2strokd on Apr 24, 2009 7:04:27 GMT -5
LMAO guys, just woke up to this lol. Thanks fer the laugh guys!
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Post by rallyrrr on Apr 26, 2009 21:23:22 GMT -5
I thought I posted here yesterday so either I'm going nuts or something else is going on with the site. Probably the former.
I won't post the detailed post I did yesterday... just kind of fill all in on the latest.
Anyway I dropped 0.8 mm off my base gasket thickness raising my CR and dropping the ports that much. I needed to install a new variator fan so I also checked out the variator, clutch and belt and found all to be well except that the clutch shoes were glazed which I rectified by sanding the shoes and bell.
I've ordered a new stock intake but put the patched one back on. Put the rest of it back together (fan cover, cylinder shroud and seat) and went for a ride.
It was like a different scooter. The weak spot between 5 & 7 thou was gone but top speed was about the same if not a few mph slower. It was still a little flat coming on the throttle so I raised the needle two positions and that seemed to cure that.
My tach has stopped working so I guess I'll check that out next. I'll probably get tired of only 50cc soon and pop on my 70 kit. I really want to upgear too.
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Post by 90GTVert on Apr 26, 2009 21:50:46 GMT -5
You need more torque, it's time for the 70. ;D I've never done upgears on a scoot, but I worry that a 70cc with upgears goes back to taking off like a 50cc and has no punch. Going 65-70MPH is cool, but I hated the 50cc acceleration. I guess enough CVT tuning can vure it to some degree though.
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Post by rallyrrr on Apr 26, 2009 22:28:13 GMT -5
I really have no desire to to ride my scoot 65-70(although if it will do it I'm sure it will happen). I just want to drop the revs for cruising around 55-60 to around 9 grand.
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Post by 190mech on Apr 27, 2009 20:37:43 GMT -5
I agree Rally,if one could cruise at less than a billion RPM would
be a good thing!Those "over range pulley kits" look interesting
but a bit costly..Looked thru all the ad hype and could'nt find
any good info on how good this system worked..I see its a set
of larger pulleys to increase gearing,could a guy get a drive set
from perhaps a 150cc scooter and adapt it to our 50 size scoots?
Just thinking out loud....
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Post by rallyrrr on Apr 27, 2009 21:33:51 GMT -5
That's good thinking, 190mech. I would venture to guess that shaft diameters and splines would be larger on the 150 machines. If one had access to a wrecking yard and the right equipment I'm sure it would be doable. I can get a primary up gear kit for $70.00 + shipping. I just don't want to go too far and dog out my acceleration too bad.
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Post by 90GTVert on Apr 27, 2009 21:53:30 GMT -5
I had thought the same thing about 150 pulleys. I would think the crankshaft splines on a GY6 would be a lot bigger than the 13 or 16mm on a minarelli, as rallyrrr said. Probably the same for the rear pulley. I'm not even sure their diameters would allow them to fit in the case. The GY6 clutch looks cover looks a bit deeper as well. It would be worth a look to know. The sad part is, there's a GY6 150cc scooter in my garage... but I can't take it apart. It belongs to a friend and he's kinda, "if it ain't broke, don't fix it". It's got 2,200 miles on it and the CVT cover has never been off. I can build a custom exhaust for it, upjet, and add a K&N, but he doesn't want the CVT cover off. He said we (I) should take a look at it after this summer, so don't hold your breath on a definite answer from me. lol
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Post by 190mech on Apr 28, 2009 19:51:52 GMT -5
There is a guy down the street from my work who has a bunch of
old scoots,think he's got a 150.I'll try to check it out in the next
few days..I see on my 50 scoot that we have a star shaped stamping that drives the outer pulley and the inner is on the stamped roller carrier,both steel,weld friendly..Perhaps a bushing
for the inner sleeve to take up for the smaller crank..Have not
thought about the rear clutch/pulley though.May not be worth the
hassle,but its worth a look anyhow!
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Post by rallyrrr on Apr 28, 2009 20:38:16 GMT -5
I'd be willing to bet that somebody in Puerto Rico has done it!
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Post by rallyrrr on Apr 29, 2009 16:58:16 GMT -5
Checked my gas mileage. Not real sure about the accuracy of my computation, but I pegged it on the North side of sixty. That makes me pretty happy. Next check will be more accurate.
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Post by 90GTVert on Apr 29, 2009 22:00:49 GMT -5
I'd say 60MPG is pretty good for a 60MPH scoot.
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Isn't it amazing what 30" change in elevation will do? ;D Anyway I decided to go ahead and take it down.
The piston has two real pretty 'eyes' in the skirt on the boost port side that lean outwards from bottom to top for cooling the pin bosses and underside of the piston. Also the upper ring is chrome plated and the rings are semi-trapezoidal in cross section and are guaranteed not to stick. I laughed when I read a description of the kit in the assembly instructions. Quote: "designed and developed by us for agonistic purposes only". I had to look up agonistic. It basically means competition. Also after the assembly instructions I read, "You will have a lot of fun and a great many emotions with your scooter thus tuned up, etc."
Wouldn't have to worry about STDs then (scooter transmitted disease). ;D