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Post by weverat on Nov 19, 2014 20:47:17 GMT -5
Test rode it last night, and it would not break 5500 rpm. The clutch is a new comet for a John deer, something I bought off e-bay or Craig's or something, and just bolted it on, with the thought of adjusting from there.
Tonight, as usual, always out of time and day light (no head light), I played with the clutch a bit. As purchased it has R weights, and a real super light spring.I gave it a heavy spring,now it engages @ 4700, and pulls like gang busters.
I was unable to get any more tach readings, as it was dark, and when the rpms came up, the gage lights blew out. I guess the used regulator I pulled out my collection was a bad one!
It will take a couple of good Saturdays to initially sort things out, then add studs, find some ice, and start the whole process over again. I guess racing is fun?
Stigerater, and Tomcat, where you guy's ben, I am gonna need some help at Clear Lake!
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Post by weverat on Nov 17, 2014 21:16:52 GMT -5
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Post by weverat on Nov 17, 2014 21:10:52 GMT -5
This project has been in the works for awhile, started out building the free air 6 bolt, and later decided to go with a 71 chasis converted to a bubble. These are really nice light weight little sleds. It is a runner now, but needs test and tune. Carbs are still crazy rich, and the clutch is way off, but good enough for some break in time. I am hoping to get it sorted out and run it at Waseca, and Waconia this year.
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Post by weverat on Nov 14, 2014 17:21:53 GMT -5
No, I have a 503 in a Lynx, plenty of power, but no traction. The Stingeroo will probably be the same,spin the track at any speed, fun to ride though.
Be sure to mount up a big Walbo, so you can crank the screw on the fly.
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Post by weverat on Nov 11, 2014 20:45:48 GMT -5
The one on the clutch is an old waldo being used as a pump to feed the Mikuni. I know normal pumps are cheap and work well, but I was thinking vintage spirit at the time. I found out the old Waldos make great pumps.
You know OBJ I can only use the Mikuni on the grass, on ice we have to use the stock carb ! (Stock appearing)
I have never checked ET with each carb on the same day, but I think it runs about the same with Waldo, or Mik. I know one year at Okaboji it was warm and foggy and it was dam handy to crank the screw a little.
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Post by weverat on Nov 11, 2014 20:34:00 GMT -5
If you were running a Waldo, you could crank the screws on the fly, and get er spot on for the moment. I know they really start and run nice with the Mikuni, butch ya know what I mean.
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Post by weverat on Nov 7, 2014 22:04:23 GMT -5
No,never Ben to the Willow party. I met you the first time about 3 years ago at Waconia, I was racing a 72 Stinger, with a 440 4 Bolt.
Two years ago at Princeton, I brought the ice racer, and ran it on the grass, you guy's gave me a good spanking.I remember it was hotter then hell that day, and I was way over clutched, and way to lazy to do anything about it. All the sleds were under powered that day.
Last year I failed to bring a grass dragger, but I did hang out with the Scorpion crew.
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Post by weverat on Nov 7, 2014 16:01:02 GMT -5
What are going to do with them. Are they both 4 bolt motors.
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Post by weverat on Nov 7, 2014 15:20:28 GMT -5
Inventory? Are you a hoarder ? Hoarding all those Tahatsus and vintage Polaris triples.
How about pipes, do you have a collection ? I know I am sick, I'll bet there is 25 to 30 pipes in my stable, not sure what they even fit anymore.
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Post by weverat on Nov 6, 2014 21:06:10 GMT -5
What would be the perfect engine to shoe horn into an old Scorp ?
My first choice would be a 503 Rotax, but there has to be something even better, maybe newer. It has to be a fanner for simplicity. Free air is cool, but we don't want to be cutting holes in them old rare hoods !
Hey, how about a Yamaha SRV 540, they make good power.
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Post by weverat on Nov 6, 2014 14:43:33 GMT -5
Tahatsu twins, is that Rupp ? Were they used on anything else? I have seen them, but never played with one.
I agree Sachs singles are great motors. What about Sachs 440 c ? I have a small collection of those, thinking about restoring one for a 71 Scorp. What is the difference between a 440c and a regular 440?
As far as favorite vintage motor, I will stick with Cuyuna for now, although I like them all. A far as modern engines, I like the 503 Rotax, or any modern 440 fan with twin carbs and a decent pipe, which includes the 485 Phazers, only problem with the phazer is they have weird motor mounts making them hard to shoe horn into an old Scorp!
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Post by weverat on Nov 5, 2014 23:26:26 GMT -5
You might be playing around with the CCW for awhile, they are tough little engines,easy to start, and can really take a beating. Oh ya, light weight too. I sure like the 400 and 440 cuyunas, but give that CCW a chance to shine, I mean try to kill it, they just won't die.
I also have a 400 CCW, hard to start, heavy rope, bigger heavy motor just not as sweet as the little 290. What's you favorite motor ?
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Post by weverat on Nov 3, 2014 23:52:16 GMT -5
I agree with Scorp11, bigger might possibly improve wide open performance, but with big carbs you need big jets.
Small carbs create lots of velocity, and therefore carburate very well.
If I can run a mikuni with a 250 to 350 main jet, then the bore size is just right. When I jump up to a 38, 40 or 44, I wind up using main jets in the 400 to 500,s and I suffer at 1/4 to 3/4 throttle, as there is just not enough velocity to make the dam thing work.
On the other hand, if the main jet winds up being real small, like 150 to 200, I jump up one bore size.
You will be surprised how nice a 36 or even a 34 will work.
Also, when adapting Mikunis, it is always good to verify the needle jet is big enough. Simply drill out an old main jet to 1/8 inch,try running at wfo, if it doesn't flood and boggle, jump up the needle jet at least 2 or three sizes. Seems like my sleds wind up using Q2 or Q8. A P4 is usually to small.
Small carbs carburate well.
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Post by weverat on Nov 1, 2014 20:46:57 GMT -5
I do not think you will gain anything, plus with the standard 38 you dont have to wonder if the power jet circut is working.
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Post by weverat on Oct 23, 2014 14:24:03 GMT -5
SeatSorry my link failed, I try again
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Post by weverat on Oct 23, 2014 14:12:32 GMT -5
linkDoes anybody know who is making these seats ?
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Post by weverat on Oct 23, 2014 12:27:23 GMT -5
Ok here is my thought, If you remove the spring, the timing stays at full advance all the time, so you have to back the timing down to .070 - .080 BTDC, otherwise the thing will back fire and jerk the start rope out of your hand.
I think of the auto advance as actually an auto retard so we can start the motor with out back fire. Some of the 2 cycle motorcycles are this way, but you are using a kick start.
As far as this modification making the engine start easy, as all I can think of is maybe it changes the break away or edge gap to a point where you get a stronger spark. ( stronger primary voltage to the points and coil)
Like Dubb say,s they are running at a constant rpm, so why not set the timing for desired rpm and leave it locked in right there, as long as you can still start it. Maybe they do start better this way ?
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Post by weverat on Oct 13, 2014 20:09:04 GMT -5
Hi elevation will cause a rich mixture, and a loss of power. If the 310 works well at sea leval, you could possibly work it down like this, 280, 260, and finally 250. Ever so carefully !
Rich on the main is safe, especily when racing your buddy all the way across the lake on a groomed path.
These little motors lean out when they get hot.
Only race for a mile at a time. I often shut it down at wfo, and then check the plug (plug chop), this way you are checking main jet mixture.
Usually we only adjust the needle, and live with the rich main. I am in southern Mn, adjusting for temperature.
The very best is them there old tunnel mount Scorps, with a nasty walbro. I like to put a big thumb srew on the high speed mixture screw, and crank on it all the time. One hand on throttle, the other on the screww. Tight woods in 1/2 turn, open smooth trail back er out till it stinks, then back in as far as you dare!
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Post by weverat on Sept 9, 2014 21:26:24 GMT -5
Check out the funky home made twin carb adapters, made from a stock manifold.
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Post by weverat on Sept 9, 2014 21:22:01 GMT -5
Princeton was a blast, realy fun hanging out with the all Scorpion crew. Certainly plenty to talk about. Leave it up to Obj to recognize Roger in the avatar pic, does he still have that sled? Strange how it works out, I have been working on a 6 bolt JLO free air conversion project for a while and it is almost done, and then I come across the real thing. This one is a 4 bolt, and I am anxious to dissasemble in order to check bore, stroke, and port dimensions. Of course being such an old motor, who knows what is factory, and whats been changed, but I can't wait to compare it to a stock fan motor. Attachments:
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