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LOL......it's all relative I suppose :rofl ,ain't no Mach or Formula-X for certain. I had the 380 H.O. Citation SS out for a "proper" rip and with my fat arse on it clocked with GPS at 110kph.(or 68mph for my American friends). I'm guessing that is pretty decent for an 81 Citation SS. Well worth the little effort to bump the comp. ratio and smooth out some casting flaws + match the cyl's to the case.

Steve
 

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Congrats on the 380HO.

How about a few photo's of the Sled, and Engine?

What was the Top Speed of the original 377/380 Stock 36hp? Did you make any more changes for the Higher Compression? After you get it broke in good, say 100-150 miles, let's see another Compression check to see if the cylinders evened out more.

Did you use the Stock Pipe, or make a Pipe change?

I just scored a set of 377 Heads for $12 off ebay. One head has a beat up chamber, other is in great shape. I may have to weld up the one first, and then machine it, or just try my insert idea on this set.
 

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Congrats on the 380HO.

How about a few photo's of the Sled, and Engine?

What was the Top Speed of the original 377/380 Stock 36hp? Did you make any more changes for the Higher Compression? After you get it broke in good, say 100-150 miles, let's see another Compression check to see if the cylinders evened out more.

Did you use the Stock Pipe, or make a Pipe change?

I just scored a set of 377 Heads for $12 off ebay. One head has a beat up chamber, other is in great shape. I may have to weld up the one first, and then machine it, or just try my insert idea on this set.
Sled looks like all other 81' SS's,engine too. Never got a chance to check it out before as the wiring was fried,steering farked up,crank bearing cages(plastic),were melted. Like I said in a prior thread rebuilt with CDI too. Just running Klotz HiTrate+91 oct.

I will re check compression at end of season. Stock pipe on this one.

Your cyl. head will clean up fine after you cut the head & redo the squish,mine was worse than that. Don't forget to cut in an O-ring.

Steve
 

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That's awesome Steve. I would love to do that to my 377 currently in an Elan frame. No speed records broke. I'd like you to direct me to the thread where you built this motor.
 

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I used to be able to ride the ditch and pass cars on the highway , 100 kph limit with my mirage special, sonim sure I must have been going at least 110, never could get a good enough look at the speedo going wot...too busy hanging on ,lol, .
 

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Idk if it was setup but I had w 4500 single carbed 377, one was points the other was cdi, the one with points was slightly faster then cdi, points would do 70 mph the cdi would do 65 mph, those were really fun sleds, easy to throw around on the trail very light, but didn't like any accumulation of snow, off trail bring a shovel if they made it that far. got stuck super easy.
 

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who know's, it was always slightly faster then the cdi engine and it was bone stock. and that was on the dream o meter, so who know's how accurate that is.
 

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Sled looks like all other 81' SS's,engine too. Never got a chance to check it out before as the wiring was fried,steering farked up,crank bearing cages(plastic),were melted. Like I said in a prior thread rebuilt with CDI too. Just running Klotz HiTrate+91 oct.

I will re check compression at end of season. Stock pipe on this one.

Your cyl. head will clean up fine after you cut the head & redo the squish,mine was worse than that. Don't forget to cut in an O-ring.

Steve
You have to remember, most young kids/people, have never even seen these old 60's, 70's, 80's, even 90's Sleds. I'm going to be 59 in March and I have seen very little of the old stuff myself, especially the 70's, 80's, stuff. I rode some different sleds in the 60's, Rupp, Skidoo, Arctic Cat, etc., when I lived in Clear Lake, IA, but we moved to Illinois in 69 where we had no snow. So I didn't even have any Sleds myself till 10-12 years ago, and there 90's sleds, 93 Arctic Cat 580 EXT, 94 Yamaha Vmax 600, 95 Yamaha Vmax 600. I bought them all in about a 2 month period, all with about 1800 miles on them.

I hope this 377 Head cleans up. Had a bad cold so I haven't been doing much in the shop. I'll get the lathe fired up soon and see if it does. They haven't come in the mail yet, so I will Glass Bead them.
 

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Idk if it was setup but I had w 4500 single carbed 377, one was points the other was cdi, the one with points was slightly faster then cdi, points would do 70 mph the cdi would do 65 mph, those were really fun sleds, easy to throw around on the trail very light, but didn't like any accumulation of snow, off trail bring a shovel if they made it that far. got stuck super easy.
Go to this website below and punch in your Old Sleds Info to see what it should do Speed wise. Then Post it.

http://www.turboaddictionparts.com/catalog/snowmobilecalculator.html
 

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doesnt' even matter now, I've gotten rid of them over 10 years ago, but I have lots of fun on them, I see them for sale all the time for 800 $ amazing, I guess they don't depreciate more in value, they were selling for that same price 10 15 years ago. that is a mint one mind you, rough ones are depends what you can negotiate them down to
 

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doesnt' even matter now, I've gotten rid of them over 10 years ago, but I have lots of fun on them, I see them for sale all the time for 800 $ amazing, I guess they don't depreciate more in value, they were selling for that same price 10 15 years ago. that is a mint one mind you, rough ones are depends what you can negotiate them down to
I just missed an old 70's 340 TNT that was in very nice shape, no spark on one cylinder, and small tear on seat cover for $150. I could have had a whole 72 Oly for a $100, but it was to far away, so I offered him a $100 for just the 335 motor if he shipped it to my door, and he took it. No Spark, but other wise in pretty good shape.
 

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I would love to find an 6500 or 79 7500, I would almost have to say that is what dreams are made of, but people know what they are worth. check this out http://www.kijiji.ca/v-snowmobile/sudbury/1972-hurricane-644/1134319029?enableSearchNavigationFlag=true too bad I don't like them really old ones.. that one would be something to talk about on the lake... after you unleash all 35 hps to the ice
You have to remember, most of those old sleds didn't use very high compression ratio's, no Tuned Pipes just mufflers, some were rated at even low Rpm's, and if you do all the modern improvements, they can make much more hp. I do most all of my own work, and have the tools to even make some parts. I wasted a lot more money drinking at the bars in the last 40 years, what's a little money invested in a fun toy! If you shop around at swap meets, ebay, craigslist, you can find cheap high perfomance parts. I have bought NOS Billet Heads off ebay for $35. You can always adapt other engine parts to these engines also. Some times, you just have to Think Outside of the Box!
 

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Well the $12, ebay 380 Heads came today. Just got them Cleaned of Oil, and Glass beaded them, cleaned up pretty good, no bent or damaged fins. Will see if the Chamber cleans up good when I machine it. I'm going to Ceramic Coat the Chambers anyway, and use the Heat Dis-percent Coating on the out sides. I might take a little deeper cut than you did. The Ceramic Coating will build it back up a little. Will see.
 

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I'm quite amazed how big of a compression bump a small difference in compression ratio makes. I just finished a second motor and got lazy & didn't take the ratio up to the 11:2 (187/195 psi) of the first one. I only went 10.8:1(175/177 psi).once I get this in a chassis I will build a pipe or pipes,not sure how to go about doing the "two into one" type pipe.

I have a small problem however.I converted this one to CDI as well but am only getting spark on one side. Tried new wires,checked stator for ohms & both sides were identical,is there a way to check coil & CDI box ??

Rich,post pics of your before & after.

Steve
 

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I'm quite amazed how little big of a compression bump a small difference in compression ratio makes. I just finished a second motor and got lazy & didn't take the ratio up to the 11:2 (187/195 psi) of the first one. I only went 10.8:1(175/177 psi).once I get this in a chassis I will build a pipe or pipes,not sure how to go about doing the "two into one" type pipe.

I have a small problem however.I converted this one to CDI as well but am only getting spark on one side. Tried new wires,checked stator for ohms & both sides were identical,is there a way to check coil & CDI box ??

Rich,post pics of your before & after.

Steve
The first photo's was the guys ebay photo's, got them cleaned last night, I still have to take some photo's.

Did your second set of 380 Heads CC the same as the first? What did you takeoff them for a 10.8:1(175/177 psi)?

Yes, it would be nice to see a Dyno Test of a say a 380 using the Stock 9.6, and then going up in say 1.0cr increments 10.6, 11.6 12.6, 13.6, 14.6 to see the changes in HP, and Cranking PSI.

Try swaping your CDI Box from other motor, and then the Coil, has to be one of them. That's the easiest way.
 
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