78 liquid fire. Wants to go Faster???

[JDT]

There is nothing wrong with tinkering but before you tear into the motor everything else on the machine needs to be working correctly before you say "I need more speed and power".

Case in point... A month ago a guy brought his old Yamaha GP to me to "fix" the motor casue it had no top end speed.
This is a center drive boggie system. 12 bearings on the boggies and 7 of them were bad.
Track adjuster bolt was broken on one side and the track was rubbing on the tunnel.

Fixed these issues and it winds out just fine. Never touched the motor.
He is happy.

[monkeystew]

Good Lord, someone help the guy out. We need more people thinking outside the box. Keep the sled, look it over, and make sure everything's working decent. Aaen makes pipes, throw out those puny carbs. 38 mm carbs from a Indy 500 would be a good start. Just re jet. Have someone match up bigger carb flanges to the intake. Remove the starter ring gear from the flywheel. Find a newer liquifier crankcase, which will allow infinite gear changes. I think that both clutches are junk, but whatever. Lighten up on the weights. Use polaris weights. Mess around with primary springs, start close to stock. These case reed motors make some BIG power. Everyone tried talking me out of running a deere oval sled, glad I didn't listen. Porting will give rather large gains 10 to 15 horse with a stock pipe is pretty easy to get. Have fun with it.

[That Girl Racing]

Kurts. In my own synical way I agree with you. Top of my list if I was to do a vintage race would be a 440 rotary valve Rotax. Ran them in open mods , lots of parts and know how out there for them. Our old motors were around 125 hp. If anyone can get 15 hp out of a Kawi stock motor pipe they need to come work for a Pro-stock grass or NHRA race team. That is phenomenal! Still maintain, the best thing for these old sleds is to get them running 100% using the factory tune ups. It takes a lot of skill to change pipes, porting ,clutches etc. and actually go faster.

[JoeRainville]

CFT,

The guys all make good points here. Its hard to make a vintage sled faster and more reliable from a well maintained stock condition. The point that you need a solid foundation is solid logic. For example, did you pull the crank and have the inner seals done? How is your compression? Are all the driveline bearings in good working order, is the suspension movement free? How is the shock? A Hewtech ignition (www.cdibox.com) seems to make them idle smoother and give better low end. Is your 102-C drive clutch worn or is it at 100%?

So, assuming you have a well maintained sled in good working order, there are some upgrades you can do that will make the sled accelerate better and take the bumps harder before you mod the motor. First up, I liked the idea of installing an 80 Liquifire chain case with the roller tensioner. You can gear down the sled for more acceleration, and add Polaris or Cat overdrive clutches to keep the top end. If you want to keep stock gears and clutching, a silver spring in the primary gives her higher engagement and a better acceleration.

For the suspension, you can take a page from the guys running the vintage I-500 and install a modern gas shock in the rear of the skid, and add a coil over in the front, or clone a 78 CC skid using an 80's LF doner. Riding my stock 84 LF back to back with my I-500 prepped sled is like night and day on rough trails. I run FOX shocks on my skiis too, keep the front end from bottoming out so easy. Once you are getting all you can from the chassis, then I would look consider motor updates.

You can go to 36 or 38 mm carbs if the 34's are limiting your power. Aaen does make pipes, but you need to have it ported to take advantage of them. Then you will need to change the clutch calibration to get that higher RPM power to the ground. If you cut the heads to raise the compression, you might have to run race gas if you go too far. (And low RVP race gas does not like to fire in a cold motor, big pain).

So, I would suggest first making sure your sled is up to its potential in stock form, just like several of the guys suggested. Then look at your project goals and budget.

Good luck, and I hope this helps.
-Joe Rainville

[JoeRainville]

However If I were looking to just go fast on a vintage sled my choices in order would be
1. 81 El Tigre 5000, I had modded one, and it was the baddest vintage sled around. From 0-70 nothing would touch it. And the parts availability is good.
2. Arctic cat El tigre 6000, either 440 or 500cc
3. SRX
4. Early liquifier, The late engine are junk for making power.

Hello Kurts,

You bring up some good points. I also agree the Kawi 440 is far more simple than the Kioritz 440 LC, but they are not all that bad. In stock form they have about 7 to 10 hp over the early Liquifire (55 hp in 76, 57 hp by 78). They are also significantly lighter too. I have mine nicasiled by Millenium Tech to address the main thing I hate about Kawi motors: chrome bores. And Jerome does my cranks and "glues" them so the timing does not slip. So far the best stock 440 Kawi's I have heard of were pulling 68 hp on a dyno with only nic'd jugs and Wisco Pro-Lites. No doubt the Kiortz motors have better bottom end torque and always seem to start better too. Plus I think the early LF's sound better.

On a lake, my stock (and tired) 84 Liquifire was just a few MPH slow than Nelson's I-500 prepped 440 El Tigre's and I think with a little tuning my 80 should hold about even with them. And the 80-84 Liquifire chassis has some strong points such as a rubber track, longer travel skid with a wheel kit, oil injection, and light weight. But without mod'ing the motor, it will always eat a 500cc LC El Tigre's snow dust.

Thanks for posting your thoughts,
-Joe Rainville

[Kurts]

Hello Kurts,

You bring up some good points. I also agree the Kawi 440 is far more simple than the Kioritz 440 LC, but they are not all that bad. In stock form they have about 7 to 10 hp over the early Liquifire (55 hp in 76, 57 hp by 78). They are also significantly lighter too. I have mine nicasiled by Millenium Tech to address the main thing I hate about Kawi motors: chrome bores. And Jerome does my cranks and "glues" them so the timing does not slip. So far the best stock 440 Kawi's I have heard of were pulling 68 hp on a dyno with only nic'd jugs and Wisco Pro-Lites. No doubt the Kiortz motors have better bottom end torque and always seem to start better too. Plus I think the early LF's sound better.

On a lake, my stock (and tired) 84 Liquifire was just a few MPH slow than Nelson's I-500 prepped 440 El Tigre's and I think with a little tuning my 80 should hold about even with them. And the 80-84 Liquifire chassis has some strong points such as a rubber track, longer travel skid with a wheel kit, oil injection, and light weight. But without mod'ing the motor, it will always eat a 500cc LC El Tigre's snow dust.

Thanks for posting your thoughts,
-Joe Rainville

I only brought up the cat stuff because it's foolish to run something with limited parts availability if all you want to do is go fast. And having a stock invader, and a stock 440 el tiger, The invader was a major pooch, and up to about 75mph the 5000 spanked em all because it had such a fat torque curve, and it was skis up and right to maintenance RPM where the vader and l/c took off like grandma and didn't go anywhere till they got woundup. Granted the 500 was modded.

This guy want's to go fast on a deere, So none of the above even matters. I think the early lfires were down on power, because that is that's all anyone else had, so they left a lot on the table. Bring it up to late lfire standards, with some 36-38mm carbs, decent reeds, a real exhaust port, and a decent pipe, and it would be up 7-10hp on the later ones, while still coming on hard from the bottom.

[SnowCrossMark]

Bolt ons that made me faster.
1. This ski is the best and is ISR legal for racing.
http://www.newbreedparts.com/newbreed/i ... uct_id=241

2. Camoplast Energy (1” paddle) track works with my widened stock suspension. Driven with two inside Ski-doo drivers on an 80’s Deere hex shaft. I get the same times off the line in all snow conditions. Perfect . . . However there is no room for studs (not enough clearance over the rear wheels when fully compressed).

3. Ignition. A necessary upgrade for performance.
http://www.hewtechelectronics.com/sledparts/kohler.htm

4. I believe this is THE THING to get top performance. Restrict engine torque movement. What I am working on now is an adjustable torque arm from the secondary shaft, under the carbs, rubber end against engine block. Then an adjustable engine brace from the front left frame to rubber against the starter bulge.

5. Protective equipment (Tekvest, nee pads, neck brace, etc.), makes me feel safer so I can go faster.

If you need new, Team clutches are available http://teamaftermarket.com/parts-catalo ... hts-934011
http://teamaftermarket.com/parts-catalo ... 30194-copy
http://teamaftermarket.com/parts-catalo ... tch-421438

P.S. I love to drive my Liquifires. I have always followed JDT's advise and my sled is better for it. DA and Peter called it. I enjoyed this thread. - Mark