My Third (and Fourth) vintage sled projects..... 1979 Polaris TXL 340 @ Centurion 500
- Thread starter kirk600
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skiroule
Well-known member
Nice work Kirk! The sled looks fantastic. Love the midnight blue paint and the graphics on that sled. Those TXL exhaust systems have a really distinct sound and that motor is silky smooth. It’s interesting that Polaris updated the TXL models to a newer hood/dash design in 79 but kept the 78 hood/dash on the TX’s. Hopefully you’ll get it out on some of that fresh snow next weekend. Think it will be fun for you to take that chassis for a ride again.
Yes it should be fun, just need to stay out of the deep snow this time..............
So today I pulled the TXL out of the trailer for a quick ride........ quicker than I hoped as the brakes quit working. Here's a few pictures and will try to ad some video to my blog....
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Here's the last few pictures..... got the centurion up on the lift now, and pulled the hood off to try and repair some cracks and replace the ski's
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My Vintage Polaris
I I Y Here's the TXL clutch checking. Both clutches the stationary sheave is .400" thick The measurements are .730" for the TXL clutch, ....
kirksvintagepolaris.blogspot.com
Here's a couple new videos... not the greatest as I found out the brakes didn't work!! The brake line on the TXL is a plastic one, (unlike the braided metal line on Centurion) and apparently I cracked it shutting the hood after I rode it out of the trailer. I will replace it with a braided line to prevent it from happening again. Then I will get a better video guys
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Here my attempt to fiberglass the hood, to repair a crack on my Centurion! Hopefully it will hold and I will add another layer.
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So not much to report, been trying to get the TXL running better but it is just too tired. Did a compression test and the best cylinder was only 100psi so I am going to put a new top end on it. Need to pull the cylinder head and get a look at things and measure the cylinders and then determine if it needs bored or just rings or rings/pistons.
In my trials to improve the idle and throttle response, I reduced the size of the pilot jet from stock 45 to 40 and finally tried some 35's and although it dried the spark plugs out, it would not idle well down low and throttle response was poor. I then dropped the needle down 1 clip with no change. I didn't have any smaller main jets than the stock 260's that is why I dropped the needle. Looking at a warm up here this week so my next ride might be a while.
On a good note I did compression test on the centurion, and on a cold motor all were between 110-120psi so it should be better from the start.
In my trials to improve the idle and throttle response, I reduced the size of the pilot jet from stock 45 to 40 and finally tried some 35's and although it dried the spark plugs out, it would not idle well down low and throttle response was poor. I then dropped the needle down 1 clip with no change. I didn't have any smaller main jets than the stock 260's that is why I dropped the needle. Looking at a warm up here this week so my next ride might be a while.
On a good note I did compression test on the centurion, and on a cold motor all were between 110-120psi so it should be better from the start.
well guys, I drained the coolant from the TXL and pulled the top end apart. What I found was a circlip was gone on one piston, and wrist pin had wore a groove in the cylinder, which wore down the piston and ring. It's too deep to repair, and being a mono-block engine I get to replace both cylinders . It is a shame as the motor is/was standard bore still. Put out some feelers and found a good cylinder just got to get a chance to get it and have it checked out, bored if necessary then order some pistons and reassemble it. Will keep you posted
Kirk
Kirk
bearrassler
Active member
That same thing happened to my Centurion back in the day. I caught it soon enough so I just had the cylinder bored and put it back together. They maybe had a problem with the clips
Apparently the oem clip was spirolocks and they are a pain to put in and take out. I can imagine on assembly line there was a good chance of not getting every one in right, every day . This motor had never been apart before, as it had original paper base gasket on it and pistons were standard bore. Possible your centurion motor was same deal. Machinist I talked to said he has seen it quite a few times before.
Good news, I got my new cylinders back from machine shop yesterday. I had them bore them out to .020 oversized and installed them with new pistons. Every thing went smooth and the motor is assembled and ready to install. Hopefully it runs smooth!
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It's been a productive couple of days here in Kalamazoo. I got the TXL motor installed back in the sled, and mostly all done. I need to finish draining the coolers and reattach the hoses and put some premix in the tank, fresh antifreeze in and try and start it. Hopefully this weekend!
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skiroule
Well-known member
Sounds like a little more horsepower to me. Pretty amazing that you have it back together already. Sorry for the dumb question ,but do those TXL cylinders get any type of plating after re-boring? (Nikasil, chrome, etc.) On my 440 free-air, they were Nikasil plated when the top end was re-done.
That sure is a sharp looking engine! Other than the clips, I’m wondering if the TXL and the Centurion engines shared much in the way of technology or parts.
That sure is a sharp looking engine! Other than the clips, I’m wondering if the TXL and the Centurion engines shared much in the way of technology or parts.
Hey Kelly, I am glad to answer your questions, after all it's a Polaris! The TXL cylinders have a cast iron sleeve in them, so they can be bored, honed and then they are ready to run. No plating necessary. Now they do take a different type of ring than a chrome or plated cylinder.
As far as the TXL and Centurion sharing motor parts, the pistons, connecting rods are the same. The Centurion was a couple years later, so they have individual cylinders &heads, not a monoblock design like the TXL or early Indy 400&500 liquids.
(The Indy were a different design and the parts don't work for the TXL)
The Centurion has cast iron sleeves also, so boring and honing process is the same. The progression of triples helped the Centurion grow into the Indy 600 of the mid 80's and eventually the famous Indy 650. Other than bore/stroke changes these triples were same family so water pumps, water manifold cylinders, heads could be swapped. Some people even swapped the whole motor, I know of a couple Centurion running a 650 triple in them...... now that sounds like fun!
As far as the TXL and Centurion sharing motor parts, the pistons, connecting rods are the same. The Centurion was a couple years later, so they have individual cylinders &heads, not a monoblock design like the TXL or early Indy 400&500 liquids.
(The Indy were a different design and the parts don't work for the TXL)
The Centurion has cast iron sleeves also, so boring and honing process is the same. The progression of triples helped the Centurion grow into the Indy 600 of the mid 80's and eventually the famous Indy 650. Other than bore/stroke changes these triples were same family so water pumps, water manifold cylinders, heads could be swapped. Some people even swapped the whole motor, I know of a couple Centurion running a 650 triple in them...... now that sounds like fun!
So I am happy to report, that I finally got the TXL back together and running . Been busy with work and other projects but it finally runs again. I need to fill the cooling system and make a few adjustments but it starts up a lot easier than before. I installed the factory air box as well.
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Deleted member 10829
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Looking brand new! 
mezz
Well-known member
I second that, & by the blue haze in the air in the third pic, she is running, congrats.....Looking brand new!
Yes it is running, that's what you get with gas-oil ratio at 24:1... had to open all the doors to air it out