ZRT600 Wrist Pins...How Tight?

[snowfish]

Just finished putting new pistons on the rods. Jugs are next. How tight should the Wrist Pins be? The pistons move on the pin, but they're pretty snug. With the New Pistons, New Seals, New Water Pump, this thing is going to be a hard pull at first start.

I reinstalled an old piston, just to be sure I didn't goof something, and it was pretty loose. My SPI's are tight. Of course, all three New ones are on now.

Any advise/encouragement would be appreciated. My first build. (not counting trucks & boats)

 

[Tito]

your good their a slip fit push in with your finger. Remember to put the gaps on the pin retainers up or down not at 3 or 9 oclock

 

[bouncer]

Just finished putting new pistons on the rods. Jugs are next. How tight should the Wrist Pins be? The pistons move on the pin, but they're pretty snug. With the New Pistons, New Seals, New Water Pump, this thing is going to be a hard pull at first start.

I reinstalled an old piston, just to be sure I didn't goof something, and it was pretty loose. My SPI's are tight. Of course, all three New ones are on now.

Any advise/encouragement would be appreciated. My first build. (not counting trucks & boats)

If the pistons are that snug that it would make it hard to pull start I would not put it together until I knew it was right. The pin is ok tight on the piston bore but should flop with it's own weight after install through the bearing. No drag should be felt pivoting the piston.

 

[snowfish]

The piston Does Not flop under it's our weight. I have to rotate it by hand. It's pretty snug; like opening a 2ltr bottle of pop. When I test fit, the pistons on the rods without the shims, it rotates fine. I can't believe that the shims need to be sanded down.

I'll call the dealer, this morning, to see if they have any additional insights. The SPI pistons and rings fit into the bore well with in spec. I may have gotten the wrong piston/pin kit, but everything else works, so I don't know.

Any additional experience would be greatly appreciated. Thanks.

 

[bouncer]

The piston Does Not flop under it's our weight. I have to rotate it by hand. It's pretty snug; like opening a 2ltr bottle of pop. When I test fit, the pistons on the rods without the shims, it rotates fine. I can't believe that the shims need to be sanded down.

I'll call the dealer, this morning, to see if they have any additional insights. The SPI pistons and rings fit into the bore well with in spec. I may have gotten the wrong piston/pin kit, but everything else works, so I don't know.

Any additional experience would be greatly appreciated. Thanks.

Pistons are too tight! I would replace the top rod bearing also. Not saying that is your problem but it's just something I do when doing a top end.

Check your cylinders! Make sure the ports have chamfer on them. You don't want to catch a ring on a sharp edge. Good luck

 

[snowfish]

I ordered new cage rollers and shims like you recommended. I'm out of town this weekend so Launch time has been move back until next week. Parts won't be in until Friday.

Thanks for your help. The project continues.........................

 

[snowfish]

Got the new cage rollers & shims installed the other night. Still seemed a little snug, again, (rocking the piston on the pin) but not like when I was using the old rollers & shims. I noticed the old shims looked like they were a little discolored by heat. Maybe the ZRT's run snug?

Got it all buttoned up & fired up last night. Idled really slow at first. Probably just tight. Go figure. Then it perked up to a nice 1500rpm. Let it run to temp and got coolant burped down. Took it for an easy 2 mile ride (nothing over 6,500rpm) with no unusual sounds other than it sounded quite healthy! Plenty of smoke though! That mellowed after the build oil was burned off.

So far, so good. Funny how a simple water pump project (tongue in cheek) will turn into a full rebuild! Figured since I was down there…………It's pretty much a brand new 97 Powder Extreme/CrossFire Hybrid now!

Special thanks to Mr. Ezra with the skid swap. Above and beyond the call of duty! And Thanks to all who lent a hand, along the way, with the rest of the project. Much appreciated! Cheers!

 

[ezra]

I had a 96 zrt600 that we put spi rebuild kit in at like 2800mi or so. I know the guy I sold it to. still the same top end with over 9000mi on that sled now and that is with a 17yr old riding it for the past 3yrs not to bad.the pins can be snug I just got doing a 900 kit in a f7 with wiseco,s took all the finger power I had to push the pin in all the way.ps that sled really woke up with the base gasket spacer kit and shave the head to match If I remember the extra thick back magic base gaskets were like 60 bucks a set and head shaving was around 90 it changed port timing for great mid range to wot power

 

[snowfish]

Ezra, I'll be in touch on the next build. I'm going to start looking for a mid to late 90's T-Cat or ZRT and build a trail sled, with a hint of lake racer, including front end mods. I can see how this can get addicting! Sounds like you're hooked, too! LOL! Thanks again.

 

[ezra]

let me know when you start looking for a tcat I know a few guys with lots of tcats from stock to 1400cc 350+hp.I know of 1 ultra light weight 136 thunder lake race rolling chassi for sale .guy bought it for the power plant and to see what made it tick.selling roller for I think 1500 with no motor.if you want a motor he has over 7sitting on the pallet racking from stock to full mod.I think he is selling a lake race 1200 with nos 260+ hp for around 5k looks show room new but faster than most anything around lake minnetonka.

 

[snowfish]

Oh Man! Let the addiction begin! I'll be in touch probably this spring. For now, Let's Ride!