How to prevent a cold seize on new top end

[Jorg Jorgenson]

As the title says. Putting a new top end in my Pro. Sled has 2200miles currently took stock pistons out Getting wossner replacement pistons (don't need to hear opinions about Weisco pistons please) no fit kit simply replacing pistons and having the cylinder re-honed.

Took a shop vac to crank bottom for any coolant / debris that may have been in there, Will be double-checking ring gap with feeler gauge from Mots, oiling-up sides of cylinder walls and pistons before re-installing, make sure oil line is not kinked, using gasket sealer on head bolts, putting new spark plugs in, filling then checking coolant level after first heat cycle.

I Plan on Doing 3 heat cycles from ambient temp up to 125 (all idling) before even touching the throttle. Will put it on a track stand for the 4th heat cycle to let the sled rev up a little.

Any pointers / tips for the first time I start it in the parking lot and head up the trail? No snow around home to ride it which is why she'll get her first re-build miles on the logging trail! I don't want to cold shock the engine with coolant as I have heard that is a common problem. Thermostat opens at 100 or 120 on Pro's?

Thanks
Jorg

 

[Tchetek]

120 I think.

 

[towerrigger]

You should be performing a leak down test after putting it all back together. This will ensure all your gaskets are sealing properly before you start it up.

 

[Teth-Air]

Has anyone ever seen one of these motors last more than 1000 kms after a new top end? My experience is that connecting rod bearings go next.

 

[Kyle89]

Make sure the ring gap isnt to tight, I cant remember off the top of my head but I'm thinking at least .015".

 

[solarguy]

Has anyone ever seen one of these motors last more than 1000 kms after a new top end? My experience is that connecting rod bearings go next.

I had an 11 pro turboed, went at least 3,000 km mountain riding after top end at 3,300 km (preventative). Sold the sled, never heard about any engine problem in the year after it was sold.

 

[neilsleder]

Let it warm up and giver! You do those heat cycles and its good to go. First tank of gas I wouldn’t do any big long hill climbs just ride it normal.

 

[JMCX]

You need to jack the front of the sled high enough that the tunnel slopes up toward the front in order to get the air out of the coolers. Heat it up once just to check for coolant leaks. Go hot enough that the system builds some pressure.

I don't know what metallurgical marvel people think they are performing idling the engine a few times to Phoenix temperatures. Warm it up before riding and giver.

 

[TDR]

Make sure the ring gap isnt to tight, I cant remember off the top of my head but I'm thinking at least .015".

Yep and closer to 020” or it will squeak.

 

[Kyle89]

Yep and closer to 020” or it will squeak.

Ya I opened mine up to .023" with the rktek pistons I put in.

 

[Dazzler]

I start my sleds and back them out of the trailer immediately, (hate the heavy smoke) I shut them off and restart so they are in forward for safety if nothing else. I do not head up the trail till I can feel heat in the tunnel cooler behind the seat.

I heat cycle all my new sleds or new rebuild engines three times as well. I add a good shot of oil in the first tank and I avoid long hard pulls for the first tank of fuel, and if the first tank/ride is in low snow conditions, I watch engine temps do not exceed 150-160 F.

 

[Jorg Jorgenson]

Thanks all for the comments. I guess the heat cycles are to let everything set before I ride. Agreed that I will put a shot of oil in the first tank. And yes I will bleed the coolant screw head after cycling to let out any air in the line. I would never get my sled past 160 before rebuild so with these new pistons I will probably clip that back to 150 or even 140 before pulling over. Just sucks that the icy trails with not much snow are where you start riding so the sled gets up to 140 in a heartbeat from 125. And yes I'll do an easy first day. I'm over-cautious when it comes to this in case you haven't noticed!!

 

[JustinMan43]

. I would never get my sled past 160 before rebuild so with these new pistons I will probably clip that back to 150 or even 140 before pulling over. Just sucks that the icy trails with not much snow are where you start riding so the sled gets up to 140 in a heartbeat from 125. And yes I'll do an easy first day. I'm over-cautious when it comes to this in case you haven't noticed!!

I try not to let mine get to 160 either. But after running half a day on low coolant and a few icy trails my first 100 miles on my new Wossner top end has seen 180+ a few times....

 

[mountianguy]

As the title says. Putting a new top end in my Pro. Sled has 2200miles currently took stock pistons out Getting wossner replacement pistons (don't need to hear opinions about Weisco pistons please) no fit kit simply replacing pistons and having the cylinder re-honed.

Took a shop vac to crank bottom for any coolant / debris that may have been in there, Will be double-checking ring gap with feeler gauge from Mots, oiling-up sides of cylinder walls and pistons before re-installing, make sure oil line is not kinked, using gasket sealer on head bolts, putting new spark plugs in, filling then checking coolant level after first heat cycle.

I Plan on Doing 3 heat cycles from ambient temp up to 125 (all idling) before even touching the throttle. Will put it on a track stand for the 4th heat cycle to let the sled rev up a little.

Any pointers / tips for the first time I start it in the parking lot and head up the trail? No snow around home to ride it which is why she'll get her first re-build miles on the logging trail! I don't want to cold shock the engine with coolant as I have heard that is a common problem. Thermostat opens at 100 or 120 on Pro's?

Thanks
Jorg

Don,t baby it too much, get her hot and shut it down. If its going to fail might as well be in the shop. I have drilled a small hole in the thermostat as a bypass before. That helps with the shock of cold coolant.

 

[skegpro]

I had an 11 pro turboed, went at least 3,000 km mountain riding after top end at 3,300 km (preventative). Sold the sled, never heard about any engine problem in the year after it was sold.

Ironically these engines do better under boost for whatever reason.

 

[Jorg Jorgenson]

Don,t baby it too much, get her hot and shut it down. If its going to fail might as well be in the shop. I have drilled a small hole in the thermostat as a bypass before. That helps with the shock of cold coolant.

Well I managed to get through the weekend if riding without seizing or going over 150 on the trail so that was nice!

The new pistons make the engine temps cool down so fast for whatever reason. Normal riding around temp was between 122-129 in snow. After turning off the sled for 5 min or even less, it would be down to 109/111, so I'd wait until it idled and got back up to at least 122 as a precaution. Although I'm sure you wouldn't be cold seizing after 5 minutes if stopping... however after lunch I did let it warm up for a good 10 minutes just because things had cooled down quite a bit.

Again, I'm probably being too safe, but better safe than sorry. Was riding a little harder second day compared to the first.

 

[TDR]

Better safe than walking!!

 

[Scarballs]

those pistons you put in, are they CNC forged or cast? In my experince that plays a factor in the break in time.
I would use lots of extra oil in the tank and ride it like i stole it, only after a few heat cycles and maybe an hour or 2 of being a baby on it.

 

[Jorg Jorgenson]

those pistons you put in, are they CNC forged or cast? In my experince that plays a factor in the break in time.
I would use lots of extra oil in the tank and ride it like i stole it, only after a few heat cycles and maybe an hour or 2 of being a baby on it.

They are the wossner forged pistons, not cast iron like the stock ones I pulled out. I feel like that is why they cool down so much faster than the stock pistons.

I lubricated the cylinder walls and pistons fairly well so they were coated but not dripping, and then have added oil to both tanks of fuel riding day #1 and #2. I noticed I was burning less oil these past 2 days since I was not WOT so naturally using less oil at a lower RPM.