Engine re-assembly.Any advise???

[lloydguy]

Besides AV tech sending me the wrong crank,my 488 fan is ready to go back together.
I was just wondering if anyone on here with engine rebuilding experience had any pointers
before I do.Should I prelube the oilpump gear,cly.walls,main bearings,ect,ect.with luberaplate
(whatever its called?) or just light motor oil or 2stroke oil?
I cant remember the piston measurements off of the top of my head,but there is .005" of clearance
w/the piston in the jug.on both cylinders,and with the rings in the jug 1/2" from the top of the jug
as per polaris sites engine spec.s . there is .012" on one and .014" on the other for a ring gap.
I honed the jugs w/320 grit stones and just used water as a lubricant.Cross hatch looks good to me,
but I dont really know F/A.
Once I get the proper crank ,I'm ready to go (I think)
Anyone have any advise before I close it up??????????
Thank's

 

[moyiesledhead]

You can use either Lubriplate or 2 stroke oil to lube the parts. I use whichever is in reach at the time. REPLACE THE CRANK SEALS! No kidding....I've seen guys actually re-use the old ones! Gotta seal the 2 crankcase halves with some anerobic sealant. Put your wrist pins in the freezer for an hour and they'll be way easier to push into the pistons. Run some 100/1 premix for breakin and you should be good to go.

 

[lloydguy]

What is this anerobic sealant you are talking about?Do you mean to seal the split?
Polaris recommends LOCTITE 515 for the split if that is what you meant.I have a tube of that.
I also will be adding 2 stroke oil to the gas ,for break in purposes.That is what polaris recomends,
So im just kinda going by rebuild manuals and advise from wherever I can get it.As to crank seals,
yes they are new.I got a reman crank because old bearings didnt roll smooth,complete gasket kit,
new pistons,rings,wrist pin bearings,ect.EVERYTHING will be new,so I hope she will have a long and
trouble free life.
Thank's for the reply.

 

[moyiesledhead]

Yup. Loctite 515 will work nicely.

 

[WopOnTour]

What is this anerobic sealant you are talking about?Do you mean to seal the split?
Polaris recommends LOCTITE 515 for the split if that is what you meant.I have a tube of that.
I also will be adding 2 stroke oil to the gas ,for break in purposes.That is what polaris recomends,
So im just kinda going by rebuild manuals and advise from wherever I can get it.As to crank seals,
yes they are new.I got a reman crank because old bearings didnt roll smooth,complete gasket kit,
new pistons,rings,wrist pin bearings,ect.EVERYTHING will be new,so I hope she will have a long and
trouble free life.
Thank's for the reply.

I've been building engines for over 30 years.
Personally I am not a fan of 515 for crankcase sealing and would be surprised if Polaris recommends it here. 515 doesn’t have enough flex agent for aluminum as there is actually a LOT of flex developed through use and with the thermal expansion-contractions of snowmobile engine's temperature cycling. (actually Loctite themselves does NOT recommend 515 for ANY aluminum to aluminum flanges) I've seen 515 develop leaks in the case within a few cycles of operation or perhaps a year or so later (depending on usage)

Much better to use Loctite 518 or 5910 for this aluminum to aluminum application OR an OE sealing solution such as Polaris 3-Bond 1215 Sealant (p/n 2871557 which is what I beleive Polaris actually reccomends) or Yama-Bond 4.

Also Do NOT use a sharp metal gasket scraper or razor blade to clean the mating surfaces as they can actually "nick" the surface and create a fissure for future leak development. Instead use a plastic gasket scraper or "Loctite wedge" like Loctite or Snap-On sells. If you used a scotch-brite pad for cleaning the surfaces you will have to totally scrub out the entire crankcase in a sink of hot soapy water and blow dry as microscopic flecks of abrasive scotch-brite material "hides" in the nooks and crannies, bolt threads and oiling passages and later make it's way into bearings/seals and can take out your brand new bottom end.
I also soak and clean all fasteners and hand-run a thread tap into any/all case threads (and a chaser over all bottom end bolts) before final case cleanup and assembly.

Then clean clean CLEAN! the mating surfaces with any highly volatile non-residue solvent/cleaner such as brake-kleen, acetone, or other solvent. DO NOT apply Loctite N primer! (it will actually cause a leaky case) After the crank is installed and clearances checked, if you need to inject any bearing grease (such as Isoflex) into the outer bearings or add bit of lithium grease to the inner lips of the end-seals- you MUST then carefully inspect and completely clean off any grease that gets on the case mating surfaces by carefully daubing it off with a solvent soaked lint-free cloth or Q-tip. (I use square cut 3M head cleaning pads I buy from B&E electronics for this as you can get right close to the bearings as compared to a Q-tip)

THERE MUST BE ABSOLUTELY NO OIL OR GREASE RESIDUE ON THE CASE HALVES BEFORE APPLYING ANEROBIC SEALANT.

Another common mistake is to use way too much sealer or miss critical sealing areas. The important thing is to be uniform. Laying a simple "bead"can sometimes backfire as you can get voids or gaps around bolt holes or it might not "squish" uniformly. So I like to use a small 5/8" rubber roller (like you can buy at an arts &crafts store) to evenly apply a uniform layer of sealer to the entire mating surface of the “empty" case half only (upper or lower depending on the engine whichever half doesn’t have the crank installed) I never apply sealer to side with the crankcase unless the OE calls for a small dab of RTV on the mating surface adjacent the rubber end seals (some do).

The big thing is to BE READY with your torquing tools so immediately after you close her up you can torque the crankcase bolts within 10 minutes of applying the sealer as it "skins over" quite quickly. Some manufacturers call for a teflon thread sealer on the bolts.(if there was a whitish compound oon the bolt threads when you removed them, then that's what should be reused on reassembly since you should have cleaned this all off on a wire wheel beforehand)
After torqing to manufacturer specs, and following the manufacturer recommended torque pattern (usually in at least 2 stages- 60% toque first then final torque) I always like to immediately put the cylinders and heads on with old gaskets (even with no pitons and/or rings) and quickly torque them to spec as well for crankcase seal curing as these will place normalized assembled loads on the crankcase as it cures. Some people say not to do this for various reasons but I've never had a problem.

THEN IF POSSIBLE I always try to let the "fresh" crankcase cure for a minimum of 24 hours (or at least 1-4 hours in a pinch) at room temperature or preferably a bit warmer.(reduces curing time) At a race track I've set crankcases on the floor of a truck with the heater on HIGH for an hour to cure the seal. But DO NOT retorque the case bolts after curing! (this can actually create a leak) -just remove the heads, cylinders, and old gaskets and continue with the build.

On the topic of gaskets, another small step that can be more easily performed BEFORE putting it all together is matching your cylinder to crankcase gaskets (if used). Gaskets are usually made too large to compensate for any casting or machining tolerances. By installing your cylinders to the top half of the case just finger tight (with the new gaskets installed) and noting any significant mismatch of gasket material (from the crankshaft side), you can then easily mark the errors with a sharp pencil or scribe then remove and carefuly trim the gasket with small sissors or exacto knife. Also IF you note any significant aluminum mismatching you can add some bluing to both mating surfaces and scribe out the error in order to dremel or knife away the mismatch with a deburring knife. But you have to be very careful here when removing aluminum as you could easily over do it or get into a coolant or oiling passage , even ruin the case! But on a piston ported 2-stroke it's amazing how these small steps can make 1-5 HP difference on the dyno. (and of course you're starting from square one in cleaning after any grinding)

HTH
WopOnTour

PS>Just use a bit 2-stroke or injector oil (preferably what you normally use) on the oil pump drive or perhaps small amount of Isoflex or Petamo grease. I try to stay away from Lubriplate, as it's not synthetic and not really designed for these applications. Don't forget to liberally lubricate your freshly honed cylinder walls and rings with injector or 2-stroke BEFORE you drop on your jugs. Good Luck!!

 

[moyiesledhead]

Hey good tip! I just checked what I use and it is indeed 518 rather than 515! My bad!

 

[WopOnTour]

Hey good tip! I just checked what I use and it is indeed 518 rather than 515! My bad!

Yea, it' amazing how much difference "3" (518-515=) makes!
WOT

 

[Warhawk]

Only thing that Wop never touched base on was when you wash out the cylinders ( you will use warm water and dishsoap works really well.) Scrub with a toilit brush works well, once done this you want to make sure that the cylinders are CLEAN.

How you do this is dry the cylinders with compressed air. Once done this IMEDIATLY take white paper towel and ATF( DextronIII) and wipe out the cylinder. If there is any honing mess left in the cross hatch this will clean it out. Wipe until your white paper towel stays white. Clean off all surfaces with acetone or brakeclean like he said and. Bobs your uncle.
goodluck

 

[lloydguy]

Thank's guy's.I put it all back together last night with 515,SOOOOOOOOOOOOOO.......
I hope it's all good.
http://www.vintagesnow.com/Polaris_files/85%20engines.pdf
That is the link I think where it said to use 515. I will know better for next time,but it's all together now,
So I might as well leave it alone .

 

[Circled-Mistake]

Let us know the end result!!!!!!!!!!

 

[lloydguy]

As soon as I find the jug and head nut's,the engine will be going back into the sled.
I have looked high and low.I have no Idea where they went.lol.
I sure hope that 515 does the trick.I will maybe put some hours on the snow with it
and once in awhile spray brakekleen around the split.

 

[WopOnTour]

Only thing that Wop never touched base on was when you wash out the cylinders ( you will use warm water and dishsoap works really well.) Scrub with a toilit brush works well, once done this you want to make sure that the cylinders are CLEAN.

How you do this is dry the cylinders with compressed air. Once done this IMEDIATLY take white paper towel and ATF( DextronIII) and wipe out the cylinder. If there is any honing mess left in the cross hatch this will clean it out. Wipe until your white paper towel stays white. Clean off all surfaces with acetone or brakeclean like he said and. Bobs your uncle.
goodluck

Well I actually prefer plastic pot scrubbers and fingernail cleaning brushes to a toilet bowl brush, but that would work fine... if you rinse it out well first. ewww

Thank's guy's.I put it all back together last night with 515,SOOOOOOOOOOOOOO.......
I hope it's all good.
http://www.vintagesnow.com/Polaris_files/85 engines.pdf
That is the link I think where it said to use 515. I will know better for next time,but it's all together now,
So I might as well leave it alone .

Hey, I've also seen people use 515 without any problems too so, dont sweat it.
The worst case scenario merely means you'll be pulling it again and adding more sled engine experience to your individual "bank o' knowledge" (and the S&M "collective") so...
JUST GET OUT THERE AND RIDE!
Well, after you find your "jug nuts" (sounds like something I paid $5 for in Thailand a long time ago...)
WOT

 

[lloydguy]

I was building this sled for the old lady and her kid,It's just about ready to go and she left me?????????
I must have been taking too long on the engine.
YA,THATS IT FOR SURE........lol