Summer sled rebuild - Snowmobile Forum: Your #1 Snowmobile Forum

05polaris550 · 06-08-2008, 11:20 PM

So i have a 1989 Polaris sprint 340 snowmobile which i am in the process of rebuilding from the ground up as a summer project.I plan on sandblasting the whole bellypan/tunnel,and giving it a good paintjob.
I'm redoing the front suspension,and the rear,also converting it from a 116" track to a 121".The new-er track also has a few studs.Im going to rebuild the engine(possibly overbore) shave the head,port the intake and exhaust,and rebuild the clutches.I will be mounting on twin SLP expansion pipes and MAYBE dual 38mm mikuni's(has 34's right now i believe).

Hopefully ill have myself a good little sled to rip around on for fun this winter.

Heres a few pics of it stripped down and the engine(broken piston skirt,but the cyls are in perfect condition)Im still debating whether i should buy std. bore pistons or .40 overbore.Both kits are 30$ Anyone know how much it would cost for a bore job?

**smallengineguy** · 06-09-2008, 06:26 AM

Looks like a heck of a project!!

05polaris550 · 06-09-2008, 10:53 PM

I went ahead and ordered the .40 over pistons, i cut the track off with the sawzall and i also had to cut out the side of the bellypan that holds the left cogshaft bearing in because they are both rusted on,im still not sure how im gunna get those bearings off though...

Skligmund · 06-10-2008, 10:58 AM

Torches, Kroil and hammers.

JheLrey · 06-12-2008, 10:21 AM

Where in MN are you from?

05polaris550 · 06-12-2008, 11:37 AM

Im in lino lakes.I have dumped on liquid wrench,heated up the bearings,and pounded the crap out of them.They still do not budge.Im thinking about just cutting the cog shaft in half and buying a new one lol..Also,would this qualify as a "vintage" sled? you might have a new contestant for the vintage contest

**RJ Gleason** · 06-12-2008, 08:26 PM

For the bearings, just break them off with a hammer and then use a chisel or a dremel cutter to get the inside race off.

lrnnorth · 06-13-2008, 05:34 AM

Just a qustion for some of you smart guys on here. Will a 340 motor run properly with that big of carbs and those pipes?

**RJ Gleason** · 06-13-2008, 07:15 AM

use 34's with bigger jets or 36 jetted to the pipes.
The 38's are too big and will not give proper air flow for good fuel misting. (will actually cost you power)

05polaris550 · 06-13-2008, 10:51 AM

I was thinking about that also,and it would be a pita to make some manifolds that would made up the the "square" intakes so i think i will just stick with the 34's.

I also have to make a custom can,what would you guys recommend doing for that? I have all the tools needed to make one,just not sure of what "style"? Stingers? Single Can?Or i also have a few other sled/other engine mufflers that i could modify to work.

Another thing,the sled always had a doggy engagement(which seems normal on this model) what could i do (as far as clutching) for a little quicker and snappier start off? Thanks

**RJ Gleason** · 06-13-2008, 08:56 PM

lighter weights and/or heavier spring in the primary then change the helix on the secondary to a progressive rate one.

Get the engagement rpm's up a bit.

IndianRvrShiver · 06-14-2008, 08:45 AM

Quote:

Originally Posted by 05polaris550

......Also,would this qualify as a "vintage" sled? you might have a new contestant for the vintage contest

Some sleds are vintage & some sleds are just plain old.....not sure where this one falls??

Good luck on the resto!!

**RJ Gleason** · 06-14-2008, 08:50 AM

89 = not quite vintage.

05polaris550 · 06-14-2008, 02:34 PM

Heres a little update.Got it painted(partially anyway,ran out of black) and tunnel polished.Came out pretty nice.Come to think of it i have an extra SLP progressive helix i can put in.Ill get a heavier primary spring and heavier weights.

paintballdude05 · 06-15-2008, 12:21 AM

Its looking good! Keep us posted!

05polaris550 · 06-15-2008, 11:59 AM

Got the chassis all painted.I used all spray paint,first cold galvanizing stuff(93% zinc) then primer then RustOleum professional Flat black.It came out pretty nice.Also made a bar riser out of angle iron and some square tubing.Its about 3".

Sam

**RJ Gleason** · 06-16-2008, 08:05 AM

Looking good so far, keep at it.

05polaris550 · 06-16-2008, 09:45 PM

Well i dont really feel like making a new thread so ill just ask it here, Are John Deere 600 (sleds) rare? ive never heard of one until now, i found a 1974 JD 600 for 100 bucks...

**RJ Gleason** · 06-17-2008, 08:55 AM

snag it at that price if it's in fair shape.

05polaris550 · 06-17-2008, 10:19 AM

I really would like to get it, but i have too many other @$#% projects and not nearly enough time haha. Heres a pic of it though.