1970 Ruppster > Fix old JLO vs. New Engine

meechee · 02-28-2010, 09:12 PM

I would love to have the old one working but I just have no idea how to work on them. The guy I bought it from knows alot more than I do about these and he couldn't get it to work consistently.
At 14 HP, I bet the JLO really makes it haul ass.

Another thing - once I get it running, I would hate for it to break down 3 miles from camp. I know so little about these 2 stroke engines that it could be a minor fix and I wouldn't know how to fix it.

So I just thought the safe bet would be to put a new engine in there.

I'd appreciate any input. Hopefully I get some input from both sides > those of you who've fixed the JLO and those who've swapped the engine for a new one.

I'd like to compare three things> cost, man hours, and results.

Results> power/ speed & reliability out in dirt country

Thanx

**gumpit** · 02-28-2010, 09:18 PM

I think you know the answer. And I would do the same thing. Drop a new engine on it and GO...................... Unless it is a restored piece and in a museum. I don't see any reason to go all original... Just my opinion... Randy

meechee · 02-28-2010, 09:22 PM

I just want to make sure I avoid any problems. Like buying a new engine that doesn't end up working in the ruppster for one reason or another.

**shoe** · 03-01-2010, 08:51 AM

to install a newer engine you will most likey have to fabricate some new stuff to get it to fit , the chances of you finding a drop in engine are slim at best ,,, Maybe you need to find someone willing to help you out in this ? Or maybe this is a bigger project than you actually thought it would be ,, Not a bad looking old Ruppster really

jesse8931 · 03-01-2010, 09:12 AM

you will need new crank seals and and a carb rebuild at the very least

The Restore Kid · 03-01-2010, 09:36 AM

Quote:

Originally Posted by jesse8931

you will need new crank seals and and a carb rebuild at the very least

That is what goes wrong in every snowmobile engine... IT MAY just be as simple as the carb needs torn down cleaned out and reassembled readjusted, it MAY have a fuel pump that is not working properly, although I don't believe those machines use a fuel pump... I would say START with a simple carburetor rebuild... If that doesn't fix the motor, it is PROBABLY your crank seals.. two cycle engines suck the fuel air mixture into the crankcase on the up stroke, then forces it into the cylinder on the down stroke.. 38 year old snowmobile engines have a tendency to leak around the crank seals from wear and USUALLY dry rt from sitting.. If they are bad the engine will never run right.. You'll have to shoot gas into it to prime it, THEN keep it running a fairly good speed or it will lose vacuum and die.. ..If the guy is a 2 stroke expert and can't make it run he probably never went very deep in the motor... I would say look into a rebuild (refurbish) on the motor.. It probably does not need rings and bored and EVERYthing.. just fix whats wrong with it.. You could take the motor to a reputable small engine place, and get an IN WRITING estimate of what they will charge to get the engine back to reliable and good running.. Crank seals and carb kits are cheap... You MAY have the engine redone for less than the cost of a new one.....

HOWEVER I think running a NEW 4 stroke motor is a great idea too.. No oil to mix at EVERY fill up.. quieter, more dependable.. I would butcher the machine as LITTLE AS POSSIBLE doing a motor swap and DEFINITELY KEEP your original motor on a shelf with the piston rolled to top dead, spark plug in it, all the little holes and passage ways sealed off... and just leave it parked where it is safe, and run a new Briggs I/C 11 horse in it's place.. Problem solved..

**quiklids** · 03-01-2010, 09:37 AM

We had JLO's in both of our Ski-Daddler snowmobiles...'when' the recoils were working, we always had trouble starting 'em. My Dad really expanded my vocabulary with those engines...

oldyeller · 03-01-2010, 09:51 AM

I used to own a 1972 artic cat snowmobile with a 340 JLO motor..I have owned a lot of snowmobiles over the years and I think that JLO was probably the most frustrating engine to keep running I have ever experienced...

oldyeller · 03-01-2010, 09:59 AM

Quote:

Originally Posted by quiklids

We had JLO's in both of our Ski-Daddler snowmobiles...'when' the recoils were working, we always had trouble starting 'em. My Dad really expanded my vocabulary with those engines...

We had a couple of those as well..My dad and uncle were dealers for a short while..

jesse8931 · 03-01-2010, 10:14 AM

if i ever pick up a ruppster i have the perfect motor for one a sachs 340ss making 26hp