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Post by 80sting440 on Jun 22, 2016 19:29:37 GMT -5
I have a rebuilt JLO Rowell 295 6 stud that I have for a '71 Moto-Ski.
I got it bored over and installed new piston, bearings, seals and gaskets along with overhauling the HR Tillotson carb.
It starts and runs well but shakes and rattles like there's a monkey inside swinging a bag of hammers!...
It ran that way when I bought it off an acquaintance. I thought that it was piston slap due to wear, so I gave it a complete overhaul...it now runs no different!
My questions to you guys:
a) is it normal for this model or did I miss something that you can think of?
b) Scorpions used other old design singles...do the run better, worse or about the same?
The reason I'm asking is 'cus although I enjoyed the engine rebuild, I'm just not feeling it for the whole Moto-Ski "refresh/rebuild"...
If all old singles run this way, maaaybe I'll save it to install in a future mild custom Mark_ Scorpion?
What do you say?
I'm all ears (actually, all eyes!).
Rene
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Post by Deleted on Jun 22, 2016 20:32:01 GMT -5
I think most single cylinder engines,have a vibration problem. I know my Sachs single 290,vibrated.The Rotax 299,vibrated.Thats the only 2 I've had.
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Post by 80sting440 on Jun 22, 2016 22:34:09 GMT -5
I think most single cylinder engines,have a vibration problem. I know my Sachs single 290,vibrated.The Rotax 299,vibrated.Thats the only 2 I've had. Thanks nitro.
Back in '73 when I got into snowmobiling I got a, very modern for it's day, Japanese twin with chrome lined cylinders, cdi, twin Mikuni, expansion chamber pipe/muffler combo. I had this engine (El Tigre) until 1988.
All I ever had to do, engine wise, was change rings and rebuild the clutch every 3-5 yrs... along with carb maint. Meanwhile my buddies with their old singles had nothing but headaches. The reason I bought this JLO project was because I wanted the challenge that my buddies and I never really took time to figure out. Well so far this is some of what I've learned.
I've learned how a Tillotson works, timing a points system with advancing the sprung flyweight gizmo with a toothpick while holding my tongue just right. I also learned about heavy flywheels. I've learned to make specials wrenches for Tilly carb mounting nuts and cylinder base nuts. I've learned what "20 lbs." of torque sounds like when you're forced into using light hammer blows on said stubby wrench (cylinder base). I've learned that if you first press the bearings into the case halves and then onto the crank...is the way to go!
Most of all, I've learned that I preffer a TWIN!!! Maybe that just me?
Rene
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Post by weverat on Jun 24, 2016 7:37:13 GMT -5
Back in the day, my uncle had a Moto-Ski with a Rockwell single, that motor shook so hard it broke the motor mounts!
I have one up in the parts loft, its a cool looking antique engine, with lots of potential as shop art.
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Post by oldscorpman on Jun 24, 2016 14:18:06 GMT -5
I have a rebuilt JLO Rowell 295 6 stud that I have for a '71 Moto-Ski.
I got it bored over and installed new piston, bearings, seals and gaskets along with overhauling the HR Tillotson carb.
It starts and runs well but shakes and rattles like there's a monkey inside swinging a bag of hammers!...
It ran that way when I bought it off an acquaintance. I thought that it was piston slap due to wear, so I gave it a complete overhaul...it now runs no different!
My questions to you guys:
a) is it normal for this model or did I miss something that you can think of?
b) Scorpions used other old design singles...do the run better, worse or about the same?
The reason I'm asking is 'cus although I enjoyed the engine rebuild, I'm just not feeling it for the whole Moto-Ski "refresh/rebuild"...
If all old singles run this way, maaaybe I'll save it to install in a future mild custom Mark_ Scorpion?
What do you say?
I'm all ears (actually, all eyes!).
Rene
View Attachment my 70 scorpion mark II with a sachs single has a 14 " crack across the tunnel from one motor mount hole to another , and several smaller cracks at each bolt hole. |
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Post by 80sting440 on Jun 24, 2016 14:40:59 GMT -5
OK then...what I have is a completely rebuilt piece of " bench art" or an engine for my next single project.
From what you guys are saying, I should make sure to go to my dentist and get my fillings checked out before going for a test ride!
Thanks, Rene |
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Post by obj1 on Jun 24, 2016 15:00:50 GMT -5
Ha! Don't tell anyone, I one time tried to brace up a 340ss so the clutches would stay in alignment for grass drags. Built all these nice brackets and braces to eliminate all movement from the rubber mounts. Well, it not only vibrated my arms to sleep, after 1 run all the stuff I so carefully designed was junk! Live and learn I guess.
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Post by 80sting440 on Jun 24, 2016 16:23:52 GMT -5
Thanks obj1. Your little secret is safe with me  .
So I suppose that I should make sure to have soft/large rubber mounts and let the engine shake, rattle 'n roll on its' own with no contact between motor mounts and chassis. The original rubbers had sagged and the motor mounts were sitting on the tunnel.
Man, I love twins!
Rene
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Post by kube1 on Jun 25, 2016 21:02:46 GMT -5
I'll agree with all these guys. A lot of those old singles are bone shakers. I've become partial to the Sachs engines myself. The worst engine I've seen for shaking is my buddies ol 71 tnt with the 340 single. Good lord. He fires that thing up and it bounces back and forth like a paint mixer! How it hasn't ripped itself free of the engine mounts is beyond me
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