1980 Ski-Doo Citation 4500 Engine Swap info - Snowmobile Forum: Your #1 Snowmobile Forum

Citation · 01-13-2013, 11:55 AM

Hello all, Im pretty sure i posted in the right forum...

I recently bought a 1980 Ski-doo citation 4500 with the 377 rotax. Now this is the older model, with the regular silver clutch, and points and condensers.

Now the engine has 121 Psi of compression which isnt to bad,, But i am looking to swap the engine out, as i am going to make a project out of this little guy.

I would like to put a 447 F/C from a 85 Safari into it. the engine is port and polished. Its been upgraded a bit

is the swap possible ? Just pop the clutch off, Take the engine mount from the 377 and put it onto the 447? Or even a 503 maybe?

i want this citation to haul @$$, i am going to use it for boon docking and climbing hills. So i want the power behind it. Its small, and as about as light as you can get for a Ski-Doo.

Thanks for reading and i hope to hear from someone who has swapped the 377 for a bigger engine. I appreciate your comments.

**RJ Gleason** · 01-13-2013, 02:25 PM

Dooable!

You will need to recalibrate the clutch for the larger engine.
Also, the mount plate may need minor modification as the base bolt spacing will be larger on the bigger motors.

**smallengineguy** · 01-13-2013, 02:40 PM

It should work with the 447. The exhaust setup on a 503 does not fit the Safari chassis.

Citation · 01-13-2013, 07:36 PM

hmm, Well from looking at it , i should just be able to use the Manifold from the 377 on the 447, and take the clutch off to put in the Engine mount. As the citation 4500 sleds have a 3 point engine mount, Which goes behind the clutch.

So i shall use the 377 manifold, and the 377 engine mount, on my 447 and it should bolt right in with no problems.

I do not understand why i would have to adjust the calibration on the secondary clutch ?? because the engine is larger, What does it matter ? the sled is small, and the engine being bigger should just make it snappy ?

**RJ Gleason** · 01-14-2013, 04:27 AM

No, the calibration would be to the primary.

Citation · 01-14-2013, 10:53 AM

oh okay, How do i calibrate the primary for a smaller sled ? i have not done this before

**RJ Gleason** · 01-14-2013, 11:04 AM

Try it and see what rpm it engages, then watch the peak rpm as you do not want the motor going over 7600.

Then it will be easier to figure out what spring and weights you will need.

Citation · 01-14-2013, 08:18 PM

Okay so, Im done. putting the motor in was a little more complicated then i had thought.

i would love to do a write up on how to change the engine from a 377 to a 447. where would i post a Write up on this ?

Now the citation is a 1980 citation 4500, it has a 377 rotax, With the old style silver clutch. and points and condensers.

What i did was put a 447 rotax (port and polished :P) this engine runs a CDI and Coil pack.

I used a 377 Engine mount ( they are a 3 point mount) i had to tap the 3 holes behind the clutch where the bolts hold the left side of the bracket to the engine. i also had to grind little grooves in the bottom of the engine plate so i could line the bolt holes up. I had to change the manifold from the 447 to the 377 (because the exhaust is on the left not the right. I used the silver clutch From the 377 on the 447. Because the comet clutch does not line up with the secondary clutch, It sits to close to the engine.

So its a 447, With
- 377 Manifold
- 377 engine mount
- 377 Clutch (the silver one, I think its a powerbloc ? But i may be wrong)

The sled is incredibly fast. RAW power as soon as you touch the throttle, It is nothing like the 377.

Now i do not have an RPM gauge on the sled. This model did not come with one. SO i cannot see what the clutch is spinning at. Although i really would like to see. How could i wire a RPM gauge to this setup ?

Wiring the engine to the old harness and making the original headlight and killswitch work was a bit tricky but i got it to work great after a bit of trial and error.

**RJ Gleason** · 01-15-2013, 05:20 AM

You need a 2 pulse tach and can wire it in ahead of the regulator.

mrmichaelson · 04-17-2013, 12:52 PM

what did you do for clutching? change jets for carb?