Issues with Ignition timing - Snowmobile Forum: Your #1 Snowmobile Forum

alaskanrider · 01-10-2013, 11:07 PM

Hello, 1st post on this forum. Probably not the last.

I just got my 380 skandic back together after a total rebuild. Toasted a mag side crank bearing, and the pieces of the bearing retainers did a good job munching the inside of the engine.

My machine shop doesn't like rebuilding cranks, they send them out somewhere else instead. For me, they ordered a crank, and then I dropped off my bad one as a core.

Installation was pretty straightforward, except for my ignition pickup. It is WAY off from the timing marks on the flywheel, there is not close to enough adjustment to make the trigger line up. When I find TDC on the mag side, the mark is a good 20* or so past the mark on the pickup.

I talked to the machine shop, and the mechanic there didn't think it was worth messing with. He said I should just make sure the clearance is good and align the pickup based on the marks left by the washers.

I did this, put it back together and it started easy and seemed to run well, but there was more intake noise than I remembered. Right as you crack the throttle, you can hear air moving in the intake. I havent run it much more than putzing around. Im trying to do a real gentle break in.

What do you guys think? Anyone else have this issue? I'm pretty particular about my timing on my trucks, and am not quite satisfied with how for off this machine seems to be.

Any input appreciated.

**smallengineguy** · 01-11-2013, 06:25 AM

Is the pickup in the same location as it was before? They can only be put one way and you should be able to see the bolt marks from before.

Snowweasel · 01-11-2013, 09:00 AM

Are u positive that is the exact crank for that machine?

Sent from my iPod touch using Snowmobile

alaskanrider · 01-11-2013, 12:11 PM

Quote:

Originally Posted by smallengineguy

Is the pickup in the same location as it was before? They can only be put one way and you should be able to see the bolt marks from before.

Yes, there is really no options on how to install it. It has a nice little spot in the case. The washers do move around on the bolts a fair bit though, so it is possible it could be a little off from where it was before.

Unfortunately I never verified timing before I tore it down, so I haven't a clue where it was compared to the marks on the magneto.

Quote:

Originally Posted by Snowweasel

Are u positive that is the exact crank for that machine?

Sent from my iPod touch using Snowmobile

Im a little worried that it isn't. The person that ordered it for me verified that it was a 97-2000 crank. Im checking part numbers right now to see if/when there was a change. Everything fit together perfectly, its almost like the woodruff key is in the wrong spot though.

I melted the pistons out of a IH 392 ci engine running too much advance couple years ago, and would like to never do that again, LOL.

alaskanrider · 01-11-2013, 12:47 PM

Whew, my eyeballs might fall out of my head. Just looked up a ton of part numbers on bombardiers microfiche

96
420887245 Crankshaft Ass’y
420886255 Magneto Ducati 12V240W. Includes 1 to 5
420996820 Magneto Flywheel
420912996 Fan Housing

97
420887247 Crankshaft Ass'y. Includes 1 - 6. Skandic 380.
420919979 Crankhalf MAG. Skandic 380.
420886255 Magneto Ducati 12V240W. Includes 1 - 5.
420996820 Magneto Flywheel
420912996 Fan Housing. Skandic 380.

98
420887247 Crankshaft Ass'y. Includes 1 - 7. Skandic 380.
420919979 Crankhalf MAG. Skandic 380.
420886255 Magneto Ducati 12V240W. Includes 1 - 5.
420996820 Magneto Flywheel
420811260 Fan Housing. Skandic 380.

99
420887248 Crankshaft Ass'y. Includes 1 - 7. Skandic 380.
420919979 Crankhalf MAG. Skandic 380.
420887653 Magneto Ducati 12V240W. Includes 1 - 2.
420996824 Magneto Flywheel
420811262 Fan Housing. Skandic 380.

2000
420887249 Crankshaft Ass'y. Includes 1 - 7. Skandic 380.
420919979 Crankhalf MAG. Skandic 380.
420887653 Magneto Ducati 12V240W. Includes 1 - 2.
420996824 Magneto Flywheel
420811262 Fan Housing. Skandic 380.

Apparently they picked up RER in '99, but the mag side crankhalf is the same number.

SO, the shop is right, 97-2000 should be the same crank. If that is what they gave me.

alaskanrider · 01-11-2013, 01:30 PM

Took it for a quick spin, seems to be running well. Started in 3 pulls, but I bet it would have in 1 pull if I had a primer pump. Fresh engines are so awesome, barely any smoke despite my 20:1 premix.

Maybe im just be over-sensitive about the intake noise, I was much more concerned with the disturbing clunk that my crankshaft was making the last time it ran. Might have just not noticed.

I also rode it way different, throttle at the bar, fast as it would go. This time im super gentle, always less than 1/2 throttle for this first bit. Makes it kind of hard to compare.

alaskanrider · 01-11-2013, 04:47 PM

I just measured how far off it is, the mark is about 3/16"-1/4" BTDC.

alaskanrider · 01-11-2013, 07:08 PM

Talked to another mechanic, he said the flywheels are not always marked, and not always marked correctly. Likely im trying to line it up with the wrong mark, and that the service manual is just wrong. It looks like I have the mark they are talking about, but they are not incredibly clear on what the mark corresponds to on the flywheel.

I'm confident that the trigger is set in its original position, and am just going to run it. Will post if I burn the thing down.

Anyone who is planning on doing a crankshaft swap should make a mark on the flywheel that corresponds to TDC. If I had it would have saved me alot of angst.

**smallengineguy** · 01-12-2013, 06:35 AM

If it was too advanced, it would backfire out of the carbs as well.

alaskanrider · 01-13-2013, 03:02 PM

Found a website with the correct way to set ignition timing on the 96 and up rotax fans.
http://www.800-airwolf.com/pdffiles/ARTICLES/part39.pdf

The 1997 skidoo shop manual is WRONG on how to set the ignition timing for the rotax 377.

Sled is running well, did a 60 mile trail ride yesterday. Didn't get hot or ping, so I think timing is good. Still havent done any long WOT stuff, but I will as soon as break in is done.