Snowmobile Fanatics banner

1 - 20 of 26 Posts

·
Registered
Joined
·
17 Posts
Discussion Starter #1
I don't know snowmobiles.

New to me 88 Indy 400 Liquid Cooled, about 8k miles. Smokes (white) like crazy when running, slowly dies when idling, and black liquid that smells somewhat like gas is coming out the exhaust in seemingly large quantities.

I've cleaned and synched the carbs, rebuilt the fuel pump, set the choke properly. I would think it is the coolant, but none appears to be being consumed.

Any thoughts?

Thanks,
Tim
 

·
Registered
Joined
·
2,488 Posts
I'm pretty sure the black liquid is gas. Not sure how to fix it though. I have the same problem.

[attachment=32163]
 

Attachments

·
Registered
Joined
·
685 Posts
Sounds to me you are running too rich. have you checked the pilot air screw?? I believe yours should be 1 full turn out from when its totally seated..

Also check your needles and seats inside your carbs, could be flooding out your motor with gas, hence it dying, and hence all the smoke usually means too much oil.

3- Speaking of which, have you checked your oil pump, I put my carbs back in and didnt dlbe check and the drainage line got caught in the oil line keeping the lever on full and giving me way too much oil and I was smoking for a bit till i caught the problem.

There is a start anyhow..
Good Luck
 

·
Registered
Joined
·
17 Posts
Discussion Starter #4
Thanks for the replies. It looks just like the photo you posted.

I've verified the oil pump is pumping, and that the lever actuated by the throttle is not being hung up on the bowl drain tubes. The has mark on the oil pump lever lines up as it is supposed to at idle. I assume that as these are gear driven, the ratio is set and there is no adjustment that could be screwed up other than the lever that is connected to the throttle?

I'll recheck the needles and seats - and I agree it seems like it is running rich. The Clymer manual tells me that an 88 400 pilot air screw should be at 1.5 turns out from lightly seated. Is this incorrect?

Is there a way to prove that it is not a head gasket leak?

Thanks
Tim
 

·
Registered
Joined
·
875 Posts
I'm gonna say you have a head gasket leak. Had an old 91 Exciter that did the same thing, white smoke, etc etc - put a new gasket in and was back to normal.
 

·
Registered
Joined
·
840 Posts
Blojo - we're talking two strokes. The reason why it smokes alot at startups, for one - all sleds smokes alot when cold. gas coming from your exhaust, sounds to me the sled has been sitting during off season hasnt yet been, out for a good run. Once you get some snow - I think it will clear up after the motor gets good and hot. Have u been out with the sled yet? WL.
 

·
Registered
Joined
·
840 Posts
And also. if you have a blown head gasket - the coolant would be coming out thru via coolant reservior.
 

·
Registered
Joined
·
17 Posts
Discussion Starter #9
I haven't had a chance to run it more than a few minutes around the yard in the grass - but it leaves a smokey white trail coming out of the grass. I've seen another 88 indy 400, and while that smokes at startup, it doesn't leave a smoking trail.

So the head is off, and I'm wondering if there is a tell tale sign of coolant leakage I could look for. I would think a clean piston would be indicative of it, but the pistons have the normal amount of carbon - about 80% covered. What I haven't seen before is the head itself is spotless, not a speck of carbon. Also, no warping of the head.

I've got a new gasket from Dennis Kirk, and I'll be buttoning it back up. We'll see what happens.

Tim
 

·
Registered
Joined
·
404 Posts
If you have a sizable coolant leak, that spark plug (and probably the rest of the cylinder) will be very clean and free of carbon. Also, the smoke trail on the grass isn't necessarily bad. Our 83 always did the same thing at the beginning of the season (its a fan cooled, so it can't be coolant). It could be do to the old gas or the fact that it sat so long, or too much oil. I just know that every winter, it smokes the first run of the season, and usually after that it goes away. As for the dying while idling problem, how long do you let it idle? If you mean you let off the throttle and it just falls off and dies, then it sounds like the idle fuel system may need adjusting. If you mean you let it sit for 20 minutes and it gradually keeps slowing down and finally stalls, that isn't necessarily a problem. Sleds (especially liquids) are not meant to really sit around idling. The liquids will get hot, which causes the idle to fall off, and the engine will load up on fuel until it finally dies. The only times I let my sled idle for 5-6 minutes is when I just start it up for the first time that day. I also let it sit and idle at the beginning of the season just to be sure everything gets lubed up and ready after sitting dry all summer.
 

·
Registered
Joined
·
17 Posts
Discussion Starter #11
Well, I don't believe it was coolant. New headgasket, all put back together and it still smokes like mad. Seems to run a bit better, but that may be my perception rather than reality.

I'm going to track down some new needles and seats and see if that makes a difference.

Thanks for all the good information from everybody.

Tim
 

·
Registered
Joined
·
840 Posts
Tim - I wouldnt worry about anything right now - just wait til the snow comes and ride the sled. Go easy at first and let her warm up real good. And then as you go along, run her a little harder. Im willing to bet, the longer you run her, the less smoke you will see and it will run a bit more cleaner. I used to have the same sled that you have now - the motor should be spinning at 8k. WL

PS - I agree with Chadd.
 

·
Registered
Joined
·
6,021 Posts
To me, it almost sounds like you are running on only one cylindar.
I say "almost" because my 400 won't go anywhere while only firing on one.
It might be something as simple as a bad spark plug or bad spark plug cap.
 

·
Registered
Joined
·
17 Posts
Discussion Starter #14
Thanks for all the help so far, just need a bit more.

I had a chance to run it for a couple miles on a dusting of snow on some grass. It had a severe low end bog just as the clutch was engaging at first. I had to run alongside the sled to get it past that point. Then it seemed to "clear it's throat" and took off.

From that point, the large amount of smoke seems to have been cleared up, and it is now normal large amounts of smoke. Off the line, it still bogs from 0 to 1/8 throttle, but if I feather it a bit it will take off no problem - though not as strong as an identical 88 indy 400 I rode immediately after.

So - here is a rundown of what I've done/checked:
Timing - spot on.
New Plugs
cleaned (3 times) carbs
new head gasket
compression is 115 on both cylinders
I have the pilot air screw set at 1.5 turns out. I've tried from 1/4 turn all the way to 4 turns and it makes no difference - still a low end bog.
I've tried half choke - still the low end bog.
I've tried moving the circlip up and down the needle - made no difference except that at the richest setting seemed to run poorly.

Any ideas?

The best way I can describe it is that the throttle response is not snappy like it is on the other one. It has the same sound that my yzf-750 had when I screwed around with the airbox to let in more air , kind of a open waaaaaaa noise that you can feather the throttle through.

You'd think if it was lean, the choke would've helped. Rich, and cranking the pilot air screw way the heck out would have helped. I'm stumped.

Thanks,
Tim
 

·
Registered
Joined
·
840 Posts
What do you have for an engagement at? If its below 4k, install heavier spring to increase the engagement speed. Im trying to remember what I have set up in my sled - I think I had her engages around 4.3k. WL.
 

·
Registered
Joined
·
840 Posts
Ok - you should be fine with the engagement - what are you shifting out at? You should be shifting at 8k. WL
 

·
Registered
Joined
·
17 Posts
Discussion Starter #18
Originally posted by white lightning
[br]Ok - you should be fine with the engagement - what are you shifting out at? You should be shifting at 8k. WL
To be honest, I don't know what shifting out means. I imagine that is the RPM the engine stays at as the secondary sheaves slide apart? If we get another dusting of snow, I'll check tonight.

Thanks,
Tim
 

·
Registered
Joined
·
840 Posts
Thats ok, no questions are dumb questions - youre learning and thats cool. So your question above, is correct. You should be aiming at 8k.
 

·
Registered
Joined
·
17 Posts
Discussion Starter #20
White Lightning,

Well, no dusting of snow so I couldn't check out what RPM it shifts out at, HOWEVER, I've got it figured out.

One of the choke plungers had gunked itself to the carb body so strongly that I had to drill it out and pull it out in pieces. A little work with a dremel, a new plunger and spring, and it rips!

Bog is gone, plumes of smoke are (mostly) gone, gas out the exhaust is gone.

Now when you get on the gas it zips up to around 4.5K, the clutch engages and off I go! Can't tell you how excited I am to have this running. Now I have to wait for snow.

Thanks for all the help - I'm sure I'll need more as things go wrong down the road.

Tim
 
1 - 20 of 26 Posts
Top