Exciter 570 help, please. Out of ideas

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Hey guys, I wont tell you that I am a polaris guy so that it will not skew your opinion of me and possibly stop you from helping me.... :D

I dont know a ton about Yamaha's and a friend and I have been trying to get his late 80's/early 90's Exciter 570 back on the snow.

Heres the history on it:

He got the sled for nothing, from people who knew less than nothing. Sled had no compression on one side. Turns out they had 2 different sized pistons among many other boneheaded mistakes.

After pricing out parts, I found an entire motor for cheaper. so heres what we are running right now: (dont know what all the numbers mean, but I think it means we have a conglamerate of years here)

Tunnel number is 82M
Block number is 88R
Cylinders are 82M
Head is 82M
Carbs are 84M (VM38's I think)

The sled will not idle and will die if you let it get below 4 or 5000 rpms. If you keep it above there it seems to run ok, but its hard to tell with out being able to ride on it. Also, need to prime it to start every time (hot or cold) and need to prime it to keep it running below 4000 rpms.

Carb settings are (1700' ab SL)
-300 main jets
-42.5 pilots
-big idle screw out 5/8 turns
-little air screw out 2 turns
-Needle @ setting 3
-coolant tubes blocked off
-Throttle over-ride disconnected
-choke (not really a choke, persay, but a choke feature none the less) disconnected
and here are the things that are really confusing me:
-Power air jet? 1.5, but seems to be by passed with tubing
-air jet in the throat (airbox side) of the carb @ 6o'clock is not there (papers I found tell me there should be a #160(LH) and #200 (RH) in there, but the local Yami dealer knew nothing about it.

Whats really wierd is that it doesnt seem to make ANY difference if we change jets, change needle settings, move the air screws, etc.

Heres a few pics of the carbs. I would REALLY appreciate ANY help. We are out of ideas....

Thanks! (will buy beer next time I see whoever offers up some help! ;) )

EDIT: Here is where I got the carb settings and where it refers to the "Power Air Jet" #160 and #200 http://vintagesnow.com/Yamaha.html
 

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crank seals still good,? sounds like a big vacume leak. It won t suck in fuel at any low rpm......seals or maybe carb boots leaking or cracked....pilot jets are not blocked?? air screw is ouit too far....should be 1.5...need more info
 
With the motor running (wont idle so its kept running with primer and throttle) we sprayed carb cleaner at the crank end and it didnt seem to affect it, so I thing the seals are good.

I will look at the boots tonight.

the carbs are spotless inside. have been apart and cleaned many times.

And I revised my first post. The LARGE idle screw is out 5/8 turns and the little air screw is out 2 turns. Whats wierd though, is we tried them at all different combinations from extreme out to extreme in and it didnt affect the performance at all!

Im thinking there is supposed to be a jet in the hole at 6o'clock in the first pic, no? there is nothing in there, but the dealer was no help to figure it out.

The #1.5 jet I was refering to was in the top nipple with the greenish-blueish tubing in the 1st and 3rd pic. if that helps

EDIT: item #28 in this pic (but not sure this is the right carb diagram because it does not have the coolant ports)
expvm.gif
 
Another couple pieces of diagnostic information....

removing the belt does not affect the performance of the motor and I have cleaned up the primary and the weights move freely.

The Throttle Positions Sensor concerns me too. One seems to be just unplugged from the carb and the other has 2 wires (red and black) coming out of it and they are cut off. How do you properly eliminate the TPS? I find NOTHING on the sled wiring that looks to be for these to be hooked up either.
 
also make sure your vacuum line is not torn or dry rotted it goes from the base of engine to fuel pump it is solid black, the vacuum from the base is what operates the fuel pressure if it has a tear or hole it will cause it not to pump fuel good
 
there is no jet at the 6 position. thats a straight line to the main jet. the ball appearing thing at the 5:00 position is a little puzzling. normally thats an air jet of sorts that runs in with the pilot circuit. that would be where your part #28 goes.

is that a total blockage and both carbs are like that? or just some weird camera stuff? i am think that should have an orifice to allow air to flow.

dont have a different set of carbs to try do you?

prior to having to prime for start, are you able to see any fuel in the lines at the carb? is the fuel making its way back to the tank? have you tried a different fuel pump?
 
Ok. I think we determined it to be the PTO side crank seal. It is a very minor leak because carb cleaner did not affect it, but ether did. I was able to keep it idling without throttle or primer by giving the crank a shot of ether about every 3 to 5 seconds. Would also explain why it did not do it last spring when we put the motor in because it was 50-60* outside.

Found one on babbits for $18 so we will give that a whirl. I was told that you can replace them on the sled, no? Any words of advice to replacing that?

Thanks so much for all the responses.


Yes, both carbs have that ball in that position. No, no other carbs to try.
The plunger for the "choke" is still threaded in, but the cables were removed to eliminate any question.

We cant find where the throttle position wires should go into the wiring harness anywhere.

There are 2 wires coming out of the mag side of the case (1 white/red and 1 white/green) with a connector on the end that is not connected to anything either. What would that pair of wires be for? I can get pics too if needed.

Sorry, long post with lots of questions and info, but Im happy we are finally getting somewhere!

Thanks agaain!
 
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are your floats set properly....maybe they are too low and not enough fuel in the bowls for the low speed jet , but enough for the high speed ....just a thought
 
I checked them last night. I did adjust them slightly, but not much. they are now level when the carb is held upside down.

The sled seemed to idle good with out primer or throttle when I was hitting the crank end with a shot of ether every 3 or so seconde.

Oh, one more thing, Was going to wait for this stuff until the sled was running, but maybe someone can suggest... The tach seems to be off by 2x. at idle and clutch engagment the tach is reading upwards of 6k rpms. I know its not running that fast and it truely seems to be reading 2x the rpms. Any thoughts there?
 
realizing you dont have alot of history on this sled, (too bad you dont), heres some food for thought on the tach issue.

the block number you listed in your first post should be from a 91. the tunnel is from 1987. the 87 exciters were kind of a breed in themselves. alot of shanges occured 88-90. the heads and cylinders and carbs should be interchangable. i havent played with the exciters for awhile, last one was a box job, similar to your situation ,but i learned a bit. others will hopefully correct me if i am wrong.

the 87 had the early style ignition system that ran through 89-90. the 91 had a completley different ignition. you mentioned a couple wires not plugged to anything. without a wiring diagram for all the years to compare the wiring to, i am guessing those colors are for the pickup coil based on a troubleshooting sheet i have but i didnt note the year.

this may be part of your problem, or may be an issue waiting to happen.
 
Interesting... The seal is ordered 2 day priority so should have it in by friday.

we will do some more diagnostics when we can keep it running stable.
 
I have been told that this seal is replaceable with out splitting the cases. is this true? any one got any tips on doing this task?
 
OK. seal was replaced and now it runs worse than it did before! Takes 20+ pulls to start and will spool up and die.

Seems like everything we do to this thing makes it run worse.

1. Plugs are always wet and seemingly oily, not so much gassy. Before we drain the tank and run premix to eliminate that, How do you adjust the oil pump?

2. Is there ANY reason that it would not run with the "choke" cables disconnected at the carbs? we unscrewed the brass connectors at the carbs and removed the cables and screwed the brass connectors back together.
 
it almost sounds like the seal change didnt seal. a normal indication of a bad seal is the multiple pulls(not enough vacuum on the pule line to the pump).

the spool up and die would also indicate a seal(lean, sucking air, then running out of fuel).

pump can be checked by removing it and measuring the amount of rise in the actuator arm with a feeler gauge, or the cable itself is adjustable.

lack of cables on the choke could factor in. the cable end should attach to the plunger with a spring inbetween. one would think the spring would be for a return, but possibly the plungers are now floating?

perhaps the seal on the mag side is bad. maybe a leakdown test is in order.
 
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