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Discussion Starter · #1 ·
I found a replacement engine for my blown one. It is a ZRT 600 and has 3900 miles on it. I got it put into my powder extreme. The day before yesterday, I hooked everything up and started it. It idled great and I could hit the throttle and it would rev up. I ran it about 4000 RPM until the coolant had warmed up (per the manual). I noticed that the fuel lines weren't full while it was running. When I shut it off, the little bit of gas in the lines quickly drained into the carbs.

Yesterday I started looking and (like an idiot) I forgot to hook the impulse hose from the fuel pump up to the crankcase. I also noticed that the hose was cracked. I cut the broken part off and attached the hose to the crankcase. I have pressurised fuel lines now.

The problem now is that the engine won't rev. It idles great. I squeeze the throttle and the engine bogs down. It backfired one time loud enough that the wife ran from the house thinking that something had blown up. The plugs are wet and have spark. The carbs have 320 jets and PSI pipes. The sled is set up for 10k feet. This is the set up that was on the sled with the old engine that had the 696 big bore kit. I had thought that the timing might be off, but I should get some kind of a rev since it worked the day before. Is it getting too much fuel?

Does anyone have any ideas on how to get it running right?
 

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I have basically the same set up as you. I have a 97 Powder Extreme with a 600 ZRT setup for an engine. Say that because I removed the compensator from mine. With the backfiring etc, it would seem you are running rich. In my sled I run 310 mains and 30 primaries and that is at 3000 feet roughly. Plugs in mine look real good and she runs like a champ. I trust you did not make the same mistake as me and not put vent/air lines on your carbs? I forgot to and my engine flooded bad and backfired. On my sled, I also have the needles in the carbs set on the second from the bottom position as well. Hope this helps.
 

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what year did the new engine out of???? some of the carb switches are different n/o n/c

get a meter check continuity on both sets simple unplug one of the switches and see if you have continuity if you do that means its n/c , then check the one on your new engine you should have the same thing if you put the meter on the second set and you no continuity its n/o

or it could be backwards you old set might be no and new set nc.

now if you ask why you could rev it yesterday and not today it could be beacuse you had very little fuel supplying the carbs and it was running real lean, you could rev to 4 or 5 grand without hitting the switches now that you have fuel its not lean so you have to push the throttle farther to get up there.

the tss works as follows or opposite depending on whether you have no or nc ignition.
ground to run
(3)n/c switches on carbs wired in series (1) n/o switch on hand throttle

when you first push hand throttle the n/o becomes closed completing the ground, as you accelerate the switches on carbs become open ,now you have closed on handle and open on all three carbs, its still runs because the closed at handle is over riding the carb cicuit and completing ground, if you let go of throttle completely handle becomes open and carbs become closed keeping the circuit complete so it still runs, now if one carb doesnt return to idle position switch is not made and it quits since you have open at the throttle and one carb is open there is no complete circuit.

Dan
 

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Danthe man could be on to something here. I would assume that you reused your carbs, so the TSS system should be as it was before, but it may not be functioning properly. The TSS cuts the ignition at RPM's approaching engagement RPM, and spark interuption can result in fouled plugs and raw fuel entering the exhaust pipes, which can result in the bachfire pop you are experiencing. Try bypassing the TSS and see if that makes any difference.
 

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Discussion Starter · #6 ·
The new engine is a 99.

The TSS is only connected to the center carb and when bypassed makes no difference.

I checked the choke cables and they aren't stuck open.

The PTO side cylinder has fuel dripping from the where the exhaust port and pipe connect. Not bad enough that I'm concerned about it though.
 

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ok, did you use the cdi that was in your machine or did you swap that with the engine????

and also how are you bypassing???? if your using your old bypass and you have the newer cdi your backwards and actually causing te problem, your either having a stator issue a ground issue,or your tss is not right. you want to eventually hook that tss back up especially on the older zrts the throttles do have a tendencie to stick, wide open too of course and the disc brake???? it doesnt even slow it down.

what i would do is remove the purple or black red wire from the 4 prong connector alltogether just for testing purposes this will disconnect all of the safety switches not just bypass the carbs.

dan
 

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Did you use your old stator in the new engine? You would want all the same electrical components, stator and CDI to be compatible. You could check on the online microfische to see if the part numbers are the same for the various years of the parts you have.
 

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Discussion Starter · #11 ·
Everything was off of the old engine. The stator had recently been rebuilt and I retested it after it was in the new engine. It was OK. The CDI is the same as what was on the engine. I changed all electrical from the old engine to the new with the exception of the ignition sensor. Being that they are the same, I didn't see the sense it changing it out. I don't think that this would cause the problem either.

It just seems that it is getting too much fuel. I'm working tonight and have the next two off so I am planning to take another look tomorrow.

:D I am appreciating the input. This has me stumped. I have worked on sleds that are really lean but not this rich.
 

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Are you sure you got timed properly when you swapped your old stator into the new engine? That may be worth checking again. I don't know if it is just too rich. If it was way rich then I doubt thatthe pipe would be able ot get hot enough to ignite the raw fuel and cause the back fire, so that is why I think it might be ignition / electrical related.
 

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I had the same problem on my 94' Tcat right after I reconditioned the carbs. The only way it would rev was when I turned the choke on (giving more fuel). I ended up raising the needles to max and it ran great after that.
 

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<div class='quotetop'>QUOTE (94ZR580 @ Mar 19 2007, 01:59 PM) <{POST_SNAPBACK}></div>
Are you sure you got timed properly when you swapped your old stator into the new engine? That may be worth checking again. I don't know if it is just too rich. If it was way rich then I doubt thatthe pipe would be able ot get hot enough to ignite the raw fuel and cause the back fire, so that is why I think it might be ignition / electrical related.[/b]
I put some thought into stator position and timing a couple months ago. Though I had it in wrong, but if these engines fire 3 times per revolution and there's three bolt holes to mount the stator there's pretty much no way to get it wrong is there? I agree that symptom sounds electrical and could also be stator related based on what I went through. Even faulty bypassed safety throttle switch.
 

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Discussion Starter · #15 ·
:super_happy: GOOD NEWS....I GOT IT RUNNING!!

I had to make a few phone calls but this is what I did.

The main jets were obviously to big. I talked to the dealer and they recommended a 260 jet. I called PSI in UT and was told to go two sizes bigger for their pipes. I put in 280s and everything sounds good.

I took the advice from everyone here about looking at the electrical (stator and timing). I talked to the guy that I bought the engine from and he had it running a couple of days before I bought it. I figured that it wasn't the timing but I should look in the about area for any electrical issues. I don't know if this played a part, but it may have. I found that I hadn't tightened down both of the grounding bolts on the stator cover. When I tightened them up, the engine seemed to "smooth" out a little bit.

I still haven't figured out how I lost the last engine, though. Hopefully I won't have a repeat. After my "failing to tighten" mistake, I looked over the engine really good. All connections, bolts, etc. look good. I am ready to ride (now that it is 80 degrees and the snow is quickly leaving). I am anxious for the late spring snow that we usually get.

:sno: :sno: :sno: :sno:
 

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Curious as to what size primaries you are running as well and the elevation you are at?
 

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That is good news. It sounds like you were trying to run the stock 600 triple with the carbs set up for the previous big bore engine. If that was the case, which wasn't clear to me from the start, then I'm sure we would have given you advise to jet down to something closer to stock jetting. Four sizes rich can cause the problems you were having, thats for sure. The loose electrical grounds is a good catch too. That stuff can come back to haunt you and be extremely difficult to figure out. You'll find lots of sledders who have thrown piles of money at parts and labour only to find that all that was needed was to tighten a screw, or two.
 

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Discussion Starter · #18 ·
<div class='quotetop'>QUOTE (JohnAB @ Mar 20 2007, 10:11 AM) <{POST_SNAPBACK}></div>
Curious as to what size primaries you are running as well and the elevation you are at?[/b]
Not sure what you mean by primaries. My elevation that I live at is 3500 but I ride between 8500 and 10000.
 

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I call it the primary but I guess proper terminology is the Pilot Jet. Smaller jet higher up in the carb body. Usually it is like a 40 or so.
 
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