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  1. #1

    Max RPM 1997 SLTX

    Quick and likely easy one guys...but all things operating as they should be what is max/wide open normal operating RPM for a 1997 SLTX 1050?? Iíve searched and not been able to find a concrete answer for some reason.

    thx!!


  2. #2
    Finding other models are in the 6200 range give or take so I’m thinking this machine would be similar??? And at that RPM I should be expecting somewhere in the 50-55MPH range given our other SLT 700 will touch around 45MPH

  3. #3
    henryb's Avatar
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    I have a 1997 SLTX and I get up near 6500 rpms on a regular basis, top speed on the MFD is around 58mph.

  4. #4
    Thanks for the input Henryb - very helpful as that of course be the identical boat to mine so as suspected I've got more work to do.

    I've been chasing a few gremlins on this machine since day one as the previous owner had claimed to have had a complete rebuild along with the deletion of the oiling system (premix now) which also had me question a few things since these oiling systems tend to be reliable. Either way - it was cheap, ran great on the hose, goof compression, and here I am. However on the water initially it would fire and run well with full choke but after a warm up and choke off it wouldn't run for s#%t. Bog - stall - repeat. I found that if I manually adjusted some choke back in (say 1/4 or so) and blipped the throttle I would get on plane and then with some continued "choke tweaking" and plug reads, I could get it to run for the most part as it should. However as one would suspect I'm not getting max performance doing this on the top (best I can safely get in the sweet spot is 61-6200'ish and 48-50MPH before if I back any more choke out it goes into the lean side of things and I start to lose RPM/MPH OR if I add any more choke in same results) as well as from a dead stop/idle situation I have to blip the throttle to get it through the "rich" condition where it's likely loaded up. Risky to continue to do so, yes and I'd like to fix it, but I've been doing it since last summer with many gallons of fuel through the tank and I'm the only one that can ride it in this condition since I've burnt my fair share of 2 stroke sled motors to feel that I'm keeping it on the right side of lean doing this.

    So the with help and previous advice from this site on the other 96 SLT 700 - - - I did all the fuel lines and carb rebuild kits on all 3 carbs, etc looking to get more fuel supply.......checked factory jetting/etc. and all is as it should be. However the situation persists.

    Since it was a rebuild I tried to also check for any additional supply of air such as a crank seal leak allowing extra air into the circuit but no testing seems to indicate that to be the problem. Not saying it CAN'T still be my problem but I tried using ether as best I could when running on the case seals...but given the set up on the machines it's not really possible to test are around the CRANK seals.

    The next question is because I've done everything listed in the fuel system overhaul of these machines is it possible that when they did the rebuild, if they went to a .030 or possibly higher .040 overbore on the cylinders I'm getting jusssst that extra bit of displacement/air volume in the cylinders that I need to increase all my jetting (pilot/needle position, main jet) by 1-2 sizes to compensate???? Which is why cutting off some air flow with the choke works BUT doesn't allow me full potential on the top and causes me some bottom/off-idle bog??? - - I know typically a minor bore is fine with stock jetting but I have encountered some sleds that needed slight tweaking after on the carbs.

  5. #5
    casey67's Avatar
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    Polaris manual states 6500 operating rpm.

    Good job on diagnosis so far.

    Correct advice would be to perform a pressure test of the engine/exhaust.
    In my opinion, if it is rock solid-duplicate everytime, I would adjust carbs. The .030 shouldn't be enough to NEED larger jetting.

    The carbs have 3 different circuits and they do stack or add up as far as adding overall amount of fuel.
    The low speed mixture screws are the easiest to adjust, I would start there.
    The accell pump should be strong enough to overcome "take off" bogg on most I have seen. Adjusting low screws till it goes away should be first.

  6. #6
    Thanks Casey67 - really Appreciate The reply and any suggestions as to what Iíve not done.

    In relation to ďpressure testĒ Iím assuming youíre referring to a leak down test where I would block off both the intake manifold and exhaust, pressure up the engine somewhat with air and watch for leak down indicating a seal failing either on the case of crank?? If so I have seen an article or post where guys used rubber balls greased to block the manifold entrance/exits to pressure up the engine so thatís definitely a thought.

    As for the carbs - I do have them at factory setting so richening up the idle mix to try and see if I can get away from needing the choke at throttle entry from complete idle is a good suggestion for sure to start. For the remaining circuits - I also keep leaning towards perhaps lowering my needle clips (raising my needles) two to three positions and increasing my mains by even as much as 2-3 sizes and see where I land. Since my understanding is that from 1/4 or 1/3 throttle in your idle circuit becomes essentially out of the equation from that point on for adjustment and you rely on your needle setting and main size as it is a combination of the two in that range up to 3/4 throttle. 3/4 up to full throttle your needle will wind up completely lifted making use of the entirety of the wide open main jet port.

    While itís somewhat of a pain in the ass to work carbs at the lake where most of my tools arenít thatís probably a good start. Perhaps upsize all jets (pilot, main) by a couple of sizes and look for improvement and piston wash/plugs. If it works or improved but still needs SOME choke - increase further and rinse, wash, repeat as they say. There is definitely something to be said about EFI and programmers.......

  7. #7
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    Since it was a rebuild, have you verified the flywheel/timing is correct? Does the CDI appear to be stock?

  8. #8
    32Deg - I haven’t taken a look at the timing but I’m familiar with adjusting as I changed out the ignition to the updated version on our 700 SLT, and also this SLTX has the original CDI and stator not the updated version. Do you happen to have the timing curve parameters??? The 700 was basically set to 18 degrees at 3000 with a pretty flat curve.

    I also questioned whether the timing would cause any of the issues I’m seeing....it starts excellent and essentially I can use fuel to get it to run at like 80-90% of its capacity. My experience was always with timing that adjusting fuel or air would not really cause all that much change in the performance or problems like a bog or hesitation. Like for example where you may have low end bog due to a slightly retarded timing, but once at higher RPM it may not be sharp but you still achieve top speed/RPM. And adjusting the fuel/air ratio at low speed won’t eliminate that bog.

    - but I could be totally off base (and anyone please correct me) where a slightly retarded timing or advanced timing may be rectified by an adjusted air fuel ratio based on the timing of the ignition??? For example in a slightly advanced situation...increasing the fuel to air ration (richer) slightly may cause an incomplete or slower/cooler “burn” and allow for a relatively full/normal ignition and operation without detonation/burn down?? But would that not result in a backfire in the exhaust?

    Again I apologize if that’s way off base - and I will be taking a look at these issues when I can get back up to the lake.

  9. #9
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    ok...so it's still stock stuff...so chances are better things should be ok...however, these machines are getting old and electronics do what they do. I suppose a CDI could go off course on it's timing curve but they are usually either good or not. I don't know the timing curve for your ski but I believe there is something in the Tech section that gives some general curves used. As far as adjusting gas/air mixture to fix a small timing issue, I have not heard of doing that...but not sure it wouldn't work. Usually it's more of a detonation issue via octane level used...but obviously the best thing to do is just fix the timing to be correct. Anyway, keep doing what you are doing and cross things off the list that could be the cause first and then go after timing last.
    Last edited by 32DegH2O; 07-10-2020 at 06:10 PM.

  10. #10
    Will do.....and I’ve been crossing my fingers on the ignition hardware since as you say it’s getting harder to find and also agree on detonation with compression, timing, and octane content being more a factor when it comes to timing issues and burn downs.

    Ill probably take one more look into any potential fuel restrictions or supply issues and then maybe try some carb adjustments and jetting tweaks to start.

    As a last note......and maybe more insight.......I took it out today for a good hour and half and again, using the choke accordingly, had a great ride. The only other points I can add to all my rambling above is that coming from start/idle And just getting into the throttle, I have to have more choke into it to get the proper RPM’s and take off. I’m almost into a half way choke position to get it to want to spook up. Once I’m at half throttle towards full out I actually have to pull out/reduce how much choke I’ve got into it to continue keeping it run the best I can. About a 1/4 choke has it running near perfect for 3/4 to full throttle aside from not getting my max RPM (61 - 6,200) and MPH (48-50). It’s crisp, quick to respond on the throttle, and giving good plug reads. Can back off to half throttle and then jam back on it and it rips right back up.

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