Rwoody

Right On Russ That is one way to clear a parking spot. Never would have thought of that. Yeah I had 6 of those 425's at one time. I am back down to 1 my original one. I started this 4 Wheeler journey back in 2007 and from that time to now I have resurrected five (5) Suzuki LT250's 85 - 86 versions, 3 LT4WD Suzuki's, 3 Yamaha's moto 4's, 2 Honda's, 2 two stroke Polaris's, 1 6X6 Polaris and Six 425's. I am one of those guys that loves to dig into old stuff and get it running again. It also helps that I have a relative that runs a scrap yard which most of these cam from. He gives me a call when one comes in and I pay scrap price for them. My real job has me traveling all over the place and when I see one in a field neglected or outside broken down I will stop and knock on the door which has worked well so far but not always. I was a aircraft electrician in the navy and just need something to keep me busy. recently I picked up a 2014 at an auction for 500$ that had been rolled. After replacing all the damaged parts I am into it for just over 1400. This thing had 22 hours and 148 miles on it. The tires still had the nubs. Runs great and will be my keeper for a while. I am also working on a Honda foreman 87 version at the moment, picked it up at the same auction dirt cheap. Cleaned carb and had it running in hour once I got it home. My first 4 Wheeler ever was that 425 that's probably why I still have her. I still have to do a little work to her the carb bogs out at times but other than that it runs great, not as cushy as the 2014 but I still like to take her for a ride now and then. The old machines definitely let you know your age but I still like to ride them. Here is the 2014 I picked up had to replace dam near all the plastics and handle bars and steering column but other then that good running machine. the other pick a friend sent me and thought you would like it Stay with it and Enjoy

Been A While. The issues above were solved eventually through a lot of digging and perseverance. I saw the last item pop up on a few forums about starting with electric starter and pull starter. Which I had an issue with as well. 1. The machines would almost always crank over without a problem but would not always start. Although would start easily with pull starter. What I have found is that when cranking it with electric start it would seem to have spark so you think its good but that spark is not consistent which you really cant tell that by just looking at it. The problem is your Pulse or Trigger coil is just a whisker to far away from the flywheel. Its close enough to run and not give you a problem in most conditions So the next question is? 2. But why does it start with the pull starter and not the electric. The pull starter engages the flywheel at the center which does not put any mechanical forces on the flywheel. The Starter gear on the other hand does and that angular stress or force is just enough to move the flywheel away from the trigger coil which in turn gives you the problem of not starting with the electric starter. Like a said its just a thousands (very small gap) I had this issue with 4 older machines (3 425"s and 1 500 90's vintage) What I had to do was access the trigger coil and adjust it closer to the flywheel I used the closest measurement. I also had to on one machine elongate the mounting holes (very little) to get that close gap. But after doing so I no longer had that issue of will not start with electric starter but will start with pull starter. Again this was all on 1990's machines. Hope this helps and RIDE ON

First I want to Thank Everyone that commented on this post. I have finally got these things going. I first had issues with a 4x4 425 Magnum with the top end as I thought 4 years ago. I pretty much left the machine sit for some time and when I got back into figuring it out. The funny part is I ended up with 3 Polaris 425's, 2 4X4's and one 2X4 all with the same issues. After getting them all back together with all parts installed. The 2 I acquired were pulled apart by previous owners trouble shooting. So needless to say I had to acquire some parts. So the over running theme was the same All would start and Idle but would not accelerate. One had bad valves and out of tune carb. One had bad valves and cam and out of tune carb. My original 4X4 had cracked carb (still have no idea how that happened) but new carb and fine tuning and she is running strong again. The reoccurring theme here is the Carbs and the air cleaner set up. The jetting on the 425 seems to be real critical for the older machines. At least with these 3 machines it was. The rebuild kits I installed apparently were not the correct ones so I induced a lot of the problems when I rebuilt them. So now with my pocket quite a bit lighter I am now educated a bit on jetting and its importance. It took me a while and lots of questions on this forum and reading others to finally figure it out. So again Thank you to all those who post here and other places about the issues and what you discover. So now the only issue I have is the starting issue when hot. I have not dug into this yet but I believe its the Starter being corroded. When hot you can actually see the spark trail off with a spark window tool. cold the machine has great spark but after you ride and get it good and hot it will only start with a pull on the rope. The spark fires once then after that is so week you can barely feel it, so something is stealing the spark or shorting it out. Once I get a chance I am going to go over all grounding connections and terminals to ensure I have good grounds and connections. this machine has a lot of rust so I am pretty sure it was out in the elements for some time or used as a salt spreader and plow. Have a good day and keep em running

I was kind of leaning toward the Battery or the starter. When I picked this machine up it would not turn over and the starter was froze up. I will test that this evening thanks for the information. This particular machine gave me so many headaches I started writing things down so I would not do the same thing twice. In the begging of the notes I put starter frozen and was able to free up but its drawing higher then normal amperage. Note: clean and see if can be freed up more> So that very well can be the issue. Thanks I really appreciate the feedback and the suggestions.

Ok so today was a great spring day here in the east side of PA, So i figured why not work on the old green machine for a bit. I started out trouble shooting the no spark and found that one of the connections was loose. So she has great spark again. Fired her up and ran it for awhile and got it good and hot. Shut it down and waited a minute or two and she would not start. Turned over great but would not start. After about 15 minutes of letting it cool down it fired up. So before I got off to the races and tried to find a problem I pulled the plug again and checked it. Burning like it should be. So i fired it up got it hot and shut it off. No start again until it cooled down. I checked a few things and after it cooled for about 15 minutes it started up. So again I ran it until it was hot. (The engine was just hot enough for the fan to come on) again it would not start with the electric starter. So just for sh#$s and Giggles i decided to us the pull start. She fired on first pull. I ran it to it was warmed up again and the same thing. No electric start but will pull start every time. I have metered and checked the connections to the starter and solenoid and ignition switch all test good. I have no idea why once its hot it will not start by electric but pull starts first try. Any Ideas???? So on to the next thing. I was confident enough to take it out for a ride and immediately it bogged at half throttle so I got a cloth and covered one hole and she ran good. So for the time being I put a small air breather on one side and that seemed to do the trick she idles great and runs up to high throttle with a load on (Me). I had no idea this machine could get up and go like it does. So next is a true test in the hills next weekend. I will post back Russ when i changed the cam on this one I installed the compression release incorrect and it almost would not turn over. Once I figured that out it turned over fine. I am glad the wrench is going to take care of that for you. Now with this one figured out almost i have 2 425 4x4's to get going. Got them all in a package deal. 1 4X4 runs great the other has issues like the greenie. Thanks for all the posts and suggestions. I will post how the run goes

Thanks for the insight and I may have to go that route

Thank you Russ I really appreciate the long and detailed response. With that said let me give an update I was able to get away and poke around on it one day this weekend. First I had to replace the rectifier since the old one was not doing its job. I fired it up and low and behold I had 13.9 at the battery and the machine would rev up without much problems. Although it would stutter on the fast rev ups> So I placed some filter material over the holes for the snorkel and low and behold she would rev right up. It seemed like it would rev to the point the engine RPM was at its top. So I let the machine warm up and was getting ready to do a test run and she died. I turned her over several times to no avail. So I checked spark and NO Spark. I checked a couple of things and got very frustrated and had to close up the shed and walk away. I hope the new regulator did not go out. But I had to walk away before I used some of my second amendment rights on this machine. It has been fighting me now for some time. Just when I think I have it fixed it throws something else at me. Well thanks again and I will post when I get some more info. I really want to get this thing up and running it should run like its hair is on fire when I m done. Or maybe I should take the advice and go by a new one.

Thank you very much for the detailed message i will see if i can get to it this weekend What is funny I mounted a small gas tank to the front because I was tired of removing all that stuff as well I will respond as soon as I can thank you

Update: Well I finally got a chance to let it warm up and test the stater and other winding's to make sure they are not breaking down when hot. The readings were within tolerances so I moved on to checking the valves. I decided that this engine has some miles on it so I changed out the valves, springs, and cam. Started right up and again at 1/3rd throttle she would start to sputter and die. So I am really frustrated with this machine. Everything tells me its electrical. So I needed to walk away. So this morning I went out and worked on it and tried to approach it like it was the first time it messed up. i started the machine and checked voltage at the battery. 12.2 static and when started 14.2. No problem there. So I thought I never checked that voltage with the machine above idle. So i got some clips and left the meter attached. At about 1/3 rd throttle I am pushing 16 volts if i push it or rev it I can get the voltage to go clear up to 19, 20 volts at the battery. So the rectifier is bad because the voltage at the battery should never get about 14.5, which in turn most likely f,d the CDI. I am going to do some more checks and will post. Hopefully this is it. This machine will have almost all new parts. I probably should have pulled the jug and got new rings and piston while I was at it. Thanks for the inputs and if anyone has any other suggestions please let me know. Thanks and I will try to ensure I post once i get the new CDI, Voltage Regulator and rev limiter. To day I am going over all the wiring and checking and cleaning all the terminals to ensure there are no other electrical issues

Update: I was able to use a known good carb. A good friend has a good running 425 and was gracious enough to allow me to use his carb for quick swap to eliminate carb. Well my carb ran great on his machine and his carb made no change on my machine. So I am still getting kick around by this machine. So without anymore suggestions I think its time to do one of two things. Tie the throttle open and put in gear and let it roll across the fields and get a few of my old friends and have some target practice or tear the engine down and see what is going on inside. The first option sounds like more fun but I cant give up and I refuse to give in to a mechanical machine. I have a sickness when it comes to machines and I hate to be beat by a mechanical thing. There is always a reason why a mechanical item does not work I just have not figured it out YET. I have to put this on the back burner for a couple of weeks due to other obligations. I was really hoping I could get this going again. If anyone has any other suggestions please let me know. The only thing I can think of is Valves. Here are the symptoms again Starts and Idles perfectly. Uses choke to start, warms up and off choke. idles without a miss. Once you give it throttle, meaning you go past idle maybe 1/4 of throttle it bogs down and will stall if you keep there, it will stumble for a bit before it completely stalls out. Plug is grayish brown and not fouled out. Please read previous threads to see what has been tested and changed (there is a long list) I will continue to update once I get back on it. Thanks to everyone P.S> I did not have time last night to check the compression once it was hot since I had to put my buds machine back together and get it back over to his house. Once I am able to get back on it I will fire it up and try that before I tear it down. Again thanks to all and hope to find a solution soon

That is an excellent suggestion Thanks. That is what I like about these sites it gets you to think outside of the box and you can tap into everyone experiences. I will definitely do that and let you know Thanks again for the Idea's

I agree I have been doing some reading and poking around on the net and I found a post on another sight that stated the Rev Limiter was getting power through the HLR shifter. The switches inside the shifter were not operating properly and caused the machine to act like it was in reverse with the rev limiter. So I will do some studying and find out how to bypass the rev limiter to eliminate that as a cause or fix. On the other hand I looked at the ETC and that also does not look like its at 100%. The armature that houses the micro switch seems to be very loose. Although when you press the throttle the switch seems to actuate and move like it is suppose to. I will update once I check into this and Ill try and remember to take a couple of pic's Thanks Frank I appreciate it

What Did you solve this problem and what did you find was wrong??

Quick update: 02/15/18 I had sometime last night so I opened the covers to check the timing marks. The cam chain does not seem to be overly warn and the tensioner keeps it nice and taunt. The timing marks and top dead center all line up. So I also checked the Stator and trigger coil for resistance readings and they all fall within the attached Chart. So here we are again I cant seem to figure this thing out. What is left to check? I am at a total loss with this machine. I am usually pretty good at figuring these things out but this one has me completely stumped. So any suggestions will be appreciated. Thanks Woody.

Thanks Dave, I agree this thing has got me stumped. I just ordered a cheepy carb off Ebay. We will see how that pans out but for the cost I figured it was worth a shot. I was thinking the same thing that it is acting like its dumping fuel when given throttle. The only problem is the plug is never black its always clean and light gray brownish. Pretty much what you want. I also picked up a spark tester so I can see the spark while its running. So here is my plan for this weekend. I want to open up the inspection plates for the cam timing area and check to ensure my timing marks line up correctly. Open up the flywheel cover and check that those marks correspond with the timing gear on cam. I just cant see it through that little hole. (getting old) I want to meter out the trigger coil, stator and ignition coils for proper ohms to see if they are good. Of course that is if the carb does not change the problem. Yeah I rescued this machine from the scrap yard back in 2010. When I got it the flywheel was loosely on and the covers where missing. I checked it out at that time, got the parts and put it back together and she ran great for several years. Then it started to loose power at top end and it progressively got worse over time until I got tired of fiddling with it and parked in the back of the shop for a couple of years. I just decided to get her going again and see if I can tackle this problem. The reason I am thinking valves is because I had a Suzuki that ran bad once hot and turned out to be valves overly warn. When cold she had decent compression but as it heated up the compression would drop off and it would become hard to start until cool. Anyway this problem is a bit different since it idles great and starts every time. It just does not want to throttle up. When I first got this machine up and running it was great fast and responsive. Then over time it seemed to loose top end power. I decided to figure it out and one thing led to another and she sat for a couple years and here we go again. I may end up tearing the top end off eventually if I cant figure this out. I read somewhere that the ETC can back feed through the reverse light to the limiter. I will need to check that out as well. Thanks for the suggestions I appreciate it

Ok its been a while since I posted. I have finally got some time to work on the Magnum 425, first off Thanks for the past posts and suggestions. First I tackled the 4 Wheel drive issue and the front hubs were totally gummed up and the oil was like a thick grease and had no resemblance of oil at all. So with a few new parts like bearings and lots of cleaning I believe the 4 wheel drive is back up to par. I have encountered a few of the previous problems. The machine will start and Idle perfect. Once you give her throttle after its warmed up it stumbles and bogs down, it does not die just stumbles and will not seem to throttle up. Here is what I have Checked so far. I Cleaned the Carb completely. I checked compression and its at the low end of the scale but within tolerances according to manual. I checked the cam mainly the exhaust lobs for wear and they seemed ok with normal wear not excessive and the lobe seems fine. It has Great spark and good plug I had some spare parts on the shelf from a wrecked 425 so I thought I would swap them out to see if any thing changed. Sparkplug CDI unit Regulator unit Vacuum fuel pump Fuel filter There was absolutely no effect with the above items, Starts almost immediately, idles great, once it warms up it stumbles with throttle and bogs almost like in reverse without override. So I am at a complete loss with this one. I tried everything that I can think of. This problem seem to be starting quite a while ago and has just progressed. Any thoughts? What about warn intake valves. Unfortunately I am not sure how many hours this machine has since I actually bought it at a scrap yard right before it was to be crushed. I will appreciate any suggestions. Thanks Woody

I believe it has something to do with the electric parts since sometimes it will engage just fine, but after a little riding you almost have to fight it from pulling really hard to the right. when you disengage the 4 wheel drive by the button it will correct and stop pulling. It does not happen all the time but its a real eye opener if your not ready for it. She needs front shocks and some other work upfront and I plan on getting back into tearing it down in near future. Also the front Gear box has a wine you can hear from a long way off and I have heard this on other models of that year. I disconnected the chain to isolate it and the wine was definitely coming from the front gear box. Thanks for the info and when I finally get to working on that machine again I will let you know what I find

I believe it has something to do with the electric parts since sometimes it will engage just fine, but after a little riding you almost have to fight it from pulling really hard to the right. when you disengage the 4 wheel drive by the button it will correct and stop pulling. It does not happen all the time but its a real eye opener if your not ready for it. She needs front shocks and some other work upfront and I plan on getting back into tearing it down in near future. Also the front Gear box has a wine you can hear from a long way off and I have heard this on other models of that year. I disconnected the chain to isolate it and the wine was definitely coming from the front gear box.

I think it was multiple problems. I ended up rebuilding the Carb and changing out he several components. The Throttle position switch, CDI and ignition coil out. The only thing that I could definitively say was bad was the micro switch in the ETC on the Thumb throttle. I replaced that along with the other parts and she has ran fine for some time. Although at the moment I have it tore apart I am working on the 4 Wheel drive unit. It seems to engage only one side and pulls really hard to the right when you don't want it to

Well I have not gone that far yet but I guess I will. The machine use to run great except the carb bowl would leak. The needle seat was worn to the point that it would not shut off the fuel and it would constantly drip out the over flow. She ran like a raped ape at that point. So I decided to rebuild the carb and since that time it just seems like there is no top end. It acts like there is a govner or something and it just hits that power end and that all shes got. But I can tell you this its no were near what it use to be. This machine used to blast up hills now it just chucks along. The engine kind of seems like its at peak so I may take a look at the belt and clutch to see if its worn or crazed.

I have a Polaris 425 Magnum. she starts fine and seems to have unlimited low end but just does not have any top end. I know she should be capable of more. Its like there is a limiter on the throttle or something. Need some advice on what to check next. I rebuilt the carb and made sure the floats and Needles are set.

No I had one that would rev up and the clutch would slip in the higher gears.

Is the engine revving? Could be the clutches are worn and slipping

Attached are pictures of the oval seat emulsion tube