Polaris ATV Forum banner

1 - 20 of 25 Posts

·
Registered
Joined
·
19 Posts
Discussion Starter #1
So basically I bought a 400L 4x4 as a bit of a fun project and bike to play on. Also, I like these style Polaris bikes since I grew up riding one.

Anyway, I went to purchase this bike and it wasn't in too bad condition for its age, but needed work. The bike didn't have a battery, but when we tried to jump start it, the starter would just tick when you pressed the button. So can anyone tell me where that might be located?

So we were left to try and pull start it and it was firing well, but I think the fuel must have been old because it would start then die. Anyway, I took it home because I only paid $950 for it.

Fast forward 2 weeks later when I fly home from work and I go to pull start it again with fresh fuel and now the pull starter won't pull! So I'm gonna remove the sparkplug and spray some WD-40 down into the cylinder just in case it somehow seized while sitting inside my garage. Do the pullstarters ever get stuck for no reason?

The one my uncle had during my childhood was flawless, so I'm sort of baffled as to why it would just get stuck. And I'm not too keen to take the pullstarter apart because I have taken those mechanisms apart before and they're not fun!

Any help is appreciated!
 

·
Registered
Joined
·
19 Posts
Discussion Starter #2
So I took off the PVT cover and managed to turn over the engine (and noticed the belt needs replacing too!) and freed whatever was stuck. Now I'm back to the previous problem where the engine starts, wants to run but conks out. Fuel delivery seems to not be a problem, spark is good and the engine has compression. I'm gonna clean the carb up, and see if I can figure out the oil injection system - I'm familiar with the oil injection systems of Honda bikes but I'm not sure it uses the same sort of system.
 

·
Registered
Joined
·
19 Posts
Discussion Starter #3
Well it seems every time I post a question, I soon after answer it myself. The bike does run now but seems to backfire a fair bit and the idle is a bit rough. I'll give the carburetor an overhaul tomorrow. I'm think the main seals might need replacing though. Slowly but surely I'm figuring this bike out. I still need to figure out why most of the lights (except the dash light for the high beam) don't work. I found that the main headlight wasn't even plugged in so that explains that one. I'll give the brakes a tune up too since they're pretty bad.

Side note: I took the head off the cylinder to find out why it wasn't running and there was an incredible carbon/oil build up on the cylinder head (worst I have ever seen). Luckily the gasket sealed up good again, but I'll still replace it when I order parts. Oddly enough, when I initially started it, the RPMs started rising and I had disconnected the oil injection and had relatively low coolant so I didn't want it to run. Turning the key off didn't help so I resorted to yanking the sparkplug lead off. Pretty quick thinking required there!
 

·
Registered
Joined
·
4,629 Posts
Glad you are able to answer your own questions :D. Good call on pulling the spark plug boot but unsure why shutting the key off didn't stop the engine?

Sounds like you have a nice little project going here. Agree that cleaning the carb is probably in order too, even if just for piece of mind.


Rather be riding, instead I'm using Tapatalk
 

·
Registered
Joined
·
19 Posts
Discussion Starter #5
Yeah, I'm not sure if the idle screw was turned up or not, but I had a play with it and it sort of idles near where it needs to be, but it still backfires. I gave the carby a clean too, and reset the pilot screw to 1.5 turns (Does that sound right for a 400L?). I think it was set at around 3.5 turns when I counted the screw back in. I'm starting to think there might be an air leak somewhere, the main seals being the suspected problem.

Is the starter motor behind the pull starter too? I am keen to give that a clean up too.

And I'm not sure if there is an electrical problem or not as well. Any ideas to narrow it down?
 

·
Registered
Joined
·
19 Posts
Discussion Starter #6
Alright, well, the good news is it doesn't appear to be backfiring anymore which is a plus so maybe the main seals are alright (I'll be replacing them though). The current problem (aside from no lights working, not even dash lights) is that the bike doesn't want to idle, even with the idle screw all the way in (yes, I know it should be revving its brains out!). Once started it seems to run fine, albeit very smokey. I have the pilot jet screw 4 turns out (Manual says 1.5, it was 3.5 turns originally) so currently I'm just tuning the carb myself as setting it to what the manual says wasn't working at all. Also, I notice when the throttle is blipped the RPMs don't fall as quickly as I think they should. I ordered a carb rebuild kit so hopefully that fixes any problems with the carb. Any ideas on why it might not be idling properly?
 

·
Registered
Joined
·
5,753 Posts
The mixture screw on them is an air adjustment. Out is leaner, in is richer. Go back to 1-1.5 turns. That's likely the cause for the poor idle and long hang time on throttle blip, and if you haven't sorted out the injection yet get some premix in it so you don't destroy a crank bearing or the piston rings and cylinder. They are a smoky machine in general. They also don't run right if you have airbox off or open. Here's a link to parts breakdowns that will help in locating stuff and seeing how it comes apart.

Browse
 

·
Registered
Joined
·
4,629 Posts
If 1.5 turns out is spec and the PO was running it at 3.5 to compensate for a carb/air problem, then the rebuild kit you bought will probably be warranted.

Yes starter is behind the recoil starter. DB electrical online has cheap ones if yours needs to be rebuilt although I am not certain if they have one for a 400L. I'm guessing your bendix will be rusted up when you get in there.


Rather be riding, instead I'm using Tapatalk
 

·
Registered
Joined
·
19 Posts
Discussion Starter #9
Thanks for the advice guys. I might play around with the idle screw a bit then and put it back in. I made it a little leaner because the plug was getting fowled up a fair bit. But the hanging RPM makes me also think it's a bit too lean.

And as I was removing the pull starter mechanism, I decided to remove the skid plate and I found the starter motor, directly underneath the engine (which I thought was weird seeing as it would get wet easily). So now I'm trying to get it off but the transmission is sort of in the way and making it difficult to remove. I'm also looking at getting a Clymer manual since the Polaris one is pretty general. Worth it?
 

·
Registered
Joined
·
23 Posts
Sounds like a cool project. Same motor as a Scrambler 400. The starter is on the bottom of the engine, the bendix for it is located behind pull start next to flywheel. Usally bendix is frozen causing starter to just click. As far as engine make sure intake and air box are all intact, drain your oil tank lines and oil injector and fill with polaris oil, non polaris oil makes these engines smoke bad and foul plug. Now as long as your in flywheel area id pull flywheel and check stator for debris and or damage also check flywheel magnets for heavy rust have seen these issues cause weak spark which fouls plug. keep us posted on this project luv those old beast.
 

·
Registered
Joined
·
19 Posts
Discussion Starter #11
Hmm, I took off the pull starter and the bendix was moving freely. I even moved it out and the starter wouldn't budge. I tapped the casing of the starter with a mallet but that had no effect either. I didn't take off the flywheel yet because the sparkplug sparks very easily. Barely have to pull the cord to spark up. The good news is, I put the air filter back on and set the carb back to 2 turns out and it ran quite well. And it sort of idles as well. I'm hesitant to leave it running though because I don't trust the cooling system yet.

I hooked up my motorcycle battery and the fan for the radiator turns on as soon as you turn the key? Any reasons why this might happen?

Also, the secondary headlights (spotlights) near the front have lightbulbs with a fitting on the end of it. Anyone know the name of these?

I'm feeling pretty good about this bike now. Cheers for the help so far (BTW I'm from Australia so Polaris quads this old are quite uncommon).
 

·
Registered
Joined
·
19 Posts
Discussion Starter #13
So I had the engine running AND idling well, so much so I was gonna put all the plastics and rear rack back on. But I thought I would make sure it's all good and what do you know, it is behaving exactly how it was in the first place. Plenty of spark, decent compression and the carb was set at the factory specs which were known to work, yet all it does it fire up and die immediately after it starts.

Regulator maybe?
 

·
Registered
Joined
·
19 Posts
Discussion Starter #15
Well decent = enough. I did a dry compression test and it was ~80 PSi, which is what my CR125 had before I rebuilt that. I would say enough that the engine should start. The head gasket has also been disturbed a few times so there's that as well. Nonetheless, I decided I'm just gonna rebuild the motor instead of trying to fix a lost cause.

Any idea how to get the oil bottle off? I'm trying to strip the chassis right down while I wait for the clutch tool and give it a good a good clean (and fix up any minor rust). Those plastic plugs don't want to budge!
 

·
Registered
Joined
·
137 Posts
Well decent = enough. I did a dry compression test and it was ~80 PSi, which is what my CR125 had before I rebuilt that. I would say enough that the engine should start. The head gasket has also been disturbed a few times so there's that as well. Nonetheless, I decided I'm just gonna rebuild the motor instead of trying to fix a lost cause.

Any idea how to get the oil bottle off? I'm trying to strip the chassis right down while I wait for the clutch tool and give it a good a good clean (and fix up any minor rust). Those plastic plugs don't want to budge!
80psi is really low for this motor, when it drops below 100psi it's time to rebuild, it should be in the 120 - 130 range. The oil bottle is riveted on, I drilled out the rivets to remove then when it was time to reinstall you can use nuts and bolts or new rivets.
 

·
Registered
Joined
·
19 Posts
Discussion Starter #18
Well I have continued tearing down the bike. Mainly I'm just cleaning away grime because the previous owner did say the oil line dripped. And it does seem like it has gone over pretty much everything. But in general the whole bike is pretty grimey (which is good since it keeps rust away) but for the most part everything is in good nick. Waiting on the clutch tool to arrive so I can take the engine out. To remove the flywheel I'm hoping my case splitter for dirt bikes will bolt up? Otherwise, does anyone know which ones will work?

And also, were the racks on the 400L red or black from the factory? Mine are black, but I've seen plenty that are red online?
 

·
Registered
Joined
·
19 Posts
Discussion Starter #19


Here's the progress so far. All the plastics are gone, expansion chamber, left foot rest, racks, seat, radiator and the middle drive chain. Another quick question, how do the front axles work? They don't spin when I roll the bike around. Do they engage when the engine turns them?

I also discovered one wire connector going to the regulator was broken in half, and another was unplugged so maybe that had something to do with the electrics being weird.
 
1 - 20 of 25 Posts
Top