Polaris 400L (Everything I know about tuning and Re-Building the Carburetor)

[@ctessier9548]

Hey bud im 38 just got a 2 stroke 400 plenty of problems but I love challenges and having a 10 second fuel injected car carbs is totally new to me since I've never had a small engine toy before or a father or brother to help me with one if I did have one .The internet is full of garbage but after many hours of electrical wiring ect ect , You will be happy to know with YOUR guidance I got her running and idling pretty good and now making the adjustments I don't know if you read the comments but take it from me , Your a absolute savior some small things to the carb that no one else mentions , god bless because of you I have a smile ear to ear today when I could really use it, Id love to have you on my discord Cheers man ive watched this 10 times now !!

[@MrFixit1]

Glad you got it figured out.

[@kawoodworks8559]

Man I have to say your videos and instruction style has saved me a lot bloody knuckles and cuss words my son doesn't need to hear, so thank you! I just purchased my 11 year old (sorry 18 year old) son the exact same 1994 Polaris 400L 4x4 as his first ATV, in fact my first as well. I'm a jack of all trades a master of 5 (random arbitrary number). Point being is I can usually fix most mechanical issues. Well this ATV has it share but I'll ask one question as they come up and hopefully you'll get back to me. Hard to start, even harder when cold, flooding, lose of power between one quarter and half throttle and would bog out and quit running if given to much throttle at once and backfired at the end. Did a full rebuild on the carburetor and put new reeds in (definitely need it). Also replaced the choke plunger and spring (needed it). Put it back in and turned on the fuel and fired on the first crank. Was idling a bit high but after some adjustment (that you taught me) I got it running pretty good. I'm doing a bunch of other maintenance work so I wasn't able to take it out and get up to operating temp. I felt good, it was late so I called it a night. Went down this morning and the shop smelled strongly of gas. Looked under the ATV, no gas on the floor but inside under the carb was a different story. Looked like it is leaking from the bowl gasket (new). Wet all the way around and under but nothing coming out the overflow drain. I know both the tube and the drain tube inside the carb were clear. The float tang was not level/parallel to the body so I made that adjustment at the hook for the float needle. Could it be the adjustment I made or did I fail to seat the new gasket properly, didn't tighten it down enough or to much? I know that was long winded but I think more information is better then some in these situations. I'll take any and all recommendations. Thank you and Merry Christmas and a Happy New Year.

[@MrFixit1]

Ok, you said carb rebuild, I'm going to assume you replaced the float needle and seat and the gasket that goes under the seat. Not uncommon for a brand-new needle and seat to leak the first-time fuel is introduced but after running the engine that shouldn't happen. Possibly the fuel line had a small bit of debris in it, and it found its way into the carb. As for the float bowl gasket, not common for a new gasket to leak. Probably didn't get it seated right. Sometimes the edges of the carb body will get bent inward slightly and cause this leak if you don't notice the bowl not seating all the way. Hard to tell from a description and not actually seeing the parts in my hand. I would just go back through everything again and see if you missed something. Hope this helps.

[@kawoodworks8559]

@MrFixit1 I'll do that, thanks for your response.

[@MrFixit1]

@@kawoodworks8559 You're welcome

[@kawoodworks8559]

@MrFixit1 Re-rebuild the carburetor, flying like only a two stroke can now! My son is beside himself, thanks for all your help!

[@kawoodworks8559]

Well get this, got it out to have a Christmas run and its was bogging down when given any throttle. Starved for air so i took the air filter out, put the airbox top back on and she took off like a bat out of hell. Ran great. It's a brand new air filter. Put it back in bogged down again. Ran the pilot air screw all the way in and that opened it up some but not great. Does this mean I need to put in smaller or larger pilot jet in? Appreciate any advice.

[@firehades2007]

One of if not the best video i have seen on carb cleaning and adjustment. very well explained and very thorough. thanks!

[@MrFixit1]

Thanks for watching

[@leviscott8519]

Great videos on these polaris 4x4s Brother! Very helpful! I had no idea how much tech is crammed inside these bikes! Must be worth working on.

[@Ladyinthemist]

You would be a "Great Instructor "! You explain everything so clearly. Great video! Thank you for your knowledge. 😊

[@larryward1082]

Structure in a really good voice for an instructor

[@MrFixit1]

I have heard a lot of people say things about me, but this is a first lol

[@amyreaves8054]

Thank you for making this video. I have taken mine to 3 guys and they haven’t fixed a thing. I want it running and I am pretty good diy gal but I know nothing about carburetors. I may have to watch it a couple of times before I get it but I need it on the farm plus I want the guys to see me driving it. 😂

[@jeffward8583]

I have a 1996 polaris 300 xployer 2 stroke. I have 120 psi compression, good spark, but the carb adjustment just isnt right. It will start and idle fine, runs smooth until about 1/2 throttle, then doesnt want to run right. Sometimes it does run great for a short period and then will shut off. Any thoughts?

[@MrFixit1]

Did you buy it like this, or did it just start happening?

[@davelocke2406]

Thank you that’s the first time I seen how to adjust the choke and throttle cable that’s what I needed I love your videos the best I seen so far I have 1996 polaris 400 4x4 sportsman with after market carb and was having trouble dialing it in I think I’m on the right track now watching your video thanks again

[@patriksteffansson6466]

Thanks for another very informative video, also thanks a lot for taking the time to make a video about the carburetor! I removed and looked at my reed valve, there was a rather large gap on one side unfortunately, I turned the tabs and almost removed the gap. However, I have problems finding replacement parts here in Sweden. Will test drive tomorrow and see if it runs better. Thanks again!

[@patriksteffansson6466]

I have a 1992 Polaris Trailboss 350L4X4, would you say it should also idle around 700rmp?

[@MrFixit1]

@@patriksteffansson6466 My manual says 700rpm idle speed for 350 4x4

[@patriksteffansson6466]

@@MrFixit1 Thanks so much! I have ordered an RPM Gauge Meter from amazon, when it arrives I will set the idle properly.

[@rapiddave9313]

Excellent video! So much info!

[@skiptaggart8116]

You are a great instructor. THANKS!

[@rapiddave9313]

I believe your needle seat is likely for the carburetor on the 250cc Polaris. From what I've seen, the 400cc seat is larger and has several small holes around the perimeter.

[@rapiddave9313]

Where did you get the fancy service manual? I have three Polaris 2 strokes (400cc 6 wheeler, 250cc 6 wheeler and a 300cc 4 wheeler).

[@MrFixit1]

Tradebit.com manuals

[@MichaelFoye-q7w]

You can download these manuals for 15 bucks but you’ll get a bunch of different ATVs. I forget exactly which ones but it’s well worth it then it’s right on your phone while you’re digging into these machines.

[@MrFixit1]

Sorry I missed your comment, I get most of my manuals from tradebit.com (not a sponsored) but here is a link to the manual I have this one is on me. file:///C:/Users/Laser%20Works/Desktop/manual%20PDF/Polaris%20%20All%20Models%20%201985-1995%20Repair%20Service%20Manual.pdf

[@SZYSZUNIA80]

hi. hello again. can you tell me how to adjust the stator?

[@MrFixit1]

As far as I know there is no adjustment for the stator. There is a timing adjustment if that is what you are referring to.

[@adamap1]

Awesome. Im just starting to dig in to one of these. Thanks for the video!

[@DennisMarchetti-k7z]

Great video. When I start the engine cold the engine will idle but will not rev up. It loads up and may backfire. After the engine warms up at idle it will rev up and runs just fine. Any ideas?

[@MrFixit1]

Running issues while the engine is cold suggests a lean condition. I would look at the needle clip position, needle jet (emulsion tube), main jet, choke plunger, intake, head gasket or cylinder base gasket leak. other possible reasons for this if it is truly "loading up" suggesting a rich condition, the carburetor is overflowing and allowing fuel to enter the engine while the engine if off. This would take some time for the engine to clear the extra fuel out. Try running it for a bit then turn off the fuel valve while the engine is off then turn it back on again after the engine starts back up and see if the problem continues. Hope this helps.

[@SZYSZUNIA80]

new CDI doesn't work old CDI works but stops packaging is damaged. tell me if 300. 400. 500 cdi is the same

[@MrFixit1]

The type of CDI is determined by the type of Stator you have. Make sure you get the CDI with the same type of connectors. Some have triangle 3 pin connectors, and some have flat 2 pin connectors. I've not had a problem with the eBay CDI box not working but it has been a while sense I have gotten one so maybe the quality has diminished but if you have bought several of them and none of them work then there is another issue.

[@SZYSZUNIA80]

yes on the new cdi there is no spark. when I go back to the old one there is a spark but it works unevenly and stops. I checked the spark and it is not always nice often it is very weak or there is none. but on the old one the engine starts, on the new one there is no spark. maybe I am not lucky and I got a faulty product

[@MrFixit1]

@@SZYSZUNIA80 This is strange, maybe a bad part but check your stator, the pickup coil, ignition and your ground connections. also disconnect the black wire from the CDI to the Cricut board.

[@SZYSZUNIA80]

The stator is new. Completely new. When I did as you said how to check the CDI. I put the black wire to ground, nothing changed, it didn't turn off.

[@MrFixit1]

@@SZYSZUNIA80 Have you checked the grounds? Should have a ground from Batt to engine and one from harness to engine inside the stator housing and one from harness to frame. Here is a link to the manual I have : file:///C:/Users/Laser%20Works/Desktop/manual%20PDF/Polaris%20%20All%20Models%20%201985-1995%20Repair%20Service%20Manual.pdf

[@MichaelFoye-q7w]

That’s funny somebody mentioned he’s got that voice some people just have it most people don’t and I do love his sling blade impression

[@richbadour6002]

Hey, at 49:32 I noticed that you do “not” have a set of wires run over that gasket going between the carburetor and the cylinder head, but mine does could it be that the wires have rub a small hole in that rubber intake boot maybe creating my real lean mixture?

[@richbadour6002]

Thank you! Mine won’t run unless coke is on full! I’m looking for an air leak between carb and intake block…… am I looking for the right cause??? Oh mine is a 1998 Polaris explorer 400 2 cycle!

[@purehenry]

Finishing up my first 400 engine rebuild. Your videos are a big help. I’ll be researching your tuning video I’m sure. Once I get it fired up 🤞🏻. The company I purchased the new block from also provided a break in oil ( low ash mineral oil), do I just dump the whole 500 ml in the oil tank, and top up with 2 stroke oil?

[@MrFixit1]

Put the mineral oil in the gas tank and mix with a full tank of gas. Top off oil tank with 2 cycle oil and run both premix and oil injection at the same time. Run for 20 -30 seconds shut off then cool for 10 minuets. Check fluids and for leaks, then run until engine is at operating temp (about 15 minuets) let cool 15-20 minuets, then go for a gentle ride and do this for the first full tank and stay away from full throttle and long high-speed runs for the first full tank of gas, then go play all you want.

[@MrFixit1]

Premix the mineral oil in the gas tank at 50/1. Top off oil tank with 2 cycle oil and run both premix and oil injection at the same time. This might fowl the spark plug so keep an eye on that. Run for 20 -30 seconds shut off then cool for 10 minuets. Check fluids and for leaks, then run until engine is at operating temp (about 15 minuets) let cool 15-20 minuets, then go for a gentle ride and do this for the first full tank and stay away from full throttle and long high-speed runs for the first full tank of gas, then go play all you want.

[@Engine4dragon]

I have a question. I have a small dribble out of the float overflow tube at higher rpm. I have adjusted the tang to level. All new carb kit. Carb used to constantly flow out the overflow. Now only a drip drop. Like two drops every other rev. Is this normal. Or do I need to lower the float level.

[@MrFixit1]

In a perfect world the carb wouldn't drip a drop but I wouldn't say this is normal but not a big issue. Did you replace the needle and seat valve?

[@Engine4dragon]

Thank you so much for the reply. I have replaced the needle and seat. It is a rubber tipped needle. Followed your video 100%. The kit is an all balls kit. Seemed pretty straightforward.

[@MrFixit1]

@@Engine4dragon Try lowering the fuel bowl level like you was talking about and see if that helps. Keep in mind the less fuel in the bowel the leaner the fuel mix will be so don't go too far down. there could also be something up with the floats.

[@matthewmaddux8435]

Where do u get the spec charts?

[@MrFixit1]

From the manual I have.

[@mkuehn5450]

at 25:25 the chart is most of what you need to know about jetting. divide your throttle into 1/8ths or 1/4th. (bottom scale) depending where in the throttle travel you feel an issue is where the adjustment is needed. 1/4 to 1/2 pilot. 1/4th to 3/4, needle, 3/4th to full, main jet. unless you've made changes to the motor, stock sizes are best! look elsewhere for your problem. for example, i have a richness at 1/4, so i moved the needle clip to the top position. no size number stamped on my pilot makes me think an aftermarket part is the root cause. just remember, fix ANYthing else before jetting. #1 dirty carb / fuel #2 air leak.

[@midsouth2strokes185]

Where can i get the stock reeds at?

[@MrFixit1]

you'll have to search on the web here is the part number (Valve 3240064)

[@stonefurball1]

How much air should it draw through the carburetor? I can put the palm of my hand over the opening to the air filter and it doesn’t seem like it’s pulling any air at all. I can spray a little carb cleaner into the carburetor and it will try to start. Would the reeds cause this? Any suggestions? Thanks

[@MrFixit1]

At engine start up speed there will be very little air moving through airbox inlet. I would check compression and check the crank seals and other vacuum leaks. It should suck your hand to the carburetor with airbox removed.

[@stonefurball1]

@ compression is at 90 psi. Bike has been sitting up for about 6 years. Thanks for your reply

[@amyreaves8054]

Is this carb the same on the Hawkeye 300? Thank you again, I am learning so much!

[@MrFixit1]

Not the same carburetor.

[@SZYSZUNIA80]

hi. i'm back. i need help again. everything put together. but it doesn't want to start. how to adjust the carburetor. it smokes very badly

[@MrFixit1]

Check out this video kzbin.info/www/bejne/d4qcfJ6kqtebbaM

[@SZYSZUNIA80]

I have another problem. The engine is still running after removing the key from the ignition. And after switching the button to the end engine. It is still running

[@MrFixit1]

Check out this video kzbin.info/www/bejne/anzWn4WHhLmlrsk

[@MichaelFoye-q7w]

I’m desperate so I’m just going to make this comment as a question to anybody preferably Mr. fix it. I bought a 99 Explorer 402 stroke real cheap not running blah blah blah. It’s been four days and I have yet to start it and I can start anything. My question is I’m only getting 90 psi on my compression test and my gauge is top-of-the-line or it’s a good one put it that way and I’ve done it way loose to no avail do you think that it’s the low compression keeping it from starting? I mean, I’ve had things start at 60 psi 2 strokes. It’s driving me nuts help

[@MrFixit1]

Yes, Low compression. 115psi is the service limit. try adding a spoon full of oil through the spark plug hole and see if the compression rises. if so then you need a rebuild for sure. (Note use the pull starter to perform compression test and not the electric starter and make sure you hold the throttle wide open)

[@toddsutherland2864]

Idles but kills when I give throttle

[@MrFixit1]

Clean and inspect the carburetor. Check out my video on, Everything I know about cleaning and rebuilding the carburetor.

[@allenbrooks9968]

Great videos! Ive been looking for information on the 400L for sometime now. Glad i found you! I have a question...have you had any problems with the machine not going into forward high or reverse? It will operate in forward low. The linkages all move as should and at the transmission where the linkage connects is moving with the linkage but the machine will not operate in f-high or reverse. Can you help me with this issue? Again..great job! Very informative and if you're not a teacher..you would make a great one!

[@MrFixit1]

On this subject the manual says to disconnect the shift linkage from the transmission, then shift fwd rev, if the trans shifts it is a shifter problem, if not then it is a transmission problem. Try this and see if you can isolate where the problem is.

[@Kingsoupturbo]

There is a seperate rod that operates low range, high everse are on a single rod that has to be adjusted perfectly. You have to take the rear section of exhaust off to check the shift fork for H\R. disconnect the Rod and see if you can push the fork to engage H\R. The shifter also has detents in it and supposed to have oil, it might be siezed up and not working right. The factory manual has the procedure on how to adjust the H\R rod, its very tricky to get it perfect.

[@allenbrooks9968]

Thanks for the info guys. I'll check these when I get some free time.

[@JanMicinik]

Very nice video and summary bro. I studied all of this last month, I was rebuilding top end of Polaris Xplorer 400 2000 (same engine as yours). I have a little problem with it, i tried different jettings,needle settings and so on but it still looks like running very rich. I need to put down float level lower and now it starting good, idles good, no smoke, but when I put full throttle it smokes white (grey) really bad.. I put new head gasket rebuilded water pump, It is not consumpting water I am sure. I thing it is still very rich at full throttle. What do you reccomend ? Main jet is 200 , pilot 30, needle is on the first clip (tottaly down in main jet)... I dont have any smaller jet. Do you thing maybe float level should be even lower ? Is it possible it should be like that because emulsion tube should be worn out or something ?

[@MrFixit1]

Well, if the emulation tube (needle jet) was warn it would not have much effect on full throttle. The main jet will only allow so much fuel into the engine. a rich condition usually makes black smoke not a "gray white smoke". I wouldn't change the float level because you could start running the bowl dry at long full throttle intervals. I would get a main jet kit with smaller jets and try to jet down and see if that makes the deference. It's possible the oil mix is too rich. Are you pre-mixing oil or are you using oil injection? It is possible the oil injection is allowing excessive oil into the engine.

[@JanMicinik]

@@MrFixit1 black smoke so on this two stroke engine ? Cause it was visible when float level was higher engine runs more bad.. and it smokes still "white-grey" even on idle. I changed it little bit lower and now starting,idle, 0-1/2 throttle OK, but 1/2- full throttle smoking white... I am waiting for spare throttle cable... oil injection pump is working , connected , but throttle cable to pump is disconnected and now in tank is premix 1:50L 100 octane and Motul 2stroke oil.

[@MrFixit1]

@@JanMicinik Not necessarily a black smoke because of the two stroke oil but will be dark. White smoke is usually an oil smoke or coolant steam. If the oil pump is connected and primed and working other than the cable is not connected, it is still injecting oil. When you say "1:50L" I am assuming you mean 50:1 ratio? I would install replacement cable and set up the oil pump according to the manual, (I have a video on that) Then run 100% gas in the tank and go from there. How does the spark plug look? Is it black and sooty, or oil soaked?

[@JanMicinik]

@@MrFixit1 Yes, I meant 50:1 ratio. 50 litres of gas and 1 litre of oil. Today arrived replacement cable so I put it on, adjusted and primed like on your video and in tank 100% gas. I went for a ride and after 10 minutes of riding it was still smoking bad. Today smoke looked more white-blue and smell bad like something burned...Right after ride I pull out spark plug. It is white...

[@MrFixit1]

@@JanMicinik White spark plug is signs of lean condition. I would suggest replacing needle clip to 3rd position and reset float arm to parallel to the carburetor body. Also check the balance shaft oil. It is possible the right side crank seal is leaking and burning balance shaft oil. There should be 100ml of fluid in the balance shaft.

[@gregvoigt551]

how do you leak vacuum?lol

[@MrFixit1]

The engine creates negative pressure and if it leaks it will leak atmospheric pressure into the engine and we call it a vacuum leak.

[@bustersmith5569]

I dont think that machine has reeds 🤔 ? Mine is the same machine no reeds ,,,

[@MrFixit1]

Yes, the 400l & 350l has a reed valve.

[@kawoodworks8559]

I just replaced my reeds, same atv

[@userunknown2645]

Hey I have the same carb on polaris 400 xplorer 1999. I cannot get the throttle adjusted properly. Iv cleaned several times with hx with my atv. But I cannot get this running right. Choke works correctly. Opinions?

[@MrFixit1]

May need to re-jet the pilot and or replace the choke plunger. Thats if everything else is in good working order. Hard to say for sure with such limited information.

[@userunknown2645]

Could I ask u a few questions on how to set the carb back to basic so I than can adjust from there. It seems I'm chasing a tight throttle to keep idel high enough not to stall, but still have no response on idel screw. Than when I adjust thumb etc switch to keep a small gap I mess everything back up with the previous adjustment at carb. I'm playing at 2 turns out on air screw. No response on idel screw. Only way I can keep it idel is tighten at carb side, but than the cable pulls or pushes when turning . Lots of slack in line, no pitch, no strapping, it's because I adjust cable so tight to get it to idel. It takes a while to Rev down into the 600 range but than puts puts puts and dies. Knowing this, could u please provide a direction or way to communicate. Ty

[@MrFixit1]

@@userunknown2645 I can only help so much. Use the chart I supplied in this video to restore factory settings. Check the engine for vacuum leaks and reeds for damage.