Step 9: How to Install Polaris 300 350 400L Top End Cylinder Piston Head Intake Exhaust Manifold

[@indcline]

Used this for a rebuild in 2024. This video walked me through bringing this old girl back. Ron Ritter sells a rebuild kit and it runs 10/10 now. Thanks!!

[@PaulStonebraker-k6y]

Show more details of how to get the cylinder over the piston

[@lmtada]

Excellent video. Covers all 2 stroke top ends. Have 99 explorer 400. Great little quad. More comfy than my lil Honda.

[@BrapStuff]

Thanks man!

[@JohnnyRebKy]

I bought a 400 scrambler from its original owner who bought it new in 1999. It still has original tires on it and has been a garage queen. So it’s barely been used and has tons of compression. I can’t decide whether to go ahead and rebuild it anyway or not. It runs so good I hate to mess with it. Everyone says it’s going to fly apart but I’m not so sure about that. It’s all stock and never been messed with. I think when people start modifying them is when things begin to fly apart. If I decide to pipe it and put a clutch kit in then I will go ahead and rebuild it. But while it’s all stock I’m not really worried about it. Some people say the piston skirt problem was fixed in them by 1999 but who knows lol

[@2wheelfamily493]

Awesome video my Brain needs all the information it can find so this helped thanks. Just bought my Polaris Sport 400 for $200 can't wait to get her running

[@somewhitedude01]

@Brap Stuff, im glad i found this video. Just got an older(late 90s to 2000 model)xplorer 400 and i want rebuild the top end. I appreciate you taking the time to make this video. You have a new sub!

[@BrapStuff]

Glad it helped!!

[@ejr4140]

Best video on the internet..thank you

[@josezuniga1883]

This is a very good and useful information.

[@BrapStuff]

Thank you for watching. If you have questions feel free to ask at anytime.

[@DennisKenneybees]

I would like to have see how you kept the rings in the correct place at the pins and inserted the piston into the cylinder.

[@BrapStuff]

You can't really screw that up.

[@omarsalinas5629]

Awesome video. Definately very good info and makes me think I can rebuild mine. I recently bought a 1996 polaris 400 4x4 and I checked the counter balance dipstick and it was rusted out. So yeah a rebuild is in the works.

[@BrapStuff]

Dear Brap, Try it! If you run into trouble just ask!

[@omarsalinas5629]

Hey there brap. I have a question. I started tearing into my 96 400 and noticed the gear on the oil pump had striped. I found a replacement gear for that. I haven't gotten to the counterbalance gear to see what that looks like. Do you know if the gear on the counterbalance that mates to the oil pump can be change as well or do I have to replaced the whole counterbalance? Thanks in advance.

[@BrapStuff]

You could replace the whole oil pump assembly with a used one for probably $20. If the gear on the pump was that worn, the mating gear on the counterbalance should probably be replaced as well if it's worn or missing teeth.

[@omarsalinas5629]

Thanks. I appreciate the quick response. Have a good day bud!

[@omarsalinas5629]

Brap Stuff thanks again. I am having the cylinder checked and bore if needed.

[@GUNSANDKNIVES]

So it can be done I had 99 sxmcrambler he put 350 top end on it

[@richardshellnutt5138]

Do you have a video of how to break it in?

[@osbornebay944]

I assembled my 2000 Scrambler today, started and runs good, but a short test run, the pto crank seal seems blown, steam puffing out from bottom water reservoir port. What issue could be too much crank case pressure? Thanks for your time?

[@Thebassguru84]

Crank seals shot

[@mariotellez2025]

One question and that's what socket? Wrench? Tool did you use to get to the cylinder base nuts and be able to torque them? I'm having trouble trying to get them tight let alone torquing them and thank you in advance!!!

[@jakea5157]

The head gasket has a little bevel on it. did you notice? Which way does it go? just ordered one and cant find the info anywhere!

[@kaeleb596]

Hey I was wonder where the straight yellow wire coming from the stator goes on the circuit board

[@andrewvasquez3190]

I just installed mine and it’s making a bad clacking sound I turned it off and haven’t turned it on yet any advice?

[@nicloewenhagen5557]

I have a 95 300 two stroke air cooled but I can't get a torque wrench in to torque the cylinder nuts any ideas?

[@BrapStuff]

Crowfoot or just use a wrench and get it close enough.

[@luismiguelribeiro5912]

Hello Friend Where can I find a manual like this one from the polaris sports 400 from 1999. I liked your videos .. I have a polaris sports 400 2t with the engine attached and I'm going to start fixing it. Help me thanks

[@daveanderson2316]

Your wrist pin clips should be installed with the gap UP! The clips can work themselves out with the gap sideways.

[@mud_man_craftsmen3458]

Hey I hope you anser but I have like a 1998 polaris trail boss liquid cooled 4×4 and can you tell me what top end rebuld I need at least 300 just drop a link

[@lylebent251]

What adapter do you use to torque the bottom four bolts?

[@BrapStuff]

Any 3/8” crowfoot wrench set 14mm or 9/16” harbor freight even has a 10pc set…

[@kariwacome6939]

did u have to use a ring compresser

[@omarsalinas5629]

Hey brad. Need some help. I am going to order a new piston and rings. Piston fell of table and broke. The old rings at 1 inch in cylinder measured at .028 with filler gauge. How do I go about ordering a new one. I haven't measured the cylinder cause I don't have the tool yet. The pistons I've seen so far are like 83.5mm over-bore and all the way up to 85mm over-bore. I appreciate your help!

[@BrapStuff]

Checking the ring end gap of an unknown ring won't help determine the piston size. You would almost need to know the OD of the ring (which is not a standard measurement) and could possibly ask someone to measure the OD of their oversized rings to find out what piston goes with it. .028" reg is too much also.

[@codymilton2614]

Does anyone know how to wire the stator to the circuit board on a 99 polaris 400 scrambler two stroke

[@kaeleb596]

Did you figure it out I’m having trouble with it also

[@djodjodubois9458]

Et une pour toute point de graissage et une vidéo..comment changé plaquette de frein break transmition..puis l ajustement merci..si non j ai gardé toute tes vidéo relié a un trail boss..moi je suis plus Honda mais j me suis dit un 4x4 a chaîne 2 temp en PLUS!! Me faire un quad mud!!

[@gabbleredneck6318]

Where did u order the pistons and rings? And head gasket???

[@BrapStuff]

Any good brand name off eBay or amazon. Namura has always been good.

[@gabbleredneck6318]

Brap Stuff like what did u type in for it to pop up because I cannot find shit lol

[@BrapStuff]

Polaris 400 piston .010 .020 .030 whatever size you need.

[@mikef8769]

First of all, awesome video extremely informative! Do you happen to know the compression specs on a 400 L motor? Thanks..

[@modelrc9500]

Did you have any trouble getting the piston on?

[@TTC2109]

yo how did you mount the carb? my original jug was angled to fit the carb, but now its to angled down.

[@BrapStuff]

There were 2 different cuts on the cylinder and 2 different length intake boots. You need to have the right year boot for the right year cylinder.

[@TTC2109]

Brap Stuff ok, my cylinder is not slanted. Could you link me the boot please. I’m in shambles about to cut/modify the boot. Lol

[@kimberleywood581]

@@TTC2109 Did you ever find the right boot that isn't slanted ? I need one

[@TTC2109]

@@kimberleywood581 www.ebay.com/itm/INTAKE-MANIFOLD-CARBURETOR-BOOT-FOR-Polaris-3085277-Big-Boss-400L-1996-500-1997-/313250396405?_trksid=p2349624.m46890.l49286

[@micflynn1]

The reason for having a gasket, don't put gasket maker on it, you defeat the whole purpose of having a gasket, gaskets aren't only there to seal but to provide a certain amount of space like a washer.

[@daveanderson2316]

In this case, it's cheap insurance, and most of it is squished out. The thickness added is probably less than .0005. Well within spec.

[@danielschaffer8430]

​@@daveanderson23167:48 7:48

[@lorettacaputo6997]

I had a 400L from a 96 Sportsman rebuilt by a professional Polaris engine rebuilder a few years ago. The machine is just used for simple chores around the homestead.no long distance rides at WOT. I think I may have about 100 hrs on it since the rebuild. Under normal operation, how often do you see a top end rebuild to be necessary?

[@BrapStuff]

If it's well maintained I have seen them last 10-15 years being ridden weekly... all depends on how well you take care of your stuff.

[@lorettacaputo6997]

@@BrapStuff Yep, I try to maintain everything and baby it. Thanks for ther reply.

[@thehellwithmanipulatineon3370]

No shit you don't say there bulletproof 😗😗😗😗🤩🤩🤩🤩🤩🙌🙌🙌🙌🙌🙌🙌🙌💪💪💪💪💪💪💪💪

[@djodjodubois9458]

Salut désollé mon anglais n est pas bon..j ai 2 trail boss 1991..un accidenté mais moteur remis a neuf..j aimerais que tu face une vidéo:refaire le fillage et installation des fil apres avoir change moteur..les encien proprio on fait une jobe de cochon avec le fillages..puis aurais besoin aussi vidéo..ajustement oil pump mixage..sa serait vraiment très apprécié car il n a personne dans mon coin veu touché a sa..même polaris ne veu pas..trop vieux et personnel pas qualifié pour sais model la

[@BallisticVolts]

I just replaced the rings in my polaris 300 and after putting it all back together i cant get it to start. Spark plug never gets wet and when i spray starting fluid down the spark plug hole it goes for a second but never starts. Did i do something wrong or do i have a different problem?

[@sled_neckx9972]

BallisticVolts sounds like the problem is in your carburetor.

[@jakobstalheim5185]

Probably figured it out by now but you mighta bumped your carb on something while taking it off and its out of adjustment

[@cecilhardy1477]

I have a 1996 polaris 400. I wase rideing it and it acted like it wase runing out of gas. But card is geting gas .and its fireing .its blowing compreasion out of the card.sounds like its out of time.im lost can i get any feed back.thanks

[@mariotellez2025]

@@cecilhardy1477 does it turn on and idle? Is it backfiring? Or is it bogging out?

[@cecilhardy1477]

@@mariotellez2025 no it want start at all whene i try to start it .it just can hear the comepreasion comeing out of the card.whene i started it up abouth 20 minutes before i took off on it but whene i started it .i had to push the throttele all the way open it wase fluded .but it ran preaty good but i road it for about half a mile .thene it acted like it ran out of gas .geting fire. Motor turns ouver good .doesnt act like not geting gas.but it did back fire out the exgust .but mostly just turn's ouver.thank's for feed back.help plese

[@yeahright302]

what the hell is that at the end?a chicking clucking?wtf!!!