Motorcycle Top End Rebuild for Four-Stroke (Part 1 of 2)

[bozillakilla]

hey i was wondering if i had to have the chain riviting tool for a 2002 crf450? i had to rebuild the top end on my yz250f and i didnt but was just wondering

[RockyMountainATVMC]

@bozillakilla - No you don't. Most bikes you don't. This RFS KTM motor is the only dirt bike one I know of.

[TheDeduction]

Cute dog ^^ Good work

[BigManlyMan4]

Did they starve it of oil?

[plakdsj]

if u got to do this i know u wished u had a 2-stroke

[plakdsj]

2 strokes r way easier

[chamblizi]

hey i'm looking for to retore a little cheap 1970 bike any advice?

[RockyMountainATVMC]

@chamblizi - yes, I have advice. Always leave the house with clean underwear!

[chamblizi]

@RockyMountainATVMC  that does not help me much

[d1rtyw0rm]

awesome video !

[ohho1]

Dream job

[Murdaland22]

This is y i will never buy a 4 stroke.. This is way 2 much work 2 strokes r so simply idc how long a 4 stroke last (if it does) 2 stroker 2 the day i die!!!!!

[RockyMountainATVMC]

@Murdaland22 - This is one of the more difficult ones. They aren't all this difficult.

[MrRshelp4u]

@RockyMountainATVMC funny thing is my rmz 450 is getting its top end done right now

it needs new intake and exhaust valves new time chain new timing chain sprockets new compression rings new oil control ring new head gasket new cams (high performance) and machined head

[1100HondaCB]

@Murdaland22 To be honest four-strokes are better than two-strokes and this is one of the most difficult ones. Most are far easier than this and will require much less attention than a two-stroke.

[BigManlyMan4]

@Murdaland22 This one is way more complicated. I can rebuild my yz450f in 4 hours with all the parts.

[dh4life100]

@Murdaland22 amen 

[deerman1212]

hey i am putting my yamaha warrior back together and after i installed it all i looked in the book and i was missing the o ring that goes around the head heads centering dowl... is it a must to rip it apart and get a ring?

[RockyMountainATVMC]

@deerman1212 - it may not be a must, but probably a good idea.

[serious101101]

what kind of wrenchs are they

[yz125rider194]

how many hours should u change piston at

[RockyMountainATVMC]

@yz125rider194 - depends on the bike, how hard it is used, etc. Refer to the manual.

[Rhino179]

Doggie! :D

[xiB1ack0utzx]

Glad i have a honda! Holy shit!

[halosavage]

HI, I would like to buy the Motion Pro chain breaker tool that you use to break the timing chain, will this same tool work on my Suzuki DR350? and could I also use this tool on the drive chain?

Thanks a lot

[RobertGary1]

I wish I worked somewhere where my dog could hang out too.

[cobrachoppergirl]

Ok, if you need to complete disassemble a vehicle to maintenance the engine, it is a poorly designed vehicle. It should be a lot simpler procedure to swap in and out an engine, only requiring removal of a few strong bolts. NOT taking apart the whole friggin motorbike cause everything is in the way.

[oSHOLLIVERo]

two words!! TWO STROKE!

[ed0985587]

this looks like a huge pain in the ass...or atleast for someone like me who hasn't done it. but the 2 stroke rebuild looks a lot easier but from what i know TheVTRainman is right...4 stroke don't have to be rebuilt near as much because they have their own dedicated lube system. excellent video though this one and the 2 stroke rebuild. i would like to give it a shot i am sure it's not as bad as it looks when you're used to doing it and have the knowledge.

[DaneBowers01]

I have a crf250r 2009 and to do the top end you need to loosen the cam chain. You need a special tool to do so, just wondering if you can use other tools to do so as the proper tool is expensive

[RockyMountainATVMC]

@DaneBowers01 - What special tool? To loosen the cam chain, just remove the cam chain tensioner.

[DaneBowers01]

@RockyMountainATVMC for the honda it reccomends cam chain tensioner stopper. its ok though ive used a small flat screw driver then locked vice grips on the screw driver. with the vice grips against the case which keeps the tension backed off. i suppose removing the cam chain tensioner would be just as easy

[RockyMountainATVMC]

@DaneBowers01 - on that bike, just remove the cam chain tensioner.  The cam will come right out.

[TheVTRainMan]

Remind me to stay away from those bikes... holy crap that is a lot of dissasembly. LOL I'm a 2stroke guy... but, what a lot of you other 2T folk are forgetting is that you don't have to rebuild your 4stoker nearly as much as a 2stroke (at least half as much). In fact, I have seen12k miles on a xt350 with the stock topend (granted it doesnt rev up as much as a mx bike). But, after 2yrs of no topends compared to one or 2 every year on my 2strokes... there is an advantage.

[Kieranmxmann1234]

this is one of the reasons why i like 2strokes

[batman16242]

i work on motors all the time and never ran into one u had to break the cam chain there isnt anyway u can take the cam out after u loosing the tensioner so u dont have to break it and does that tool work on all cam chains?? or just ktms cause u can just remove a couple of links instead of replacing the whole cam chain in the older junk machines

[RockyMountainATVMC]

@batman16242 - The RFS motor requires the removal of the link. Most 4-strokes don't.

[171apples171]

Was this motor blown up?

[RockyMountainATVMC]

@171apples171 - the stator cover broke and the oil dumped out - the rings seized!

[wory8]

@PINKEYEDJOE thanks man, its rought for us this age lol

[thehundredsrocks]

what benefits do you get by rebuilding a top end ? is it normal maintenance or an upgrade?

[RockyMountainATVMC]

@thehundredsrocks - normal maintenance. They wear out.

[davidsim96]

u have to do a 199 things and u still dont have the motor open lol

[bencasey217]

I'm just wondering... How do you buy a master link or could you just take out one pin and put that pin back in?

[RockyMountainATVMC]

@bencasey217 - kind of a critical part that is made to be peened once. KTM sells the part. We actually stock it.

[bencasey217]

@RockyMountainATVMC How much doe's it cost for the tool and new master link?

[RockyMountainATVMC]

@bencasey217 - The Tusk Chain riveting tool is $49.99. The link is $5.46. Note that this is only necesary on some KTM's.

[highdeserthater]

i like to leave the bolts in the pieces. (i loosen them until i could lift them out but i dont. i remove the piece with the bolts just hanging out in the holes so that i dont mix up/lose bolts. :) )

[kcb13]

holy hell, you have to take that whole bike apart!

[LIP15]

@yamaha250Frider62

Valves, piston rings, cracks... theres MANY things it could be.

[ch0l0sk8r]

how come 2 stroke pistons are biger than 4 strokes cuz they have no valves !??

[kawitwofiddy]

@ch0l0sk8r they dont

[ch0l0sk8r]

my 93 yz80is makin a weird noise from the top end the clutch doesnt work but it sounds like it needs a top end beairing i hope not im trading 2 yz80s for a blown cr250

[velhonen]

cooldog

[curtismundy]

hey thanks alot for making this vid, im going to need to rebuild the top end on my 1986 suzuki lt230s four wheeler

[wory8]

thanks for the help man, i been watchin your videos, i do better with hands on then watching lol

[wory8]

im 14 and i love dirtbikes, but my dad want let me ride and im tryin to learn how to work on them, do you have a book or anything i could buy about being a mechinic?, and great video.

[RockyMountainATVMC]

@wory8 - I am not aware of any books, but i am sure there are several out there.  i started working on bikes when I was 14 as well. I wish they had youtube videos then to help me out. Then again I wish they had the internet when I was 14! keep up the interest and willingness to learn!

[halosavage]

hey, im 15, i have a great book called motorcycle maintenance by mark zimmerman. another book that is great, is any service manual for a bike, i have one about my rm125 and it literally shows you how to do any job on the bike.

[lentzy249]

@wory8 if u like workin on bikes try find some dirtbike maGazines they have some Great info

[autolover3]

@wory8 keep searching things on google. like how things work and whatever youre curious about. ur dad not lettin you ride is B.S.!! do what you love to do. just follow your interests

[PINKEYEDJOE]

@wory8 If your still looking for good repair books u should look at Four-Stroke Performance Tuning by A. Bell or The High-Performance Two-Stroke Engine by John C.Dixon, these resources helped me on some projects, their pretty simple to understand, im the same age so i cant afford a mechanic either.

[cinecicleta]

why you need to take out two pins off the chain? wont only one will take the chain apart?

[RockyMountainATVMC]

@cinecicleta - Because you have to replace the master link. Both pins must be removed to remove the whole link.

[RockyMountainATVMC]

@yamaha250Frider62 - i could certainly be both. Check the valves first.

[0000000000kc]

hey again eric! did as you said, ´checked spark, i did get spark but still no improvement, so i took it to my dealership, and they checked same things, but still nothing happened, then i asked if it cut be the valves, they checked and the right intake valve was cloesed and i needed new ones placed, now she starts just fine and runs even better, so thanks for your help enyway! (;

[ad017510]

Hi Eric, need your overseas help, cause my KTM Dealer was not able to solve my engine noise (!). Please listen to it ...and let me know what you think about it! Many thanks from Italy !!! Chris.

[0000000000kc]

hey Eric! first i love your videos. but i have a little problem, my honda crf250r (07) wont start. i was on the track and just pressed the kill-switch cuz i wanted to take a break, then it just wouldnt fire up, checked the bikes wires petcock, and gas, and everything semed right, if you got any ideas, please reply, thanks!

[RockyMountainATVMC]

@0000000000kc - did you pull the plug to see if you are getting spark. If you aren't, you need to have each electrical item checked out. good luck.

[skatejordan12]

i have a 2006 honda cr85r and i have stock reeds,i would like to replace the reeds with boyesen dual stage power reeds.if i do so,will i need to re-jet the carb?

[RockyMountainATVMC]

@skatejordan12 - you shouldn't need to.

[1727267241]

isent it hard to move everything? isent there a easyer way

[luisbalderrama]

do you have to put the cam chain at the exact place from were you took it off first ?

[RockyMountainATVMC]

@luisbalderrama - not really, but the cam and crank need to be in sync.

[craig562]

whats every1s views on ktm?? reliability etc???

[rama6maiden]

is that a ktm 525 sx 2003 model??

[meda789]

it looks sooooo comlex and hard, i can just imagine how hard it would be to remember stuff

[ext3reme]

If that is complex, don't repair your own motorcycle. 2 strokes are history. Who wants a motorcycle that does 1 mpg ,smokes all the time, don't have torgue under the powerband and need a piston change every 6 000 miles?!? 4 strokes are the future

[bloodyboy8]

Holy crap. I'm glad i have a 2-stroke o.O

[Sachemfs92]

if i do my top end (yz125) like i get a new piston and rings do i have to get gaskets to?

[KrazyRMjumps]

@Sachemfs92 yes you do

[Sachemfs92]

alright cool thnks shuld i get wrist pin and bearing to ?? plz respond!

[pege07]

@Sachemfs92  it's better if you do

[pab338]

great video could you guys refer me to a 2-stroke carb cleaning video

[hendragster]

Need help: make video for Yamaha TW200 service guide: 1) How to replace base gasket (a lot of us who own '05, '06, '07, and '08 TW200 have problem with gasket leak) 2) How to adjust valves 3) How to bore it up to 225cc or 300cc ... Thx!

[rama6maiden]

in the yamaha yz450f manual they say that the piston and the cylinder is supposed to be changed as a set!!

is that necessery??

[RockyMountainATVMC]

@rama6maiden - Really? That is insane!  unless the nikosil coating is damaged, a light hone will make the cylinder good as new.

[rama6maiden]

@RockyMountainATVMC

alrigth thanx for the help dude!!!

[dirtbikekid12]

agreed crf seems 10x easier

[dcsktr52]

KTms seem to be a pain in the ass compared to my CRF

[vankyfwa]

where do you get a service manual for a honda xr 100 r

[RockyMountainATVMC]

We sell the OE honda service manual. Part # 1021800021.

[coltengangwer]

My 250 f started makeing some noise in the top end and i heard the chain tensioniser can become stuck in the release position. I rode it back to my house and all of a sudden it locked up. do you think the timing chain jumped a tooth and valve hit the piston? i want to find a service manual online that i can print.

[RockyMountainATVMC]

i guess you won't know until you pull it apart. i strongly suggest buying a manual. Highly worth the investment. They are a tiny price compared to the bike, gear, and everything else that goes into the sport.

[jeremyzdead]

When are you gonna do a 4stroke bottom end? Got a seized kx450f that needs a new bottom end.

[RockyMountainATVMC]

unless I have to, never. I don't have any plans to do it. if you can pull your top end apart, watch out 2-stoke bottom end video. The principle is the same. a service manual will guide you on any differences.

[RockyMountainATVMC]

Chain tensioner is easy. Just remove it during disasembly. Retract the auto tenstioner when you put it back on. don't force it on.

[atvPBALLsnowmobiles]

ok thanks

[atvPBALLsnowmobiles]

ok thanks, and stock does it have a sleeve or is it just the piston inside the cylinder

[RockyMountainATVMC]

that machine has a sleeve.

[atvPBALLsnowmobiles]

inside the cylinder where you got it resleeved could i just buy a new la sleeve and put it in or is that something completly different (on a 02 honda 400ex)

[RockyMountainATVMC]

you can put a sleeve in your 400ex. The cylinder has to be machined to fit in, and the sleeve has to be bored for the new piston. pretty much you need to have a machine shop do it. That is why we sent ours out to be done.

[icool247]

this is the reason why i would get a 250 2t before i buy a 450 4t. 2t's are hella lot easier

[paul1495]

hell yea

[digitalniche]

I want to Thank You for a great video on how to do this top end rebuild. I just did this to my 06 450 sx and every step you went through was correct. I did have a couple of small issues trying to finger the Rings into the head but other then that if you follow the directions here you will be very happy with the result. The parts shipped fast from at a reasonable price! Please keep up the great work and if you get bored could you post a video on the 4 to 6 speed gear box upgrade?

Thanks!

[sodia1]

what is a motorbike stroke?

like some say this bike has 2 stroke or 4 stroke etc

[RockyMountainATVMC]

it is the stroke of the piston. do a youtube search. Lots of videos will explain it.

[jdirtbiker1]

how mutch do u charge for parts to do this

[Dayberry]

I have a 1992 Ktm 300 Exc and I need a rad. Could I switch it for one from newer model with the same cc or higher and just fab brackets?

[RockyMountainATVMC]

I am sure the capacity is similar. If you can fabricate it to fit, it should be fine.

[kombikevo]

Thanks heaps,

you seem to cover every queiry i have with doing these jobs, I am new to 4 strokes and this is all i need to do the job in confidence,

Great stuff mate!

[BajaSuckzDick]

loved watching this man, fun to watch but i would never want to tackle this with out training! lol this is why i love my 2 stroke yz 125! thanks for the post, im going watching part 2!

[gooch758]

i was wondering if u could do a video on how to replace shift forks..also was wondering how to find the vavle video..thanks

[RockyMountainATVMC]

We have a bottom end video that shows how to split cases (you can change shift forks while you are there). The valve video is coming soon (the goal is next week). thanks!

[mudbug1356]

very good vid i have watched it atleast 5 times and just now saw the rocky mountain mascot in the background haha

[RockyMountainATVMC]

Yeah, the dog sneaks into our shots every once in a while:)

[Jarridb94]

I really like these videos i was wondering if you could make a video of a 03 polaris trail blazer engine rebuild... thanks!

[RockyMountainATVMC]

Thanks. i won't have time to rebuild your specific machine. Refer to our 2-stroke top end video. The process is all about the same. Refer to a manual as you go.

[Yorsoull]

You're doing a great job thanks man.

[TheJimmy2939]

Eric your my best friend :)

[jojojorgeton]

thanks man! this is trully PROFESIONAL HELP. a lot of dudes make 4stroke repair sound like its WAY 2 dificult. cant wait for the valve, CR and YZ videos.hopefully someday you could find time to help us with an overview of the art of suspension tuning.we the riders and wrenchers salute you!

[RockyMountainATVMC]

Thanks for your comments. I am trying to finish up the valve replacement video now. i will move onto the CRF250 rebuild we filmed a coulpe weeks ago.

[ramseymactam]

hey am really need some help i have had to put three sets of bearins on my 05 yz250f in a month and i dont power wash in round the bearings and every time i put new ones in i used contact cleaner. and the bearings were not just moving slightly the wheel was moving about a inch from side to side it has so far cost me £120 pounds . PLEASE PLEASE PLEASE HELP .

[RockyMountainATVMC]

I assume you are talking about wheel bearings??? Are you using grease and new seals? Are you making sure the center spacer is in between the bearings? If not, they will fail in no time.

[7404yamaha]

i have a 2008 250sxf with 40hrs on it and when i ride it whenever i slow down and close the throttle is backfires alot is it normal?

[RockyMountainATVMC]

I could be the exhaust you have on it. Alot of aftermarket exhausts do this because they are more open. It could also be lean jetting.

[craig562]

hi i need to rebuild the bottom end and top end on a ktm exc 125 2000 model but am concerned about the oil pump how do i bleed the air out of the pump

[RockyMountainATVMC]

125 2-stroke? What oil pump?

[craig562]

On most enduro or road legal dirt bikes there is an oil pump on a two stroke which pumps engine oil directly into the carb driven by the crankshaft. i have been told that i will need to bleed air out of the system otherwise there wont be any oil getting to the engine(soz i didnt mean a motocross bike)

[RockyMountainATVMC]

Oh, the oil injector. I don't know much about bleeding them. I haven't seen one of those is a while.

[craig562]

are most motorcross bikes just premix then, just petrol and oil into the tank

[kxdirtrider85]

im sticking with 2 strokes

[extenze]

another reason why I'll be getting a 2 stroke... :) thanks for the videos, very imformative for the curious ones

[devfuse]

Really in deth and some really good tips, thanks.

[kamykkamyk]

awesome, yet to much complicated 4 me ;] thanks for input

[blkout15]

this is why two strokes rock, takes 30 minutes to rebuild a top end.

[oKIERANo]

You make it look so EASY!, but honestly if i done that i would have to pay someone to put it all back together :(

[peckiledorf]

awsome

[pixuma]

very good video!

but i just gotta say, damn 4 pokes are complicated!

[tioz1990]

I love you guys

I just happen to have a KTM EXC 450 so these videos are just perfect! =D

[k0ent]

at 1:57 - 1:58 you pull a hose of the carb, what is it and what does it do? (I couldnt hear what you said it was in the video because of my lack of english)

[RockyMountainATVMC]

crankcase breather tube. It prevents the crankcase from building pressure.

[k0ent]

thanks

[motorcyclesuperstore]

great work indeed.

[mxchamps]

Thanks you guys! This is very helpful!

[JoshatSuzuki]

There are also some pretty in-depth guides on ThumperTalk you can look at...

[RockyMountainATVMC]

the piston is part of the top-end. i would pull it apart and inspect. It shouldn't be too expensive to fix on your own. if you have a two-stroke refer to our two-stroke video.

[cawille6694]

Why do they make it so difficult to take a4 stroke apart. A 2 stroke top end is a piece of cake. Also why do 4 stroke need rebuild less often as 4 strokes?

[k0ent]

To dissasemble a 4 stroke top end, you also need to dissamble the cam(s) located in the cylinder head, a 2 stroke cylinder head is just a combusting chamer, spark plug and some other stuff. And 4 strokes need less rebuilds because 4 stroke (generally) make less rpm then a 2 stroke, also, a 2stroke pistons has to go past the intake and exhaust ports thousands times a minute which causes extra wear.

[CRACKERonRM2FIDDY]

a 2 strike has no valves to worry about and you dont need to adjust timing too

[Xy2kBloodX]

hey, ive got a CRF450 and ive had it for a year, would i have to ajust the timing chain at all with the tensioner? or is it automatic.

[RockyMountainATVMC]

It is automatic.

[Nk00037]

hey my yz250 makeing sounds in the top end and will not run good. and it was jamed till one day i wanted to kick start it worked so here i am now i talked to the dealer and they sayed it will cost about 1.5k they saying its the top end but i thinks its the piston.

[yourmom922]

even if it is just the top end, it shouldnt cost 1.5K!!!!!!!!!!!!!!!!!!!!!!!!!!­! you can get a complete top end kit for a 2 stroke for $120 on rockymountainatv . com