I just finished disassembling my 1993 MX 470 because the #2 piston was stuck. Using your video, I came to realize that the pistons were installed backwards by the previous owner and this caused the ring gaps to align with the exhaust port. The end result is a scored cylinder by a broken ring on #2. The #1 cylinder was also scored and the ring was already bent - caught it before it broke! Will be getting new pistons, rings and cylinders. Thanks again for the video!
@davison1021 Check the float and float needle in the carb. floats are getting stuck of the needle isn't sealing. It causes the bike to flood when you let it sit
awesome explaination man... this is my first time rebuilding a 717 rotax 2 stroke engine from my 1997 Seadoo GTS jetski and i didnt have much idea of how emsanbling everything... i got a manual, but i still need someone watching how they do it but thank much man ! good bless you for sharing your knowlegdes with the world !
@BriZav squeeze the rings with one hand and lower the cylinder over the piston. Don't force anything. Make sure you line up the ring gaps with the ring stoppers
@KeepItRoostin658 make sure you tighten them all the same amount then, using a torque wrench, or if you are very experienced you can do a pretty good job at getting them all around the same tightness
@117nathanmyers i don't know it seems pretty clear to me. you can see the pin in the center of the ring gaps where they have to be when you install the cylinder over the piston. That pin stops the ring gaps from moving to a place where when they are installed could potentially catch on one of the ports in the cylinder. It doesn't matter in a 4 stroke because there are no ports in the cylinders.
@1skiinIan Hey there.I've rebuilt a couple of 521 rotax motor's.These are one amazing motor.I've got the manual for this motor.In the rebuilding section it say's a good rule of thumb for keeping you jug's straight is a feeler gauge inbetween the jug's both end's and centre when torking down the jug's to keep it as straight as possible.Just thought I'd throw that out there.Chee's Bud.
@MegaDanTheMan1987 you're going to have to take the jugs off to see if you have a crack anywhere. if there isn't it's probably the base gasket. replace it and reassemble
@KubotaTee Thank you for that post. this proves to @DangerZONEpixel that pistons have to be installed a certain way so that the ring gaps don't end at a port
@outdoorsman310 no, there are groves made in the piston. This is what I am talking about in the video. you lign the ring gaps where the notches are on the piston. You also make sure once you put the piston in that the ring gaps don't end at any ports
@haloass123 yeah, in a 4 stroke they would be. in a 2 stroke you don't have a choice. you have to lign them up with the groove on the piston and install the piston the right way so that the ring gaps are in between the ports. Typically in a 4 stroke you want to have the ring gaps 120 degrees away from eachother. In this case, they are only about 90 degrees because they didn't have a choice because of where the ports were
@ballockybill they are power valves. dirt bikes have them too but they are internal. They are like sliding plates that close off the exhaust ports a bit and open at higher rpm so that you can still get good power and torque at lower rpm's without sacrificing high rpm power and torque. good question though thanks
@LegittGod39 no, if it's oil injected, reattach the oil injection hose and loosen the bleed bolt untill oil starts coming out of it. after that, pull over the engine with the oil injection lever wide open untill you see oil coming out of the tiney holes in the bottom of the ports (this is with the carbs off of course). also, just to make sure I always mix oil into the first tank of gas on top of the oil injection. (mix at about 100:1)
@1skiinIan yeah I stopped letting friends borrow my tools years ago . Every time I lent out a tool, it never returned, so I decided I cant be the local rent a center anymore lol.
@danceGIRLIES101 A lot of the newer 2 stroke motors can't be honed and therefore you must send them off to a machine shop to be re-plated or resleeved.
@Maximusfool The head has been planed for higher compression. I have it tuned pretty well. It's bored .20 over, so maybe 5hp more than stock? so like 120? ish
@danceGIRLIES101 It's very rare that the piston get damaged without damaging the cylinder as they are in full contact but, if so, you still need to measure the bore of the cylinder in at least 3 different spots to make sure it hasn't worn in a taper or too much in an oval before you figure out the size of piston you will need to order. if your standard piston has become too small you will need to have the cylinders bored and honed for the larger sized pistons. always hone
@117nathanmyers The ring gaps should NEVER end in the same spot on the piston in any type of engine. This would result in a loss of compression. In most 2 strokes though, there is a tab where the ring gaps have to be so that they don't spin and catch a port.
@KeepItRoostin658 you keep doing it like that and you'll end up with a warped mating surface , every motor has been giving recommended tq specs by the factory usually a looser spec to seat the surface than the second spec to tighten the seal.
@DangerZONEpixel you're joking, right? I have so many people that have brought engines to me, where they installed the pistons in the opposite way and the rings had cought on the port. IF YOUR RING GAPS END AT A PORT, THEY WILL CATCH. Warning you. It doesn't matter how precice the part is, you can still install it WRONG!
@iamchevyman5 go on ebay. Wiseco makes very high quality pistons. So does JE. Get forged pistons, because they are the strongest. These were wiseco in the movie. This IS a basic tutorial. Just take it apart the opposite way I put it in. You don't even have to take the engine out of the sled if you're only doing a top end job. I did the crank seals and checked bearing play in the bottom end so I didn't have a choice. It shouldn't matter how long it takes you to do it. It's not a race.
116 HP is good enough for me. putting a thicker base gasket in is going to lower compression and change engine timing. Trust me I like it the way it is, and rotax has already done their homework on this one
Oh yea.... thats right.. I never take the manifold off... just the pipe!! Duh lol. Yea ours sucks cause we just have no snow all winter. barely 4 inches in some spots. Good video!
not sure if it would apply here but many new rotax engines call for the head pipe to be installed befor the torquing of the cylinders to prevent leakage
@1skiinIan no its a yamaha dt i already did the top end the other day and it is actualy really simple i put a wiseco forged piston in as i didnt want to let it break in the first place
If you add a bigger base gasket under the cylinder jugs, it will change timing regardless of whether you shave the head or not. The only thing shaving the head does is restore your compression ratio. I think you are also forgetting this is a rotary valve induction 2 stroke, unlike the common reed valve induction 2 stroke. Buy one of these motors and put a thicker base gasket on. I would like to see it create more HP than this one
@lacossanostra I'm assuming he doesn't actually know why. It is not all ways "down." It is Up or Down. The reason being that you can't imagine how fast the piston travels up and down. placing them with the gap at the top or the bottom is kind of extra insurance to keep the clip from popping out while the engine is going. It is not anything to worry about on some old thumper, mainly very high rpm engines.
Those pins on the side of the piston is what keeps the rings staggered and from moving ! If they don't have stagger you will lose compression and get blow by the rings witch kills power !
@impakt750 yes it's really not hard to do top end work. Just do your research. This video already gives you basics that you can use to rebuild your 125. Is it a YZ?
@1skiinIan first I like the vid I get bored sometimes and watch shit like this, I already know how to do a two stroke but figured Id watch anyways. Im sure you know this but there is a special pair of pliers for the piston circlips they look like needle noses with little nipples on the end when you look at the circlip you can see the two holes one on each side for compressing the clip
I'm pretty sure that Rotax never made a monoblock. They probably came tegother because ther were stuck together with the manifold or head? We WERE having a good winter. tons of snow, till we had a week of rain and above zero temperature. sow there is barely enough snow to snowmobile. it's so lame
is there like a basics tutorial for rebuilding a rotax engine? I'm pretty into intermediate level car stuff but I haven't tackled a job like this before. I hear it takes about 7-8 hours? What's a good place to get quality rebuild parts? Btw, I said "giggity" and "that's what she said" to like half the sentences you said in the video. lol
Let's say a piston gets damaged in a 2-stroke and you want to rebuild it, do you have to hone the cylinder if it looks good? Or can you just replace the pisons as the cylinder is?
NICE JOB: you people should get a shop manual, download $9. do it with the manual, hes right..... they did the homework, that is why you bought it...it worked.
I noticed the base gasket moving around when installing the cylinder, shouldn't this have had gasket adhesive installed between crankcase and gasket? I'm asking because im getting ready to do my motor.
@KeepItRoostin658 maybe as good but certainly not better because obviously I take my time and go by the book,where as just kinda "wing it" and see what happens.Im not saying you cant build a motor,Im saying your doing it carelessly, thats all and that someday it might catch up to you.
@KeepItRoostin658 oh and when you ignore factory specs to save a little time thats called cutting corners, you can word at as you please but a turkey will always be a turkey.It might not be a big deal on these little two strokes but I dont know if you caught the sn I build Hondas as in four stroke engines with much more specific tolerances and I bet you any amount of money if you did the same thing on a fourstroke it wouldnt run nearly as long.
nice vid :) i have the same engine in mine 670 :) moster power! but i was wondering, are thos hardchrome? and do you have to replace the cylinder while doing this, or only the piston?
Not nesceserilly, but you have to split the cases, and probably get the crank rebuild, wich is costy. But probably cheaper still than buying a new engine
see this guy right here? this is a smart man that will do well in life. Thanks for watching!
I just finished disassembling my 1993 MX 470 because the #2 piston was stuck. Using your video, I came to realize that the pistons were installed backwards by the previous owner and this caused the ring gaps to align with the exhaust port. The end result is a scored cylinder by a broken ring on #2. The #1 cylinder was also scored and the ring was already bent - caught it before it broke! Will be getting new pistons, rings and cylinders. Thanks again for the video!
@TaKeItLiKaMaN Correct! 1993 formula Mach 1 670
The purple heads are found on the 670HO (high output) engines that had a bit higher compression.
@davison1021 Check the float and float needle in the carb. floats are getting stuck of the needle isn't sealing. It causes the bike to flood when you let it sit
extremely well done video, best engine rebuild video that i have found on youtube
Very helpfull video for all 2 stroke engines, it's basicly the same.
awesome explaination man... this is my first time rebuilding a 717 rotax 2 stroke engine from my 1997 Seadoo GTS jetski and i didnt have much idea of how emsanbling everything... i got a manual, but i still need someone watching how they do it but thank much man ! good bless you for sharing your knowlegdes with the world !
@rfphm The 2 wiseco pistons with wrist pin, wrist pin bearings and gasket set I think were 280. ot it off ebay
@BriZav squeeze the rings with one hand and lower the cylinder over the piston. Don't force anything. Make sure you line up the ring gaps with the ring stoppers
Seems like the manifold would have given you a little trouble putting it on after words. Always great watching rebuilds.
@KeepItRoostin658 make sure you tighten them all the same amount then, using a torque wrench, or if you are very experienced you can do a pretty good job at getting them all around the same tightness
@dmainesYZ85 you have to use a torque wrench and you have to use new gaskets
@117nathanmyers i don't know it seems pretty clear to me. you can see the pin in the center of the ring gaps where they have to be when you install the cylinder over the piston. That pin stops the ring gaps from moving to a place where when they are installed could potentially catch on one of the ports in the cylinder. It doesn't matter in a 4 stroke because there are no ports in the cylinders.
@1skiinIan Hey there.I've rebuilt a couple of 521 rotax motor's.These are one amazing motor.I've got the manual for this motor.In the rebuilding section it say's a good rule of thumb for keeping you jug's straight is a feeler gauge inbetween the jug's both end's and centre when torking down the jug's to keep it as straight as possible.Just thought I'd throw that out there.Chee's Bud.
@honda1296 who knows? sometimes they last a long time and others don't even last a few minutes. make sure that arrow is pointing to the exhaust
@morominaolenmina yes 670 piston that's 0.020 overbore. The cylinder was too damaged and had to be bored out a bit
@MegaDanTheMan1987 you're going to have to take the jugs off to see if you have a crack anywhere. if there isn't it's probably the base gasket. replace it and reassemble
@BrownLabRanch yeah no problem. glad to help. Nice sled btw
@ed563 these cylinders came back from the machine shop bored and honed. Ring gap was checked by them too
THAT'S HOW i learned to change my moped rings
@maxamo007 I had to get a new one because it was so worn on the joint from rubbing with the expansion chamber, so it wasn't an option
@KubotaTee Thank you for that post. this proves to @DangerZONEpixel that pistons have to be installed a certain way so that the ring gaps don't end at a port
@outdoorsman310 no, there are groves made in the piston. This is what I am talking about in the video. you lign the ring gaps where the notches are on the piston. You also make sure once you put the piston in that the ring gaps don't end at any ports
@haloass123 yeah, in a 4 stroke they would be. in a 2 stroke you don't have a choice. you have to lign them up with the groove on the piston and install the piston the right way so that the ring gaps are in between the ports. Typically in a 4 stroke you want to have the ring gaps 120 degrees away from eachother. In this case, they are only about 90 degrees because they didn't have a choice because of where the ports were
I'm in the process of rebuilding a El Tigre 6000, and Exciter 540.
Nice tips...
@TheNoisePolluter most of the time they actually snap or bend causing catastrophic engine failure. I've seen it happen many times
@iamchevyman5 So set aside a full day and do it RIGHT!
@joesudbury yup, seals were done too
@1Rugbrn I never have used gasket adhesive. I've never had a problem
@ballockybill they are power valves. dirt bikes have them too but they are internal. They are like sliding plates that close off the exhaust ports a bit and open at higher rpm so that you can still get good power and torque at lower rpm's without sacrificing high rpm power and torque.
good question though
thanks
@LegittGod39 no, if it's oil injected, reattach the oil injection hose and loosen the bleed bolt untill oil starts coming out of it. after that, pull over the engine with the oil injection lever wide open untill you see oil coming out of the tiney holes in the bottom of the ports (this is with the carbs off of course). also, just to make sure I always mix oil into the first tank of gas on top of the oil injection. (mix at about 100:1)
@GunsClap315 yeah of course! 1500 km's now
@1skiinIan yeah I stopped letting friends borrow my tools years ago . Every time I lent out a tool, it never returned, so I decided I cant be the local rent a center anymore lol.
@gasperantonic it's from a bombardier Snowmobile
@danceGIRLIES101 A lot of the newer 2 stroke motors can't be honed and therefore you must send them off to a machine shop to be re-plated or resleeved.
@Maximusfool The head has been planed for higher compression. I have it tuned pretty well. It's bored .20 over, so maybe 5hp more than stock? so like 120? ish
@ComicalFerret used lots of 2 stroke oil
@danceGIRLIES101 It's very rare that the piston get damaged without damaging the cylinder as they are in full contact but, if so, you still need to measure the bore of the cylinder in at least 3 different spots to make sure it hasn't worn in a taper or too much in an oval before you figure out the size of piston you will need to order. if your standard piston has become too small you will need to have the cylinders bored and honed for the larger sized pistons. always hone
@MrYonnie1987 not to do a top end job. You only need a torque wrench to put it back together
@impakt750 yeah dt's are air cooled so they're very easy to do
@justinyoface911 yeah just 2 stroke oil
@117nathanmyers The ring gaps should NEVER end in the same spot on the piston in any type of engine. This would result in a loss of compression. In most 2 strokes though, there is a tab where the ring gaps have to be so that they don't spin and catch a port.
@KeepItRoostin658 you keep doing it like that and you'll end up with a warped mating surface , every motor has been giving recommended tq specs by the factory usually a looser spec to seat the surface than the second spec to tighten the seal.
@bettafish110 you're gonne need to buy new needle bearings. They should come in a cage
@1skiinIan i see that now because i took apart my engine i read that in an auto book from the 80s
@ballockybill I was going to make a drag bike out of my yamaha warrior, or finding a banshee with a siezed engine
@dmainesYZ85 I usually never do. just make sure the surface is clean and smooth
@yoshman139 yes, usually that's the case
@DangerZONEpixel you're joking, right? I have so many people that have brought engines to me, where they installed the pistons in the opposite way and the rings had cought on the port. IF YOUR RING GAPS END AT A PORT, THEY WILL CATCH. Warning you. It doesn't matter how precice the part is, you can still install it WRONG!
@iamchevyman5 go on ebay. Wiseco makes very high quality pistons. So does JE. Get forged pistons, because they are the strongest. These were wiseco in the movie. This IS a basic tutorial. Just take it apart the opposite way I put it in. You don't even have to take the engine out of the sled if you're only doing a top end job. I did the crank seals and checked bearing play in the bottom end so I didn't have a choice. It shouldn't matter how long it takes you to do it. It's not a race.
116 HP is good enough for me. putting a thicker base gasket in is going to lower compression and change engine timing. Trust me I like it the way it is, and rotax has already done their homework on this one
@rsqr12 Once you've rebuilt a 2 stroke, you've rebuilt them all. They're all the same
Oh yea.... thats right.. I never take the manifold off... just the pipe!! Duh lol. Yea ours sucks cause we just have no snow all winter. barely 4 inches in some spots. Good video!
@morominaolenmina you mean what overbore?
not sure if it would apply here but many new rotax engines call for the head pipe to be installed befor the torquing of the cylinders to prevent leakage
piston circlip opening can be at 6 or 12 o'clock...
@Dave72mph I was 19 when I made this vid. I'm 21 now. Why?
to take that motor apart and reassemble do you have to have special tools
@117nathanmyers 4 smokers are totally different ball game than 2 stroke engines. 4 stompers need more maintenance. long live the 2 strokes.
Thanks man helped me a lot! :)
@impakt750 ohhh ok lol. you forgot the R
@1skiinIan no its a yamaha dt i already did the top end the other day and it is actualy really simple i put a wiseco forged piston in as i didnt want to let it break in the first place
ROTAX =MONSTER POWER
very nice vid man keep them vids a coming your good at rebuilding engines
@1skiinIan 1-2 hp. it's only 20 thousands of an inch
@1skiinIan its liquid cooled its the dtr
If you add a bigger base gasket under the cylinder jugs, it will change timing regardless of whether you shave the head or not. The only thing shaving the head does is restore your compression ratio. I think you are also forgetting this is a rotary valve induction 2 stroke, unlike the common reed valve induction 2 stroke. Buy one of these motors and put a thicker base gasket on. I would like to see it create more HP than this one
@lacossanostra I'm assuming he doesn't actually know why. It is not all ways "down." It is Up or Down. The reason being that you can't imagine how fast the piston travels up and down. placing them with the gap at the top or the bottom is kind of extra insurance to keep the clip from popping out while the engine is going. It is not anything to worry about on some old thumper, mainly very high rpm engines.
@yak55x You need a clutch puller
Thanks. This was very usefull!
@B16BBOB Yeah I know. I actually have the tool just hadn't gotten them back from a guy I let borrow them at the time.
You should have honed it if you got new piston and rings.
Excellent vid, by any chance do you have kinda info for Rotax 447?
@honda1296 if you have them on wrong the piston would not go into the cylinder and you would not be able to complete the assembly, your fine.
@steveo8776 They really do. From an engine first produced in the late 80's, the 670 is still up there power wise even today.
I'm definately a fan
the early 670's were almost identical to the 617. look it up
@bettafish110 USE A HEAVY GREASE TO HOLD THEM ON THE CONECTING ROD BUT I WOULD SPLURGE AND JUST BUY SOME CAGED BEARING FOR 25 DOLLARS
Those pins on the side of the piston is what keeps the rings staggered and from moving ! If they don't have stagger you will lose compression and get blow by the rings witch kills power !
Just did a fresh top end on my 787 SeaDoo Rotax, 0.040 over.
couldn't find someone to help me film when ALL the crank seals where done in the bottom end (that's why it blew up in the first place
@1skiinIan thanks for the advice, i appreciate it(:
@impakt750 yes it's really not hard to do top end work. Just do your research. This video already gives you basics that you can use to rebuild your 125. Is it a YZ?
@1skiinIan first I like the vid I get bored sometimes and watch shit like this, I already know how to do a two stroke but figured Id watch anyways. Im sure you know this but there is a special pair of pliers for the piston circlips they look like needle noses with little nipples on the end when you look at the circlip you can see the two holes one on each side for compressing the clip
@1skiinIan when you replace pistons and/or rings
I'm pretty sure that Rotax never made a monoblock. They probably came tegother because ther were stuck together with the manifold or head?
We WERE having a good winter. tons of snow, till we had a week of rain and above zero temperature. sow there is barely enough snow to snowmobile. it's so lame
@TheMos2818 Thanks man
@ballockybill many times, but ended up selling the bike I wanted to put it in lol
is there like a basics tutorial for rebuilding a rotax engine? I'm pretty into intermediate level car stuff but I haven't tackled a job like this before. I hear it takes about 7-8 hours? What's a good place to get quality rebuild parts?
Btw, I said "giggity" and "that's what she said" to like half the sentences you said in the video.
lol
good work man, hope she runs nice
i know that, :P correction ive rebuilded my old two stroke in 30minutes :)
Let's say a piston gets damaged in a 2-stroke and you want to rebuild it, do you have to hone the cylinder if it looks good? Or can you just replace the pisons as the cylinder is?
NICE JOB: you people should get a shop manual, download $9. do it with the manual, hes right..... they did the homework, that is why you bought it...it worked.
@TheSkutty but I wasn't talking about the Iraq war, was I...
I noticed the base gasket moving around when installing the cylinder, shouldn't this have had gasket adhesive installed between crankcase and gasket? I'm asking because im getting ready to do my motor.
it's for a snowmobile
@KeepItRoostin658 maybe as good but certainly not better because obviously I take my time and go by the book,where as just kinda "wing it" and see what happens.Im not saying you cant build a motor,Im saying your doing it carelessly, thats all and that someday it might catch up to you.
@KeepItRoostin658 oh and when you ignore factory specs to save a little time thats called cutting corners, you can word at as you please but a turkey will always be a turkey.It might not be a big deal on these little two strokes but I dont know if you caught the sn I build Hondas as in four stroke engines with much more specific tolerances and I bet you any amount of money if you did the same thing on a fourstroke it wouldnt run nearly as long.
nice vid :) i have the same engine in mine 670 :) moster power! but i was wondering, are thos hardchrome? and do you have to replace the cylinder while doing this, or only the piston?
great motor
Not nesceserilly, but you have to split the cases, and probably get the crank rebuild, wich is costy. But probably cheaper still than buying a new engine