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did i kill my bottom end?

By txknucklehed,
in YZ400F/426F/450F/450FX

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txknucklehed

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howzit folks, i am new to TT looks like there is a lot to learn from this site. i have an 06 yz450f..... can you say MONSTER... hands down the best bike i have ever owned!! So I am Riding over the weekend and it stalled at the end of a high speed flood plain pass. It was hot so i stopped a minute to let her cool down. after roughly 5 minutes i tried to kick her and it wouldn't catch. usually she starts on the 1st kick, even when it is hot and the hot start lever is engaged. needless to say this struck me as funny. I was about 3 miles from the truck so i started pushing, about 10 minutes later i tried kicking her again this time it spun once and started then stalled almost immediately. now i checked the oil and low and behold none. So i pushed her all the way back to the truck, loaded up and headed home. when i got home i put in a full quart of 20/50 and let that sit till last night. when i got home from work i went to the shop and drained and changed the oil cleaned the air filter checked everything and tried to kick her. kick start wouldn't budge!! i dropped it into first tried to roll it and then tried to kick it no start, but it did kick over. after the second kick (start of the third kick) the lever wouldn't move again. almost felt like the motor wasn't decompressing. only after time the it didn't bleed off. i popped it back into first and rolled back and forth and i tried to kick it it did the same thing 2 kicks and on the 3rd it wouldn't budge. i stopped before i f%#@ed something up worse. can anyone out there help me out? i only have about 15 hours in the saddle on this beast and the previous owner assures me he only had about 6. it is practically new. i love this bike please help.

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kdxFREAK42

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oh boy. unfortunatly i would say that you ruined the crank. i myself had an experience with a klx-250 that i got in peices. i put it back together and after a few cleanings of the carb,she started. i let it run for a while and then it stalled. so i went to kick it and the kicker was sort of stuck. then it let up and started again. but after 3 or so times doing this, the crank locked up and now im stuck with a box of unused parts. and also my good friend had did the exact same thing as you did.hit happend to him on his suzuki race bike. it just was real hot and it stalled. then it wouldnt start anymore. and he had oil. he found out that his connecting rod was no good. sorry to deliver the bad news. i could be wrong but it seems to be the same thing

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txknucklehed

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take the plug out and see if it kicks over easy how much oil did it take to fill er up the high speed water tang makes me wounder

no water involved. it is just a flood plain next to the river, not even muddy just flat and wide and super fast. if there was water it would make a little more sense to me. thanks

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kdxFREAK42

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well look on the bright side. if you decide to take the bottom end apart and fix the problem, you can get a high performance hot rod crank or somthing of that nature. all in all its only gonna costa few hundred for labor(unless you do it yourself),and a few hundred in better than original parts. my advice to you is to take the top end apart yourself.(take the engine out of the bike) then give the bottom end to a local powersports mechanic to fix. that will give you an easy way to save a lot of money in labor. your doing half the work yourself,just the easier part

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txknucklehed

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Have you done a bottom end job before? My shop manual makes it look like you are rebuilding a solid rocket booster!!! I know my way around a V8 , i used to work in a hot rod shop, but this seems like it could get tricky. i want to put in a Hot rods stroker crank that is ready to install out the box but i feel a little intimidated. do you know of any reference material or any place you can guide me for instruction? i found a place up in PA. that does machine work on tops and bottoms for what seems to be relatively cheap. but i don't know if it is worth crating the motor to send up there. Is this something that you think I should have a pro builder do or should i do it my self? i have a blown (seized) YFM 350 warrior motor that i was going to rebuild to get acquainted with the thumper motors but i need to have something to ride during the rebuild! Maybe i have the yz 450 done by a local shop and Redo the 350 myself. the local yammie shop told me the 350 motor would cost about 1500 to 2 grand to repair. they charged me 280 bucks to pull the motor and take off the top end. needless to say they will never touch another one of my machines. Sorry about the long post i am just trying to figure out how to best spend my hard earned money and time. i would rather be spending my money on fuel and my time riding. thanks to all who have put in their 2 cents, and thanks in advance to anyone who has suggestions.

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erickdj

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I'd suggest fixing it yourself. You say that you're comfortable working with a v8 engine, that should be enough to do this kind of work yourself. It's really not that hard, there's just quite a few small pieces involved, but nothing too hard. Seems like you already have the repair manual, that's great because you'll need it every step of the way. Earlier this year I swapped the cams and changed the timing chain on my wr450f(pretty much the same engine as the yz), and I also split the cases on a smaller ttr125 engine. Here's what I'd consider essential to do this kind of work:

Read, and re-read the manual, pay special attention to the torque specs, most will be in inch/lbs instead of ft/lbs.

Take your time.

Double check everything you do.

Separate and label all the parts/bolts during the tear-down process.

If something seems like it would be complicated to put back together, take pictures when taking it apart.

Get all the right tools ahead of time, impact wrench(for flywheel nut), INCH/LB 1/4" torque wrench, clutch holding tool, flywheel puller, feeler gauges, case splitter, etc...

Ask questions here on the forum when in doubt, or do a search to see if the topic has been covered.

If you do your research ahead of time, it shouldn't take too long to repair.

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kdxFREAK42

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i agree. i will tell you from experience that a v-8 engine is like fixing a lawnmower compared to a motorcycle engine, which the bottom end looks like a maze of loose parts. but all in all its not bad if you know what to look for. ill tell you what i did for a little help on my klx-250. go to www.***************. get an online manual for a few bucks and use the step by step directions on how to take the bottom end apart. they also have good,clear pics of all the steps. give it a try,it cant hurt! by the way make sure whenn you split the case that the side that is supposed to be down...is down. other wise you will end up with parts rolling around on the floor that you dont know where they go. i did that

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txknucklehed

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that sux. i am pretty sure that my problem is confined to the crank. i have been second guessing my clutch though. i am wondering if i fried it. i have adjusted it all the way in and out and it doesn't seem to engage all the way i don't think this would effect the ability to start in neutral though. I am really nervous about splitting the cases. this is a tough one.

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shimla4

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Drain the oil remove the right side cover(not only the clutch cover). Now start inspecting all the gears to see if they are meshing good and that there is no material stuck between. That is what I did and was so scared that I would mess something up, that is how I slowly started to eliminate problems. If you see nothing you can still just button it up and send it off to a shop.

My 426 had the square key shear so long story short, it only cost me $285 for 2 new gears,key,water pump,new gaskets and of course an excellent deal on a vertex piston and rings from e-bay. So maybe there is hope.:busted:

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txknucklehed

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thanks you guys. looks like i will be doing some serious inspection work this weekend. this website is awesome. you peeps are a wealth of knowledge. i appreciate all the responses i have gotten. It's also really nice to see that the people posting on here are not smarmy and attitude infected like some of the other forums on the inter-web. TT is great.

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mkporn

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Have you done a bottom end job before? My shop manual makes it look like you are rebuilding a solid rocket booster!!! I know my way around a V8 , i used to work in a hot rod shop, but this seems like it could get tricky. i want to put in a Hot rods stroker crank that is ready to install out the box but i feel a little intimidated. do you know of any reference material or any place you can guide me for instruction? i found a place up in PA. that does machine work on tops and bottoms for what seems to be relatively cheap. but i don't know if it is worth crating the motor to send up there. Is this something that you think I should have a pro builder do or should i do it my self? i have a blown (seized) YFM 350 warrior motor that i was going to rebuild to get acquainted with the thumper motors but i need to have something to ride during the rebuild! Maybe i have the yz 450 done by a local shop and Redo the 350 myself. the local yammie shop told me the 350 motor would cost about 1500 to 2 grand to repair. they charged me 280 bucks to pull the motor and take off the top end. needless to say they will never touch another one of my machines. Sorry about the long post i am just trying to figure out how to best spend my hard earned money and time. i would rather be spending my money on fuel and my time riding. thanks to all who have put in their 2 cents, and thanks in advance to anyone who has suggestions.

unfortunately a solid rocket booster is way easier and has less parts....now if you were talking about designing a solid rocket booster, that is a whole different story and requires mass brain computing power....As for the motor....take pictures, take your time and ask questions, it is nothing more than taking peices off, replacing the bad ones and putting pieces back on....with a little bit of know how, plenty of reference material (thumpertalk), some time and mechanical ability you can do it.....biggest pain of the whole thing is getting the main bearings and crank in...then butting the two case halves back together (might i suggest owning a propane torch and a freezer)...those are about the only real specialty tools along with a flywheel puller....other than that you need a couple wrenches (8mm, 10mm, 12mm and a 14mm, same size sockets plus a 19mm, 22mm and a 24mm a couple screw drivers and a ball peen hammer and small chisel, maybe a pair of snap ring pliers if you have the stock piston..)......I think that about sums it up....I may have forgot an items.....

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  • 1 month later...
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txknucklehed

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Well it didn't jump a tooth. my main bearing locked! the coating also was coming off of my cylinder. new valves, new Athena cylinder new hot rods OEM crank assembly and 2243.57 later i have a rebuilt motor. 3 heat cycles later i rode it like i stole it!! oh yeah and a new cam chain! just in case! this thing feels like a new bike. 2 + grand and now i know it is all fresh. now it's time to ride!!!

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