i think its broken bad??? help please

[hypersnyper6947]

Im going to start by saying i dont beat on my quad at all, i dont rev to the limiter and pop the clutch or any of that.

So today i was riding a croom when all of the sudden it just stopped and stalled, i was on putting maybe 5-10mph when it happened. I can turn the motor only 1/4 of a revolution. Thats all it will move then it just stops, i can go back and forth doing that 1/4 turn. It will still go in neutral and first a second, thats all i have checked since its not running. I pulled the valve cover off and nothing looked out of the ordinary. I will be tearing it down more this week. What could this be?

Thanks

i wanna say a valve is bent and stuck open. when my brothers wouldnt make a full revolution the one valve was bent and it would touch the piston. Good thing we didnt try to start it because it would have chewed up the piston

[rideracelivemx7]

pull up on the intake valves, if they are loose then you know why, i droped my intake valves, hondas are notorious for that. dinged up my new 440 piston too. nothing was damaged. just dropped new ones in and went. of course i had the seats cut.

[hypersnyper6947]

Originally posted by rideracelivemx7
pull up on the intake valves, if they are loose then you know why, i droped my intake valves, hondas are notorious for that. dinged up my new 440 piston too. nothing was damaged. just dropped new ones in and went. of course i had the seats cut.

I hope thats all it is, i just did this rebuild

[rideracelivemx7]

you said you just did the build. did you do new valves? new valves with a cam are recomended. the intaktes cant handle the new lift.

[hypersnyper6947]

I thought stock valves were ok with hot cam, so i didnt change them. Now that im going to have it apart anyways im going to through some KB valves in there, is there a better brand or will that be good? I hope thats the only problem just a valve thats open and bent with no other damage.

[rideracelivemx7]

its a hit and miss kind of game. The intakes from honda just blow. they sell kits for alot of bikes to replace the intakes. Kibble white is a great brand. work just like there suposed to. Mine dropped mabe a month of riding with the new cam. nothing is made to last. hopefully it didnt damage your piston like it did to mine. tear it down and let me know. its recommended that you check your spring rate with a micrometer when doing new valaves. you dont have to get kibble white springs with the valves, even though they say you do. oem springs from motosport are alllloottt cheaper lol. tahts what i did and they were all in spec. id give you the numbers but my E-Book i put on here of the manual got taken off the internet by the supplier for some reason lol

[Ruby Soho]

you should be fine with the stock valves.

im running a 440 in mine, have been for 2 years now on all original 1999 valvetrain. no problems what so ever

[hypersnyper6947]

Im taking it apart tomorrow, so if it is the a valve which i think it is, im going to buy all 4 new kibble white valves, should i buy the springs also, there like $90 plus the $120 for the valves themselves. Or will the stock springs be fine?

[hypersnyper6947]

Ok so it is broken really really really bad, the whole motor is effed. It dropped 2 valves one of each, the valves busted the piston all up which made little pieces of metal squeeze between the piston and the sleeve, this cause the sleeve to break at the bottom, which put large chunks of metal into the bottom of my engine. WOW i was hoping for the best and i definitely got the worst. What should i do now, hybrid? Or buy another ex motor and put it in and go. Any advice would be great or if you have a motor for sale i need one.

Thanks

Here some pics enjoy

[hypersnyper6947]

Piston

[hypersnyper6947]

sleeve

You can see how much of this sleeve ended up in my tranny b/c i didnt find any of the missing metal you see

[Pipeless416]

wow...:ermm: can't say ive seen an ex engine that bad. xr650r time! or L

[hypersnyper6947]

Originally posted by Pipeless416
wow...:ermm: can't say ive seen an ex engine that bad. xr650r time! or L

I cant find the xr650r motor i have looked, i cant even find a yz426, the only motor i have found is cr500, and some 450s but there not cheap. THIS SUCKS!!

[400ex28]

What a bummer. :(

[rideracelivemx7]

ouuchhh. hate when im right sometimes. mine wasn't nearly as bad. mine dropped nicley iontop of the piston head facing down. and only dinged the top a little. it happened the second I shut off the bikes. what luck.

[kodymx13]

so it made no noise at all?? that doesnt happen instantly...

ive seen one where he said "yeah it just quit, right after it sounded like a grenade going off"

[brian76708]

chit, that will buff out haha jk

at least know you have a excuse to build a hybrid.

[hypersnyper6947]

Originally posted by kodymx13
so it made no noise at all?? that doesnt happen instantly...

ive seen one where he said "yeah it just quit, right after it sounded like a grenade going off"

Unfortunately i was not on it when it happened. I was near it, my friend wanted to take it for a spin, he wasn't beating on it or anything and he was going slow and it just stopped. He said he didn't hear anything.

[Honda#4]

WOW! what a mess, looks exactly like my Polaris motor in my shed. Theres only three things i'd do may four. I'm sure you could find a cheap EX motor though.

1. Buy a new motor
2. Do a hybrid (money permitted)
3. Part out (last resort)

4. Back up plan and buy a cheap 450

[rideracelivemx7]

actually it does happen instantaniously. do you realize how fast everything in that motor is spining? apparently not.

[sc400ex_rider]

it is highly rec you get new springs with a cam. there the weak link. i put kibby's on mine when i did my piston and cam just for insurance. i also kept the stock rev box for the lower limit. i only hit it a couple times but it was when i missed a gear and really zinged the crap out of it. go big and put a r6 motor in it, you can find one alot cheaper

[hypersnyper6947]

Originally posted by sc400ex_rider
it is highly rec you get new springs with a cam. there the weak link. i put kibby's on mine when i did my piston and cam just for insurance.

I wish i would have known that i would have changed them out for sure, i always try to do things the right way not the cheap way.

I decided to buy a whole new ex motor, i was lucky and bought zrpilots 416 it puts 37hp to the wheels i got the dyno charts, and its a 416 done right so it should be reliable.

If i had the money and the fabrication skills i would have gone for the hybrid though.

[rideracelivemx7]

just becuase the springs might have been a little worn won't mean you'll drop a valve. just means it would be out of spec. and might run a little funny. just means the valves were beat. if you did new springs it would have dropped the heads even sooner.

[justin1022]

^^^^^^^^^^^^^^



yea im with him. i put HOTCAM stage 2 in mine a few months ago and i still didnt drop a valvue or anything been perfect.

[hypersnyper6947]

Are valves a wearable part, do they become weak or brittle over time? If so how often are you suppost to change your valves? I was under the impression that if they sealed they were good.

[mooseracerX]

Hey hyper that's a bummer but good thing you got another motor. You have a PM also.