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2007 rancher 420 FM Bottom end questions

17K views 27 replies 5 participants last post by  vermhot  
#1 ·
Ok, I need some help from you guys. I just picked up a 2007 420 rancher 4X4. It was not running when I bought it the guy had just rebuilt the top end and it would not start back up after the rebuild sounded like the timing was way off in it.

Step one.
Got bike home tore down top end. Everything looked normal except a small place on the piston where it looks as if it had slapped the valve.

Cylinder wall is in good shape with little wear in it.

However, the connecting rod for the piston to the crankshaft seems to have a lot of play in it.. Is this normal?
Any help would be appreciated.
Thanks!
 
#2 ·
Welcome dude !!!! That thing should be tight and since you got it that far down you should have the cylinder checked for if it's in round or if it needs to be over bored .
 
#3 ·
Thanks for the reply, It is definitely not tight it will move all around. I am taking the head and cylinder to the machine shop tomorrow to let them service them and do their thing.
So now the question is, do i replace the crankshaft with a new one? Or can the main bearing be replaced on the connecting rod? Is this a really hard job to do?
I have the complete manual downloaded for the ATV also.
 
#4 ·
You don't know if the guy that had it last swamped it do you ???!! I think I would just do the whole thing to be on the safe side !!!!
 
#5 ·
I would not doubt it has been swamped it has had a rough life the plastics are in decent shape but it needs all new wheel bearings and different odds and ends. Only paid $300 for it so its def worth fixing.
It has a snorkel on it which was broke so it definitely could have been swamped there is no water in the oil though.
 
#6 ·
Man ....... I hear story's like that all the time ,you make sure it's not hot ???!!! I know a guy that got a deal kinda like that and dumped a lot of cash in to it to just have tha cops take it from him !!!!
 
#8 ·
WOW That is a great deal !!! Then for sure an do a full rebuild man !!! Well worth it !!!!
 
#13 ·
ok is the rod loose side to side or up and down
do you know if the valve that hit the is bent
 
#14 ·
Like Rich said, you need to determine if the rod has up and down play or just side to side play. If you have up and down play when you pull up and down on the rod, the rod bearing is bad. Some side to side play is normal.
 
#16 ·
It does not appear to be bent but I am dropping the head off at the shop today to let thenm clean it up and remove a broke off bolt from it. I told them to check it all out and see if anything was wrong with it or the valves so we will see. Also, Most of the play is side to side. But i will have to check for the up and down play tonight.
When I got the atv when it turned over it turned over slow and sounded like it was trying to spit back. However it did not sound like it was locked up at all.
 
#17 ·
the timing chain may be streched and jumped timing or the cam chain tentioner may be broken
 
#18 ·
lol jeb..replacing the crank is all about time..well...and cash !!..lol...you will need to split the case..and this means..lotssssss of parts !!..you already done the first thing..you got the service manual !..that alone is priceless !..now..how much cash you willing to invest in it ?..you want a new crank ?..or used crank ?..a new one will set you back quite a bit !!.. a used one will do just as good as a new one. now comes the time part....if you got alot of extra time..then tear it down...guessing you got the tools to do the next part ??...an air compresser..and some good metric tools are called for. got a nice dry warm area ?..yu'll need it !. now..yer gonna need a complete engine gasket kit..a complete oil seal kit ( this is optional here..but i alwayssss do this when i split an engine case )..new rings. and all your new bearings and seals if you really wanna do this right...sooooooo..now yer thinking back..geeee..i only paid a few bucks for it ??!..yeah..we allllll get them cheap..butttttttt..when it comes to rebuilding them..THERE IS NOTHING CHEAP ABOUT RESTORING THEM !!!..LOL. this is where the cash part comes in !!..to do it right..yer probally looking at anywhere from 500 to 700 or more to fix your bike back up..oh..and don't forget a timing chain ( cam chain )..and valves !. sooooooo..there you have the basics of what is involved..now the question is...how bad do you wanna ride ??????...lol.
 
#20 ·
Shadetree: I WILL ride! Haha.
As far as the parts goes I already have a new piston, timing chain, valves.
I think I am just going to get a new crankshaft I found one online new for around $300. New from honda it is $680.
I will just order the new gasket and seal kits from the honda dealership when they open tomorrow.
If anyone knows where to find a cheaper crank or a used one from a reputable place please let me know.
Thanks!
 
#23 ·
Shadetree: I WILL ride! Haha.
As far as the parts goes I already have a new piston, timing chain, valves.
I think I am just going to get a new crankshaft I found one online new for around $300. New from honda it is $680.
I will just order the new gasket and seal kits from the honda dealership when they open tomorrow.
If anyone knows where to find a cheaper crank or a used one from a reputable place please let me know.
Thanks!
before you rush out..and fork out 300 bucks for another crank..make sure yours is bad !!...if it's just a bad connecting rod bearing..your better off just replacing the crank's connectiing rod and bearing ..thats what i would do...a helllll of alot cheaper than buying a new or used crank !..now..this is up to you ???. if you really don't want to mess with this much..then look on ebay for a used crank....only down side..is you have nooooo idea if that crank is gonna be any better than the one you have now ???!!..sooo..if you really want to do it right ??????..then fork out that 300 bucks..and rebuild it the right way...i know this is a tough call..money wise..it's just something you gamble on..as you and i both know..you cannot see and inspect used cranks for yourself...until you have them in your hands !..lol. soooo..is it worth the gamble ????..do you want to take the time and risk in buying a used crank that you have no idea if it's any better than what you got ??..if it were me..i would replace the connecting rod and bearing..and i would know for sure it was fixed right !..unlesssssss..you want to fork out 300 or more bucks for a new crank ???. your call.
 
#24 ·
after seeing your atv..lol...i'm not even gonna comment on it..other than it's nice..lol...personally..i hate to see a good looking atv be ruined by all that bs on it..glad it's not mine...good luck on your rebuild !.
 
#26 ·
lmaoooooo...ok ok..if yer gonna put it back to stock..well..close anyway..minus the antlers ??..lmfaooo..then yes..i think your doing a great job !!..nowwwwwww..if yer gonna keep using it as a boat ????..well..i hate to sound like a butt head...buttt..i just don't like it when ppl do this....yes..i know...it's thier atv...then again..most ppl don't have a clue as to what kinda cash it's gonna take to rebuild it back to a running bike !!!!..i do know !!..and i do not like seeing ppl fork out hard earned cash !!..still..it's thier atv..their cash..if they wanna tear it up, so be it..i just refuse to help anyone that does this to a prefectly good machine..oh well..chit happends !!..lol.
 
#27 ·
3hundo is still a good deal and for a grand or less in the motor it's still worth it to me !!!