Top/Bottom end rebuild..

Lindso

Lindso

Member
Oct 3, 2008
116
11
65
Albuquerque, New Mexico
www.myspace.com
To start, if I'm posting this in the wrong place, go easy on me- I just signed up. And too, if this has been answered somewhere else I apologize. There's just so many posts you can look through before giving in and buggin' somebody ;)


TOP END;
A couple weeks ago I shattered my piston. Tore up the inside of the head some so I'm having a machine shop take car of that for me, and I've got some Wiseco piston options in mind.
What I need advice on is how much to have the head bored out. Wiseco offers pistons .25, .50, .75 and 1.00 oversize. Is there any benefit in going with a 1.00mm over stock size compared to a .50?


BOTTOM END;
I just finished watching the YouTube videos on the bottom end rebuild from the DIY sections (
) and I dunno if I'm up to the challenge, mainly because I don't have access to any special tools like the one the guy uses. I already have pretty much everything out (the clutch, gears, stator and flywheel) from both sides, but for some reason I can't for the life of me get the bolt that holds the engine to the swingarm to budge. That makes it difficult because I can't get the engine outta the frame. I've gotta get the stray pieces of piston out and see if I need to rebuild the crank, but I'm stumped.

Has anyone cracked the case on their own before, and if so, how?
 
Last edited by a moderator:
You want to go with the smallest bore size possible. YOU only get so many rebuilds on one cylinder dont waist them going on over bore. Also that gives you some left if say you want porting done in the future.
 
Wildcard2 said:
You want to go with the smallest bore size possible. YOU only get so many rebuilds on one cylinder dont waist them going on over bore. Also that gives you some left if say you want porting done in the future.
Click to expand...

So going a little further with the bore won't get me any extra power? Again, excuse me for any dumb questions..

Is there also something else that I might should be focusing on that I'm missing? So far, the above mentions details are the only ones I'm paying attention to. I don't know if I should be looking at getting other things done, or replacing anything beside what I've mentioned.

Thanks for taking the time to help me out.
 
if you have a book or use the one online from this site, it is just like a puzzle. Lay each piece out one at a time on a bench. You may need some tools like an impact driver but it sounds like you got most of the hard parts off. Its not that hard really, just take your time.
 
I rebuilt my bottom end at home and it wasn't too hard. used rubber mallets and wooden blocks to split my case. just take your time go slowly and work your way around the case going a little bit at a time. you may have to use a pry bar to keep the case from trying to come off crooked. just dont use it to pry the case halves apart you could damage the sealing surface or even worse crack the case. you will most likely have to make a tool to pull the crank through the case as it is a press fit.
 
I used a dead blow hammer and tapped the cases apart and then to get the crank out get 2 long bolts and a steering wheel puller. That will press the crank out. There are 2 spots on the stator side that are open for the bolts to thread to. They arnt used for anything else.
 
i found the splitter for about $50 on ebay....makes it real easy to get them apart. worth $50 in my opinion, but that's because i work in the garage a lot and i have 3 bikes in there right now along w/ my wheeler.....
i found the crank puller for about $60. i think the puller is more advantageous than the splitter. you can more easily get the cases apart w/o the tools than pulling the crank in, but it is possible esp if you sweat it in.
after you've cleaned the metal bits out of the crank area, you should probably pull the bearings and dunk them and the rod bearing in some 2 stroke oil and turn em a bunch to get all the little shavings out of em and hell while you're in there you might as well replace the crank seals too.
as far as pulling the swingarm bolt, just get a wood block or 2x4 or something to protect it and hammer the ever livin sh*t out of it. that's the only way i could get it to budge, in fact i had to hit the bolt straight on w/ no block a bunch of times to get it started.
it helps if you jack up the ass end a little bit to relieve some of the weight off the swingarm.
 
just to clear it up. boring your cylinder out .040 does not make it a 240cc. that is what people asume but its not. i think it only puts it up to 200cc or something. the blasters acualy 195cc stock. so go the smallest size up to clean it up so you can have more room in the future to bore it out without resleeving or buying a new cylinder, which both are pricey.
 
quam said:
...as far as pulling the swingarm bolt, just get a wood block or 2x4 or something to protect it and hammer the ever livin sh*t out of it. that's the only way i could get it to budge, in fact i had to hit the bolt straight on w/ no block a bunch of times to get it started.
it helps if you jack up the ass end a little bit to relieve some of the weight off the swingarm.
Click to expand...

Thank you guys for all your advice.

With regards to this problem I'm having- OMG I'm gonna shoot someone around here in the face, it's so frustrating. Every piece of wood I've used, blocks of metal wrapped in a towel..NOTHIN'. I resorted to using my BFH directly impacting the bolt, almost an entire bottle of WD-40, jacking it up millimeters at a time trying to find the best height::torque ratio...and have gotten the thread side of the bolt flush with the frame, though to the demise of the bolt now I've compacted the end to where the first couple rows of threads are pretty much just one thread now.
I can't generate enough power to hit the bolt with another bolt to get it further through, and none of my family or friends will sit there holding it for me. Weirdos. I can't seem to pull it from the other way out either. There's nothing that I'm fckin' up in there somewhere along the inside of the motor mount or swingarm, is there?
Would removing the rear shock help relieve the pressure at all? If so, how much of a pain in the ass will it be to get back on? Keep in mind, every bolt, nut and screw still on the bike has been there since 1990..
 
Lindso said:
Thank you guys for all your advice.

With regards to this problem I'm having- OMG I'm gonna shoot someone around here in the face, it's so frustrating. Every piece of wood I've used, blocks of metal wrapped in a towel..NOTHIN'. I resorted to using my BFH directly impacting the bolt, almost an entire bottle of WD-40, jacking it up millimeters at a time trying to find the best height::torque ratio...and have gotten the thread side of the bolt flush with the frame, though to the demise of the bolt now I've compacted the end to where the first couple rows of threads are pretty much just one thread now.
I can't generate enough power to hit the bolt with another bolt to get it further through, and none of my family or friends will sit there holding it for me. Weirdos. I can't seem to pull it from the other way out either. There's nothing that I'm fckin' up in there somewhere along the inside of the motor mount or swingarm, is there?
Would removing the rear shock help relieve the pressure at all? If so, how much of a pain in the ass will it be to get back on? Keep in mind, every bolt, nut and screw still on the bike has been there since 1990..
Click to expand...


Your trying to get the main bolt that holds the swinger on right? If you remove the rear shock the swinger will just drop to the ground. Its not hard to put back because the only thing holding the swinger up is the shock.

Next to remove your shock try using an impact gun on the bolt. That will spin the bolt really fast. While its spinning pull on the bolt with your free hand. Make sure your wearing gloves first. With the bolt spinning it should be eaiser to pull out.

Good luck brother.
 
yeah you definitely want to take the rear shock out first prior to trying to remove the swing arm bolt, secondly try using a punch with a flat head on it, it should go...
 
i just used a socket and extension. then once i got some room to work on the other side, i got my channel locks around the head of the bolt sideways and hammered against them like a platform.
 
Alright SWEET I got it all out. Sucker had god knows how many layers of rust and other crap on it..

ANYWAY...I'm down to the meat of things and I need more help! I spoke with a Yamaha shop tech the other day who expressed that, while putting in a stroker crank would give me the edge on my buddies, it'd be a ticking time bomb in the 'longer' run. I didn't specify Vito's or Hot Rod's in particular, he was just speaking generally and was pretty convincing about it. Has anyone had the experience with 'em, and is this guy a jackass or does he know what he's talking about?

In reply to the question about my riding style, I do what I can. I've been riding for about 14 years but never have had the money to make a race machine out of it. I like goin' fast and love riding hard, but at the end of the day I guess I'm just a trail rider.
 
well, you must know that no matter what you do or don't do to any engine, there's always gonna be wear. esp in a 2stroke. crank bearings, pistons and rings, top end bearings, rod bearings, crank seals, cylinder sleeves......no matter what, if you ride your 2stroke bike long enough, you'll wind up having to do some maintenance on all these things eventually.
way i figure is, it costs money to recreate.
i mean i got the thing to ride and fun and do dangerous things with. i went into it knowing that it was gonna suck money outta my pocket, and i think that someone who understands that has a lot more fun w/ these things!
the stroker prob does put a little more stress on the crank bearings, top end bearing and rod bearing.
but remember: it costs money to recreate.
 
Yo what up dude I am in the process of doing what you are doing right now except i'm a bit further ahead of you. Hell yes that engine bolt was tough to get out but i just kept working it out. As for the stoker....i wouldn't put it in your bike personally because I had a stroker in my bike before and it doesn't really give you that much more speed although some extra torque. I'm getting my bottom end professionally rebuilt because the tools to do it are more expensive then getting it done professionally. I'm getting wiseco everything put into my bottom and top end like the over sized piston for my 240ccblaster, gaskets, bearings, seals and crankshaft. Wiseco is very reliable and is one of the best names in performance. My bike getting rebuilt and will last longer most likely and is gonna run better, drive better and will give me some extra power without going for the stroker. if you have heard a story about somthing going wrong with a stroker then dont do it because personnaly id rather be safe then sorry. GoodLuck bro, any time aim screenname spikehead728 or email fordsport@cox.net
 
What tools are needed for a bottom end rebuild? i didnt know anything special was needed. unless u are refering to the machine work. we have 2 vitos stroked motors. one is a 244 bb the other is a stock bore ported. i noticed a huge difference in rev. the ported stroker stock bore runs like a raped ape and will put a 400ex to shame.i have seen it.like stated before parts wear and things break. i havent had any problems what so ever out of either one of the stroked motors and yes i built them both.
 
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