Engine Rebuild tips or advise

[bfd811]

I will soon be buying a 2002 Blaster YFS200R. The bike needs a crankshaft. I have some good experience with engines and my dad has a lot of experience with car engines and some bike engines from when he was a kid but my main concern is are there any special things I need to do when disassembling and reassembling this engine? Are there any positions of gears i need to take notes of? All help and advise is greatly appreciated.

Thanks,
Ben

 

[blasterboy91]

first and for most get yourself a clymers...unlimited info that will keep you from comming back and asking questions...granted you might still have to and were always more then happy to answer anything you may have, but just might save you some time ya know???

 

[Surfrjag]

remember where the shift shafts go, lap the cases, and use a crank puller to install the crank.

 

[bfd811]

Alright man I got what you mean by remembering where the shift shafts go, but im not sure what you mean by the other 2. I know what lapping is i just dont quite know what you mean by lapping the cases. How do I use a crank puller to install the crank?

 

[lasxgames]

make sure u true the crank, even new ones need to be verified.

 

[Surfrjag]

when you get the crank and try to install it into the bearing in the case you will see. a tusk crank pulling tool is what i use Tusk Crank Puller Installer Tool Motorcycle ATV NEW on eBay! . for case lapping i usually use a larger peice of mirror and a peice of sandpaper like 400 grit and tape it to the mirror then wet it and rub the case halfs on it to be sure they are straight and clean. i hear some people use a compound and some granite that is perfectly flat but i havent tried that method maybe someone else can chime in on that.

 

[hawks2011]

ken o'connor has a great video posted on youtube for case lapping

 

[Braaaptor]

Also, don't beat or pry on anything when disassembling the engine's bottom end/case halves. They make a special 'case splitter' tool that works wonders when taking a bottom end apart. Don't do a rebuild without one IMO. Same goes for a flywheel puller: Get one and use it. There is NO OTHER good way to get a Blaster flywheel off. Use the puller and an impact wrench if needed.

Other tips? Be sure to use a torque wrench when re-assembling the engine. Use only OEM or Cometic gaskets and seals. Work slowly when taking off Phillips head screws; they strip easily if you are not careful. This is especially true for the two screws which hold the stator plate in place. I've had to replace these two on every Blaster I've owned, except for my 2005, because some fool before me was in too big of a hurry with too small of a screwdriver.

 

[99LRDblaster]

when you get the crank and try to install it into the bearing in the case you will see. a tusk crank pulling tool is what i use Tusk Crank Puller Installer Tool Motorcycle ATV NEW on eBay! . for case lapping i usually use a larger peice of mirror and a peice of sandpaper like 400 grit and tape it to the mirror then wet it and rub the case halfs on it to be sure they are straight and clean. i hear some people use a compound and some granite that is perfectly flat but i havent tried that method maybe someone else can chime in on that.

Haven't done it on the Blaster, but on other engines. I usually use a rubbing compound and a piece of glass.

 

[bagds101]

when i lapped my head, i put down a sheet of glass, taped 400 grit sandpaper to it, put oil all over it, and went in a figure 8 pattern with my head until i saw the sand paper marks all over the bottom of the head. then i went 15 more times and called it a day.

 

[bfd811]

Alright I see the use of a crank puller because I realize you cannot get the crank pressed onto the bearings correctly if you don't use one but this is just project that i hope to finish and then to ride the bike for a month or 2 and sell. I'm all about doing things right but I'm looking to save money, do I really need a case splitter or can I do it another way that is affective at splitting the cases but yet doesn't hurt anything? (Just a little rougher, maybe like a rubber mallet or something???)

 

[Surfrjag]

i used rubber mallet before but sometimes i would think that wont get it...

 

[sicivicdude]

A harmonic balancer puller is what I use to push the crank out of the left side case.

I always flip the cases over onto the left side after I've taken all of the case screws out and then use a rubber mallet to gently knock the right side case loose. I then wiggle the right side case up off the dowel pins and take it off the motor. Once the right side case is off, I pull all of the transmission guts out and store them in ziploc baggies (quart size freezer bags are perfect). I put all of the nuts, bolts, washers, keys, everything in ziploc's. Not only does it keep the parts bathed in their own lube but it keeps things separated so it is easier to figure out where they go later.

Once the only thing left in the left side case is the crank, I hook up the harmonic balancer puller (with very long 8mm bolts) into the blind 8mm holes provided in the case and push the crank out of the case.

I have a tusk crank puller for installation because that takes a little more finesse.

The only thing I can recommend if you plan on learning how to ride and want to sell this thing after a while (and don't care to learn about the blaster or motorcycle bottom endds) is to buy a bottom end somewhere and install it into your bike. It's going to cost you but it'll be quick and dirty...

 

[bfd811]

I see what your saying Ive built dozens of Briggs & Stratton karting engines so I've done a lot of things. I'm just new to the press on bearing thing (I think ill just take it to the Yamaha place and pay them to install the crank). I already know how to ride I've had YZ250's and stuff in the past. This is more than anything a project to make money (Trying to buy a 5.0 mustang, turning 16) but I always like to play with it for a month or 2 after I finish it to enjoy my work... Oh and try not to break anything else haha

 

[sicivicdude]

The only bearing you cannot easily replace yourself with a few not too expensive (I consider $100 for a special tool not TOO expensive) tools is the main bearing which is pressed between the crank webs with a LOT of force. The other bearings can be pulled by sweating or bearing pullers (depending on which way they need to go)

The crank can be pulled into the left side case using a "crank puller" tusk makes a kit which is about $60 brand new and can used for any engine which has a vertically split crankcase (dirtbikes and 4 wheelers) where the crankshaft is held in place by a slight press fit into one of the case bearings.

 

[bfd811]

Yea that's the thing, its hard for me to buy a $60 tool that Im gonna use once. There is a place in Garner, NC that Im close too that does all sorts of thing. Ill call them and ask If they can pull the crank through the left side for me. From what I understand all the other bearings are inserted in the block and can be sweat in to the block, but do all the other bearings besides the mains fit into the block or do they go onto a shaft? Once I get the Crank pulled can I just put the other side on with a rubber mallet (Keeping it as parallel as possible)

 

[sicivicdude]

How close are you to Garner? I live north of Durham and I have all of the tools needed... I'd be up for a blaster brother hookup if you threw a couple of coins my way.

I'm already doing a bottom end for blkblzr.

 

[bfd811]

I'm down here in Apex, NC. You don't seam too far. I'd be glad to pay ya for your help. Let me know when your gonna be around. My flywheel puller should be coming today or tomorrow so I should be able to get that off. Then Ill try to get the right side case off and the transmission out. Ill have to figure out what to do from there.