Top End Rebuild

Is the cylider already bored .20 over?

Your crank bearing might have debris in them that is causing the crank not too spin freely. I would split the cases to be on the safe side. Its not hard to do. One great thing about a Blaster is they are easy to work on.
 
Nope, stock bore. The crank looks pretty marred up, thers actual divots in it, I just picked up a crank for it. Are there any posts on rebuilding the bottom end?? I've never done it before, and have no idea what I'm getting into. I also dont have any kind of a crank or flywheel puller or anything to press the crank back in. I'm also wondering if the main bearing is alright. Any suggestions or help on the bottom end, please let me know!
 
Well first for the top end you are going to have to get the cylinder bored out to fit the .20 piston. As for spilitting the cases I am not sure if there are any posts on it. But you could use the search for it. I would replace the crank/main bearing get new oil seals, complete gasket kit and a tube of Yamabond. You will also need a flywheel puller and I suggest getting a clutch holding tool also they are a big help for taking the motor apart and putting it back together. you dont need anything to take the crank out once you split the cases the crank will come out.
Did you get a complete crank?
Here is a downloadable manual so you can read up on doing the motor. One of the best things about a Blaster is they are very easy to work on.
http://www.blasterforum.com/general-support-17/downloadable-yamaha-blaster-manual-17325/
 
I got the entire crank assembly and also purchased the main bearings and seals...I think going to have someone do the bottom end for me, I'm pretty sure I can handle the top end, are there any measurements that I need to make sure of in the top end??
 
As I stated above, it is the stock bore. How about piston to cylinder clearance? Also, how about ring gap? When installing the rings on the piston, how should I stagger the rings so that the gaps do not line up? Do they need to be in a certain position, or just put them on making sure that the gaps are not lined up?
 
Sounds easy enough, Just have to look at the torque specs in that manual for the head and cylinder, anybody know them off hand?
 
The head is 20 ft-lbs or 27Nm and the base is 18 ft-lbs or 25 Nm.

For the head you have to start on the back center nut, then the front center nut, then the back right nut, then the front left nut, then the front right nut and finally the left rear nut. This is from looking from the front of the motor.

Also dont for get to put the head gasket on right the point goes to the front and if it has up written on it the that side faces up.

Dont forget to torque the reed cage and exhaust flange also.

Reed cage is 5.8 ft-lbs or 8 Nm.

Exhaust is 15 ft-lbs or 21 Nm.
 
fioz600r said:
The head is 20 ft-lbs or 27Nm and the base is 18 ft-lbs or 25 Nm.

For the head you have to start on the back center nut, then the front center nut, then the back right nut, then the front left nut, then the front right nut and finally the left rear nut. This is from looking from the front of the motor.

Also dont for get to put the head gasket on right the point goes to the front and if it has up written on it the that side faces up.

Dont forget to torque the reed cage and exhaust flange also.

Reed cage is 5.8 ft-lbs or 8 Nm.

Exhaust is 15 ft-lbs or 21 Nm.
Click to expand...

oops i didnt know there was a cetain way to torque the head nut down but i did it in a star pattern and i think i put the gasket on the right way cuz i think i made it point the same way as the piston
 
stephen12091985 said:
oops i didnt know there was a cetain way to torque the head nut down but i did it in a star pattern and i think i put the gasket on the right way cuz i think i made it point the same way as the piston
Click to expand...

It is a star pattern the way I explained. I dont think it would make any differance which way you did. The way I do it is the way the manual calls for it. I use cometic gaskets and it didnt say up on one side. But if you put the point of the gasket the way the arrow on the piston goes like I did you will be fine it is the same.
 
Thanks for the torque specs., thats going to save me alot of time looking them up. How about the gaskets for the top end? The base gasket, head gasket, and reed valve gasket...should I use any type of silicone on those? Or clean the area and put them on?
 
Oh, and my piston kit also came with a large metal washer looking piece, is that the exhaust header gasket?
 
Friday9158 said:
Thanks for the torque specs., thats going to save me alot of time looking them up. How about the gaskets for the top end? The base gasket, head gasket, and reed valve gasket...should I use any type of silicone on those? Or clean the area and put them on?
Click to expand...

I do not use silicone or rtv myself. I would just clean the areas really good to make sure there is none of the old gaskets left so the new gaskets have a good base.

And yes the ring is the exhaust gasket. It slides right into the exhaust opening on the head.
 
Alright, should be able to get the cylinder bored tomorrow, taking the bottom end to someone to do for me, I don't have a flywheel puller or anything, so I figured that would be easiest. Anything else I need to watch for? Ring gap? I just want this thing up and runnin with no problems, trying to ask every question I can before I get it all back together.
 
The ring end gap should be between .20-.35 mm top and bottom. That is measured with the rings slid in the cylinder. So you should do it after the bore is done. Just make sure they are straight when you measure them. I know when I have my cylinders bore I give the machinest the piston and rings and he does all the piston and ring gaps for me so all I have to do is put it together.

Just let us know what other questions you have.
 
Got the cylinder bored today, everything looks like it should go together well. The bottom end should be done monday, so we should have a running blaster by monday night.
 
Got everything back, in the process of piecing it together here and there until I get some actual time to myself tonight to finish it all up, On the base gasket for the cylinder, the gasket has a kind of silicone line on one of the sides, does that go up or down?
 
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