Okay, so the other day my blaster seized, not sure what happened. I am rebuilding it, I work at a machine shop an we have everything we need to bore the cylinder our selves. I need someone to tell me the clearances, if I am right the piston is undersized, we are trying to clean it up and I need the boring clearances and specs.
Boring my cylinder. 2003 Yamaha Blaster.
- Thread starter JohnstonOctober
- Start date
I have done posted on here, an diagnosed it, either got to hot and the ring caught the port or there was not any oil, the bearings and everything were gone. I have already ripped it apart rebuilt the bottom end, removed the oil pump with a block plate all I have left is to bore it, I need the specifications, what's recommended I just got the manual out of the forums but I would still like to know the best recommended bore specifications and clearances.
Cast or forged piston ??? Different clearance for them. Manual should give clearance for cast.
Don't have Blaster manual with me, but Clymers Banshee lists taper limit of .002", out of round .0004. Because fatory pistons are select fit it gives no clearance.
IIRC cast is .002, forged is .003.
Don't have Blaster manual with me, but Clymers Banshee lists taper limit of .002", out of round .0004. Because fatory pistons are select fit it gives no clearance.
IIRC cast is .002, forged is .003.
Don't know what this is about, small print bottom of home page :
--------------------------------------------------------------------------------Please note that Namura Technologies is not directly affiliated with any online auction sites; any representation of Namura Technologies' products by an online auction site is under no control or influence of Namura Technologies. Warranties will not be honored on products purchased through online auction sites.
Hypereutectic Casting Process: Provides higher silicon content for reduced expansion rates and additional wear resistance; it also has an ability to withstand higher cylinder temperatures.
Considering you need the piston before you can bore it, maybe get hold of them and make sure it either comes with the clearance specs, or they give them to you.
--------------------------------------------------------------------------------Please note that Namura Technologies is not directly affiliated with any online auction sites; any representation of Namura Technologies' products by an online auction site is under no control or influence of Namura Technologies. Warranties will not be honored on products purchased through online auction sites.
Hypereutectic Casting Process: Provides higher silicon content for reduced expansion rates and additional wear resistance; it also has an ability to withstand higher cylinder temperatures.
Considering you need the piston before you can bore it, maybe get hold of them and make sure it either comes with the clearance specs, or they give them to you.
Had it bored today with what I got out of the manual, how smooth should the finish be. My yz was sent off to be plated, and it was slick as a babies a**. This one not so much. Mÿ dad who used to rebuild engines says its fine.
it should not be smooth like a nik'd cylinder, it should be honed and have the cross hatch marks from the honing stones after the boring is done.
it needs to be honed also, not just bored.
namura pistons are cast, so the specs in the manual should be correct, but a call to namura wouldn't hurt if the specs weren't in/on the box.
don't forget to chamfer all the ports
measuring your cylinder.......
it needs to be honed also, not just bored.
namura pistons are cast, so the specs in the manual should be correct, but a call to namura wouldn't hurt if the specs weren't in/on the box.
don't forget to chamfer all the ports
measuring your cylinder.......
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Okay thanks for the help. It's kinda rough just didn't know wanted to be sure, he helped me bore it and he said cast shouldn't be smooth. I have to get new honing stones for my honing tool then ill be done, looking at the manual we brought the cylinder bore to 66.504mm (2.6183 Inches) the piston I ordered is 66.492mm. I have to chamfer the ports tomorrow.
How critical is chamfering the port, I did the best I could with a air grinding tool then took fine grit sand paper to it. My finger dorsnt catch and it doesn't feel sharp, I honed it after that.
Okay I will check it when it's here. I am having trouble getting the split case back together. Everything was where it was supposed to be but when I get all the bolts in and snug if I tighten them the crank locks down and won't turn, my kx 250 and my yz 125 was just tap together easy, this one is a lot different.
Has the crank been pulled fully into the case or are you trying to fit it with the soft hammer method
Well I tapped it in little by little like I did on my yz and kx, the inner part is less than a 16th of an inch from each side of the case. It doesn't lock down when I tighting the bolts but it gets tension on it. It's not as easy to turn I don't wanna throw the rod.
a hammer is not on the tool list for crank installing.
you need a crank puller.........
Tusk Crank Puller Installer Tool Motorcycle ATV NEW on eBay!
you need a crank puller.........
Tusk Crank Puller Installer Tool Motorcycle ATV NEW on eBay!
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Just a rubber mallet work twice before did it the same exact way, it's all together crankshaft moves fine ordered my piston today should be here next week.
66.504 - 66.492 = 0.012mm = 0.0005" leaving you room for honing.
Cast does turn rough but it sounds like your dad knows his business, hopefully the honing will clean up the tool marks.
Yes, I read that thread, you didn't really know what caused the sieze and just jumped to the conclusion it had to be the oil pump.
You will never succeed in life if you just "guess" your way through, using emotion as a guide post. You need logic.
Think this through. Motor siezes, you guess oil pump, bypass it.
Rebuild motor. Seizes again. What have you learned?
"There is nothing new to be learned from the second kick of the mule."
OK, think this through: Motor siezes. You wonder "why"?
Ask advice, research troubleshooting and diagnostic techniques.
Smartest advice suggests:
1) Leak test before disassembly, any air leaks?
2) record jetting and check carb for flaws, getting fuel, jetting right?
3) Check fuel and oil tanks and oil pump operation.
4) Check timing and spark. Flywheel or stator loose?
5) Check plug condition, what does it tell you? Oil? Overheating? Jetting?
6) Pull cylinder head, What does the burn pattern and piston top tell you?
7) Pull cylinder, any oil in bottom end? What do walls and skirts tell you?
8) Check bottom end, loose? damage? Heat? oil? debris?
All of this will give you a very accurate picture of what happened.
Blocking the oil pump off and premixing will not solve a crack in the case letting air or gear oil in, advanced timing and detonation, retarded timing, overheating, wrong oil, bent rod, wrong jets, fuel restriction, air leaks, bad gas, too much compression, overheating, or whatever. If the same problem is there, it is going to blow up again. Logic, deduction, and test your deduction.
Prove your guess because guessing is expensive. How much is this rebuild costing?
So, don't give us this "pump failed" BS. That is honestly clueless.
Really, clueless.
So how do you assure it will not fail again?
Besides careful assembly and torque wrenching,
build a leak tester and check it,
check the jetting to suggested specs,
bleed and test pump if you are using it,
compression tests,
heat cycle and break in,
New plugs, do a plug chop and adjust jetting,
Hopefully I have saved you another $500...
Steve
