1999 Rebuild, will need your help!

A7xschecter6661

New Member
Mar 10, 2014
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Hey guys, my name is Peter and I am going to rebuild my childhood toy.





Completely stripped it already and only broke 1 bolt! One of the foot peg bolts into the frame. I should be able to get it out though so I am not concerned.


History of it: A family down the road from my parents house used this is a racing quad, just about everything unnecessary was stripped including headlight, brake light, oil mixing tank etc. They were selling it for $650 because they thought the engine was going (This was probably back in...I'd have to say 2003/2004). I road this thing countless hours from middle school on until I got my license and haven't really touched it since. The noise the engine was making was simply the exhaust pinging. We talked them down to $400 due to not having reverse, being modified for racing etc.

Why I'm rebuilding: This thing gave me countless hours of fun. Over time the brakes got worse, no biggie. It actually needs new cables not shoes but the shoes will get changed anyway. At one point the thing started bogging down in the higher gears. I asked around on here back then but didn't go anywhere with it. It will work fine in 1st/2nd gear usually. Once you hit the higher gears it might go all the way to the end of the gear fine, but usually it would start bogging down like it was getting fuel poured into it like crazy.

I was also thinking the bogging could be from a bad ignition coil or one of the control units in the front? You tell me experts. Any way to test these?


I will be doing all the repairing myself, I know enough to do everything I just wanted to post on here and get some insight on rebuilding (at least) the top end maybe the whole motor if it doesn't cost too much. I have never done small engine work, and not much internal on a car so it will be fun. I already have a new (used) wiring harness because the original people cut wires for a few things. I got the new harness, cleaned it up and before I disassembled mine, I marked all the wires and plugs on the new one and what they went to.

My only concern is they said this was bored 20 over, so I am not sure if I need a special rebuild kit or carb kit. That I leave to you experts.

Things I know it needs:
Top end rebuild kit
Carb rebuild kit
Front Brake cables (might as well do shoes too)
New Chain


While I am taking it this far I am painting the entire frame, springs and plastics. Also sandblasting the wheels, front exhaust pipe too.

Look forward to having some fun here!
 
Anybody know of a good engine tear down video? Should I leave the engine alone and just do top end or should I change everything after it's been raced and then I drove it around forever.

Seems better just to rebuild everything fresh and new.

I am just awaiting some input for what I need to order for engine rebuild kit/ Top end rebuild kit and a carb rebuild kit. Don't want to order the wrong stuff!
 
Do you need to hone the cylinder?
With a 20 over bore, you need a 66.5 piston, unless larger needed for bore/hone
You need to measure the bore yourself to know what size!!


Bogging could have been a number of things

Mainly could have been TORs or fuel problem

To remove your TORs system (really should be done)
Order these:
http://www.ebay.com/itm/Motion-Pro-...Parts_Accessories&hash=item4d191f34e6&vxp=mtr
http://www.ebay.com/itm/IDLE-ADJUST...Parts_Accessories&hash=item58a0bb8e4f&vxp=mtr

Do this:
88-02 http://www.blasterforum.com/threads/how-to-remove-your-tors.655/
03-06 http://www.blasterforum.com/threads/03-06-tors-removal-diy.41973/

Install:
http://www.blasterforum.com/threads/aftermarket-carburetor-cap-and-idle-screw-install.22174/

Dont go cheap on a chain. nothing super expensive needed, but dont buy shiny ones from ebay

Rather than paint the stock pipe, why not have some fun and get a new one? A better one?
 
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I could but I am not looking to dump a ton into it, I just want to back to ride able. I am talking about the front pipe. The second piece is an FMF something or another but the front is just a little rusty. A little light sandblasting followed by some header paint will strike my fancy.

As for the cylinder I need to find a good video on the tear down of the engine and I will get working on that.
 
i highly suggest taking/sending that cylinder to a professional to have measured, bored/honed if needed and correct piston fitted.

as for the bottom end, the connecting rod should have zero up/down play, and like .028 side to side clearence.
those and other specs are in the manual, which i also suggest having if you don't already ?.........
http://www.blasterforum.com/threads/downloadable-yamaha-blaster-manual.17325/

here's some vids to help with the engine....

disassembly:
http://www.blasterforum.com/threads/blaster-engine-disassembly-vid.42997/

assembly:
http://www.blasterforum.com/threads/kor-engine-assembly-vids-no-crank-puller-needed.51169/
 
I started ripping the top cover off already. Carburetor was pretty clean, just old fuel. No ethanol gumming or anything like that. This thing always starts right up first or second kick.


Here are some pictures.



 
You can put a little money to get this thing to ride again and have it breakdown in a month or more who knows or you can do it right, like the boys around here like to do, and it will last awhile. I'm pretty mechanically inclined when it comes to cars but for my blaster I'm gonna send the whole top n bottom to ken and get it done right the first time (when I get the money). Some things are best left to the pros. And if your getting a new chain you need to get new sprockets too. If you get rid of that front pipe aka expansion chamber and pick up a decent one on ebay you'll get some more power, but you'll need to jet your carb accordingly
BTW welcome and good luck!!
 
How far off is the piston sleeve supposed to be from the size of the piston?

I don't see any actual wear on the piston or sleeve, just carbon build up on the piston.

I measured the piston to be 66.5mm
The lower portion of the piston sleeve was 66.90
The upper portion of the piston sleeve was 66.93
 
Nope just one.

So what exactly do I need to do if my piston says D00C9...573M06700

It measures 66.50mm with digital calipers, the lower part of the piston sleeve measures 66.90 inches and the upper portion of it measures 66.93.

Does this piston look like it's my problem of the blaster bogging down randomly in the upper gears?

Trying to get by without spending a crazy amount :p
 
I think I am going to go with a brand new cylinder head all ready to go. It's basically the same cost by the time you pay shipping, pay for the bore service, pay for the parts and then pay for return shipping.

$245 for the complete kit ready to go. One of my exhaust studs stripped out a long time ago and I just put a new one in, but it's probably best to just get a brand new one.

Then it's just the few other things I need and painting it