Top End Rebuild, Need Help!

[Brenden]

Rebuilding my 2002 yamaha blaster and just have a few questions in the video. If you could help at all it would be great! Don't need expensive parts, just need to get it running so I can sell it.

Here is the cylinder head...looks pretty bad, what should I do??

Here is the nick in the cylinder...should I have this bored out? It is already bored 0.04 over

 

[Blaaster]

Head can be cleaned up.

Hope this helps!

 

[Awk08]

just lightly sand the gouges and carbon off the head, only in the combustion area, not the gasket mating surface.

yes, the cylinder needs bored/honed, preferably by a reputable shop who will bore it past the gouges, tell you what size piston to get, then finish hone it to match that exact piston

 

[Brenden]

Here is an update...getting it bored out to where the cylinder will be smooth, getting a top end rebuild kit from a yamaha shop and the machinist will match the bore to the piston
What should I use to clean the head? just light sand paper and some sort of like brake cleaning chemical maybe?

 

[Awk08]

Here is an update...getting it bored out to where the cylinder will be smooth, getting a top end rebuild kit from a yamaha shop and the machinist will match the bore to the piston
What should I use to clean the head? just light sand paper and some sort of like brake cleaning chemical maybe?

yes to the sandpaper, maybe wd-40 as a lubricant while sanding.
careful not to sand the gasket surface.

or ask the shop if they modify heads ?
best bang for your buck...........

 

[OConnor Racing]

The combustion chamber of that head is grey and showing tell tale signs of detonation. You've got some other problems in there Boss.

 

[Brenden]

What other problems could there be???

 

[blasterkid1998]

What other problems could there be???

wrong jetting and/or air leak

 

[Brenden]

wrong jetting and/or air leak

How do I adjust that?? is there a good video on it?

 

[98blaster]

What caused the gouge in the cylinder? How is the crank, does it have any play in the rod, some side to side is normal, but no up an down allowed, also look at the lower rod bearing you can see the rollers through the slit in the rod make sure they look straight an none missing or broken.

 

[harley1-5]

x2 on head

 

[tbrooks]

Whatever caused that gouge, it may have left debris in the cases which will destroy the lower bearings, so it should at a minimum be flushed out. To really do it right the cases should be split, cleaned, and bearings replaced. You could do that yourself cheap, if you can that is. If it was me trying to sell it I'd part it out. No paying for fixing, and you could prob still get about what its worth. And your not selling someone else a problem waiting to happen.

 

[Brenden]

Here is a closer picture of the cylinder head

 

[speedyslyder]

what do you think caused this damage?
no air filter?
circlip on piston came off?
not premixed right?
airleak?
was rebuilt with wrong sized piston,or worn out cylinder,not bored fitted with new piston?
detenation?

did you buy it like this or was it running?
either way there has got to be some crap in lower end,connecting rod should have no up n down play,a lil side to side is ok

head i not pretty but could be run like that if cant replace or get modded

 

[Brenden]

So I test drove the quad when I picked it up and it ran completely fine there...got it home took about 15 kicks to start and drove it for probably 2 minutes and it died....

 

[speedyslyder]

you got a lemon unless you altered or touched summin..
i hope at least the price was low to compensate for the engine
i guess it is up to you if you want to fix or part out.
bore and top end is not too much money,but if summin is in lower end,or whatever reason this happen could be a lot more money

 

[Brenden]

I paid $800 and everything else on it is solid...just bad engine...most 2002 blasters go for around $1200 where I live

 

[speedyslyder]

it is interesting why this happen
did you see anything broken off? a ring or reed cage bolt got sucked through.
is oil injection still on it or is it being premixed?
i would look for broken missing parts,what size main jet is in the carb ect.
hard for you to tell i know cuz you just bought it and it happen right away.
close up pic of piston,lets see it lol

 

[dirtysquared]

I paid $800 and everything else on it is solid...just bad engine...most 2002 blasters go for around $1200 where I live

Are the reeds still intact? That 15 kicks to start screams low compression, or a reed problem.

If the rest of the blaster is solid, read up on here, the info on the forum will help you get it back together right.

Here is some helpful reading watching
Service Manual
http://www.blasterforum.com/threads/downloadable-yamaha-blaster-manual.17325/

KOR Engine Assembly Videos
http://www.blasterforum.com/threads/kor-engine-assembly-vids-no-crank-puller-needed.51169/

Welcome to the forum too, Is that your baby in the pic?

 

[Brenden]

Are the reeds still intact? That 15 kicks to start screams low compression, or a reed problem.

If the rest of the blaster is solid, read up on here, the info on the forum will help you get it back together right.

Here is some helpful reading watching
Service Manual
http://www.blasterforum.com/threads/downloadable-yamaha-blaster-manual.17325/

KOR Engine Assembly Videos
http://www.blasterforum.com/threads/kor-engine-assembly-vids-no-crank-puller-needed.51169/

Welcome to the forum too, Is that your baby in the pic?

haha no thats my niece...I have already started on the top end rebuild. The compression was terrible it was at like 30 when it should be around 140