1990 yamaha blaster project, dunes bike

[oregondunes1]

Hey there fellow riders, I came across a project about a month ago, and would like some help! This is my first time attempting to fully rebuild a bike, iv rode trails and dunes sence I was 7, I'm 25 now, so its time lol
Ok down to buisness,
1990 yamaha blaster
Was told it was a 240 when I bought!
Had no crank,rod or crank berrings, motor was in a milk crate
Fmf fatty gold series,
Came with 2 carbs
After getting quad home I look and see, everything is there from coil to every bolt, just no crank rod or crank berrings!
First thing I did was found a Cnc crank,rod,
Crank was $80 and came with good berrings and a 2002 side case where the crank sites in and has a serial or vin number, ill post pics! Crank was used but is in perfect condition!
I also tore down the bike completly, just frame ,and painted it black after Samsung it for a couple hours, also piston looks good so does cylinder! Gaskets are in the mail, complete engine gaskets kit off eBay,

My questions and main reason besides sharing, for joining are

1 do I need to balance the crank?

2 what advantages does a Cnc crank have over a stock crank?

3 how do i tell if the cylinder is bored?

4 iv never tuned a carb, internet says 1 an 1/4th turn but if bike acually is bored what would it be?

 

[oregondunes1]

Won't let me post pics threw my phone,

 

[blasterBruce]

Welcome to the Site , Lets see if I can help some ! ,

1st Off you need to take your Cylinder and Piston to a Know shop that does Cylinder Boring And Honing , Also ask them If they Chamfer your Cylinder after the hone .

2nd . This Crank your Speaking of Cnc , What is this the brand , - More info needed here .

Copied this from member here Awk08 ,

airscrew..........
try 1-1/2 turns out to start, then 1/2 turns, in and out, waiting 15-20 seconds to allow engine to catch up to the change,
1/2 turns at a time until you find the position it idles the highest, then very small turns if needed until it revs past 1/2 throttle cleanly





here's a few links

Yamaha Blaster Forum - The #1 Community For Yamaha Blaster Owners!

leakdown tests........
Yamaha Blaster Forum - The #1 Community For Yamaha Blaster Owners!

Yamaha Blaster Forum - The #1 Community For Yamaha Blaster Owners!

Yamaha Blaster Forum - The #1 Community For Yamaha Blaster Owners!

carb cleaning...........
Yamaha Blaster Forum - The #1 Community For Yamaha Blaster Owners!

plug chops........
Yamaha Blaster Forum - The #1 Community For Yamaha Blaster Owners!

jetting..........

Yamaha Blaster Forum - The #1 Community For Yamaha Blaster Owners!

Yamaha Blaster Forum - The #1 Community For Yamaha Blaster Owners!

 

[Awk08]

/\ good info bruce !

1. i've never heard of a cnc'd crank for a blaster
pics will be needed.
true balancing is not needed, but can be done = big $$$$,
my builder does a static type of balancing to all his rebuilt cranks

2. get the photoshop.com app for your phone. upload the pics to there, then post the .IMG code for forums into your post, the pic will appear when posted

3. like stated, a reputable shop will be able to measure your piston to cylinder clearence and tell you if it is within specs, just throwing it together could be disatrous.
you can also measure that yourself, here........

4. the above 1.5 turns advice is for the airscrew/pilot jet circut only, that controls from idle to around 1/4+ throttle, then the needle takes over, there are clip settings on the needle for adjusting lean/rich, but i've yet to build a bike that needed anything other than the middle clip setting, your results may vary,
you will also need to follow the "plug chop" link posted above to get the correct main jet, i see fmf pipe listed, i'd start around a 300 main jet, and plug chop down, you'll prolly end up in the 270/280 range ?
buy main jets...300/290/280/270, about 6 b8es plugs and do the plug chops !
other factors influence jetting also... elevation, temperature, humidity, air filter type, airbox lid on/off, oil injection used/or not, what oil to fuel ratio used (i suggest the standard 32:1) ect.
plug chops are the only sure way to factor all that in and get it jetted spot on.

 

[oregondunes1]

I'm going to transfer pics from my phone to computer and put em up,
As far as the crank, my uncle told me it was a Cnc machined crank when he looked at it to make sure it was a usable crank,rod.
The cylinder and piston can't just go back in? My uncles honing the cylinder for me, he has my top end rite now, thanx for responding guys, I'm gunna.look at those links cause talking about main jets has me interested to learn,

 

[blasterBruce]

The Rings are used correct ? , If so then you need new ones for the fresh hone , Otherwise the rings will not seat Properly against the Cylinder wall and you will not have a very good running motor !

Yes you want to learn everything you can about jetting , Its the main thing to keeping these motors lasting !

 

[oregondunes1]

Yea the rings are used, ill ad those to my list of needs, I need reeds also, , when I find out what the bore is I need rings to fit that bore correct, thanx again for responding

 

[oregondunes1]

here they are................

 

[oregondunes1]

not the best pics,,,

 

[oregondunes1]

the head got thermal paint,
oh yea i forgot to say that the oil injector was takin out so its mixed gas

 

[oregondunes1]

And I asked my uncle if he's gunna chamfer the cylinder after the hone

 

[sporty982000]

Weclome and awesome.

here are a really great bunch of people on here, who will help you all the way.


Have you downloaded the free manual from here ? and the site always likes, a kind small donation !


Yes you should put new rings in , new gasket kit, and you will want to put in new crank seals. Sounds great, you got a relative helping you out !

And Bruce and AWK and others, did a nice job getting you going on a list.

Sporty

 

[Awk08]

when I find out what the bore is I need rings to fit that bore correct, thanx again for responding

no, the rings need to match the piston, not the bore, it could be worn.
see if the numbers on top of the piston are readable and
measure the piston to cylinder clearence as the vid above shows and report those findings here

 

[oregondunes1]

So I found out my crank is a stock crank from a 2002 blaster
My fault for being golable! Also if I had paypal I'd make a donation, I asked about a money order but its paypal only,

But, I came across a Fmf power core 2 muffler for a 4 stroke, my question is will it be bad for my motor if u use it on the blaster?

 

[blasterBruce]

Do not use a 4 Stroke pipe on a 2 Stroke !

 

[oregondunes1]

2 stroke question....
When u kick ur 2 stroke over and gas leaks out the part where the pipe sits on the motor! What would cause that?

 

[sicivicdude]

It's probably a stuck float. Either from trash in the float needle, a sinking float, or from a damaged float needle.

The induction system on a blaster is all slanted "downwards" towards the engine. If the float sticks, fuel will flood into the intake and down into the bottom end filling it (at least partially). When you go to kick it over, liquid fuel will pour out.

Disassemble the carburetor and try this to stop it from leaking: http://www.blasterforum.com/do-yourself-20/easy-almost-free-way-stop-leaky-carbs-33335/

 

[oregondunes1]

Float was stuck, I took carb off, it dnt leak any more, I think its got low compression.
Should the kick starter be able to hold my leg wieght, I mean if I'm sitting on my bike about to kick it over, my foot on kicker, and it just slides down, does that make sence???

 

[blasterBruce]

Sounds like It Could be low on Compression , A Compression Tester Installed with the Throttle Wide open , 10 Good Kicks should prove to be max Compression Psi !

 

[oregondunes1]

Today my uncle dropped my blaster motor off and.said I have a suprise for u! He told me to put the motor in, so I put it back in its frame, need a.couple things, but has way better compression, he told me I need a nut that goes on the crank are, the stator side, cause its stripped,
I do have.another question, above my carborator there is a mechinism the has a wire plug, that I can't figure out were it plugs into?
I'll post pics when I'm near my computer