My first dirt bike ....... tips required

[motardpilot]

Hello to all my new Kawasaki brothers in here. I have been riding road bikes for over 12 years now and have never owned a dirty squirty bike. Anyway....................... I bought a KX250 97 model from a mate of mine for the grand sum of $50. Its in fair cond with the only things wrong bieng a cracked right hand crank case, a small crack in the expansion chamber and a broken front brake lever.
My intentions are to pick it up this thursday night and take it to a mates place. From there we are going to re build it and re paint it. My questions are; how do I rebuild it ...........LOL............. I mean is there anything tricky I should be looking out for? How do I run it in? When working ratios does anyone know what I should be mixing?
I'll be posting pics as the re build starts and for the duration of it .....

CANT WAIT

[motardpilot]

The Fiddy dollar beast in all its glory LOL

[greenblur80]

that's a nice looking bike for $50 i'm jealous my 97' cost me more,where's the crack in the case is it leaking oil.are you just rebuilding the top end of the motor or u going over the whole bike.there's really no trick to rebuilding the top end just need to know how to do it & you need a few special tools.you have to make sure the power valve move's freely & is clean they get gummed up pretty bad.i recommend disassembling it but there's a main power valve flap & 2 other valves that have to be timed with each other it's not that difficult.as far as run in just don't lug the motor,don't over rev it,don't hold a constant rpm.let the bike warm up for 1 min then ride mostly keeping it at decent rpm were it's not lugging but rev it a little now & then for 2-3mins then u still just ride at moderate rpms you can have a little fun but only rev it to were the power band starts to come in don't hold it there more than a few seconds still change rpms every so often.do this trough 1 tank of gas with a 32-1 ratio.then have all the fun u what.as far as oil/fuel ratio that depends on a couple of things like if your running lean or rich/comp ratio/power vs dependability/ceramic or moly coated piston/what fuel u use/what 2 stroke oil u use/what kind of trails u ride like open trails with a long high rpm runs or tight trails.you'll be fine with 28-1 to 40-1 if you don't plan on lugging or reving high for a long time but 35-1 of premium fuel & good oil should be about perfect for dependability of both the engine & the spark plug,good power and throttle response.i run up to 50-1 ratio but i run bell ray synthetic 2 stoke & c12 race fuel which is leaded so i get extra lube from the lead & my piston is ceramic & moly coated so the piston/rings/main & wrist pin bearings run cooler.the moly coating reduces friction a little & does a great job of preventing the piston from seizing in case of lack of lube.i'll run my bike at 35-1 to 40-1 if i run out of c12 & have to use 93 octane pump gas.so u might have to change ratio depending on a few things.

[Saleenguy]

Get the complete gasket kit, piston, rings from Wiseco...also it will need new reeds, so change them.

Have you already ordered the new case?

Once rebuilt I recomend a goood oil ( i like amsoil dominator ) and mix it at 40:1 gas to oil ratio.

Always warm the motor up well before you let it rip, or the motor will go boom prematurely.

I be the suspension needs work to, and the bearings.

So why not pull the swingarm and steerring head, and rebearing them.
Drain and refill the forks with fresh oil, but put new fork seals in them first.
And send the rear shock out for a fresh seal, oil, and recharge to.

Run ATF type F in the gerarbox.

Flush the cooling system, and refill with fresh coolant?distilled water mix 50/50.

Oh and put the o-ring for the head in the freezer a few hours before you go to rebuild the motor.
Its easier to install if cold as it shrinks a bit.

[greenblur80]

yea get a complete top end gasket set.cosmetic gaskets is good & they have 2 different kits one has a thinner base gasket that raise's the comp ratio up about 1 point but give's you a little less over rev & a little more bottom-mid-range power cause it changes port timing u can gain some over just by raising exhaust port height .003-.008.the head gasket is the same in both kits it about the same quailty as oem it's just a multi-layered metal gasket

wiseco piston's are nice there light & strong they make a few overbore size's
for are bikes & if u have a good stock cylinder they have a stock size piston with 1 ring for better acceleration and high rpms.make sure u replace the wrist pin bearing it should came with the piston/ring kit

i like to use mobil 1 synthetic oil made for bike's in the trans.it's good but not cheap but neither is rebuilding a trans.

definitely check/clean & grease all the bearings on the bike wheel bearings & steering stem bearings are really important but so are swingarm/shock upper & lower & linkage bearings

on your bike if u use a torque wrench like u should to tighten the cylinder down you need a special wrench that has a square drive for the torque wrench in the center & a 12mm & 14mm box end on either side.cause u can't get a socket on the one nut that holds the cylinder down but 3 other three u can.i think it's motion pro that sells one.

check your reeds for damage but for real peace of mind change them.boyesen make's reeds for the stock reed cage but i never tried them i replaced the stock reed cage with v-force reeds they were nice stock tons of bottom end,okay midrange but top end power would fall off quick i ported them that helped but top end power still fell off to quick.there good for tight trails and tight mx tracks.i then tried boyesen rad valve but i ported it right away so don't know how they felt stock probably had a good bottom end-great midrange.but i like the boyesen better than the v-force.

[greenblur80]

i noticed your bike don't have plastics to protect the front forks/seals from dirt and rocks u should get some

[FULLAUTO]

What a deal. We have the same year bike. I had to rebuild all the swingarm and suspension linkages. If you need to do the same, get the kits. Much less money than buying each OEM piece.

Keep us posted.

[FULLAUTO]

Where are you from? There is nothing in your profile.

Don't forget to repack the muffler.

[motardpilot]

Hi again guys. First up thank you all for such fantastic input. It has certainly been the best fourum for answers such as this. There seems to be some very knowledgable people in here so Im looking forward to updating and posting pics of my latest project.
ATM I am waiting for my mate to move into his new place in order to utalise his gararge. We are going to be pulling the whole thing down and rebuild/paint the whole bike.

FULLAUTO I am from New South Whales in Australia.

GREENBLUR80 yeah thats on the list mate dont worry about that.

[motardpilot]

Well shes been a while but I have finnaly been able to get time to start the stripping of the bike..... Some updated pics.....

[motardpilot]

I just cant get the swing arm of !?!??!?!?!?!? Any tips on how to pull the bolt out so as the swingers can come out????

Also How do the reed valves work?? I know mine are stuffed. And thats all I know about reed valves ......

[motardpilot]

Reed valves

[Saleenguy]

Originally Posted by motardpilot

I just cant get the swing arm of !?!??!?!?!?!? Any tips on how to pull the bolt out so as the swingers can come out????

Also How do the reed valves work?? I know mine are stuffed. And thats all I know about reed valves ......

I assume you got the nut off, just the long bolt is not coming out.

Get a drift, just smaller than the bolt size, and using a hammer pound it out.....its not uncommon for them to be rusted in there.
After you replace the swingarm bearing, and before reassembly, lightly sand off any corrosion fromm the bolt, and then coat it well in a water prrof grease ( often whitish in colour).
If you need phone tutorial, PM me.

[Saleenguy]

Originally Posted by motardpilot

Reed valves

Reeds are flexible, and as the piston goes down they get sucked open allowing the fuel/air into the cylinder....then they close, and are stopped from flexing the other way by the cage they are mounted in.

I like V-force III reeds myself...but lots of brands are good.

[FULLAUTO]

Originally Posted by motardpilot

I just cant get the swing arm of !?!??!?!?!?!? Any tips on how to pull the bolt out so as the swingers can come out????

I fought with mine. The bolt would not come out after pounding on it, using plenty of penetrating oil, I broke a big c-clamp, tried an air hammer, tried cutting with a reciprocating saw, bought another c-clamp and cranked it down and left it for days while hitting it with a hammer to break it free, used some heat, all to no avail.

I had to get a heavy duty air hammer to work it loose and then cut the head off with a plasma cutter.

Edit: The swingarm was removed without a fight - the bolt that goes through the frame for the linkage was the problem child.

[terranno]

Just had my linkage done,boy o boy did I have to thrash that bolt.5lb lump hammer,24" SDS plus tapered concrete bit,fully extended arm swing,belted bike from one side of my garage to the other,and back .yes I won and the bolt survived all that.All back together now(allballs kit fitted).

[motardpilot]

Originally Posted by Saleenguy

Reeds are flexible, and as the piston goes down they get sucked open allowing the fuel/air into the cylinder....then they close, and are stopped from flexing the other way by the cage they are mounted in.

I like V-force III reeds myself...but lots of brands are good.

Thanks mate I can see how'd they work now.

[motardpilot]

Originally Posted by Saleenguy

I assume you got the nut off, just the long bolt is not coming out.

Get a drift, just smaller than the bolt size, and using a hammer pound it out.....its not uncommon for them to be rusted in there.
After you replace the swingarm bearing, and before reassembly, lightly sand off any corrosion fromm the bolt, and then coat it well in a water prrof grease ( often whitish in colour).
If you need phone tutorial, PM me.

Yeah shes looking like a big hamemr type of job

[TIZZLE13]

Just wondering if you replaced your cases yet
I have 2 sets of 97 kx250 bottom ends, 2 cranks etc.
Let me know its all for sale

[RichLockyer]

Regarding running it, if you don't have experience on 2-strokes, take it easy.
That 250 has got the power of a 450cc thumper, but it's all in a very tight powerband and it comes on QUICK... You'll hit the gas, the engine will start to come up, and suddenly WAAAAAAHHHHHHHHHHH and if you're lucky you're only flying a wheelie

When hill climbing or in sandy washes, keep the revs up... slip the clutch if needed, to keep the engine in it's powerband. As quick as it comes on, it'll fall on it's face just as quickly if the revs drop too far... not something you want to happen climbing a hill or running 60mph in sand.

$50? Ya... I'm jealous too. That was a $5k bike.