So… Turns out the it250 has a spring loaded pin inside the oil drain plug. This spring loaded pin puts pressure against the trans gear cam selector. Mine was missing since I bought the bike.

This is why it would pop out of gear and shift shitty. So technically I could’ve bought the $2 spring and not taken the trans apart at all ha. Anyway, shifts / runs great now.

What I’ve done since owning it

• New piston
• New (used) crank / connecting rod that I had balanced
• yz250 head
• yz250 swingarm
• DG pipe / silencer
• Racetech front suspension with vintage Terry-kit dampers
• NAMC rebuilt yz250 rear suspension
• New Mikuni VM36 carb
• Clutch

On the dirt bike, I feel like it matters more to attempt to tune the suspension. Ya know… Jumping shit. Wheelies past friends.

On my 1979 IT250 here’s what I did

• Racetech front springs: .43kg stiffness. I weigh 175 on a good day. I said it before but Racetech is great since you can choose different spring rates.
• Terry Kit vintage dampening rods. eBay find. Apparently these give you 1″ more of fork travel and make for a more plush ride at high speed on bumps? Can’t find much info.
• I set preload to just under an inch
• used 300mm of 20 weight fork oil
• new all balls fork seals

So will these improvements make the IT feel better? Who the fuck knows. I want to see how it feels without doing modern front $200 Racetech emulator cartridges.

Front combined with my beefed up rebuilt YZ250 rear monoshock should be good.

Preload

So how exactly do you measure preload? It’s pretty simple. When you screw the top cap on, it’s how much you are compressing the fork spring. My manual calls for about half inch but I went with just under an inch. Preload below.

Below pic is from Racetech website… The Terry kit dampening rods had less holes, but the holes were bigger I think? I find the dampening rods the most confusing part.

For clarity, other than popping out of gear which is the reason for the tear down, my it250 runs super crisp. Gobs of power. Compression is spot on.

After taking the cylinder off, the piston looks perfect. Zero scoring on piston or cylinder. Rings also look perfect. So I didn’t plan on doing the piston which is a happy surprise.

However, here’s where things get weird. WTF… the connecting rod is bent. Slight bend to the left. How the F did this happen and why does the bike run great?

The only conclusion I came to is that before I bought the bike I assumed the previous owner seized the motor in a gnarly way, hence the slight rod bend, which is still impressive to bend a rod. So I assumed I’d now be at the 2nd or 3rd oversized piston.

Extra weird: nope. I’m at the stock size piston and cylinder. How the F did the rod bend?

Is it possible the dude replaced the entire cylinder and piston with a STD size? That seems unnecessary.

Is it possible when I submerged the IT in water in the pines, it got water locked for a second and that created the slight bend? I doubt it since I turned the bike off right away and pulled plug to drain water before starting it. Nothing makes sense.

So that’ll be another $150 to replace the crank and rod. Shit.

Thoughts anyone?

My IT250 suspension is clapped out like mikes moms squeeze box. It’s beat the F up.

Since it’s the start of winter I’m taking some time to redo a couple things. My bike always pops out of gear so gonna sort the trans, but more importantly… do the suspension.

So, this is my way of saying, we have about 4-5 months till prime dirt bike riding weather. Your bike is junk. Put some time into it.

• Maybe do your forks. Mine were leaking bad
• Maybe get new, stiffer fork springs. Mine are too soft
• Maybe put on new tires
• Maybe check your jetting. Mine was rich
• Maybe do an oil change / air filter / clutch
• Maybe do the crank seals. I can name several people that have air leaks

Pretty soon everyone will be old and have kids. We’re not there yet. We slacked hard on dirt bikes this past year. 2018 I want to ride more. Reading / Pines / Bridgeport / Millville vet track. I want to do some sort of race. Maybe actually do mid Ohio race this year. Fuck, let’s have a few more fun years.

Anyway…
Turns out there are more little differences between a YZ and IT. My forks are 36 where YZ is 38.

What I’m doing to my suspension:

• Racetech front springs only is about $140. I’m going this route. With .43kg spring stiffness. You can choose based on how fat you are. Was going to, but not doing cartridge emulators which are an extra $200
• Racetech rear was too expensive. Was gonna be around $500-700. I found a guy on eBay that sells an all-rebuilt yz250 shock beefed up for racing. Got it for $380. It has thicker oil, better bump stop which I was missing, and pressurized to 185psi. Dude says he uses this one on his vintage yz465 he races.

Read this: Test of a couple 70s Yamaha YZ’s with Racetech suspension:
http://www.pulpmx.com/stories/vintage-corner-race-tech-suspension-test

Watch this: Having fun on old YZs:

More pics of rear suspension:

Some pics from Brian R, vids from Jake, and Instagram random.

@chinonthetank hill climb #readingdirtbikegetaway

A video posted by Nate King (@natemking) on May 30, 2015 at 5:06pm PDT

Getting cocky on the IT and starting basically on the hill. Fail.

A video posted by chinonthetank (@chinonthetank) on Jun 6, 2015 at 5:13am PDT

@chinonthetank

A video posted by Brian Robert Radke (@brianrobertradke) on May 30, 2015 at 5:18pm PDT

The IT is coming along.

• Got the Vermont registration so I can actually ride the thing legally now
• Sorted out all the little missing bolts and retarded shit from the previous owner. Needs a different silencer. Looking for a good, used DG piece.
• Got it cleaned up. The blue and yellow is pretty wild looking. Minus some missing OEM yamaha decals which I haven’t bought yet… this is actually how it’s supposed to look from the factory. Pretty ugly, but I’m really into it.
• Had Adam loosen some stuck bottom-end bolts for me with his air compressor. Doing crank seals tomorrow.
• I get some “false neutrals” between 2nd-4th gear sometimes. Not sure whats up with that yet. Anyone ever experience this? Does thicker crankcase oil help?
• It runs semi okay, but the carb needs some adjustments. I have some Boyesen reeds to put in too. Then it should rip pretty good.

Someone in middle-north NJ put a Yamaha IT250 on craigslist. Within 2 hours I called him and decided to go check it out.

The guy wanted $650. I bought it for $540. No title. Stuff like this goes quick, so you gotta be prepared to pull the trigger asap. Huge thanks to neighbor Brian for helping me get it!

It needs some TLC, but it seems to run legit. It’ll shape up well. It’s gnarly fast.

In case you don’t know what the IT is… it’s basically a full on race YZ version with lights and street legal. So it’s the holy-grail of street legal and off-road 2 stroke Yamahas. IMO.

I’m not 100% positive on all this… but differences between the normal Yamaha DT/CT versions and the IT versions are that the IT had:

• YZ motor
• YZ suspension
• better expansion chamber
• bigger carb
• different head and piston
• similar gearing to YZ – 6spd
• light aluminum wheels
• no oil injection
• plastic everything
• light magnesium hubs
• footpegs, shifters and rear-brake levers that fold in

I’m hoping to not put much of any money in this thing. Fingers crossed.

The motor sounds good. It runs pretty good as is. Tires are good.
I’m hoping to clean it up. Do the wiring. Give it a full tune up. Do the VT registration trick, and just rip on it. It has a sweet custom Kawasaki spark arrester ha. Def keeping that.

Honestly, I’d prefer the IT175 but they’re super rare. I don’t need the fastest bike. I haven’t seen many IT’s pop up on the east coast at all. I always see them on eBay in Cali. I’m an avid ebay/CL stalker. Yann has the IT400, he got it out at mid-ohio.

I rode it around the neighborhood last night and on del ave for a bit. The front wheel pops up in every gear.

For comparison. The 79 IT250 had around 35hp. Where the 79 DT250 had around 18.

All were 69-71 era, piston port motors, before Yamaha really knew what dirt bikes would become. And all were relatively about the same dimensions, just different weight.

Lately I’ve been regretting buying my 71 CT1 since it’s lacking the newer technology compared to the late 70’s. I really wish I had bought a 78-82 dt175 instead; way better suspension and faster.

Regardless… I’ve been looking at ways to make mine better from a performance and suspension standpoint and after finding all these cool images, it gives me some solid inspiration. Some of these bikes below are badass! This is what I’m thinking:
– already have pod filter and jetted carb
– GYT expansion chamber exhaust
– aluminum rims. small front hub. no front brake
– plastic front and rear fender
– smaller front gear. bigger rear gear
– front end from a YZ or MX
– maybe take all my lights off and put a number plate on it

Yamaha had a power kit from the factory called “GYT”. (Genuine Yamaha Tuning)

You could walk into a Yamaha dealer in 1970 and get a new piston kit / carb / gear / exhaust (all yamaha parts) to make it go faster. I’m trying to find some of this stuff on eBay but its super rare.

FYI – the hot exhausts were:
– GYT
– hooker
– DG performance
– torque engineering
– bassani
– moto tech