A forum for owners of Yamaha TTR250 trail and enduro bikes!

Welcome to the Forum, Matchy.

The bike looks to be all there - including a kicker.

You will find loads of info. stuff on here to keep it running right - together with improvements,

I hope you have got over the Christmas celebrations and that you cope all right with the New Year this coming week-end.

Then you can get cracking with your TTR. 

Martyn

Hey Pricey,

I do intend on dual-sporting it, that's part of the reason why I choose the TTR so I could find one that had a compliance plate. I just need to do some exploring to find some good off-road rides.

I have all the parts for full road registration.

Just a little update of what I've done since I had the bike..

The bike was running okay when I got it, Started up fine, except when I pulled the choke it would cut out.. I took it for a couple short (15 minutes) rides at fairly low speeds, maybe up to about 40km/ph (speedo isn't hooked up) and there were no issues that I could notice.

Then I proceeded to strip it down to the bare frame as mentioned, used rust converter then wire-wheeled whatever as left. Gave it a really quick double-coat with Wattyl KillRust.

I've cleaned the carburetor as per the stickys on here - except I couldn't remove the main jet as I can't get it undone (I did do my best with a fine needle, reaching through the other side of the carburetor.) and re-assembled all the running gear and it wouldn't start, bugger! I'm not getting proper ignition.

So here's what happening/I have done..

Fuel

• The carb bowl does have fuel, albeit the seal is leaking, 
• the main jet is squirting fuel when I apply throttle,
• the fuel tank valve is flowing freely,
• I've put in fresh fuel,
• I have tried "start ya' bastard" direct into the combustion chamber. 

Air

• Cleaned the air-box and ensured all breathers are clear.

Spark/Ignition

• I am getting a consistent normal spark,
• New/clean spark plugs,
• Cleaned the contacts on the voltage regulator & ignition coil.

Engine 

• The piston, crankshaft, and camshafts are moving freely. 
• The valves are also moving, however the intake valves appear to visually move slower than the exhaust valves.
• Compression is very low, a dry test resulted in 75 psi, and a wet test came in at 98psi.
• When turning over, I can hear an audible 'bloop' come through the exhaust, there is some air coming out of the unplugged breather on the cam/valve cover. 
• I tried a very crude leak-down test with what I have at home (a bicycle pump + some random fittings) and there wasn't any hissing coming through the valves. There was a very small amount of air coming through the crank positing testing hole.

I pulled everything off for further investigation - I forgot to check valve clearances :( The piston and barrel looks unscathed, there was a little bit of light-scouring on the piston.

Most of the engine gaskets/seals appear fine, the one I'm not sure about is the piston rings. The top compression (topmost) ring  appears fine, however the wiper and oiler ring aren't expanding at all. They're pretty much flush with the piston. (Photo attached.)

My conclusion is that I probably need to change the piston rings to regain compression.

So I've ordered pretty much all the carb, engine, valve gaskets/seals etc as well as piston rings and they should arrive pretty quickly as I ordered locally. I bought a lapper and compound.

Oh one other thing I noticed was that one of the small head bolts and its threaded hole on the barrel had a build up of sludge, as you can see at the bottom left corner of the photo of my barrel.