tzr running problems

[tzr trouble]

i recently had my cylinder barrel rebored with a new piston because i seized the old one, it then run for 3 days then stoped i stripped it down and cleaned out the carb and cleaned the plug it then run for 2 days it then stopped again show i checked the rings and they were ok cleaned the plug and it then run again, it run for 35 miles before stopping again when i removed the plug it had oil on it, when i looked in the manual it was oil fouling i cleaned it up and it started again does anyone know what causes this.:bike2 please help

[Lateshift]

Could be a number of things, although i am no authority whatsoever on strokers, let alone the TZR.

Firstly did you get the cylinder honed when you had this new piston fitted?

The oil sounds like its a case of the piston rings not sealing correctly which may have come about after the piston has been fitted and not run in correctly, it could as mentioned be that the cylinder needed honing.

But first, we need more information like whether or not there was an increase in smoke over the normal amount you tend to get with the strokers? whether it felt like it was lacking in power (which again would suggest whether there is a compression problem).

Strangely enough a good test to see what the compression is like is to whip the plug out and crank it over using your thumb to seal the hole, if you are strong enough to keep your thumb over it then chances are its losing compression either through the rings and into the crankcase.

As much info as possible and i am sure someone will be able to add a bit here and there ;)

Oh and an introduction might be nice when firing your first post in for advice, but welcome to the forums all the same ;) :)

[tzr trouble]

thanks for your reply it has about the same amount of smoke and the power seems to be better than it was its starts and runs but it sometimes runes for 30 miles and other times for a few hundred yards on monday i set up the oil pump and cleaned the plug it worked fine, when i went to use it on tuesday it run for a few hundred yards later that day i cleaned the plug and it run for 5 miles when i checked the plug it was still dry is it over fueling:bike2

[old diehard]

hi there, i see you got a rebore because you siezed the bike did you find the cause of the siezure? i mean have you found the problem rather than just treat the symtons? any way here,s a few things i used to do bay in the day when i were lad!!
if a 2stroke siezes
:check it had oil in the tank ,on rebuilding drain and flush 2stroke tank,check all pipes and clips,strip and clean,rebuild carb,check for induction leaks,blead two stroke pump ,check settings,check spark plug type etc.also check coil and stator.best of luck

[Perilous]

Is it just stopping or dying as if it's running out of fuel?

Plug oiling can be the autolube pump's set wrong.
It isn't just something daft like you've changed the plug for a colder one?
Never had aTZR 125 but I assume it has a power valve in which case have you set that up properly since you put the barrel back on. If not that can cause plug fouling if it's not opening.
At the more drastic end, if the gearbox oil is going down the seal between the gearbox and crankcase could be gone.


If it seized it was either lacking oil or getting too hot. (e.g no water or weak mixture cause by lack of fuel or too much air.)

Apart from my LC days years and years and years ago I've only raced a two stroke without the oil pump where we mix the oil in the tank but as far as I remember the oil pump keeps delivering oil when the throttle's shut to keep the bike from siezing on the overrun. (On a race bike you blip the throttle to keep a bit of oil about.)

If it seized across the port bridge then it's quite likely it was weak so you have a fuel starvation problem going on, although as a rule that wouldn't be so erratic on how long the bike runs.
Make sure the fuel pipe isn't kinked or the filter in the tank isn't blocked. Also take the needle valve seat out and make sure there isn't a lump of cr#p under it. A piece of rubber off the fuel pipe is a classic for erratically blocking the fuel flow.While you're at it check the float height in case it was set too low and part of your seizure problem.

With the erratic running time it's quite likely an electrical problem.
Before you do anything change the plug, even if there's a new one in it.
If it has an electrical problem every time the spark cuts out and the bike turns over it'll foul the plug. You may plain and simply have a loose lead and when you muck about with the plug you move it so the bike fires until it moves again.
Make sure it's not just something silly like a dodgy connection in the plug cap.
Check the low tension leads to the coil and any connectors in the ignition circuit and make sure any earths to the frame and the battery earth aren't loose. (e'g in the wires to the ignition pickups.)

Sorry can't be more specific than that. I know Aprilia 250s inside out but I've never even looked at a TZR 125.