DT125R ARCHIVE

2strokemx · Guru

RE: Any suggestions engine problem ty250

Jesse_DT · DTR Senior Member

Isn't a TY250 2 stroke?

2strokemx · Guru

Yep

Calum122 · Guru

Lol. Then there are no valves mate.

Two strokes use port openings in the side of the barrel as 'valves'. Valve timing is simply the piston moving up and down. To adjust 'valve timing' on a two stroke is to vary the size and position of the intake and exhaust ports. Sounds like your chappy doesn't know what he's doing on these engines. I'd stay clear of that.

The only valve that modern two stroke engines use are either powervalves or the less modern rotary valves. And of course reed valves....

Calum122 · Guru

Fuel delivery on a two is controlled via a carburettor. If it was working fine before on those jet settings then it will work fine now.

Fuel delivery can be affected by a dirty carb. A clean up and clear of the carb may bt the problem.

If you don't know what you're doing I'd suggest taking to a mechanic. But not this guy cause I think he's a little confused.

2strokemx · Guru

Yes well you know that i know jack, he was on about putting strips in between and adjusting it so's its just gripping the strip... I dont have a clue and have now got a migrane by typing that, hate engines

Well as previously stated anything to do with fuel and air flow has all been cleaned

Another fella said take the spark plug out, stick your finger in the top and gently push the kick start... Should push your finger out the hole, this is to check the compression?

Calum122 · Guru

I wouldn't really know. Never needed to do a compression test. Two strokes are so simply. You ride them till they die. You rebuild it and ride it again. On a four stroke you have valve guides and springs and timing belts and all that other good stuff where the cost of rebuilds are so expensive you don't really want to be doing very often. That's the beauty of the two stroke. When they go bang, couple hundred quid and they're as good as new.

As said if you feel that way about engines and don't have an interest in learning then either sell the bike spares or repairs or pay the price for a mechanic to have a look. At the end of the day two strokes are high maintenance machines and thus an appreciation of how they work is a must. I'm not saying you need to know how they work, just appreciate that they are high performance motors and as such life expectancy is cut a little short

Jesse_DT · DTR Senior Member

The finger in the spark plug hole is a way to check for compression, not the way to go about it however.
Get a hold of a compression tester and test it.
Find out how much compression the engine should have and unless you meet that or thereabouts maybe think about replacing the rings.

2strokemx · Guru

Ok cheers again, i will get one of those then and test it, yeh cal i know what you mean it would be good for me to learn and that, i think i've just got to take it apart and have a look physically, all this talk of valves and barrels and that just gives me a headache, at the end of the day i will just dump it wouldn't even put it on the web, but if i manage to rebuild it and it runs sweet then i will start doing it up abit like powder coating the frame etc, but atm its worthless

2strokemx · Guru

m.ebay.co.uk/itm/261512919331

Worth it??

or could i do a full rebuild for less, just haven't got the time atm though and i wanted to do some enduros on this thing

-- Edited by 2strokemx on Saturday 5th of July 2014 10:40:59 PM

Calum122 · Guru

No valves on two strokes. Not like cars anyway. Very simple machines.

I reckon from what that video sounds like. There is no operation on the powervalve IF that bike has one then I'd say that's the problem.

Test this for me mate.

Go to your dt. Start the engine. Kill the ignition. Turn the bike off.

Disconnect the powervalve and ride the bike. If the bike rides how your TY does then I bet that is the problem.
From the video it sounds okay. But doesn't rev. If the exhaust port is lowered it will have that effect. I don't know if this bike has a powervalve and off road powervalves tend to be driven from the gearbox.

You'd be able to build yourself an engine for cheaper. Might be able to pay someone to do it. But ultimately there is no sayign whether that engine works as well. If you can fix yours

-- Edited by Calum122 on Sunday 6th of July 2014 12:17:03 AM

2strokemx · Guru

Yes dt does the same thing, gets to a certain rev then maxes out

Im betting you this is the problem... So how would i go about adjusting it? Im sure i read somewhere on my travels through the web about the ty250 having a powervalve and how certain upgrades manipulate it...

2strokemx · Guru

Na f*** this bike im gonna give up and burn it soon, if it ran like it should i would be fkin happy but it runs so bad i cant see any other solution other than a total rebuild and it still might not solve the problem...

Anyone on here willing to do the rebuild? I know theres a couple of good guys on here just cant remember who

Calum122 · Guru

If its just the powervalve then it just needs correcting. Most off road bikes run off gearbox for their powervalves. You could just remove it. It will do the opposite then. No bottom end but full peak power. Or just fix it. I'm sure it's not hard. But without physically having it in front of me I'm as good as a wet paper bag!

Calum122 · Guru

I know NORFE does rebuilds. For this engine it is unlikely but always worth a shot.

I can but without a manual I wouldn't attempt it on something that is not mine.

2strokemx · Guru

But cal how can you remove the gearbox? I will do it i just wouldn't know what to do, is it something i would need the manual for?

Calum122 · Guru

No it's driven off the gearbox. But you'd touch it from the cylinder. Again I'm just guessing. But that would be my first point of call. Have a quick mooch up the exhaust port. And have a look to see where the powervalve is positioned.