DT125R ARCHIVE

2strokemx · Guru

Any suggestions engine problem ty250

MDK · DTR Legend

any restrictions that could be hidden ?

have you tried it side by side on a long stretch of road or field .

is the carb cable correct and will it open the carb fully for full revs .

2strokemx · Guru

Yeh we tested it on the straight, dog piss my ty 80's quicker

I took the silencer completely off, ran abit quicker nothing special

I think it use to run quicker and almost keep up with my cousins, but i was young about 13-14 so i cant really remember

Calum122 · Guru

You sure the engine is in good nick? Not due a rebuild?

2strokemx · Guru

Most probably due one, but i dont want to pay silly money and my knowledge with engines is extremely limited... Is there any specific reason why its lost the power? Anything i can single out or isit almost impossible to say and the easiest option is the full rebuild?

Calum122 · Guru

A good look up the exhaust port will tell you a lot.

Scoring down the bore will cause loss of performance.

Calum122 · Guru

Most trials bikes are two stroke ain't they. Two strokes are incredibly simple.

2strokemx · Guru

Yeh its a two stroke 250

2strokemx · Guru

How much would it cost to get someone to rebuild it do ya think?

Calum122 · Guru

Don't jump the gun. Just have a little look.

If it's not the carb, plugs, fuel or air then it'll be something electrical or mechanical.

Just take an inspection torch up the exhaust port and have a look. A top end rebuild is cheap.

2strokemx · Guru

What am i looking for? I despise mechanics and i have pretty much 0% knowledge of engines

Calum122 · Guru

Gee bit of a bad time to despise mechanics if you're looking to fix it.

If that's the case wheel it down to a mescamic to sort out.

Exhaust port jobby is a five minute job and will save you £££ trying to diagnose the issue. You just want to check the condition of the bore, piston and rings.

But as said if it ain't your cup of tea then best have someone else sort it out.

2strokemx · Guru

Aye definately not my cuppa, but say i did have a look up the port, will it be obvious if something is wrong? Or do you need to know what you are looking for; i dont mind looking and inspecting but i cant be taking stuff apart, i know im not really helping the situation here and probably being abit annoying but if it was a guide for dummies what would you suggest looking for? Cheers

Calum122 · Guru

As said scoring along the barrel and piston. The rings will be completely flush with the piston with no spring in them. Coked up and jammed.

Damage to the piston/rings. Anything like that.

Have a look through some engine failures on the forum and it should be clear.

MDK · DTR Legend

also may be worth finding what the compression should be and get a tester if possible .

have a read throu this topic some good sugestions or is that already you ?
www.trialscentral.com/forums/topic/50802-ty250-mono-88-lacking-power/

-- Edited by MDK on Wednesday 7th of May 2014 12:16:29 PM

2strokemx · Guru

Haha yeh thats me, thought i'd get as many people's opinions as possible then take the majority's opinion

Calum122 · Guru

I'd stay away from high octane fuels unless you know what you're doing. Easy way to destroy a two stroke engine.

Luke · Guru

Take the exhaust off, shine a torch up the exhaust port, turn the engine over slowly to look at the piston. Don't kick it just move the kickstart up and down slowly with your hand. Or get a friend to do it slowly so you can inspect.

A new piston:

0000-Moose-Racing-High-Performance-2-Stroke-Piston-Kit.jpg

Yours wouldn't look nothing like that in colour, as its probably been in the bike a while so covered in oil.

This is a bad piston.

Looking through the exhaust port, you'll only get a look at the rings and the wall of the piston, not really much but here's a side picture, if you see this (scoring) you need a new topend.

If you've had the bike since you was 13-14, and the bike has been used regularly it probably is the topend. If its been sitting a while, then it'd probably be more to do with the carb needing a clean. smile

Calum122 · Guru

Top man luke. That's good examples. Obviously it's not going go be like new. And a few scores ain't the end of the world. But make sure it's not excessive and you can't fit.

2strokemx · Guru

Ok i'll have a look thanks for the advice guys, say its scored up pretty bad would it be a fairly simple task of replacing the piston?

Luke · Guru

Take the seat off, tank, plastics and exhaust then take it to a mechanic. 4 Bolts going on to the bottom of the engine, undo them them take the cylinder to a mechanic tell him the bike, he'll send your cylinder off to get replated and tell him to order you a piston. Then ask if he'll fit it. About an hours labour if it's all stripped if a good mechanic (like I go to) about £20 in labour. Looking between £100-£250 on the topend replacing. Don't bring the bike to him before the part has arrived, some mechanics are funny and charge storage costs.

The topend is easy, and you could be shown how to do it on here, but you don't really sound willing to go down a mechanics route. It'll cost you a dime in the future, especially if you're into MX bikes. Heck, even DT's need topends doing after 10,000-15,000.

Of course, don't strip it down until looking up the port and being sure it's the topend.

Upload some pictures here, or a video. A video might be better, just shine a torch up and get someone to move the kickstart over slowly with their hand.

2strokemx · Guru

Allright mate thanks for the help, i'll try get a video uploaded tomorrow

Dt's done over 15,000 miles, best sell it soon!! Ha

2strokemx · Guru

I have a gopro video of me riding it just messing round in my woods when i was 17 i think, might be worth listening to the engine as im riding to help you understand what i mean?

Luke · Guru

Seems a bit boggy and struggling up the hill at 1:51.

Does appear very sluggish and lacking power.

That's like my DT when it had a blown topend. Does it make any slapping or knocking / ticking sounds?

Calum122 · Guru

Top end is like a 4hr job for someone who has to read a manual the whole way. It's a real simple job with only a few things that need you to take care. On a two stroke that is.

Namely the few careful things are: Piston ring end gap, Circlips position, Piston in correct, Head gasket on the right way.

2strokemx · Guru

Yes i was gonna mention the bit at the hill, thats the most depressing bit, the rest i can get along with but its the straight/open areas

So we deffo think its the topend then yeh?

It doesn't make any ticking/knocking slapping sounds, runs fine just no power, got it out about a month ago for the first time in over a year, second kick it started

Luke · Guru

It's hard to say without any pictures of up the exhaust port.

If you've left it sitting for a year and it wasn't like this before, then it could be something else. Did you put fresh petrol in? BTW avoid super unleaded. Makes 2 strokes that you run premix run horrible mine was back firing and everything. Emptied tank and used Unleaded and ran fine again.

Calum122 · Guru

I wouldn't say it's anything yet. Just have a look up the exhaust port. Takes two seconds.

2strokemx · Guru

Ok, i'll get a vid going

No literally i refused to ride it after it seemed to loose all its power, only reason i started it the other month is because my friend really likes it because it easy for him to learn on because of the lack of power

Cheers again, i'll try get a video uploaded early evening

2strokemx · Guru