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The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> Bought a 'cheap' TTR... what to check?
Post Info TOPIC: Bought a 'cheap' TTR... what to check?
Barry


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Bought a 'cheap' TTR... what to check?
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Hello everybody, first post here.

I have just bought my first TTR250 with the intention of touring around Australia on it. Having just arrived back in the country, and still being used to european bike prices, I may have gone a little too cheap on the bike I bought. And particularly I think I wasn't observant enough when I went to take a look at it. no

Anyway, since purchasing it I have spent plenty of time and money on this thing, doing one thing then finding more problems as I put it back together. Finally, after rebuilding the rear suspension and discovering that the rear wheel bearings were buggered when putting it all back together tonight, I have decided that I am being far too un-systematic with this thing. I have decided that I will go about checking the bike systematically and figure out how much more work and money it is going to take before I will have this thing in running shape. I have my doubts as to how much care the previous owners have taken of the bike, and believe it was probably ridden hard, so I would like to be rather thorough in my investigations.

I guess I am posting in the hopes that someone with good mechanical knowledge and experience with these bikes can review what I plan to check, and point out if there is anything significant I am missing. I have a decent understanding of mechanical things, and have worked a bit on my other bikes, but never dealt with anything in the engine beyond adjusting valve clearances. The bike has 24,000km on it.

So far, I have done the following work to the bike:

  • Removed the front forks and changed the oil. Oil seals seemed seemed good, so I did not want to completely dismantle them. Are there parts inside the front forks which may fail? Are there any flaws in the action of the suspension I should look out for that may indicate a problem inside?
  • Replaced the muffler. Original muffler had baffles removed, not good for long distance riding.
  • Repaired and bled the rear brake. Original hose from reservoir to master cylinder had a nice 1 inch hole in it.
  • Cleaned the air filter, changed the oil
  • Rebuilt the rear suspension: Replaced the rear shock absorber. Original one was leaking oil, and a second hand shock was cheaper than having this refurbished. Replaced the swingarm & linkage bearings.
  • Replaced the chain, sprockets, and chain guide. Now running 15/49 sprockets. The chain had eaten halfway to the bearing in the swingarm.
  • Fixed the speedo cable. I say the bike has 24000 on the speedo. But the wheels may have been turning a while since the speedo stopped.
  • Cleaned and regreased steering bearings

Now, there are still issues with the bike. These are what I know about:

  • Rear wheel bearings are no good. Found this out when it started making ugly clicking sounds after torquing it up. I tried to use a punch to hammer the bearings out without success. I'll be making a trip to the mechanic on Monday to try have him cut them out.
  • Carburettor leaks fuel if I forget to switch the taps off. I guess it's the float valve.
  • Engine makes a nasty bang on starting and when turned off. From all I read this suggests it's the sprag clutch.
  • Front brake hose is worn, so I will be replacing that.
  • After replacing all the bearings in the rear suspension, there is still about 5 - 10mm of vertical play in the rear suspension at the wheel (only when the bike is raised off the ground). Is this normal? It seems to be caused by small amounts of play between the shafts and bearings in the linkage & shocky bearings (no single bearing is to blame, they just all have small amounts of play that adds up then is magnified by the leverage).

So, other than fixing these problems I was thinking to do the following diagnostics:

  • Electrical: Check that the battery is being held at a decent voltage regardless of revs and load.
  • Front wheel bearings: Well, they feel fine on the bike, but given every other bearing is knackered, perhaps a closer look at these is warranted.
  • Strip the carby down. Any advice on how thorough I should be with this? Anything I should look out for while I have it apart? The engine is running fine, and I don't want to cause any problems where there were none before. However I do think it may be running a bit rich from looking at the spark plug...
  • Check the compression.
  • Check the valve clearances. This bucket & shim system on the TTR seems a fair bit more complex than what I have dealt with on my other bikes, so I have been putting this off.

So... I think I should be OK to do all of that. But then, thinking about where else there may be wear in the bike, such as the gearbox or the engine bearings, I do not know (A) how likely wear or failure is in these parts, (B) how difficult they would be to check or (C) how likely I am to cause more problems by getting in there to take a look.

Any advice on things to look out for would be greatly appreciated.

Cheers,

 - Barry



-- Edited by Barry on Saturday 8th of March 2014 04:59:11 PM

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ronny


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And breathe



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ttboof


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sounds like you have got most things covered .i wouldnt worry about the grearbox and engine internals as long as it rides ok with fresh oil .

with the wheel bearings thier cheap and witb all the work your doing id  do the ftont ones as well .

the rest of the list looks spot on just atention to detail when working on the bike as check everhthing as you go .new oil in the forks is a good start not much else to worry about there 

the back suspension  usualy has a bit of play i recon 5mm is ok .if you have done all the bearings the top shock bearing kit that you can get through brain . is one of the best and cheap mods you can do .

prob a good air filter and open up the airbox is up there as a must .

heres a pic of how i get the wheel bearings out makes it so easy .dyna bolt in then punch out from oppisite side easy as IMAG1014.jpg



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BM Steve


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ttboof wrote:

heres a pic of how i get the wheel bearings out makes it so easy .dyna bolt in then punch out from oppisite side easy as IMAG1014.jpg

Great idea, thanks, I'll remember  that one

 



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2004 TTR250 - Highway Dirtbike Hand Guards, 38mm Bar Risers, D606 Front & Rear, Opened up Airbox with Twin Air Filter, Re-jetted Carby, B+B Bash Plate & Frame Guards, DIY 3mm Alloy Tail Tidy, 14/47 Gearing.

 
Barry


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So, today I checked the valves. All in spec, good. Then I measured the compression. And it is low - 800kPa (125psi) in a hot engine. I am wondering how concerned I should be about this measurement? The bike seems to be running well - starts easily, doesn't smoke, idles well, low down torque seems OK. Maybe it's a bit lacking on the high end: max speed with 14 / 49 gearing was 107 km/h.

Should I be overly concerned about the low compression measurement? Is it likely that my valves aren't seated properly, so if I don't fix this I'll burn them and it'll just get worse? If it's not the valves but rather the rings or cylinder shape... well, does that lead to other problems down the line if not fixed now? I guess I am a bit hesitant to start removing the cylinder head because (A) it's summer outside and I feel like I am spending all of my time in the garage rather than out there and (B) I have a suspicion that if I take this apart it's not going to go as well when I put it back together.

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TTRfan


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My advice is to get out and ride it - not seen any burnt valves on any of the TTRs I have stripped so far - which is a lot wink

Brian



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ttboof


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TTRfan wrote:

My advice is to get out and ride it - not seen any burnt valves on any of the TTRs I have stripped so far - which is a lot wink

Brian

 I agree . Fresh oil and enjoy . 



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