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Alastair
Borekit Bruiser



Joined: 13 Dec 2005
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PostPosted: 10:49 - 26 Jan 2006    Post subject: Reply with quote
When I get the replacement engine I'll be needing to pull it apart and check out the internals and maybe get new piston/rings etc.

Is it a must to replace the gaskets even if I just open it up and put it back together? Guess there might be compression problems otherwise?!?
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Davo
Davo To The Rescue!



Joined: 05 Apr 2004
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PostPosted: 11:10 - 26 Jan 2006    Post subject: Reply with quote
Quote:
Is it a must to replace the gaskets even if I just open it up and put it back together? Guess there might be compression problems otherwise?!?


I would replace the gaskets as they won't create a seal between the surfaces. When you get the replacement engine it may be worth doing a compression test on it as well.
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Kickstart
The Oracle



Joined: 04 Feb 2002
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PostPosted: 12:43 - 26 Jan 2006    Post subject: Reply with quote
Alastair wrote:
Is it a must to replace the gaskets even if I just open it up and put it back together? Guess there might be compression problems otherwise?!?


Yes. They are single use items. You can get away with reusing low stressed ones sometimes, but partly because those ones are often on external covers and easy to change when they leak.

All the best

Keith
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Alastair
Borekit Bruiser



Joined: 13 Dec 2005
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PostPosted: 17:28 - 30 Jan 2006    Post subject: Reply with quote
Right, I won an engine on ebay for the huge amount of £31!! Will be picking it up this week.

Any tips on what to look for when I go to pick it up. No way for me to do a compression test but is there anything that may wobble etc that may hint at a ballsed up engine. If I push the kick-start it should turn right but that's about all I know.

Could someone suggest what is involved in a top-end rebuild too as I guess that may be a good place to start before I stick it back in the bike. Is it just piston, rings and new gaskets between the cylinder, head and exhaust? Would any Yam dealer be able to source all the parts for me on an old engine or just any bike workshop?
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Kickstart
The Oracle



Joined: 04 Feb 2002
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PostPosted: 00:03 - 31 Jan 2006    Post subject: Reply with quote
Hi

Feel how the kick start feels compared to you existing engine. Maybe take the rotor cover off and feel for any vertical play in the crank.

To be honest without stripping it down you are not going to be able to tell that much but at only £31 it is probably not worth worrying about especially if you intend to fit a new piston.

A Yamaha dealer should be able to get the parts. Only issue is that your model of TDR is not a UK model so it is likely they will not have the parts list (been told that one of the models of DT125 parts are the same but not certain on this).

All the best

Keith
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Alastair
Borekit Bruiser



Joined: 13 Dec 2005
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PostPosted: 11:02 - 06 Feb 2006    Post subject: Reply with quote
Found out the old engine had NO THERMOSTAT Exclamation Could that have caused all my problems. I did briefly notice that it never seemed to get warm in the 2 and a half days it worked but I put that down to the cold weather.

For the replacement engine I have a few questions too:

Arrow If the cylinder is slightly scored (I can just feel it when I rub my fingers on it) should it be re-bored? Piston is pretty scored so will be replacing that but want to know if I should wait to order it as I'll need a bigger one if I need to re bore.

Arrow Inside the head is pretty covered in black powder that is proving difficult to remove. Have now got about half off with the help of wd40 and a rag, anything dodgy there or just the sign of an old engine that's not been cleaned inside?

Arrow The wiring has been cut off the loom rather than disconnected Rolling Eyes can I just solder the wires up to the same colour ones before the connector blocks I have from the old engine?

Arrow Finally, It looks like the engine was left sitting outside without a cover for a while and as a result there was a bit of rusty water inside. Will this have caused any problems? How should I flush the bottom end out? I really don't want to split it.

Truth be told I'm getting pretty fed up with this now and it's taking a long time to get sorted but thanks to everyone that's offered advice so far as I wouldn't have got anywhere yet without your help Thumbs Up
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Kickstart
The Oracle



Joined: 04 Feb 2002
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PostPosted: 12:01 - 06 Feb 2006    Post subject: Reply with quote
Alastair wrote:
Found out the old engine had NO THERMOSTAT Exclamation Could that have caused all my problems. I did briefly notice that it never seemed to get warm in the 2 and a half days it worked but I put that down to the cold weather.


It will cause problems. Generally extra wear on the top end and possibly provoke a seizure.

Alastair wrote:
Arrow If the cylinder is slightly scored (I can just feel it when I rub my fingers on it) should it be re-bored? Piston is pretty scored so will be replacing that but want to know if I should wait to order it as I'll need a bigger one if I need to re bore.


Not sure the cylinder can be rebored. Think it is a plated bore. Without seeing the score it is hard to say, but if you can barely feel it then probably worth just replacing the piston.

Alastair wrote:
Arrow Inside the head is pretty covered in black powder that is proving difficult to remove. Have now got about half off with the help of wd40 and a rag, anything dodgy there or just the sign of an old engine that's not been cleaned inside?


Not really anything to worry about. Can cause problems on its own but easy enough to clean up.

Alastair wrote:
Arrow The wiring has been cut off the loom rather than disconnected Rolling Eyes can I just solder the wires up to the same colour ones before the connector blocks I have from the old engine?


Eeek, butchers. You can do what you suggest but I would be tempted to try and replace the connector. Or possibly just take the ignition system from your old engine.

Alastair wrote:
Arrow Finally, It looks like the engine was left sitting outside without a cover for a while and as a result there was a bit of rusty water inside. Will this have caused any problems? How should I flush the bottom end out? I really don't want to split it.


Quite probable it will cause problems, with rust on the main and big end bearings. You might get away with it. Flush it out (paraffin might be a good choice) and then put some fresh 2 stroke oil on the bearings.

All the best

Keith
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Alastair
Borekit Bruiser



Joined: 13 Dec 2005
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PostPosted: 15:09 - 06 Feb 2006    Post subject: Reply with quote
Kickstart wrote:
Quite probable it will cause problems, with rust on the main and big end bearings. You might get away with it. Flush it out (paraffin might be a good choice) and then put some fresh 2 stroke oil on the bearings.


Big end and small end bearings you mean right?

Thanks again for all your help Keith.
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Kickstart
The Oracle



Joined: 04 Feb 2002
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PostPosted: 15:29 - 06 Feb 2006    Post subject: Reply with quote
Hi

Main bearings as well. Getting oil to these will probably be more difficult.

All the best

Keith
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ZRX61
Victor Meldrew



Joined: 05 Nov 2003
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PostPosted: 22:13 - 06 Feb 2006    Post subject: Reply with quote
Alastair wrote:
Do I win any prizes for the most spectacular piston failure?

Not even close... First pic is what a brand spanking new Pratt & Whitney R2800 piston looks like ...
https://img.photobucket.com/albums/v317/ZRX61/DSC01597.jpg

This pic is the only remaining piston from the front row, the other 8 were even worse shape...
https://img.photobucket.com/albums/v317/ZRX61/DSC01596.jpg

& this pic shows both of em with a 50p piece to show scale. (actually a '82 IOM 50p coin with Joey Dunlop on it)
https://img.photobucket.com/albums/v317/ZRX61/DSC01598.jpg

If ya want to hear an engine energetically disassemble itself I can heartedly recommend an 18 cylinder 45litre Radial at the EXACT moment the wheels disappear into the undercart bays for sheer excitement.
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Alastair
Borekit Bruiser



Joined: 13 Dec 2005
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PostPosted: 10:28 - 10 Feb 2006    Post subject: Reply with quote
Shocked I had to google that, is it from a plane? Bet you love posting those pics though eh Wink

Have decided that the engine needs decent bit of love and attention so took it into a garage yesterday. He's going to split it and then let me know everything that needs doing but I'm expecting over £250 realistically. Wont find out 'til wed next week though Sad

He did suggest that a Malossi kit may be only slightly more expensive than the re-bore and new piston that it already needs and would take it up to 170cc. Does that sound like playing with fire? He has plenty of experience tuning 2T's though so I think he knows what he's doing.
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Kickstart
The Oracle



Joined: 04 Feb 2002
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PostPosted: 11:31 - 10 Feb 2006    Post subject: Reply with quote
Hi

Not sure how the DT based engine copes with a big bore kit. If you are a learner it will be illegal to ride it on the road (not that you are that likely to get caught), and for many people it would knacker the resale value.

All the best

Keith
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Old Thread Alert!

The last post was made 20 years, 253 days ago. Instead of replying here, would creating a new thread be more useful?
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