A forum for owners of Yamaha TTR250 trail and enduro bikes!

Members Login
Username 
 
Password 
    Remember Me  
The TTR250 FAQ web pages -> TTR250 -> Just joined the forum? -> Why did I buy this..
Post Info TOPIC: Why did I buy this..
Moabmatt


Newbie

Status: Offline
Posts: 3
Date:
Why did I buy this..
Permalink  
 

I'm kicking myself a bit for this one, but let's see if I can get it running at least. 

 

Low compression (45-50 dry), no spark (before me), new wiring harness and tdi box installed by questionable methacanics...

 

Leakdown and simple tests indicate carb, valves, rings, or something bigger. 

 

After top end breakdown. I'm thinking rings!  Look at the blowby... needs carb job too. But the valves are still in spec, closely. 

 

What would you do? 

 

The head looks OK, the bore OK, the rings no. Rod slop, acceptable. Valves might need a job... but I couldn't get this thing attempting to firing on ether either. And they're tight. Bore mics out at 73, pretty close. 

 

Threw it back together for the night.

 

I'm Thinking new piston and rings, not gonna get to perfection, just want it running. Plus would like any advice on upgrade or mods that might be helpful at this point of teardown?. Help? 

 

Think the previous owner, ran it rich for too long, burnt up the rings. Thoughts?

 

 



-- Edited by Moabmatt on Tuesday 2nd of January 2024 02:05:05 AM

Attachments
__________________
Ttboof


Veteran Member

Status: Offline
Posts: 99
Date:
Permalink  
 

i wouldn't do anything until it has spark. ive recently posted replacing the pickup coil, you need to check it with a multi meter, looking for 400 ohms. the ignition system is pretty simple however I'd recommend the workshop manual and work through the checks and work out what's wrong in your case. (the reason i mentioned my pickup was its a cheap fix with no need to replace the Stator assembly)

once it has spark, if the piston and cylinder are with in tolerance chuck a set of rings and gaskets at it .

with the valves clearance is one thing, but are they seating, ok? (its not unusual to have an ordinary fit from new)

 

thinking out loud is go spark rings /gasket , clean carby , ride it and check that it selects gears ok and there isnt the dreaded sprag bang when it's turned off. from this you can work out where you want to put your money .

all just suggestions from someone who likes TTRs but loathes parting with money. ( i let the sprag clutch go until i needed a starter and gears as well much more cost than just a sprag) 

 

wiring just time and patience and fix it once it's going. 



__________________
Moabmatt


Newbie

Status: Offline
Posts: 3
Date:
Permalink  
 

Thank you! I does have spark, the po allegedly replaced the stator, but I haven't checked for correct install yet. The low compression and the states of the rings think that's all it is plus s clean carb. How do I check the stator install and timing? 



__________________
Ttboof


Veteran Member

Status: Offline
Posts: 99
Date:
Permalink  
 

The timing is fixed.  The cdi  unit determines  the spark curve 

Only check is that everthing is tight and the wires routed correctly 



__________________
mossproof


Super Guru

Status: Offline
Posts: 1387
Date:
Permalink  
 

Welcome to the forum!
You haven't bought a basket case, you've bought a project!
There is loads of info in the repair and maintenance stickies section. Cam timing is here:
ttr250.activeboard.com/t57843009/timing-chain-or-cam-chain-or-camchain-replacement/

The hardest thing to fix is the carb, if there is anything wrong with it - they are not a common type, and very sensitive to blockage from bad/stale fuel. 


Have fun!



-- Edited by mossproof on Tuesday 2nd of January 2024 09:16:05 PM

__________________
Page 1 of 1  sorted by
 
Quick Reply

Please log in to post quick replies.
The TTR250 FAQ web pages -> TTR250 -> Just joined the forum? -> Why did I buy this..


Create your own FREE Forum
Report Abuse 		Powered by ActiveBoard