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Dirt in engine HELP

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Recently picked up an 04 crf250r for a pretty good price that was sitting for over a year, needed new fluids. I tore it down to take the carb off and clean and i noticed a large amount of dirt and sand in the carb and intake, and the intake valves had dirt coated on them. Blasted it with carb cleaner and vaccumed it all out, cleaned the sand out of the carb, and tried starting it anyway and it seems to be running fine and pulls hard. Motor sounds very good too it's very quiet and no clicking noises and starts up pretty easy too. What at all could this dirt have damaged? Should I keep the bike? Will I possibly have motor problems in the near future? Thanks IMG_20170616_112226115.jpg

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That's probably carbon deposits not dirt. It's normal and occurs when the fuel is ignited and burned in the cylinder.

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If there was actual dirt and sand in the intake boot & port (say due to a bad air filter seal) damage has likely already been done.

 

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That's probably carbon deposits not dirt. It's normal and occurs when the fuel is ignited and burned in the cylinder.

Carbon diposits on the intake side of the motor? I swear it was dirt and there was also sand in there too. Throttle slide was getting stuck because the whole thing was loaded with sand and dirt

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If there was actual dirt and sand in the intake boot & port (say due to a bad air filter seal) damage has likely already been done.
 

What damage should I be looking for? What issues may I have? also I've been told the bike has never been rebuilt

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Letting dirt in the motor through either air filter or leaking boot is the fastest way possible to blow up a bike besides running it without oil . It will get in - chunk up the top of the piston and get in your bearings everything will need changed at some point if I was sure that motor was sucking dirt I'd have a new air filter in it and have it posted on CL immediately .. sorry next guy

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Carbon diposits on the intake side of the motor? I swear it was dirt and there was also sand in there too. Throttle slide was getting stuck because the whole thing was loaded with sand and dirt

My bad I thought it was the exhaust

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OP you just discovered why the price was so good.

To repair this engine properly, it may cost more than the bike is worth.

I'm sure some signs were visible that shouted 'stay away' beforehand.

 

Out of curiosity, carefully cut and unravel the old oil filter's pleats and inspect for debris.

Inspect the air boots for cracks, also for a torn air filter foam.

Edited by mlatour
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Hey guys thanks for responses. Now given that there is absolutely no more dirt getting into the engine, should I be okay? I cleaned out all the dirt from intake port, cleaned carb, and cleaned air box and air filter squeaky clean, bike runs fine doesn't make bad noises smokes or ticks or anything and whatever dirt was in there is gone now. Should I be okay

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I only trail ride, no super high rpm riding and no rev limiter and I will be keeping maintenance on top for sure

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Not knowing just how much dirt made it in the engine

the extent of it is something you'll unfortunately find out if/when problems start.

 

For strictly trail riding, you surely didn't pick the most simple and economical bike to run.

Edited by mlatour

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No doubt 250f are ticking time bombs as it is add dirt now your sand blasting the piston ,cylinder walls,valve seats and bearings it's not a matter of if it's when it blows .

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Tear it down

Mic it out for wear tolerances

Decide if the motor is worth saving or is toast.

.....or, you could just clean off all the visible dirt, run a few oil changes, and wait for it to blow up.

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3 hours ago, 93rm125P said:


My bad I thought it was the exhaust

Rubber intake boot gave it away i think  :doh:

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No doubt 250f are ticking time bombs as it is add dirt now your sand blasting the piston ,cylinder walls,valve seats and bearings it's not a matter of if it's when it blows .

Well all the dirt has got to be out by now, and just wondering how exactly would dirt going into the intake get into bearings? I don't see how it could get into the bottom end and I also took the valve cover off and it looks fine under there no dirt obviously

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So assuming it WILL blow up. What part of the motor will fail most likely due to the dirt?

 

 

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Dirt will accelerate wear,

the longer you run the engine with contaminants inside, the more parts get worn.

 

It may not 'blow up' catastrophically with your usage but by the time you start having problems (hard/no starting, excessive blow-by, low power etc.)

and decide to fix it, more components are going to be worn out and it will overall cost much more to repair properly.

 

As mentioned in earlier posts, maintenance wise (and due to many features as well)

a used 250F MX race bike is likely the worst possible candidate for an 'economical' trail bike.

 

As I suggested, have you inspected the old oil filter for debris?

Apart from dirt , depending on size and colour, metallic particles may show the engine was already due for a rebuild previous to injesting dirt.

Edited by mlatour
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Dirt will accelerate wear,
the longer you run the engine with contaminants inside, the more parts get worn.
 
It may not 'blow up' catastrophically with your usage but by the time you start having problems (hard/no starting, excessive blow-by, low power etc.)
and decide to fix it, more components are going to be worn out and it will overall cost much more to repair properly.
 
As mentioned in earlier posts, maintenance wise (and due to many features as well)
a used 250F MX race bike is likely the worst possible candidate for an 'economical' trail bike.
 
As I suggested, have you inspected the old oil filter for debris?
Apart from dirt , depending on size and colour, metallic particles may show the engine was already due for a rebuild previous to injesting dirt.

Yeah man I just inspected the filter today, I only saw some dirt particles no metal shavings or metallic anything. This is normal to have dirt particles in the filter chamber? I am well aware that a 250f isn't a good reliable bike to trail ride I just like to rip. Hoping the bike will last the summer so I'm able to save up enough to do a full rebuild. How reliable is a full motor rebuild of a older 250f compared to a new bike?

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Dirt will accelerate wear,
the longer you run the engine with contaminants inside, the more parts get worn.
 
It may not 'blow up' catastrophically with your usage but by the time you start having problems (hard/no starting, excessive blow-by, low power etc.)
and decide to fix it, more components are going to be worn out and it will overall cost much more to repair properly.
 
As mentioned in earlier posts, maintenance wise (and due to many features as well)
a used 250F MX race bike is likely the worst possible candidate for an 'economical' trail bike.
 
As I suggested, have you inspected the old oil filter for debris?
Apart from dirt , depending on size and colour, metallic particles may show the engine was already due for a rebuild previous to injesting dirt.

Also, you mentioned the longer I run the motor with contaminants inside the faster it will wear, although I have thoroughly cleaned the whole intake system so will wear still occur quickly from dirt being temporarily in there at one point, (all clean now) or are you just obviously stating that wear will continue to occur if dirt continues to get in

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Early CRF250R aren't known for the great longetivity, (valvetrain / cylinder head)

over the years there were some improvements in components and

luckily you can likely interchange some parts with up to the 2009 model year 250R.

 

Thing is, no matter the amount you spend making the engine 'like new'

the rest of the bike (suspension components, chassis bearings, etc. etc.) 

will all be 14+ years old and also require investments.

Having great power on a poor handling / crap suspension bike is useless.

 

Sometimes it's better to ride older bikes 'as-is' with minimal investment and,

put money aside not for a rebuild but rather for another bike altogether when the current one fails.

Edited by mlatour

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