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The TTR250 FAQ web pages -> TTR250 -> Repairs and maintenance -> intake questions
Post Info TOPIC: intake questions
commanderjjones


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intake questions
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Hey guys. I just picked up an '05 TTR 250 this past Wednesday (so I haven't had a chance to get a manual yet) and have a few questions. I was hoping to ride it tomorrow, but ran across a couple of issues when I started servicing it last night.

 

When I started to clean the air filter, I noticed a couple of hoses and nipples that weren't connected to anything, but looked like they definitely SHOULD be connected to something or plugged. I've attached pic's with descriptions below.

 

This is the first one thing caught my attention. I had to remove the seat to confirm, but just as I suspected, that fitting (circled in red) goes directly into the intake tube. So it has been sucking unfiltered air facepalm.gif ......NOT good. Other than these minor intake issues below (which I unfortunately didn't notice BEFORE I bought it), the bike appeared to be in good shape, does not smoke, and compression is good, so all I can do is hope no damage has been done. Since I don't have a manual yet (but will be correcting that immediately), I looked up the parts fiche and discovered there is a small chamber that is supposed to be there. The fiche calls it an "air chamber"......Yamaha part # 4GY-13591-00-00.  Although the drawing is poor, it appears to have 2 holes......so I assume there would be another hose hooked to that chamber. Can someone confirm if that is correct and, if so, where does the other hose go to? Also, can this chamber just be eliminated (by plugging the hole in the intake) or will removing it affect performance?

20160128_202005_zpswuzlwppx.jpg

 

20160128_202049_zpstruojahd.jpg

 

So here are the other problems. Just below the intake is what Yamaha calls a "breather assembly". It has one hose presently attached, but has a fitting on top with nothing attached to it (center red dot at 12 o'clock position). There is a hose that comes from the carb (left red dot at 9 o'clock position) that isn't attached to anything.....it has a one-way check valve on the end, but unless there is another section of hose missing, it doesn't appear that it's supposed to attach to the breather or to the air box. Is that hose supposed to attach to the missing air chamber? Also, there is a nipple on the air box (right red dot at 3 o'clock position) that doesn't have a hose hooked to it.

 

Can somebody help me with the hose details? I have a ride planned tomorrow and was REALLY wanting to ride this thing, but it isn't looking good so far.

 



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Moo


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Left red dot and 9o clock is the carb overflow, so fuel can come out of that.

The black chamber in the bottom picture is the emulsifier pot and will fill with emulsified oil occasionally, so can need checking sometimes. If memory serves me right it connects to the airbox and the engine crankcase breather.

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commanderjjones


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I've found some pic's online and confirmed that the line from the breather does connect to the airbox, as stated above.

So is the carb overflow line supposed to attach to the missing "air chamber". And if so, are there any negative effects by eliminating that chamber, or do I need to replace it?

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Moo


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Nope, the carb overflow just hangs free downwards

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Cubber


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Will these illustrations show you where and what are attached? confuse

These are the carb pipes

Carb.jpg

 

AND here are the filter box fittings

Filter.jpg

Martyn



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mossproof


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The cut off pipe on top of the air inlet hose can be blanked off/plugged with no discernable affect. There was a thread a while ago about what the "air chamber", part 21, actually does - sort of balances out the resonance and backwash of airflow through the 4 stroke cycle, IIRC. (Sounds good hey, but I don't really have a clue what I mean Part 22 is a cyclone filter that removes oil from the air coming down the tube from the crankcase beather before it enters the airbox. It MUST NOT be blanked off. Side inlet from crankcase/engine top cam cover depending on age of bike, top outlet goes to airbox (upper of the 2 small tubes), bottom outlet goes to a short collector which, as Moo states, needs emptying from time to time.
Enjoy the ride, and welcome to the world's friendliest forum!
Simon.

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TTRfan


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Trying to find some helpful photos:

Emulsifier 1.jpg

 

Emulsifier on airbox.jpg

 

Air chamber.jpg



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commanderjjones


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Moo wrote:

Nope, the carb overflow just hangs free downwards

 OK, thanks. It just struck me as needing to be attached to something. I have worked on A LOT of bikes over the years but have never seen a check valve attached to the end of an overflow tube. Is that valve really supposed to be there??? I'm not seeing it on the parts fiche anywhere. Looks like part 34 and 47, but their description just says "pipe". Maybe the description is wrong.



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TTRfan


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Both of the carb breather pipes are open at the top where they bolt to the airbox and have one-way valves at the bottom of their run.

Carb pipes with one-way valves.jpg

The petrol overflow pipe from the carb float bowl attaches to the underside of the carb float bowl.

Carb overflow pipe.jpg



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commanderjjones


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You guys are great. Thanks for the welcome.

I'm gonna plug the intake port where the air chamber "should" be and run it like that for a few rides and see how it runs. If there are no running issues, I'll make the plug a permanent fix.

I can't wait to go ride this thing. I've owned NUMEROUS Yamahas since I was a kid, even a few Yami 4 strokes, but this is my first TTR. Looking forward to something with more manageable power than my previous YZF.

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commanderjjones


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TTRfan wrote:

Both of the carb breather pipes are open at the top where they bolt to the airbox and have one-way valves at the bottom of their run.

Carb pipes with one-way valves.jpg

The petrol overflow pipe from the carb float bowl attaches to the underside of the carb float bowl.

Carb overflow pipe.jpg

 Excellent. Thanks for the confirmation. I feel better now.



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