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

Thanks for sharing,I done the same thing and it cured all my carb problems after upgrading the jets,etc. The hole covers the top area of the air box all except a 10mm margin, also had a mate that moulded a plastic "lip" to stop water entering,works well now.

The original snorkel mods recommended by others just didn't hack it for my bike.

Its odd how some things work for people and the same mods don't for others.

It did not make any noticable difference to the inlet, if anything it is quieter with the larger hole.

However, the exhaust becomes quite a bit louder from the larger hole & seems to pick up in revs much quicker.

Thanks Andy for adding your method & findings. It was good to know that someone else came to the same conclusion as I did.

Cheers.

Jarrah

Raggis45 wrote:

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Hey Jarrah
How much more 'opening' did you make in the top of the box - when compared to the original hole?

Rob

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 Just a suggestion- don't cut or drill the hole larger until you have a larger snorkel to fit. You should be able to find an old cold air induction pipe from an old wreck.

This was the difference below, as you can see there is A LOT!

Jarrah

TTRfan wrote:

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Interesting stuff - thanks Jarrah and Andy - food for thought!

Out of interest, is the induction noise louder or quiter with the bigger hole on top?

Brian

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 Just check your seat bolts Brain, as if you site down & your seat comes off you would be eligible to join Exeter choir

On my son's and my TTR's have had the snorkels removed by previous owners, only problem is running through deep water, water came onto the air box between the seat and mudguard. So I cut up a plastic container and made a flap to cover the gap (bolting through the seat), I have fitted a piece of scouring pad (obtained from Matadors head of domestic services) over the hole to minimize what can go down the hole (induction noise up a bit), works ok but I like the larger raised adaptor. 

matador wrote:

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petenz wrote:

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The XT660R has a airbox snorkel the same design as the TTR... May even be the same one...
Removeing it from The XTR is worth 1.5/2hp... It's injected so no re-jetting is required..

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 You have got me thinking about my XTR, at present it has a K&N air filter, but if air flow is restricted I assume it won't benefit.

I have run it through deep water, over the wheels - bike was ok

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 I won't go anywhere near a K&N or DNA filter on a dirt bike.... I use Oiled foam as I like to keep fine dust

out of the motor....

Read this ==== >  http://www.dieselbombers.com/chevrolet-gmc-diesel-tech-articles/16611-duramax-air-filter-testing.html

What other mods dose your XTR have ?

Are you on  ?..    http://www.xt660.com/site/node/78

matador wrote:

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My son had the XTR before me and fitted the K&N, I will read the article later - where can I buy a foam air filter for my XTR?

I haven't spent a lot by some peoples standard, I based the mods on when I built a 500cc BSA Gold Star in trail trim back in 1968 - worked well as a big trailie (there's a picture of it in Aprils 'Trail mag'.

For the XTR I found the front a bit soft so fitted a pair of Honda Transalp 600 springs & 18mm spacer from Hagon. lowered the back by 1" (from Germany 'off the road'), metal pegs. a folding gear lever but extended 1.5", Hi level pipes were too expensive, so I made up a sump guard from a steel shovel ( I got the idea from my Bultaco Matador as the sump guard looked like a shovel), and a mud shield on the front of the frame + engine bars. MTC cans (my son again) I lost one of the baffles a while ago so used the old remaining one on the TTR in a FMF silencer to quieten it down a bit .Renthal bars & hand guards. Rubber fork covers & MX mud guard with rad vents. I run x3 sprockets depending on what I do 13T- goes up most steep Cotswold hills in winter, 14T - trail & road,15T - road. X3 sets of Tyres, all Metz; Karoo (Block tread), Enduro 3 & a new pair of road tyres on order for summer use.

Not much but enough to make it a good but heavy trail bike, will add a bit more later.

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 OTR "Off The Road" have oiled form air filters for the XTR XTX XTZ  660s....

There is also  "Piper Cross" have a oiled form filter also..

my XTR has - Metal Mule high pipe/Ohlins rear shock/ Showa twin chamber USD forks.

Rekluse WR450 EXP clutch/pivot pegs/ 2X fuel injection mods/Gillimoto 22.5L tank.

B&B bash plate/moded to fit Yamaha Tenere engine bars/Rally Raid Daka screen...

Hi Jarrah,

(firstly new at this so not sure if it best to message you or post this question so have done both, please disregard whichever you get second)

I am going on a ride involving some deep water crossings and looking to raise my snorkel somehow and came across your great Air-box snorkel modification.

I want to do the same and hope you don't mind me asking a couple of questions.

1) Getting your old one out and enlarging the hole. Did you drill a couple of holes then saw it out or some other method??

2) How did you secure the "cold air intake from an old Ford" to your airbox, glue??

Thanks, Michael

Thanks mate I will visit my local Ford wrecker and get started.

Cheers,

If you have a look at the picture above, notice the carb pipes in the right hand side of the picture above? As long as it is not more than 20mm (roughly) above these you should be fine.

Let me know how you go and pictures?

Enjoy!

Jarrah

As the original snorkel has a bend in it my concern on my next big ride that crosses several deep rivers is that there is a low point that would easily allow water to flow into the airbox. As shown in the pics while the top of the modified snorkel is comparative to where the top of the original one sat (just held in front for a demonstration) the water level would have to be 30-50mm higher to flow over the top of the modified one and into the airbox. Well that's the theory anyway. 

In answer to your question I guess too low and it would defeat the purpose, too high and it might not get adequate airflow if hard up against the underside of the seat. 

Cheers, Michael

-- Edited by Michael TTR250 on Saturday 10th of August 2013 01:10:00 AM

Have never adjusted carbies or jet needle will have a poke around this site to see if I can find a beginners guide to it.  I ride in the mountains around Canberra (our elevation is already 575m) up in the mountains it ranges between 700-1200m. As a rule with the lower density of air what do you think, should I aim for slightly richer or leaner mix?

Cheers, Michael

Thanks Jarrah,

I am trying to think about this logically, and would be really interested in your thoughts. If the density of air is lower with altitude (as most of my riding is) the bike needs more air and accordingly should be set up a little leaner than normal for best performance.

So inadvertently by trying to solve the possible flooding of the air box my bike will get a bit more air (as you pointed out) and run a bit leaner which for my circumstances will be great.

Does that sound right to you?

Cheers, Michael

If the mixture is lean, the engine will loose performance and if too lean it will get hot at the header and may do damage to piston & rings.

If the mixture is too rich it will be sluggish and may pop in the carb on deceleration. This rich condition over time will lead to back-burning from excessive carbon build-up.

Do a plug reading after riding full throttle for some distance and shutting the engine off before returning to an idle. If it is white or clean you are running lean, if it still has a nice chocalate brown color to it, it is perfect.

When the mixture is perfect- if lower the jet needle position 2~3 settings richer it should become too rich and bog a little after 1/3 throttle. In addition, it may pop in the carb apon deceleration and the engine will loose performance.

Of course, the best mixture is somewhere in between. That said, doing this mod does not change the air-flow all that much and if anything, you may need to lower the jet needle clip position 1~2 settings (if at all). It wouldn't hurt to check if you gain performance from lowering the jet needle position. However, this is not essential and I'll leave that up to you to decide.

Enjoy!

Jarrah

Michael TTR250 wrote:

 

Jarrah - In answer to your question f..king heaps more power, it seemed to pick up revs and torque much earlier down low, hard to explain but it didn't seem to get as bogged down at low speed on steep inclines as it has in the past. It might just be as you said they run a bit rich here and add in my altitude and it just really need that bit more air to run as it should. Don't know or care just f..king love it!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

Thanks heaps mate. Cheers, Michael

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 No problems Michael

Yes, standard they do run rich in AU and also the fact that the TTR250 has very restrictive air-flow. In addition to the snorkel being too small, the cylinder head ports (exhaust/intake) are not matched. The intake is much smaller than the exhaust and both have casting imperfections.  If you want a REAL upgrade start there by porting and polishing the ports, making sure that the intake is left rough-cut and polishing the exhaust port. Also adding a GYT-R air filter and exhaust upgrade helps heaps! Just remember to re-jet and adjust the jet needle clip position accordingly.

Glad you liked it!

Jarrah

Can anyone suggest why trimming the original snorkel results in running richer? Can't really understand it,  although I'm happy to accept it from those that have done it.

Jarrah does your snorkel protrude into the airbox like the original, or stop flush with the top?

Simon.

I need to see another 20 pics to be half convinced it's the norm...

I just done the DB1K on the week end... 1000km of back roads tracks/trails in 2 days

prob done near 20 river crossings... deepest was about top of engine case... that would

be normal... was on the XT660R

Surely the internet is the home of speculation?  

I've been toying with the idea of putting a perspex side on the filter box and using a smoke pellet to see how the air flows, but at the moment I haven't got an idle hour or three!

Thanks for the reply,

Simon.

No problem. As you will see from the pic, the inside of my air box looks a darker colour, that's because after each air filter clean and re oil (very dusty where I ride) I spray some filter oil on the inside of the airbox which helps trap some of the dust on the way in reducing the amount that gets dumped directly onto the filter (I then just wipe it and the crap out at the same time as cleaning the filter).

I couldn't give you figures on how much extra power I have with this bigger opening but with it and the secondhand Staintune exhaust I put on the bike is noticeably more powerful. I do a lot of tight steep hill climb stuff so want the grunt down low so run a 13 tooth on the front and 49 on the rear but even with this low gearing it can still do 80-90kph on flat trails.

Cheers, Michael

ttboof wrote:

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Only reason I put the lip on mine is I go through a few creeks that are a bit on the deep side 

I ride with an air filtration engineer he doesn't see a need for the snorkel Other than maybe noise reduction .

In the end it's just a need for a bigger opening .

-- Edited by ttboof on Saturday 8th of March 2014 05:45:57 AM

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 That's a downpipe spout isn't it, Why didn't I think of that, I have a couple floating around for sure

Thanks

yep its a down pipe fitting .love finding uses for stuff around the shed