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

davecambo · Senior Member

snorkel, air filter options

TTRfan · Super Guru

Hi Dave

The message seems to be from other owners that reducing or removing the snorkel alongside fitting a TwinAir or similar air filter can help. The warning that goes with this is regards going through deep water whereby removing the part of the snorkel that sits above the airbox can allow water more easily into the airbox with possible bad consequences. So it all depends on the type of riding you do.

What is different on the 2011 models that doesn't require rejetting when fitting a more open exhaust please?

Brian

davecambo · Senior Member

well from what i read aparently the jets are different than earlier models. i have no idea though.

Ok so if you simply get rid of the snorkel and put new filters on, do you need to rejet?

TTRfan · Super Guru

You should be OK with the standard jetting but the only real way to check is with an exhaust sniffer or to take the bike for a run and cut the engine after a hard run (don't let the engine idle before cutting as this may give a different plug reading) and see what colour the plug is.

Sorry but a lot of this is guess work unless you have ready access to a dyno. Brian

TTRfan · Super Guru

davecambo

can you tell me what to look for on the plug please in relation to lean or rich.

thanks for the help so far.

----------------------------------

A really lean mixture gives a white colour - a rich mixture is a sooty black.

If you do a bit of Googling you should be able to find some pictures showing the range of plug colours including what it should really look like.

It won't apply to you but, on a worn engine, a false colour can be given as the burning oil will give a shiny black colour.

Brian

Cubber · Super Guru

Haynes manuals have a page dedicated to spark plug conditions.

This CLICKY THINGY will take you there.

Martyn

TTRfan · Super Guru

Brilliant stuff Martyn - excellent pics. Glad they agree with my statements wink

Have I explained the "cut dead" operation clearly do you think? I haven't done it recently but used to have a longish straight that I used many years ago for my A10. Basically when going flat out, you just pull the clutch in and hit the kill switch.

Brian

davecambo · Senior Member

yep i understand this concept.

thanks for the info guys. ill do the snorkel mod tomorrow. and check the plug. i doubt just the snorkel mod with affect lean/rich running.

dfaz · Veteran Member

I have done the snorkel mod not taken it out altogether just cut it back and with a K and N the bike runs too lean and required rejetting.

davecambo · Senior Member

dfaz wrote:
I have done the snorkel mod not taken it out altogether just cut it back and with a K and N the bike runs too lean and required rejetting.

What year model is your bike?

dfaz · Veteran Member

Hi its a 2004 I will be tackling it this weekend and then just need a new drain screw ( had to drill it out) will let you know how it goes existing jets 50/147 ,new jets 52.5/140 mikuni ( which aparently is close to 150 tekei)

Clutha · Veteran Member

I've been having ongoing misfiring problems.

My previous TTR 250 ran faultlessly. (It got nicked)

The replacement had a very loud silencer and better half insisted I put quieter one on as she wanted to keep neighbours friendly hmm

I thought jets might have been tampered with but all seemed normal. It has K&N air filter.

The misfire wasn't always there so I lived with it.

Last week I joined the old Yamaha Diversion club for a wee section of their run up here, leading them along the road from Loch Lomond to Faslane and then to Arrochar.

The wee bike was at max rpm in 5th and 6th and wasn't happy.

Remembering the advice on here to try the airbox cover off, I gave it a go and viola, a different bike!

Great acceleration, no misfiring and a lovely noise from the air intake.

Now to study the snorkel removal method smile

peteBLUEttr · Super Guru

You probably do have a bigger jet in there Gordon and thats why removing the airbox has evened out the mix

locky · Guru

I modded my airbox like this ttr250.activeboard.com/t60170249/modded-my-airbox/ but already had a 52.5 Mikuni jet in as it ran better when all standard standard, it ran very well after the airbox mod. I recently fitted an aftermarket exhaust along with a Mikuni 140 main jet and it runs spot on. It revs so much faster than standard and just seem more responsive. Iv'e done a few plug chops and its a very nice biscuity colour.

Clutha · Veteran Member

Out in the garage today having a tidy up prior to attending to Granddaughters (2 off) Wendy house, (freecycle, rusty bolts wink )

TTR won.

Seat off with a view to snorkel mod, found this,

Previous owner had already hacked it away.

Oh well, might put in a lip as described elsewhere, although at my time of life riding in deep water doesn't appeal

Did the inner end of the snorkel attach to the original air filter?

Mine is a K&N job, fitted by previous owner.

I've put the airbox cover back on, so fingers crossed she still runs ok, test run awaits wink

edit, 1/8/15

Here's the hole mod, pad saw + Stanley knife.

Out the other night on roads where the choking/missfiring was worst, no sign of any problems. 6th gear useable on hills!!!!! Accelerated on gentle inclines and tractable right down at 50mph.

Very happy bunny.

sorry if pic is in wrong place, iPad not built for fitters fingers😎

-- Edited by Clutha on Wednesday 17th of June 2015 04:21:07 PM

-- Edited by Clutha on Saturday 1st of August 2015 09:25:29 AM

Clutha · Veteran Member

I have to report my suspicion of greatly improved fuel consumption was verified yesterday.
64 miles of mixed stuff, trails in 2nd & 3rd gear, main roads at sometimes enthusiastic speed, fuel used = 4.8lts.
This is a near 50% improvement. There must be a giant main jet in. I'm accelerating up inclines in 6th!

Yippee!