Carbon Build-up

tiz_mark · Post by **tiz_mark** » Mon Dec 11, 2006 8:04 am

Hi,
I'm popping my first post cherry. Im new(ish) to owning a TRX850. i have '97 mod with de-baffled standard pipes, 37,000ks and i have a fair bit of carbon build up in pipes which blows a bit of soot out when i start riding. i'm getting 190km out of a tank and thats taking it easy. The exhaust smells fuely. does this sound like its running rich (pardon my ignorance!!)
What should i be getting out of a tank?
Can anything stop coke build up or remedy this?
Would a dyno tune fix problem?
I just changed oil + filter so thanks for the guidence on the old site everyone.
Im always up for a ride if anyone in sydney is looking for someone to go for a blat with.
Can anyone help? Thanks, -Mark.

jpe · Post by **jpe** » Mon Dec 11, 2006 8:15 am

U probably need to rebuild your carbs. Sound like needle jets and needles are badly worn.

I've got akra exhaust, k&n-filter and 155 main jet, I usually get about 250 km out of a tank before hitting reserve. 300+ if a stretch that. Think that is fairly standard mileage.

tiz_mark · Post by **tiz_mark** » Mon Dec 11, 2006 8:32 am

Thanks for the reply.
Is that a big job? more to the point is that an expensive job? wow 300ks sounds like it'd be worth it.

Post by **phuk72** » Mon Dec 11, 2006 10:17 am

You really should be getting another 50 or so clicks per tankful if you are taking it easy - I get that sort out mileage per tank thrashing the motor!

Most likley diagnosis is worn emulsion tubes

Replacement isn't especially hard and will cost you around Ãƒâ€šÃ‚Â£20 each - obviously more if you have to pay someone to do it!

rjen · Post by **rjen** » Tue Dec 12, 2006 2:12 am

My TRX also sometimes smells slightly of petrol when sat still. It's very faint. I also assumed this was because it was running a bit rich (which I heard is common/standard). However it seems to run perfectly. I've no idea how far it goes on a tank full but will investigate.
I keep reading on the forum about these emulsion tubes. I've had a look at the carb section in the service manual but they aren't mentioned.
The only emulsion I know about is the Dulux variety!

Can someone explain what these emulsion tubes are, what they do and how you know if they need to be replaced?
Secondly what does the TPS do? It's measuring the throttle position but what is it altering as a result?

The service manual is great but obviously doesn't explain what things do.
Does anybody have the Haynes manual? Is it worth getting?

THANKS!
-Rjen.

Waz · Post by **Waz** » Tue Dec 12, 2006 5:40 am

Emulsion Tubes are another name for Needle jets ie: the tube/jet that the needle sits in (the main jet is screwed into the bottom of it). On the TRX, the emulsion tube "ovalizes" through wear therefore allowing more fuel though hence running rich. The TPS is wired to the ignition, changing the advance/retard based on the throttle position.

Wombat · Post by **Wombat** » Tue Dec 12, 2006 6:10 am

I think mine (emulsion tubes) are starting to go as well. Used to get well over 200kms per tankful. Now she hits reserve anywhere between 180 & 200, and has always had that faint whiff of petrol. Still runs alright though.

Trying to weigh up the cost between getting new Yamaha or aftermarket tubes and needles or a set of FCRs (and the complexity of setting them up? A lot of questions later to the "techies" on the forum)

Haynes manuals are fairly good. Cost around $50 and can be got from most motor book shops, or by mail order.

Bob

tiz_mark · Post by **tiz_mark** » Tue Dec 12, 2006 6:25 am

Great,
Thankyou very much. It will be the first thing on the books to to do.

Triton · Post by **Triton** » Tue Dec 12, 2006 8:56 am

My 9000km 2001 does 343km EXACTLY per tank (including reserve) of PULP.

Ms T came to the rescue.

So please, for the sake of your wallet, invest in a carb rebuild!!

BTW: welcome!

Post by **phuk72** » Tue Dec 12, 2006 9:21 am

My TRX also sometimes smells slightly of petrol when sat still. It's very faint. I also assumed this was because it was running a bit rich (which I heard is common/standard). However it seems to run perfectly. I've no idea how far it goes on a tank full but will investigate.

Could be that your fuel tap is allowing fuel to drip into the carbs

burty · Post by **burty** » Tue Dec 12, 2006 9:35 am

I regularly get 160 miles from a full tank until having to switch to reserve (260 km). It used to be around 120miles. I had the same symptoms as you tiz_mark, very black output, smelly backpack, and a whiff of part-burned fuel everywhere, especially when stopping at the lights etc.

I made a number of changes, fitted a factory pro carb kit (new needles and a few other bits) and I changed my emulsion tubes which were very oval.

There's lots of information on the factory pro web site.

If you are capable of removing carburettors, and opening them up then it's a fairly straightforward job. (Mind you getting the old philips screws out of the bottom of the carbs can be a bit of a bugger, if they've never been apart before)

John M · Post by **John M** » Thu Dec 14, 2006 12:21 pm

Welcome tiz_mark from another 'Shire boy;' as suggested by others it sounds like the carbs need a serious seeing-to & the problem may be fixed by simple adjustment/set up/ balance unless of course those 37,000km have been especially hard, then a rebuild may be on the cards. For the record, i went for a run up the coast last weekend- my 'rex has 44,000 on it- a mix of freeway cruising + some heavy handed fanging, hit reserve at 284km one way and 287 the other on PULP, so your 190 is way low!
Let's catch up for a ride some time, maybe next track day (see Triton's post).
cheers,