Ignition or fuel problem - new trixie owner needs help!!

[steve speed]

the problem with the faltering is the same as i had when i ran std carbs and it went once i took out the slide and cleaned and polished the edges were it rubs against the inside of the carb ,, mine was scored a bit and there travel was not smooth i used a bit of T cut to clean them up ,, give it a go

[Norfolk Boy]

Guys - you are really great at helping people out...

I will definitely go and find some kind of inline filter to try and prevent crud building up again..

Steve – you mentioned cleaning the ‘Slide’ What part is this? I must admit this is the first time I have had a carb apart so I’m on a steep learning curve…

I wonder if the hesitation I am now getting when I roll off and then back on in 5th gear is a combination of over fuelling. Looking at my dyno print, if I was in 5th at 5500rpm (which is when the bike is fuelling worst), rolled off and then went back on again below 3500rpm (which again is when the gike is running rich) it may have too much fuel to cope for a split second?? If this is the case, from what i have read i could adjust the mixture on the pilot Screw ??

Mincehead - will check out that site when I get a moment… Cheers

[trixynut]

Mate,

Noting too technical in my comments here: I'll leave that to the people who know! ..... but .....

....rolling on from 3.5k rpm in top is pretty low revs, specially if you are running standard gearing/sprockets which most consider is a little tall, and if you crack the throttle wide open it is bound to dump a load of fuel into the engine, making it flood/falter slightly?

....also worth checking your chain tension and the slack in the throttle cables as if these are not spot on, the TRX can be a bit 'jerky' just like beef!

....as for crud in the float bowl, a mechanic freind once told me this:

"So, what was the problem then?"

"Crap in the float bowl sir"

"Oh. How often do I need to do that?"



Dave

[idl1975]

The slide is the big black plastic bit in which the needle sits, which itself sits in the bore when the carb's assembled. He's saying those edges might be binding up in the little grove they sit in.

As to cures for minor jetting woes, I'm sure someone will know...I personally regard the whole thing as a black art and leave it to professionals...

As trixynut says, TRXs are also very sensitive to their throttle cables and chain adjustment. Either one can _potentially_ cause something that may feel like hesitation...

Guys - you are really great at helping people out...

I will definitely go and find some kind of inline filter to try and prevent crud building up again..

Steve – you mentioned cleaning the ‘Slide’ What part is this? I must admit this is the first time I have had a carb apart so I’m on a steep learning curve…

I wonder if the hesitation I am now getting when I roll off and then back on in 5th gear is a combination of over fuelling. Looking at my dyno print, if I was in 5th at 5500rpm (which is when the bike is fuelling worst), rolled off and then went back on again below 3500rpm (which again is when the gike is running rich) it may have too much fuel to cope for a split second?? If this is the case, from what i have read i could adjust the mixture on the pilot Screw ??

Mincehead - will check out that site when I get a moment… Cheers

[idl1975]

In the words of Spike Milligan: I arrest you for old jokes!

Mate,

....as for crud in the float bowl, a mechanic freind once told me this:

"So, what was the problem then?"

"Crap in the float bowl sir"

"Oh. How often do I need to do that?"



Dave

[dandywarhol]

Minor fueling issues can be resolved by accurate fuel level settings, a couple of mm make a difference - how many folk check them???

[Mincehead]

Possibly something to do with the process required to check it though,the mickey mouse haynes manual isn`t the best for giving assisstance in that area.
I made a guage from a small syringe and clear poly tube,when I say `small` syringe I mean those readily available at chemists for insulin,already marked with a scale.You can get 0.3,0.5 and 1ml sizes,makes the float measurement/fuel level thing much easier believe me.
Although I found reference on the forum somewhere to a float height of 15 mm if I remember correctly?
I think it was a factory pro link,the measurement is taken from the top of the larger of the two floats and down to the float bowl gasket face/carb body.It`s easy to do but the carb needs to be held at just the right angle so as not to cause any deflection/pressure on the float needle valve,so just lightly resting on it is the way to go.
When I checked my stock carbs the float levels were 12.5 and 13.5 so both were out,the performance difference from just setting the fuel/float levels was certainly noticeable.

[Norfolk Boy]

Well i'm gutted tonight, On the way home from work i managed to get a bit of good road with no traffic (obviously i'm talkinga about a local track) and realise that whilst i thought my bike was better - its still running bad when you get to the 80mph mark!

It sounds like i need to get my floats tested as well, so its either time to take the bull by the horns or get pay someone to do it

I've been trying to scan a copy of my dyno print out, but it looks like my computer (or scanner) is headind down the same road as my bike.. 3hrs i've been at it 'Diagnosing' potential problems, with no luck at all.

I've now given up and will transfer the data to an excel file and try posting that instead. I think i will put it on a new thread as well, coz this one is getting a bit big - although i have ot say it's rammed full of really useful information.

[Mincehead]

No need for a new thread Norfolk Boy,just post it here when you`ve fended off the gremlins.
Are you `feathering` the throttle at 80 mph (holding a constant speed) or were you still accelerating?

[Norfolk Boy]

Mincehead - thanks for your comments under the dyno graph i posted....

In answer to your question, I was holding a constant speed on a bit of straight, and could feel the bike surge then hesitate, in almost a rhythmical pattern.. I suppose one way to describe is like small waves of power. I say small because it was nothing violent, just quite subtle... Like when you hit a gust of head wind.

As it was playing up on the constant throttle, i tried the old trick of dropping the revs off and then opening up again, which resulted in quite a jerky split second deceleration - then pick up.

Looking at the dyno graph, and going by my limited knowledge of carbs (built up over the last two weeks).. I would guess that at 80 / 85 mph i was pretty much 3/4 throttle open (bike has been dropped at least one tooth on the front) so i would have been running a lot on the main jet. The dyno graph indicates the the more the main jet comes into play, the more the bike is over fuelling. Could this kind of feeling be a result?

I dont think i've mentioned before that the bike has been fitted with a 2-1 Akrapovic full system.. but i suppose that's not really important since we have the dyno graph to see how it's fueling.

I think my course of action is to:

a) make sure no more crud is getting to the carb, but inspecting & cleaning the tank, tap, pump and hoses. I have already ordered a nice glass in-line filter and will put this between the tap and the pump.

b) take the carb apart again clean up the slides as you have suggested (n.b When i had it apart last time i looked at the diaphrams and they seemed ok)

I will also note the size of the main jet in place, and order a smaller one - but is suppose the question is, how small? by taking a ' mean average' across what looks like the Himalayas on the dyno chart over 5500rpm, I know that I need to move the AFR from around 11.9 to 13 (thats assuming the guy in the garage was right and i need to aim for an AFR of 13). but is there anyway of calculating what this means in terms of a jet, or is it just trial and error?

Lower end fuelling is not a million miles out, and if i'm correct in my thinking the smaller main jet will also have a small effect early throttle position (i.e low revs) - and i can further adjust the needle drop if i need to make it any leaner.

The only other consideration is the pilot jet / mix.. could this be having an effect when i roll off ? The bike does seem to vibrate intially from take off, and manoeuvring from at low revs, appears to be all or nothing (appreciate the gearing has a lot to do with this)..

My God - Only 3 weeks in and i'm starting to talk like i know what i'm doing!

Thanks again for your help... I cant wait to get her going properly!

[idl1975]

The Akra system may explain a lot. I know I've said it before, but I would just take it to someone like PDQ and pay them to do the jetting for you and reset your float bowl level (can be a bit fiddly to do if you're clumsy like me!).

That's an absolutely top quality bit of kit o/c, but my GSX-R had an Akra system on it (the cheap one ) and I spent 3 months trying to get it to fuel right from one day to the next. IMO, any full system is really a bit more work to get right than just end cans, plus you've thrown in the K&N and some holes in the airbox. Then you're trying to figure out what the problem is by seat-of-the-pants impressions on the road. Works if your name's Stan Stephens, but otherwise it's a painful way to do things.

Checking fuel system still sounds like a good idea. On the AFR, I would just reiterate that the ideal AFR will very possibly vary by rev and throttle position.

Mincehead - thanks for your comments under the dyno graph i posted....

In answer to your question, I was holding a constant speed on a bit of straight, and could feel the bike surge then hesitate, in almost a rhythmical pattern.. I suppose one way to describe is like small waves of power. I say small because it was nothing violent, just quite subtle... Like when you hit a gust of head wind.

As it was playing up on the constant throttle, i tried the old trick of dropping the revs off and then opening up again, which resulted in quite a jerky split second deceleration - then pick up.

Looking at the dyno graph, and going by my limited knowledge of carbs (built up over the last two weeks).. I would guess that at 80 / 85 mph i was pretty much 3/4 throttle open (bike has been dropped at least one tooth on the front) so i would have been running a lot on the main jet. The dyno graph indicates the the more the main jet comes into play, the more the bike is over fuelling. Could this kind of feeling be a result?

I dont think i've mentioned before that the bike has been fitted with a 2-1 Akrapovic full system.. but i suppose that's not really important since we have the dyno graph to see how it's fueling.

I think my course of action is to:

a) make sure no more crud is getting to the carb, but inspecting & cleaning the tank, tap, pump and hoses. I have already ordered a nice glass in-line filter and will put this between the tap and the pump.

b) take the carb apart again clean up the slides as you have suggested (n.b When i had it apart last time i looked at the diaphrams and they seemed ok)

I will also note the size of the main jet in place, and order a smaller one - but is suppose the question is, how small? by taking a ' mean average' across what looks like the Himalayas on the dyno chart over 5500rpm, I know that I need to move the AFR from around 11.9 to 13 (thats assuming the guy in the garage was right and i need to aim for an AFR of 13). but is there anyway of calculating what this means in terms of a jet, or is it just trial and error?

Lower end fuelling is not a million miles out, and if i'm correct in my thinking the smaller main jet will also have a small effect early throttle position (i.e low revs) - and i can further adjust the needle drop if i need to make it any leaner.

The only other consideration is the pilot jet / mix.. could this be having an effect when i roll off ? The bike does seem to vibrate intially from take off, and manoeuvring from at low revs, appears to be all or nothing (appreciate the gearing has a lot to do with this)..

My God - Only 3 weeks in and i'm starting to talk like i know what i'm doing!

Thanks again for your help... I cant wait to get her going properly!

[TimTrix]

Apologies if you've already checked this but my bike had some of the symptoms you mentioned and it was a badly adjusted throttle position sensor.

[trixynut]

I think if it was a TPS setup problem, the tacho would go into the 'sweeping' diagnostic mode, maybe?

[dandywarhol]

Not always - I chased my tail looking for a fueling fault and it turned out to be the TPS out a tad- I used the 4000 rpm thingumy to reset it............

[Norfolk Boy]

Just an unpdate , incase anyone else was following and finds it useful..

Over the last few days i have:

1) Cleaned all old fuel out of the tank
2) Cleaned the fuel pump and all fuel hoses
3) Fitted an in-line filter between the pump and the carbs

Hopefully this will keep the fuel nice and clean !!! for the carbs i have:

1) Cleaned all jets and main body
2) Made sure all slides were clean and put a bit of silcone dry lubricant on them
3) Bit the bullet and paid for a stage 1 dyno kit & fitted the recomened 148 main jet, along with the needles that came with the kit.
4) checked float height - both were the same at around 15mm so left well alone..
5) changed the pilot jet to 2 1/2 turns out.

RESULTS =

The bike now runs without fault... God knows what part of the work I have done actully cured it, but so long as she's running that's all i care!

Given that the bike was running rich on the standard 142.5 jet, and I've now fitted a 148 and what looked like a lot thinner needle I'm now concerned that she's running even richer.. But i will play with that over the next few weeks, one things for sure I certainly have the knowldege to play with it now !

Thanks all for your help.