xt600 weird starting problem
 

After getting my needle and set fixed my problem now is the motor will not start when its cold i have to use aero start to fire it up. Once its warmed up then i can stop it and restart it with out probems. Whats the deal? Choke seems to be fine(no sticking)

It also has a hickup (backfire)while its running once every few secs.
Can any body help out?

niko.:confused1:

Read on
 

Hi Niko,
You are where I was about 2 months ago; new bike (to me) and an issue with poor starting and a newbie on the HUBB.
I am no expert on the engine and I don't want to try to diagnose your problem but I do advise you to read the back-threads in this technical forum for some great advice from others who do know what they are talking about! It sorted me out. It is a simple design and one of the guys out there on this forum has seen it before. Look at the threads for both the XT and the TT (my bike) - the engines are much the same.

For quite some time I thought my bike had a fuelling problem but it turned out to be electrical (the earth and, maybe, a dirty spark plug).

Thing is to change one thing at a time and look for the effect that has, be methodical and patient also; if you have a spark and good fuel then it will fire up and then you can adjust/fine tune.

Hope this helps,

Dave

Idle mix
 

If before the replacement of the needles etc (why did you do that anyway, never seen an XT where that was necessary), the engine ran, and you did not change anything else, I'd guess the idle mix is now too lean, as you have installed new, not worn jets.
The easy fix is to adjust the idle mix, see earlier posts.

Always a good idea to have a good, new spark plug BTW.

If the above doesn't work, start worrying about the following:
Further, to install new jest you have taken the float bowl off. You sure you did not bent the float or something?
Is enough fuel arriving in the float bowl?
Are the connections between carb and cilinder head airtight?

Auke

thanks guys for replying, first off its got a new battery(drycell) a new spark plug, and new needle and seat( old one was worn out and had stuck)
the float is ok and not bent and the rubber manifolds are good.

Now it could be an earth problem(will test that out tomorrow)
One thing it does do once its running is if i put my hand over the air cleaner hole the motor starts to really rev this normal??

Or maybe the spark plug gap is not right or idle screw not adjusted right(its 2 turns out now)

niko.

Idle screw
 

Niko,
My idle screw is set at near enough 3 turns out from fully in; there are two different values in the cd information that I have and this is the average of those recommendations; all of this for the 3AJ engine in a TT600R. Set at 2 turns it would be running lean I guess, but I don't know how sensitive the idle screw is to one whole turn!!

Cheers,

Dave

Choke
 

Hi,

in the swimmer chamber is a channel where the pipe for the choke fits in. I check that channel with some water drops and look if they make it through the channel into the chamer. If the channel is blocked, this is often the problem if the XTs don`t like to start when it is cold. This happens often after bikes did park for a long time with fuel in the carb.

regards Thomas

www.motozulu.com

again thanks guys , i'll try the idle screw at 3 turns and see how that goes.
One thing ive noticed with the spark plug its blackish not gray once i remove it this means its running rich?

Also motor has bee sitting awhile with out been started so water could be an issue.
niko.

Niko,

I would not want to send you down a dead-end road! Everything so far sounds like a fuel problem (but it could be electrical!!)

As aukeboss says, have a look back (do a search in here) at the past threads about setting the idle screw; there is loads of good information for the XT and TT (so look for both) with lengthy descriptions of what to do.

Good luck. If you are systematic and change one thing at a time and look for what happens it will get sorted out, :thumbup1:

Cheers,

Dave

well today i tried to start it again with the same problem. I had a look at the spark and it was there and didnt look to strong(not blue)
I went over the earth conections and made sure they were clean.
Once it started it again with aerostart and once warmed it ran(still backfiring) Took it for a drive and had a few misses when i gave it a boot full.
Next thing im going to get rid of the old fuel(98oct) and put some new 95 in.
See how that goes.

niko.

Plugs and things
 

Again, as mentioned before, it's worth fitting a new spark plug - I am getting a spark with my old one but I don't know how old it is so I have a brand new one ready to fit the next time I have the tank off (and that won't be long!!).
It's an Irridium type which are supposed to be better at starting as well as running and they don't cost too much here in UK.

My earth problem was sorted by cleaning the back of the coil where it touchs the frame - it was dirty/greasy - once that was sandpapered the bike was much easier to start!!

Cheers,

Dave

sparkplug is a new one, and i did the same sanding the area under the coil mounting.

One thing Dave, what gap did you use on the plug?

niko.

0.8 mm
 

Hi again Niko,
The recommendation is 0.8 - 0.9 mm. I used 0.8mm on the NGK DPR98EA plug.

I was not sure if cleaning the plug made any difference as well as "re-earthing" the coil - I did both at the same time, hence my comment about changing one thing at a time and checking for the result.

Cheers

Dave

thanks Dave, ive set that gap right, set the idle screw to 2.5 (3 no good)turns and took it for a test drive and well its till not happy. Its fine running around in 1st and 2nd but as soon as you floor it it bogs down bad.
Must try again.

niko.

`One thing it does do once its running is if i put my hand over the air cleaner hole the motor starts to really rev this normal??`

No, not normal. It means two things: 1) the idle mix is way, way too lean and 2) the idle speed setting is way, way too high.
If you block part of the air intake, apparently the mix gets better ...., ie richer.

When you said you replaced needle and seat, did you mean the float needle and seat or the needle and jets in the carb throat(s)?

Just presuming you mean the float needle, I'd go back to the float level setting, check that one by either removing the float bowl and measure or by using the way described in the manual with a piece of transparent hose.
Or the check the other possibilities for the lean mixture: false air drawn in somewhere, blocked jets etc.

Auke

thanks for that,i'll have another look tomorrow does sound like theres must be another air leak somwhere. Yes you were right i did replace the float needle/seat. I did use the air compressor to clean the inner workings of the carbie so im sure the jets are fine.
Could be the manifold rubber inlets leaking.
So to richen up the mixture the idle screw needs to wind out more to 3.5 will try that tomorrow too.

thanks,
niko

Inlet manifolds: the rubber comes away from the metal part. They look ok but will leak a lot of air.

hi Niko,
How are you getting on with the pilot screw setting?

I have just taken another look at my cd; there are two recommended settings, depending which bit of the data is read! One says 3.5 turns out from fully in and the other says 2.75 +/- 0.5 turn. This is for a 2004 TT600RE with the 3AJ engine.

I deduce that a movement of around, say, 1/2 turn either way in adjusting is a reasonable way forward (and a full turn in total is not un-reasonable).

Suggest you search in here for "setting the idle screw" or pilot screw - there is lots of information in more detail.

Cheers,

Dave

Float chamber
 

hi Niko,

did you check the choke channel in your float chamber?

I guess that is your problem.

regards

Thomas

sorry guys have been away, but will have another look at it on the weekend.
At the moment ive got it at 2.5 turns out.I will try and take it to 3.5 or more. Remember im running a pod air filter not the original one and i think its getting alot more air.

Choke tunnel i will have a look and give it a clean too.

niko.

heres a pic of the beast, it took me two years to design and build it.

Niko,

2 wheels good, 4 wheels not so good, unless it is two motorbikes!! :rolleyes2:




Just kidding!!!!!!!!!!!!!!!!!!!:innocent:


Good luck with the engine adjustments,

Dave

ha ha, the funny thing is i also have a xt600 bike which i got to pull apart for a spare motor but when it came it was too good to wreck so now ive got a bike to ride. Probably not the right bike to learn on but im doing ok so far.

niko.

I reckon the XT will be fine for learning; crack on with that while fixing the 4 wheel transport!!

Good luck with the engine tuning,

Dave

right on, now found the problem today the rubber gaskets were totally broken(both of them) they had looked perfect but when i removed them discoverd the problem.

Now to find a new pair, any ideas were to get them from???


niko.

Never had to buy them Niko but I have read elsewhere that they are expensive as Yamaha OEM (isn't everything from the main dealers!?).

Those on the road say that they have used car hose as a replacement or repair - depending on where the splits are that may be an option? Maybe, the car wholesale parts people have the same type of hosing available - I'm talking here for the upsteam side; I guess the downstream side of the carbs need the proper fitting that bolts onto the cyl head.

I am currently sorting out a gasket problem on my bike - when the carbs go back in I will be using liquid gasket goo to seal the carbs to the airways - maybe the same stuff can be used to make a repair of your splits. Just a thought,

Good luck,

Dave

thanks dave, i did use a loctite product which is a alloy to rubber super glue but it really only lasted a few runs so i think im up for a new pair. EBAY here i come!!


niko.

Pirate
 

Hi,

you also get the manifolds as pirate part (at least in south africa and germany) , not the same quality but also less than half the price.

2nd hand is not an option I think because they all break with the time.

regards

Thomas

sounds good, where to buy?

niko