XT 600e tune up?
 

Hi there.I'd like to start off by saying that this has been an ongoing situation for me, and I have got a lot of helpfull advice off the Hubb which has helped me chip away at my problem XT. A while back I had running problems with my 4PT, which left me stranded on the side of the road in the middle of winter a few times:thumbdown:. I have since thrown a lot of money at it (as you do when you not a mechanic), with only a moderate amount of success. I have so far changed: the Coil, with lead and cap
cut out the sidestand switch
cut out the clutch switch
installed K&N filter, DEP silencer, and DynaJet stage 2
swopped the CDI unit to prove it
installed new chain and sprockets
all wiring checked and terminals greaced
changed the spark plug about 4 times

The chain and sprockets actually made a big difference, because they were exagerating the flat spot which has been there all along. I have had the bike at a Yamaha Main dealer, twice, and my local bike shop, twice. I would like to take this oppertunity to say my local guys were WAAAAY better than Yamaha, but still didnt get to the bottom of the problem. The bike problem is as follows. When I'm riding along at slow speed, from about 2-3500RPM the bike feels like its starving for fuel, just a little. There is a pop or two sometimes too. If I pull the choke out just a little it comes right, but the bike doesnt like this when really hot. If I give it a handfull of throttle and it shoots past this point, it seems ok, and its ok on full throttle cruising. Idling is sweet too. Its just that initial bit after pull off. Since the choke kinda fixes it, and chokes enrich the fueling temporarily, it must be starving for fuel just a bit. Is this something to do with the fuel/air mixture screw? And if so, how come the bike shops I went to didnt see this? Is there a bike mechanic in London who knows a lot about singles? Can I just turn the screw and hope for the best?:rolleyes2:

hi mate just check plug gap and elimanate that mine used to do that also try another garage for petrol. you may have checked these before but its the simple things that sometimes we miss good luck

Adjust you CO screw out a bit, that should richen it up a bit.

Otherwise, get it on a dyno, so you can see the fuel/air mixture over the whoole powerband..

Inlet Rubbers???
 

Have you checked the inlet rubbers for splits, de-lamination, pin holes yet?

It may be a long shot but easy to check.

Cheers from Oz.

Dyno is the way to go you may have an air leak which the dyno should spot. Gibson exhausts (see web for their address) are having a dyno day on Saturday and its only £10 a run and there is free food you could take advantage of that they are just off junction 28 of the M25 so easy to get to.

Thanks for the response. I think Dyno is the way to go. I get petrol from multiple stations, plug is good. Rubbers are new looking, but that could be something to look at.
A mate at work has said something about lifting the needle one notch. Without a dyno this would be like shooting in the dark though. I need a tuner, just running it on the dyno is only half the job. Thanks again for the replies. Cheers

carb basics
 

rule of thumb for carbs in basic terms are mixture screws are for idle to low revs, needle adjustments are for the transition from low to mid revs and the main jets are for full revs:cool4:

dyna needles tend to be more tapered than standard to give that smoother transition so i'd go up 1 notch or even beter if you can go half a notch some kits have tiny washers for those .5 increments :eek2:

I just did a little experiment. I rode home with the choke pulled out just a little. It seemed to almost cure the problem. The problem is definitly lean running, from low to medium throttle. Thanks for the info Wolfzero, that is what I need. What do you rekon I should do? The idle is good, so probably the needle position. Do I put the little clip one notch down to get the needle to raise a little more?

yep clip one notch down will raise the needle but like i said if your dyno kit came with those tiny washers they are nomaly half as thick as the gap between the grooves in the needles so you can raise the needle by half a clip by putting one washer under the clip as you fit it into the slide but dont worry if you aint got em you just might be ok going a full notch and a little mixture adjusting as the idle mix might alter slightly :cool4:

Any shop with a dyno will (should) be able to explain what the dyno read out means and be able to tell you what is causing the problem and how to sort it. I use the dyno at Gibson exhaust and they can tell me exactly what to change from the read out, but that should be the case with any shop with a dyno.

unfortunatly thats not always the case some dyno owners are just that:(

if your looking for a dyno go for one attached to either a carb or exhaust specialist preferably both as thats what dynos were developed for and if your really lucky the guy running it should be in his sixties an ex racer with a passion for perfection:thumbup1:

Is it popping a bit between low gear changes, and upon deacceleration? It should if its lean.

The CO/fuel-screw affect the whole area, just not much in the top. But i needed to adjust mine after the change of primary jets.

hence the should, i can read a dyno sheet and its not rocket science, modern dyno's do most of the work for you older ones require a bit more mechanical knowledge or trial and error for some. If they own a dyno they should have done a course on how to use it, but i agree thats not always the case.......

Inlet rubbers?
 

It is easy to check, use a spray bottle (atomiser) with a bit of fuel and spray onto inlet rubbers.

I did the same with a hose pipe once and sure enough steam came out of the exhaust :)

my 4pt kept cutting out at odd times, turned out it was a dodgy neutral switch (on the left side of engine under gear pedal) and a loose vibrating connector on the CDI (under the tail unit). i found out after spending a fortune on trying to mend it, and a tweak with some longnose pliers sorted it.

How do you get into the neutral switch? I can see where the wire is mounted with a screw (mine is kinda stuck:() Do you take the whole sidecase of? Can't really remember how it looks down there.

Mine is working from time to time, i figure its the switch itself beeing bad, not the connections, and I wanna have a look.

jens the wire to the neutral switch is hidden in the side cover but you dont need to take the side cover off as its just in front of the gear shift shaft they do wear out but wont affect running as when they wear out the stop coming on unless your really unlucky and it shorts out:(

cos it starts and idle's ok i doubt its the carb rubbers :innocent:

i'd try the needle first and you can check the inlet stubbs at the same time if you want to be sure :innocent:

Is it popping a bit between low gear changes, and upon deacceleration? It should if its lean.

This is exactly what happens. I will alter the carbs accordingly. I've yet to find a Dyno tuning shop with a 60 year old racer guru dude. I only know Dyno owners :thumbdown:

Right! I made a little T piece out of a screwdriver so I could adjust the air mixture screw without taking the bike apart. It worked like a charm! God-Damm! Its a whole different bike! A mate at work said if I need to wind out the screw so much, I probably need a bigger slow running jet. How many times can you turn this mixture screw? I dont know where it was before, but I turned it out 4.5 revolutions. Is there a chance the screw is holding on by just a thread and could pop out?

wind it all the way in and count your turns so you can return it to your current setting :innocent: then wind it all the way out counting your turns again and see how many turns in total you have before it comes out then you have a better understanding of how many threads you have left:thumbup1:

When stock, my screw was 6 whole turns out, i dont think anyone have ever messed with it, it showed nice fuel/air ration at a dynorun.

So that can be done. But for the peace of mind, you might want to consider a bigger idlejet

In the manual it say the standard Pilot jet is a size 48. How much do you think I should go up by?

One notch should be enough.

What's you're specs? (exhaust, airfilter and such)

K&N filter, Dep Silencer, DynoJet Stage 2, although I'm starting to suspect the installation side of that:thumbdown:. I think I need a bigger pilot jet. How many times can you wind the pilot screw out? I've got it out 5 whole turns. How many turns does it have before it pops out? I'm gonna adjust the needle when I get chance, but the pilot screw has made such a difference already, I suspect its the main problem.

like i said erlia wind it all the way in and count your turns so you can return it to your current setting :innocent: then wind it all the way out counting your turns again and see how many turns in total you have before it pops out then you have a better understanding of how many threads you have left on that pilot screw:thumbup1:

i'd try the needle adjustment first before going up one size on the pilot jet mainly cos its free unless you have a stack of jets in stock :rolleyes2:

you can drill your're 48 pilet jet with a 0.50mm drill... thats almost free.

As I said, when mine was stock, it was 6 turns out, so that should be within the safezone. Otherwise do as wolfzero explains.

You can make a rough idlejet adjustment at home....

Make sure the bikes is warmed up a bit. Rev the bike, and let if fall to idle, if it pops when the revs go down, you're lean. Adjust the CO screw out and try again, till its not popping/backfiring...


WHat did you're dynojet stage2 kit content of, what was "in" it?

My ride is just rejettet, with appropriate jets.

Whens the engines properly warm, turn the pilot screw in until the revs drop. Then turn it out until the revs increase, and keep going until they start to drop again. Count how many turns it is from each extreme then set the screw in the middle position.
SO, EXAMPLE: winding out 2 turns, carry on (revs go up) then keep turning and they start to drop - say 4 turns out. Set to 3 turns! If you have to turn the screw otu more than half a dozen then you need to replace the pilot jet.

Awesome guys. I commute on my bike, so I cant do too much work on it till I have a Saterday to play with, but my tinkering and turning of the pilot screw has fixed my bike a great deal. I still want to bump the needle up one notch, and then tune the pilot screw accordingly. I dont get any popping any more, but there is slight hesitation at low speeds. I must stress, after I turned the pilot screw, this hesitation is minimal. I've had to learn about this stuff quick, because my attitude before was, let the bike shop do the stuff I dont know how to do. But recently I've discovered that they dont know everything, and it would seem their knowledge is a bit thinner in the single cylinder category. They completely missed the pilot screw and it cost me HUNDREDS of pounds in labour. So now I'm gonna tinker as much as I can, because the bike shop doesnt have all the answers. Thanks very much for all your input!

The dynaJet kit came with a needle, and a couple of drill bits, which the bike shop now has.:thumbdown: I will see If I can get it back sometime and check the sizes.

Hey are a few pics of my bike, and the little T-piece I made to adjust the air mixture screw

Great pictures, I love looking at other XT's :D

Cool little screwdriver, I found a similar tiny one on an old keyring this afternoon.

Derek, are they Avon Distanzias I see on your bike?
If so how do you find them on the road in wet and dry conditions?

They are. I did fall off at my work once in the wet, but I think the tar in the parking lot was mouldy/winter-ed up:oops2:. Other than that, I cant fault them. I give them a good blast everyday and they remain good. I do, however, want to go more offroad bias tyres. Pirelli MT 21's :funmeteryes:

Ok thanks.
I will order a pair on Monday.
The new ones that were put on it when I bought it are awful on the road even in the dry.
It will be good to get some tyres that I can be more confident with.

Distanzias arrived today, the front came off and went on no problem but I had a hard time getting the 4.60 off the rim.
I think the shop I bought the bike from put the wrong size tyre on.

Derek what pressures do you use front and back for road use.

I weigh about 90KG's with my protective gear on, no pillion or luggage.
Place I ordered the tyres from said 26 front 32 rear.
Avon said 33 front 36 rear.

Get different pressures from every thread I read from google.

People have different preferences :)

WAAAAY too high.

From the Yamaha Owner's Manual -

Front 1.5 bar (22 psi)
Rear 1.5 bar (22 psi) up to 90Kg load, 2.25 bar (33 psi) over 90Kg load or high speed riding.

I run my Distanzias at 22F/26R and they are fine. The higher figure for the rear is because I am a lardy old git and also have a topbox permanently fitted which adds a few Kgs to the back end.

I ran my old Kingstires at 21/26 but thought I should ask the manufacurer regarding the Distanzias rather than going by the XT owners manual that are referring to the Dunlops and Bridgestones.

I would have thought the individual tyre makes have their guide pressures rather than using the same owners manual recommendations for any make of tyre but I am probably wrong about that.

I probably weight in at about 110kg with my riding kit on, and I use the Yamaha recommended pressure. 1.5 on the front, 2.25 on the rear, for motorway commuting:thumbup1:.
I works for me.

All tires should have the recommended PSI labeled on them on at least one of the sides next to the rim size and width....

Just go from there and then go lower or higher depending on how you feel the bike matches your likings or not

Vando :cool4:

That makes sense but, as you said earlier, there seems to be no consensus on what the pressures should be. All I can say is that I stick to the Yamaha recommendations and they work fine. Anything much lower or higher gives noticeably worse handling. True for the Avons and the TrailWings I had on before.

I have finally solved my running problems. I upped the primary needle up one notch, and leaned up the air mixture screw a bit. Job done. She starts with no choke now:clap:

mmm i'm pretty sure i said to do that first :innocent: glad you got it sorted :thumbup1: the standard xt carbs are quite forgiving and are not hard to work on.

fitting different carbs and a big bore is not so easy mine is still in need of some fine tuning but its getting closer :thumbup1:

If it starts in cold temperatures and around sealevel, with no choke, and keeps going, you're running to rich in the low end.