250 Txt Pro Starting

[steveenduro]

Hi.

I've just bought a 2002 txt pro and I'm having problems starting.

It is getting fuel and has a spark (though looks a little weak).

It is difficult whether hot or cold, and there does not seem to be a pattern to it. Best so far seems to be a few kicks with choke on, then an open throttle kick with choke off. Normally takes 10-20 kicks either way.

I've cleaned carb, changed air filter, checked grounds, stator gap.

I'm about to strip top end and check rigs etc, but compression feels fine (too much if anything)!

Any other suggestions appreciated.

Also just drained coolant and it is a light brown, with a greasy feel. Is this just very old coolant of a sign of oil contamination. Gearbox oil looks fine.

When throttling off, say downhill, I get a loud whirring, regardless of what gear I'm in. There is also a lot of clutch noise until the the clutch is pulled in, and the bike is placed in gear. I've ridden a 2003 bike, and it is much much quieter. Could it be gearbox related?

The rear wheel spokes are seized on nipples, and most are loose, I guess I'm looking at a wheel rebuild?

Many thanks

Steve

[peterb]

Hi Steve,

This has a Kokusan ign system and these rarely go wrong. The HT cap may need to be removed, cut off 10mm of HT lead and screw back on, just to rule this out as a problem. Less than 5 kicks is the norm for hot/cold start. From cold, I always lay the bike down to the left to flood the carb. Could be a dirty carb, completely strip the jets and the emulsion tube (needle jet) then blow out all passage ways. Check float arms are parallel to the carb bowl mating surface when carb upside down. Check fuel is getting through fuel tap.

Change the coolant, I use 100% anti freeze for the PRO.

Does the plug get wet - is it water or petrol?

Loud whirring may be std feature of your bike, it isn't usual for these. Check the clutch centre bush has not worn. Some had rather excessive clutch rattle, problem with having very thin, straight cut primary gears.

There are two different lengths of spoke on the rear wheel, check out which length goes where. Assemble spoke/nipple with water proof grease.

Hope this helps, bye, PeterB.

[steveenduro]

Thanks Peter.

The a worn clutch bush would seem sensible - I'll check it out. Are they prone to wear on these bikes?

Carb has been thoroughly cleaned, and jets blown through. Float height is good.

I've already cut back the HT lead. The spark from the lead will jump 1/2" to ground, but spark seems feeble at the plug. The cap resistance is ok at 5kohm.

I think I'll do the top end anyway, just to have a look. Are the bikes still difficult to kick even when compression is low? I think zero maintenance was done on this bike previously, so I'll work through it bit by bit. I'm just hoping it stops short of splitting the crank!

Steve

[yamahaty250xox]

the whiring could be the main bearings. i have a freind with a gasgas and it was grumbly and whiring. turned out to be the main bairings.

[dabomb]

Has the bike got fresh fuel in?and have you changed the plug?.Simple questions,but with a bike thats new to you,it worth checking.

Good luck

[sectionone]

IMO, Pros are harder to start than other brands even when brand new and especially if you are vertically challenged. What I do is stand on the pegs when starting by leaning against a tree or leaning the front wheel against a rock and put all your weight into the kick.

[cdn280]

My previous 2002 280 was also sometimes hard to start. Check the plug wire as mentioned and also check the gap on the ignition pickup which should be .4mm. Before I finally got a starting ritual down I also found leaning the bike over til it peed out some gas helped when it was very cold. Maybe it needed a slightly richer pilot, but I found it was better after turning in the air screw a half turn or so. On that bike the ritual was an easy kick through to clear things out, then choke on and 1 or 2 quick stabs on the kicker. By quick stabs, I mean a short fast kick, not a jump up and slam down with all your weight until the kicker SLAMS on the footpeg. The kicker doesn't have a lot of leverage, nor does it spin the engine very fast. The same kicking method applies to my 2008 250, but on it when its warm I don't need the choke when the engine is cold and the air temps are warmer. Once it fires I play with the choke for a couple seconds until it accepts throttle. Using this method is a lot easier on my foot without the slamming, and the lever rarely hits the peg any more.

[sectionone]

True, the lever should not slam the footpeg, but it is designed to hit it. The key is to kick hard and fast at the top of the stroke, then the lever slows down and hits the peg, but not too hard.

[steveenduro]

Thanks for your help. Kicking technique is something I need to master, but I can't help thinking there is something else amiss.

I too the barrel off tonight to have a look. All seems suprisingly good. The chamber is a bit sooty and wet, and there is more oil in there than I expected. Gear oil level seems a bit lower, could it be making it's way in?

The barrel has very light marks but no real scores.

I can't feel any play in small or big end bearings.

I left the piston in place and removed the rings, and looked at end gap when placed 10mm from top of bore.

They were:

Top ring = 0.35mm

Middle ring = 0.50mm

Bottom ring = 0.40mm

My take on them is that they need replacing, but are not as bad as to cause sig. loss of compression and starting problems, but would welcome your expert opinions.

I don't suppose I should re-use existing base gasket and top o rings? (I think I know the answer to that)!

To get the right base gasket is it good enough to mic. the thickness of existing gasket, where not squished, and place the same thickness in?

BTW, if anyone is removing their radiator for the first time, remember to take of the top hose (with thermocouple) and the HT coil first. It took me a while to work that one out!

Cheers

Steve

[peterb]

Hi Steve,

I forgot about this posting! Your rings are fairly worn but not such a bad thing, .5mm is 20 thou, usually for a bore this size (250) 6 thou is the norm when new. I am not sure if you have L section Dykes rings or plain, if Dykes then 20 thou is still ok!

Always fit new head O rings if you strip off the head. I have re-used base gaskets many times, always been ok but best policy is to fit new ones, on the 250 std size is 0.8mm thick - but best to check what was in there as sometimes the motors came out with other thicknesses. You should be able to keep the rad in situ when removing the barrel/head.

You've probably got it going by now - is all ok?

Ta ta, PeterB.

[steveenduro]

Hi Peter.

Not going yet, but mostly back together.

I couldn't get the barrel of without taking rad out - must be a knack to it!

I did have a dykes ring, but replaced them all anyway whilst it was apart.

Old base gasket was 0.8mm, so replaced with the same, and also the top o rings and exhaust seals.

Found dirty water only in rad - no antifreeze, and lots of scaling.

Tomorrow I plan to start it with a 50/50 mix water and white vinegar to clear scale, then refill with coolant. Unless I get a "OMG, don't put vinegar in it!" reply.

I'll let you know how it pans out, but for now, as long as it runs it will have to do, as I need to do a mains/crank rebuild on my KTM 200.

Took the flywheel of that tonight in about 5 seconds with my new cordless impact wrench, after hours of struggling with makeshift holding tools, locking back wheel etc etc.

Should have bought one years ago!

Suppose I may need it to do mains on the txt one day too, but don't want to think about it. Mind you that rough whine on shut off is suspicious, but definately sounds more clutch/gearbox than mains. Think I'll have a drop of rough whine myself now.

Oh well, we enjoy tinkering really, don't we?

Cheers

Steve

[jse]

Tomorrow I plan to start it with a 50/50 mix water and white vinegar to clear scale, then refill with coolant. Unless I get a "OMG, don't put vinegar in it!" reply.

Steve

Steve,

As far as I know, a short stint with vinegar should be o.k., I haven't tried it myself but my chemist buddy says that a normal 5% acetic acid dulution of vinegar (or ethanoic acid, glacial acetic acid, ethylic acid, methanecarboxylic acid or vinegar acid and it's also known) should be safe as long as it's not left in contact with the aluminum for any length of time. Let us know how it works.

I know the malty stuff goes well with chips.......

Jon

[steveenduro]

The vinegar worked a treat!

I put the solution in, started the bike (eventually), and run it until the fan came on. Drained the solution, and flushed with water. The scale that I could see just inside the top of the rad was virtually clear.

So it's all back together, but still a pig to start. It's getting a good healthy kick (my right leg muscles are much bigger since I bought the bike).

The carb had a good clean. I've tried all settings of the mixture screw. The flywheel to pick-up gap has been tried at 0.4mm and 0.7mm. (The videos say 0.7mm, but a recent post said 0.4mm)?

I've tried conventional plug (BP5ES) and iridium plug. New air filter. Fresh gas. Changed plug cap.

The plug gets wet, and there is a spark at the plug, though it still seems a little weak and does not always spark between the electrodes.

What seems to work sometimes when hot is - couple of kicks no choke, couple of kicks with choke, the kick wiyhout choke and full throttle. It seems as though I have to flood it intentionally and clear it!

I've also noticed that if I tip the bike over on it's side, the carb doesn't pee petrol out. Is this right? Every bike I've owned did, but the delorto may be quirky. I've checked float height and it's as spec (18.5mm to the tangs IIRC).

I guess it has to be spark, or fuel. If I could find out which one, it would narrow the search.

Is there a definitive way of checking ignition side - coil resistances etc.

Steve

[cdn280]

Guess the next step is to make sure the float level is ok, it should pee out fuel if leaned over on its left side. Maybe a new needle/seat would help too. I adjusted the float height on mine as it didn't seem like it was closing the needle/seat even when the float was fully raised. I changed it about 1mm so it would close sooner and it was better. No problem with fuel starvation.

For the spark plug, only ones that are gas or oil fouled will will spark up the side where its finding a path of lesser resistance. Is it smokey after it warms up? I had to lean mine out by opening the air screw to about 3 - 3.5 turns and then ended up raising the clip 1 notch (leaner) and set the air screw in a bit to about 2.5 before starting wasn't a real issue.

I don't think you said what oil mixture you were using, but 50:1 should be the richest needed with a synthetic oil. I've always used 70-80:1 for normal trials stuff and up to 50:1 only when trailing it at higher speeds.

[steveenduro]

I'm using 80:1 synthetic.

Plug does look oily though - more than I would expect.

Started today after about 6 or 7 kicks, choke on but throttle open!

I may take the carb apart again even though it looks clean.

Steve