Plug Fouling - Still Got issues

[louis]

If i look to the plug it is to rich, i have a tzr125 4dl who had something like your tzr250.

It started nice but after a few second it started to run badly, way to rich. i did clean the carbs a couple of times
it stays the same (if i turn of the fuel and let it run, the last seconds when the bowls are getting empty the engine runs great)
So i thought the carb is overflowing so i order new floatneedles but still the same.
but after a good inspection (it a 32mm dellorto carb with i don't have a lot off experience with) it turns out that the air jet was blocked off by (something) that did not go away with compressed air i had to make it free with a 1mm drill

I think perhaps yours has a blocked airjet to, when blocked off the carb is getting way way richer. (extremely)
 You can try to remove your rear carb rubbers and blow gently in front of the air jet (they are mounted in the lower part at the front off the carb)
But the right way to do it is to remove the carbs and clean them then.
Do not underestimate the function off a air jet

It is just a idea fore you to consider

Cheers

ps. My English is still not good, hope you understand what i mean

[m3-paul]

I have taken all the info on board and will try it tomorrow morning. Going to have a good look through the left hand carb before i start looking at the coil, rings etc etc. Work through one thing at a time until I find the cause. I am a computer systems engineer for Sun Microsystems (now Oracle) so am used to working in a methodical manner, just not on motorbikes .

Well, I hope to have something positive to report back tomorrow.

Looking at the workshop manual I assume the air jet is referred to as the "pilot" air jet?

Thanks again for all the advice guys, and Louis, your english is fine .

[maccas]

if you swap the left hand suppressor cap and lead over to the right hand cylinder and vice versa does the problem switch to the right hand cylinder?, if it does then surely it is ignition related? the bike runs a wasted spark so if the bike were running normally this wouldn't cause any problems

[ndwedwe]

i wonder
could it be the LHS crank seal?

[m3-paul]

if you swap the left hand suppressor cap and lead over to the right hand cylinder and vice versa does the problem switch to the right hand cylinder?, if it does then surely it is ignition related? the bike runs a wasted spark so if the bike were running normally this wouldn't cause any problems

Ah, I wondered if I could do this. That is excellent info to rule out the coil. I actaully hope it is the coil but somehow suspect not but will try in a second.

i wonder
could it be the LHS crank seal?

I really hope not. Will check the oil level as it was at max as I only changed the oil maybe 150 miles ago or so.

[m3-paul]

Swapped the plug loads over and it started for around 5 seconds on both cylinders then dropped to the right again, remember it has stood overnight and I wiped off the plug before I put it back in.

The main thing is, for those 5 seconds it ran as good as it normally does so I don't think I have a goosed left cylinder.

Sounds like carburation so that will be my next port of call. Any other suggestions then please add them.

[maccas]

when you say left hand cylinder you mean as if you were sat on the bike? if thats the case then the lhs crankseal wouldn't cause the plug to oil up i wouldn't have thought, there is no oil in the generator side of the engine

[m3-paul]

when you say left hand cylinder you mean as if you were sat on the bike? if thats the case then the lhs crankseal wouldn't cause the plug to oil up i wouldn't have thought, there is no oil in the generator side of the engine

That is correct yes. If you sit on the bike it is the cylinder on the left of you.

[m3-paul]

You bunch of clever buggers . Sorted!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Stripped the left carb and even though it was really clean inside I took out the pilot air jet, and the pilot jet, gave them and the main jet a quick blow through and checked the other passageways etc. Nothing obvious to me causing this but i also see the float to be bang on 17mm. It was around 15 to 15.5mm which I know is in spec but felt it was worth adjusting to 17mm.

Also checked the fuel tap and that is not allowing fuel to pass when the engine is off so happy with that.

Started her up on choke and it fired after two kicks and settled to a nice fast idle. Thirty seconds later switched off the choke and it settled to idle at 1500rpm. Nice and responsive again on the throttle so all appears well.

So happy and the main thing is with the help of you guys I have learned more.

Gonna put the fairings back on etc and take it for a small ride tomorrow but yep, you could say i am one very happy bloke, cheers guys for all the help, sincerely appreciated .

Will be getting the top end overhauled over the winter as well.

[Warwick]

Even more usefully, you'll now be more confident with your own diagnoses when you have similar problems in the future (and you will, lol). Pleased you've got it sorted. Such problems can be frustrating to trace, but it's always a good feeling when you've cracked it. Nice one.

[m3-paul]

Must admit, I have had a few issues before but this was the one that worried me the most because of what I feared it could be. Had a real sense of achievement when it fired up and I got that familier noise of both cylinders bubbling away and more importantly, a nice bit of smoke from BOTH exhausts .

[ndwedwe]

when you say left hand cylinder you mean as if you were sat on the bike? if that's the case then the lhs crankseal wouldn't cause the plug to oil up i wouldn't have thought, there is no oil in the generator side of the engine

yes, there is no oil on flywheel side, even if the crank seal was blown, it wouldn't let oil in, not to that degree anyway.
what it does do it muck around with your crank pressure and can cause huge confusion and problems as described. it can have the exact same time delay thing as when the seal is cold it can seal better, then after a minute or 2 it expands or gets a little softer and the problems start. it could still be the seal, problem might reoccur. i don't think a blocked pilot jet would make the plug oil up, i never completely understood the air jets with solenoid, that only worked later in RPM??
LHS crank seal can be changed behind flywheel, RHS involves more work.
not to be defensive, i seized LHS barrel twice and it cost me dearly.

[m3-paul]

Hopefully all should be good. I took it for a 60 mile run yesterday and the only thing that happened was it started spluttering and losing power about .5 mile from home. I though it might be happening again but i switched to reserve and it evened out again and was fine. Went to the coast and much of the journey was on the motorway cruising at 70 to 80mph. Got the engine really warm according to the temp guage .

Just about to take it out again to fill it up (like to keep the tank full whenever possible).

The oil level is on max still from when I last changed the oil.

The oil pre change must have been there ages and was pitch black. The current oil is going the same way so I am going to drain that again and refill with fresh, i guess this oil has done a job of cleaning up as much as anything else .

[m3-paul]

Okay, the problem is still there. I have swapped a spare carb onto the left side to see if it is a carb problem but the problem is still there. The left cylinder does run but you have to keep the revs up to over 5000rpm otherwise the left cylinder starts to miss, giving it the full beans seems to clear it a bit. The left exhaust is also cooler than the right. I took the left plug out after running it with both cylinders firing. It was a little damp on the electrode but was obviously able to just keep on firing without totally fouling

Went to Taymar Racing today as they are only eight miles from me and spoke to Martin. I am booking the bike in for a fresh set of rings next month hopefully. He said it may need new pistons and possible rebore if a peg has snapped in the exhaust port etc but lets hope it is just rings needed. It would seem to be around £170 for the job including the parts if it is just rings.

I would give it a go myself but I haven't got a torque wrench and the fact that the cylinders may never have been removed makes me think it is better to let the pros do this one thing on it this time.

Does rings sound like a likely culprit for this problem? Certainly seems to be the mileage and time to do them regardless.

I think things like the crank seals etc are okay but again, I guess Martin will give it the once over just for the sake of it.

[mickey]

The Carb you put on..did you strip it and make sure it's all good before you fitted it..??In your previous post you said once you unblocked pilot jet bike ran fine so why all of a sudden is it rings.??Has the bike been stood for awhile since you last rode it.?...If you take the float bowls off and they have alot of dirt in them them your tank will need flushing out otherwise the problem will always be there..