Engine problem

[Planx]

Hi All,

I wonder if anyone can help me with what, to me, is a strange engine/running problem. Here's the story.

I started the engine a couple of weeks ago on a project TRX for the first time in about 18 months (drained tank and new fuel first). It started like a dream. Smooth, idled with no problem and revved freely. I ran it for probably 10 minutes or so to warm up decently in order to drain and change the oil. Really happy with the result, I got on with other jobs on the brakes, etc.,

A couple of nights ago, having obtained a new oil filter I went out to fit it and do a second oil change (the original stuff was REALLY horrible) and discovered that I had somehow left the ignition on - probably on the weekend - and totally drained the (new) battery. Charged it up over two days and tried starting the engine. Unlike the previous run, it was very reluctant to start and when it did it was rough and totally refused to run below about 1500 rpm. I ran it for no more than about a minute, and then noticed that the left-hand exaust downpipe was literally glowing red hot, while the right-hand one was barely warm.

An ex-motorcycle mechanic friend suggested (without having chance to see the bike) that my ignition leaving on incident might have damaged one or other of the ignition components with the effect that firing on the left cylinder was so late that most of the burn was in the exhaust. Seemed plausible to me and I'm fortunate enough to have pretty much a complete spare set of TRX electrics, so I have just changed - one at a time - the igniter unit and both coils. No difference.

The right downpipe still stays very cool, so I wondered if the right cyliner is operating. To test, I disconnected the two coils in turn and tried starting the engine. With the right disconnected, no noticable difference in running. With the left disconnected, no response; won't run at all. I tested the spark on the right-hand plug lead while running on just the left cylinder and it is a good 6-8 mm spark.

Has anyone experienced similar symptoms and found the cure? Could it be something to do with the ignition triggers/pick-up coil? I haven't tried changing these. Any other suggestions?

Any help appreciated.

[M.V.]

Haven't experienced anything similar, but if the battery was completely dead, it may be useless now... I'd try another battery & go from there.

[Con Rod]

not the battery, you have power, you have spark, do you have fuel in that cylinder? Have a look at the carb float bowls

[BigAl-TC]

This might seem like a smartarse question, have you tried changing the plugs ? one could have died,it does happen. I like to try the simple things first. I have been bitten by a brand new plug that was a dead one.

[cobbadiggabuddyblooo]

yer good point, I had an iridium plug die within 500km's

[skull-candy18]

How do you set ignition timing on a trx? Hot down pipe to the point it is glowing could be serious retardation of the ignition.

[sanddune51]

Am I missing something here?

It sounds to me as simple as one of your ignition coils failing. I think you've proved that by swapping the coils over. I had the same thing happen to me a year or so ago.

Look for the simple explanations first and prove them correct or not before moving along the fault finding avenue.

Of course trying to diagnose other peoples problems via the internet is fraught difficulties. Good luck.


Mark.

[Planx]

Hi All, and thanks for the replies.

The point here is that I appear to have two simultaneous problems with an engine that was running fine a few days back, when nothing has been done in the meantime except leaving the ignition switched on.

One is the right cylinder not doing anything and the other is the glowing exhaust on the left.

Yes, a fuel fault could have occured or the spark plug could have failed to kill the right cylinder, but it seems like a bit of a coincidence. Definitely not coils because I've changed them and checked the spark at the plug.

As for the glowing left, it does sound like serious retardation, but, according to the manual, there are no timing adjustments. And definitely, absolutely, nothing mechanical has been changed. So if there is retardation it seems to come down either to the igniter or maybe the triggers. I have swapped the igniter for a spare - admittedly of unknown condition - but it did exactly the same as the original. I'll have to get a look at the triggers on the weekend.

Barry

[phuk72]

Am I missing something here?

Yes - he says his pipe was glowing red hot. If that is correct, he has a serious problem.

Let's start from the beginning - something must have happened or changed to stop a perfectly running bike from working.

So we know we need spark, fuel, and compression. Have you defintely got all of those to both cylinders.

the TRX will run on one cylinder so you shoudl be able to move leads etc around to confirm where the problem is. eg if the right pots runs fine with x coil, y lead and z plug swap all of them to the left pot. Does it run? No? is there fuel? No - sort it. Yes leaves you with a compression or timing issue

be methodical and report back your findings. Even running on one cylinder for prolonged period should nt result in the pipe glowing. Can you also whip off teh pipes?

[Planx]

be methodical and report back your findings

I'm pretty cretain I am being methodical. Just to reiterate:

• Engine running fine. Shut down and leave for a week or so.
  Absolutely, definitely, nothing done to the engine or anything related to it.
  Work in the meantime limited to brakes and general cleaning.
  Somehow, ignition switched on and left. Battery run down to nothing.
  Battery charged for two days and now holds voltage output under repeated starter operation.

Checks made:

• Swap the igniter for a another one. No change, so swap back.
  Swap the LH coil for a spare. No change.
  Swap RH coil for a spare. No change.
  Disconnect LH coil and try starting on RH only. No start.
  Disconnect RH coil and try starting on LH only. Starts and runs exactly as when the RH coil was connected.
  Check spark on RH plug while running on left cylinder. Good spark.
  Reconnect RH coil and swap igniter again to try it with the replacement coils. No change.

So the only 'event' between running fine and the current state has been leaving the ignition on. There is no possibility whatsoever of the basic mechanical timing being out and there are no other adjustments. Of couse, I could have a fuel/plug/other fault on the RH cylinder, but that wouldn't explain the overheating exhaust on the left.

As I understand it, these engines have an odd firing pattern (i.e. not 180 degrees apart). Correct? If so, is it possible that something is retarding the electronic ignition sufficiently cause different effects on the two cylinders - overheating pipe on the left and complete failure of burn on the right?

[Killerwhale]

How do you set ignition timing on a trx? Hot down pipe to the point it is glowing could be serious retardation of the ignition.

Crap in the carbs has made a friends KTM begin to have glowing headers.
Lean as hell....

[Planx]

Hi Killerwhale,

Thinking about it all day, I begun to wonder if the idea of an electrical/timing fault resulting from leaving the ignition on was maybe a red herring, and whether fuel/mixture might be more plausible. As I said, the engine ran absolutely fine a couple of weekends ago, but that was the first time for around 18 months or more. Maybe it had stirred up gunge in the carbs that then settled/coagulated somewhere inside over the following week, resulting in no fuel to the RH pot and a very, very lean mix on the LH.

Anyway I decided that a clean of the carbs couldn't do any harm in any case, so I have removed them and (after 3 hours of trying to undo the screws) managed to remove the float chamber covers. It is not a pretty sight inside. I haven't looked carefully or removed anything else, but there are some nasty-looking deposits in the chambers, and the visible jets look green and furry - I'm pleased to say. It would have been irritating to find them clean and shiny after all the work of getting the carbs off.

I will strip and clean them over the weekend, and report back on the result.

[cobbadiggabuddyblooo]

Check both spark plugs while at it to just eliminate that too while at it before putting back together.

[pbear62]

Yep, I've had a new Iridium sparkplug just die too - will definately only run on one cylinder then &
the header pipe is cold to the touch.

Also, there has been discussion on here previously about glowing header pipes - a few guys have
reported that when starting the bike in a dark garage the glow is visible. (mine does this too)

Andy

[Planx]

Just reporting back that the problem is now fixed, and was fuel after all and not some weird timing fault.

I was going to clean/overhaul the original carbs, but had serious problems getting the diaphagm cover screws out, so I eventually just dropped a spare pair on. Immediately the fuel came through, the engine started and ran like a dream - both cylinders and no glowing exhaust pipes. So, it looks like the complete starvation on number 2 and extremely weak on number 1 theory was correct.

This time I won't leave it for over a week before running it again - just in case these carbs decide to gum up.

Thanks again for all your suggestions.

One other question. There is a drain (vent?) pipe from the air box which, as far as I can tell, goes to a pipe connection on the inside of the chassis. I can't find anything about it in the manuals. Can anyone tell me why they would drain or vent the air box into the chassis?

Barry