Firing on one cylinder.

[cobbadiggabuddyblooo]

Good chance as Rod said it may be the choke sticking to actually foul the plug...

[Shroom]

Thanks for the replies so far, time for an update, I stripped and cleaned the carbs again, this time I completely disassembled and gave the carbs an ultra sonic bath before rebuilding so I can completely rule them out. The bike ran for a bit with a bit of a bike fire through the carb and then the RH cylinder died again.

I was at a complete loss so I checked the valve clearances again, then vaguely remembered seeing a couple of puffs of whitefish smoke the last time she was running, the compression checked out ok but the theory was there could have been a small leak, which was enough to kill the spark.
Got her back together yesterday and she ran for well enough for a few test rides to set up the carbs. Today's job was to lift the needles up a notch and she should be spot on.....get home from work to start her up and the RH cylinder is dead again !

Work so far,
New battery
New plugs
Ignition unit swapped out
Continuity check on coil signal wires
Valve clearances checked ok
Ht leads and caps tested ok
Coils swapped from left to right
Compression tested ok
Carbs stripped and rebuilt 3 maybe 4 times
Coils powered direct through relay
New head gasket
New carb rubbers

So now I have no ideas left and feel like I'm spending far too much time and effort looking for what is most likely a simple problem staring me in the face.

If there is anyone Qld who could lend a hand it would be much appreciated. I'm happy to pay for your time.

Cheers.

[Mincehead]

Thanks for the replies so far, time for an update, I stripped and cleaned the carbs again, this time I completely disassembled and gave the carbs an ultra sonic bath before rebuilding so I can completely rule them out. The bike ran for a bit with a bit of a bike fire through the carb and then the RH cylinder died again.

I was at a complete loss so I checked the valve clearances again, then vaguely remembered seeing a couple of puffs of whitefish smoke the last time she was running, the compression checked out ok but the theory was there could have been a small leak, which was enough to kill the spark.
Got her back together yesterday and she ran for well enough for a few test rides to set up the carbs. Today's job was to lift the needles up a notch and she should be spot on.....get home from work to start her up and the RH cylinder is dead again !

Work so far,
New battery
New plugs
Ignition unit swapped out
Continuity check on coil signal wires
Valve clearances checked ok
Ht leads and caps tested ok
Coils swapped from left to right
Compression tested ok
Carbs stripped and rebuilt 3 maybe 4 times
Coils powered direct through relay
New head gasket
New carb rubbers

So now I have no ideas left and feel like I'm spending far too much time and effort looking for what is most likely a simple problem staring me in the face.

If there is anyone Qld who could lend a hand it would be much appreciated. I'm happy to pay for your time.

Cheers.

Sounds like a job for Macca, http://www.trx850.com/phpBB_forum/membe ... ile&u=3818
or one of the `other` Queenslanders with some bike skills.

[Shroom]

Thanks Mincehead,
I've been chatting to Macca already as I know him from other circles.
Also another local TRXer has been kind enough to let me swap out any parts I need to help troubleshoot, so I'm sure now we will get to the bottom of it.

[Mincehead]

Thanks Mincehead,
I've been chatting to Macca already as I know him from other circles.
Also another local TRXer has been kind enough to let me swap out any parts I need to help troubleshoot, so I'm sure now we will get to the bottom of it.

[Racer-unk]

looks like the only place you have not looked is the pick-up coils, rotor......for what it is worth....and whether those plugs make a decent connection

[Mincehead]

Just ONE other thing, although your valve clearances are in spec your valves may not be. What I`m talking of are these types of issues:

http://www.boatlife.se/forum/uploads/mo ... 790114.jpg

Now that of course is a very badly affected example but exhaust valves especially can have cracks that open up, small chips around their peripheries, small chips in the hard valve seats and even heads distorted and not parallel to the valve stem anymore. Hopefully you`ll find your problem and sort it but don`t rule out at least a top end strip.

[Shroom]

Thanks once again for everyone's help with this issue, after about 3 months it seems that the problem has been found and temporarily fixed.
After speaking exhausting every other avenue and speaking to a couple of people far more knowledgeable than myself. (Thanks Macca) a porous head, inlet track was suspected. To test the theory I added a $20 bottle of K-Seal and the bike ran better within a few seconds then after a few cycles the fault disappeared completely. I've just com back from. 1600km trip with no issues at all.
I'll be looking for a replacement head if any one has a spare?
But does anyone know the longevity of K-seal?
Has anyone had this problem on the TRX?

Cheers.

[yammyman]

WOW.....what a rough road you've ridden to find the problem. Interesting as my TRX has a similar problem but to a lesser degree. Was you bike using a large ammount of coolant. I might have to try the K seal myself and see if it fixes my issue.

[Shroom]

The bike wasn't really using any coolant, I noticed a very small drop in the expansion tank but I put this down to losing a bit from the carbie preheat system, as I had to keep removing them, there was also no difference in compression between cylinders, and no bubbling in the rad.

[Mincehead]

But porous heads can really be difficult to find. Obviously heat plays a big part due to expansion of the alloy, also atmospheric pressures and humidity in inlet tracts.

[wurlyvalve]

Hello,

Sorry to ask the dumb question. K-seal is leaky head gasket fixer gloop? You drained the coolant and sploshed some of this down the rad? Your crack/porosity was on the intake tract which is adjacent to a cooling jacket?

My left hand cylinder has never fired 100% of the time. Would drop out in the rain every bloody time. Now the left hand cylinder will not run at all until the coolant gets to 70c and then the cylinder switches ON (like digital ON/OFF). I wonder if I'm suffering this problem too.
I'm not losing coolant of any note. But like you, strip the blighter apart too often to be 100% confident.
The previous owner stated that the owner before him had claimed to have ported the inlet ports. And there was a load of dyno work to semi vindicate that an owner had some sort of interest in power.
Was/is your head "ported"?

Cheers,
Glen.

[cobbadiggabuddyblooo]

Intake manifolds bolt on and have an o ring seal.
Maybe there is a leak there and once up to temp your finding a seal due to expansion.

[Dion31]

HI There

I am having the same problem with the right cylinder intermittently operating.

1) I replaced the ignition with one from Cobber
2) Purchased installed a a good set of carbs
3) Checked the coils as per manual
4) Replaced the plugs
5) Full carb rebuild and ultrasonic clean

After all of this she ran well for one decent ride and then after sitting for a while I went to start her up and she only ran on the left cylinder again. Seems to be a very common problem for this bike. Has anyone actually been able to diagnose what it is once and for all?

[dandywarhol]

HI There

I am having the same problem with the right cylinder intermittently operating.

1) I replaced the ignition with one from Cobber
2) Purchased installed a a good set of carbs
3) Checked the coils as per manual
4) Replaced the plugs
5) Full carb rebuild and ultrasonic clean

After all of this she ran well for one decent ride and then after sitting for a while I went to start her up and she only ran on the left cylinder again. Seems to be a very common problem for this bike. Has anyone actually been able to diagnose what it is once and for all?

Unscrew the HT lead from the coil and check for corrosion where the coil screws in. The stock leads are steel cored - if you haven't already done it, replace the leads with copper core leads and see if your problem disappears - it did for mine