Firing on one cylinder.

Shroom · Post by **Shroom** » Fri Aug 04, 2017 8:13 am

Hi Guys, I've been having trouble with Rexie since the last group ride on the sunny coast. She never missed a beat all day then the next morning she only fired up on one cylinder.
I've had some keyster carbie rebuild kits siting at home for a while so I rebuilt the carbs to rule that out. She fired straight up! Problem solved.
She ran fine for a couple of weeks when about 2kms into a ride she drops to one cylinder again. Cold RH pipe no spark? The coil checks out fine chuck in some new plugs and she starts up. Problem solved. A few days later and same again. I swapped the coils dried off the plug stuck it back in and she's good again.
A day later same problem. Plugged the original ignition back in, still no spark, checked for continuity on the coil signal wires while wiggling them about and they seem to be ok. Came back a day later to have another look at her and I have a spark.
Again she ran for a few days and same again. This time though I have a spark (at least while the plug is out) but I'm just getting a wet plug and she just won't run on the Rh cylinder. I've checked and double checked float levels and all is good.
Am I missing something simple here? Chasing more than one fault? The only thing to check is the compression but my tester doesn't have the right adaptor.
Any help would be appreciated, chances are she start up again tomorrow but I can't really ride anywhere except around the block incase I get the same problems.

Post by **dicky** » Fri Aug 04, 2017 8:17 am

I haven't tried this myself so I'm not sure if the leads will reach, but try and swap the coils over.
If you find you then have intermittent running on the left pot then you can bet it's the coil.

Rod.s · Post by **Rod.s** » Fri Aug 04, 2017 1:06 pm

dicky wrote:I haven't tried this myself so I'm not sure if the leads will reach, but try and swap the coils over.
If you find you then have intermittent running on the left pot then you can bet it's the coil.

might be easer to swap the leads at the coils...

Post by **dicky** » Fri Aug 04, 2017 1:58 pm

Rod.s wrote:
dicky wrote:I haven't tried this myself so I'm not sure if the leads will reach, but try and swap the coils over.
If you find you then have intermittent running on the left pot then you can bet it's the coil.
might be easer to swap the leads at the coils...

That's what I meant, sorry for any confusion.

Shroom · Post by **Shroom** » Fri Aug 04, 2017 7:35 pm

I have swapped the coils and leads with no success, which lead me to checking the feeds to the coils. There are no apparent faults but I'm thinking of wiring the coils directly to the battery to eliminate any possibilities of intermittent faults. Has any one done this? It's also why I'm thinking the spark or lack of any one could of been a red herring (maybe not grounding the plug and properly when testing previously) and the problem is fueling (which is why I rechecked the float heights) or compression loss. (Which I can't check easily) ?mmmmm?

cobbadiggabuddyblooo · Post by **cobbadiggabuddyblooo** » Sat Aug 05, 2017 2:32 am

Yep, I run my coils through a relay with a built in 30 amp blade fuse.
Just don't use the original R/H coil power feed to trigger the relay. If it's an intermittent power feed to R/H coil you'll still have an intermittent problem because it powers the relay switch to open the direct power feed from the battery.
Use a larger single 15 amp power feed from the relay and branch it at the coils to feed both.

http://www.trx850.com/phpBB_forum/viewt ... il#p109554

Shroom · Post by **Shroom** » Sun Aug 06, 2017 8:41 am

Thanks Cobba,
I have a dual contact relay here so I'll try and mount it near the coils then run a feed and earth from the battery and use the LH coil as the switch. I guess this will help to eliminate the ignition as a problem. Although looking at the wiring diagram the RH coil feed is tapped into the LH feed somewhere near the front of the bike, so if the power feed is the problem it's somewhere in that small section. Do you feel that it's worth powering the coils with a direct feed any way?

Cheers

cobbadiggabuddyblooo · Post by **cobbadiggabuddyblooo** » Sun Aug 06, 2017 12:02 pm

Makes it a little more responsive especially noticeable down low and cleaner, faster starting.

Shroom · Post by **Shroom** » Tue Aug 08, 2017 7:39 am

Ah well, that didn't work, it started on both but quickly dropped the RH cylinder again. I guess I could tap in to the signal wire near the ignition box just to be sure that's not the issue but I'm leaning towards stripping the carbs again. Maybe I missed something there, the keyster kit is pretty comprehensive but maybe one of the passage ways are blocked.
It would be good to check the compression also to make sure I'm not wasting my time.
Any tips or pointers are appreciated.

cobbadiggabuddyblooo · Post by **cobbadiggabuddyblooo** » Tue Aug 08, 2017 11:52 am

Did you replace the plugs at all.
I've had 1 fail on me about 8 yrs ago and they where only replaced 500km previously.

Shroom · Post by **Shroom** » Tue Aug 08, 2017 11:20 pm

Yeh new plugs installed around a month ago just after the start of the problems and covered less than 50kms. I've also tried swapping them from left to right.

yammyman · Post by **yammyman** » Tue Aug 29, 2017 11:06 am

Mmmm....this is beginning to sound all too familiar but mine does it less frequently and on the left cylinder. It did it too me on Sunday before a quick blast up the Clyde montain. Sometimes it will quickly clear and fire up on both cylinders but not this day. I whipped the almost new plug out, cleaned it up, threw it back in and hey presto....two cylinders firing and I'm off. It has me beat and has done this off and on over the last year. The carbs have been rrebuilt and the valve clearances checked recently and all is good. I feel the left cylinder is down on power as it runs a little cooler than the right...weird.??

Rod.s · Post by **Rod.s** » Tue Aug 29, 2017 1:18 pm

The choke on these can stick on giving one rich cylinder, try lubrication the choke slides (external front) and pulling the choke on and off a few times the next time it happens.

cobbadiggabuddyblooo · Post by **cobbadiggabuddyblooo** » Tue Aug 29, 2017 1:26 pm

Quite common for cylinder 1 to run a little cooler than the other on the trx and it's been discussed a few times. Some even run 1 jet size richer on cylinder 2.
Some feel it may be due to the cam chain galley next to cylinder 2 not allowing the same dissipation of heat but I have my own theory being exhaust pulse due to the uneven firing pattern of the 270* crank.

yammyman · Post by **yammyman** » Wed Aug 30, 2017 10:14 am

Thanks Cobba, I was starting to think there was something a bit more sinister going on with the left cylinder, yet in every other way the bike performs flawlessly and with 91,000 klm on the clock is doing well......luv it to bits. I'll get that rear brake set up installed soon.....after I do the emulators and springs, if I can keep my arse off the seat that is.

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Firing on one cylinder.

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