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Trophy '98 1200 Not firing on cyl 1

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Chriss217
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Joined: 03 May 2021
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PostPosted: 12:54 - 03 May 2021    Post subject: Trophy '98 1200 Not firing on cyl 1 Reply with quote

Can anyone suggest what to do next?
My 4 cylinder Trophy 1200 starts but the exhaust temp on cylinder 1 stays at ambient. ie. No fuel or spark.
Compression and valve clearances checked ok. Splugs replaced. Crankshaft pickup changed. Igniter swapped. LT leads from coils to igniter checked. HT leads swapped between 1 & 4. HT Coils swapped over.
Carbs removed and cleaned out.

I'm clean out of ideas on what to do next. Any thoughts out there?
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Robby
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PostPosted: 14:23 - 03 May 2021    Post subject: Reply with quote

You have compression and you've done lots of things to get spark - and I'm assuming you have verified that the plug is still sparking outside the cylinder - so the next thing is fuel.

When you open up the drain plug for the no1 carb, is there any fuel in it?
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Chriss217
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PostPosted: 15:28 - 03 May 2021    Post subject: Reply with quote

Thanks. I connected 2 plugs (to compare) outside and thought lead 1 was less sparky than the other. I also tried an "Adjustable Spark Tester" (red knob to adjust the gap) and thought the spark from lead 1 appeared weaker.
On this basis I brought an Igniter "from a working bike" on Ebay. No difference. Still being suspicious I sent my original Igniter to Carmo electronics. They report it is working fine. Currently waiting for it to be returned so I can do another set of tests, this time when its dark hopefully to show the spark (or lack of) better.

Re: Drain plug. Excellent idea. I hadn't tried that but have done so just now. There *is* fuel in carb 1.
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jeffyjeff
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PostPosted: 17:10 - 03 May 2021    Post subject: Reply with quote

Check the high tension leads and cap. Also make sure that you aren't using resistor plugs in conjunction with resistor type lead wires.
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Robby
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PostPosted: 17:50 - 03 May 2021    Post subject: Reply with quote

Seeing as bikes still tend to start with a weedy yellow spark, making subjective judgements between two plugs when you're looking for a problem is a recipe for trouble.

You changed the plugs swapped the HT leads between cyl 1 and 4, and the problem didn't move. That means it probably isn't ignition related. You checked compression, I'm assuming on all 4 cylinders to compare. As long as they were within 20 psi, it would still work.

Seeing as it appears that cylinder isn't working at all, fuel is the next place to look. When you checked it I'm assuming you looked at what came out to verify that it was fuel and not water - the left-hand carb is more likely to accumulate water, being downhill of the others.

Next thing I would do is go through that carb and look for something broken enough to not let any fuel through.
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Chriss217
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PostPosted: 18:37 - 03 May 2021    Post subject: Reply with quote

Thanks Guys.
@JJ. The leads and caps are as originally fitted, hence I haven't replaced non-resistive with resistive or the other way round. Of course either a cap and/or lead may fail however I swapped lead+cap between 1 & 4. Fault was unchanged.
@Robby. TBH I took my bike to a local m/c workshop, they checked the shims and compression and reported it was ok. They also stripped the carbs (twice) and cleaned the crap out.
Re: Petrol or Water. It definitely smells of petrol.
My igniter is due back on Wednesday, I'll refit it then do some more ignition checks then focus on the carbs.
Its starting to sound probable that some jets or pathways in carb 1 is blocked.
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jeffyjeff
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PostPosted: 19:55 - 03 May 2021    Post subject: Re: Trophy '98 1200 Not firing on cyl 1 Reply with quote

Chriss217 wrote:
Can anyone suggest what to do next?
My 4 cylinder Trophy 1200 starts but the exhaust temp on cylinder 1 stays at ambient. ie. No fuel or spark.

If no spark on #1 even after swapping leads, and you know the igniter is good, try swapping the coils. By now, it's the only thing you haven't changed. Normally when a coil goes, both sides go bad, #1 and its companion cylinder (#4 if the firing order is 1-3-4-2). I suppose that one of your coils could have an abnormal fault, or excess resistance internally to cyl #1. If so, swapping coils should move the dead spark to a different cylinder.
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Chriss217
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PostPosted: 22:09 - 03 May 2021    Post subject: Reply with quote

Thanks JJ.
As mentioned in my OP I swapped the leads and HT coils. I'm expecting my igniter (tested as ok), to be returned on Wednesday, so I will reconfirm the effects of swapping leads/plugs/coils.
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Chriss217
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PostPosted: 09:18 - 04 May 2021    Post subject: Can I swap HT leads connected to the same HT coil Reply with quote

This may be a silly question. When the HT coils are triggered is a spark sent to both the HT leads?
ie. As cyl 1 is on compression does it get a spark AND simultaneously does cyl 4 on exhaust stroke also get a spark. Likewise, half a stroke later, does the 2nd coil send a spark to both 2 and 3 (one on compression, the other on exhaust).
I'm wondering if I can swap the HT leads between the outputs on the same coil.
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Robby
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PostPosted: 09:40 - 04 May 2021    Post subject: Reply with quote

Yes. Bikes typically run a wasted spark system, so you get a spark at ignition and another one on exhaust. I thought you had already tried this when you said HT lead swapped between 1 and 4.

If you swap the leads between two cylinder on the same coil, then if the problem is related to spark the problem will move between cylinders.
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Chriss217
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PostPosted: 10:23 - 04 May 2021    Post subject: Reply with quote

Unfortunately I didn't document the combinations I tried, hence the plan for a redo once I get my original & tested igniter back on Wednesday.
I think I swapped the 1 & 4 leads by moving both ends. In case there was/is a problem with one of the HT coil outputs I swapping the HT coils over, while keeping the LT leads in the same order.

ie. Before the coil swap the order was: Coil left: LT1 to left connect, LT2 to right. HT1 (left o/p) to cyl 1, HT2 (right o/p) to cyl 4. Coil right: LT3 to left, LT4 to right. HT3 to cyl 3, HT4 to cyl 2.

After the swap: Coil left (was right coil): LT1 to left, LT2 to right. HT1 to cyl 1, HT2 to cyl 4. Coil right (was left coil): connected in the same order as before.
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Robby
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PostPosted: 10:38 - 04 May 2021    Post subject: Reply with quote

Ok, so you swapped the coils over but kept the wiring the same, and the problem didn't move. This tells you that everything upstream of the ignition coils was OK. So you can trust the igniter/CDI, LT wiring, and coils.

That means the only potential things to be wrong in the ignition side are the HT lead and the spark plug.

For future reference, the usual way to do this bit of diagnosis is to do the easiest thing. Unplug HT leads from your suspect cylinder and a working cylinder on the same coil, and swap them over. If the problem moves then the problem is with the HT lead or that side of the coil output. Diagnosis is all about minimising the number of things you're testing each time.

That said, it looks like pretty much everything that could cause a problem with the spark has been looked at, and a spark problem is unlikely.

Important question that I should have asked much earlier. Was this bike previously running fine (in your ownership), and did anything happen to stop it running fine? Or was it sat in the shed for a long time doing nothing while 2020 was happening?
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Chriss217
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PostPosted: 11:05 - 04 May 2021    Post subject: Reply with quote

For several years the bike was my daily commute, but over the last 15 years it has been ridden several (10 or so) times each year. In 2020 I probably only rode it a few times. I think I've gradually got use to a misfire until recently when the misfire became more pronounced and a real PITA to handle.

My original igniter is now scheduled for return today. So I hope to do some checks later.

Thank you for your help.
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Chriss217
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PostPosted: 00:17 - 06 May 2021    Post subject: Better but still misfiring Reply with quote

Yesterday I refitted my original (and tested) igniter. To give a baseline before running further tests, I reconnected the coils and tank lines. Firing up showed cyl1 exhaust with a low temp but I could hear it firing occasionally.

Today I took it for a blast. Between 30-50mph it misfires around 40% of the time giving a very jerky and unsettling ride. With the throttle wide and speeds above 65 the bike is pulling like a train and firing on all cylinders. Wahoo!

Although the bike is better than the last time I took it out, it feels rather iffy at low speeds, it even stalled on me as I started out. I'm guessing that the carbs have a couple of jets and that carb 1 still has junk in it.

I think my next step next week is to remove the carbs and strip carb1. I'm hoping that providing I keep the carbs connected together I can open carb1 without unsetting the balance. Any suggestions?
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Easy-X
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PostPosted: 01:55 - 06 May 2021    Post subject: Reply with quote

Most of the essentials - main jet, emulsion tube, pilot jet - should all be accessible through the float bowl so you should be fine.
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Robby
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PostPosted: 16:48 - 06 May 2021    Post subject: Reply with quote

You can keep the carbs on the bank to avoid upsetting the balance. You'll need to remove the float bowls to get at the jets, and the tops to get at the needles and check the diaphragms, but the bodies can stay on the rail and you don't need to touch the balance adjusters.

It's a powerful bike, so low speed stuff will be relying on the idle circuit, small jets and the needle. Main jet only comes into play at full throttle, along with most of the needle. So I would be looking for a blockage in a narrow passage, making sure all the idle circuit (mixture) screws are set the same, and making sure all the needles are set the same.

If it has a fuel filter, worth changing that while you have access.

Any problem should be fairly obvious- a very clogged jet, or a lot of crud coming out of a passageway when you squirt carb cleaner in from the other end. Most bikes run surprisingly well with what looks like quite significant problems - partially blocked things, fairly big air leaks, that sort of thing.

If fiddling with the carbs doesn't sort it, then it's back to electricals. Cleaning up any earthing points and replacing the HT leads and plug caps is pretty much a service job on a 10 year old bike.

The wonderful world of fault diagnosis. It's nearly always a little bit of dirt or corrosion in the wrong place, or a minor break in an important wire.
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