Triumphrat

craigfortune · 04-23-2009, 10:59 AM

Hi guys,

I'm new around here so... hi

I'm looking for some advice in regards to a Trophy 900 (P reg/1996 - I believe it was the first of the newer body style) I've bought recently. I'm having a terrible time with the idle. I've attempted to set the idle to roughly 1150 (a tad high by some people's opinions, but sounds right to me for something just shy of a litre - the mechanic seemed a little surprised when I said I had seen people suggest about 900).

When I'm sat at a junction etc my idle will sometimes shoot up (sometimes even up to 3k) and take a while to come back down. Sometimes just oscillating around a bit. Occasionally it may even drop lower than 1150 for a while. It's just simply erratic and I never really know what it wants to do.

For a few things to cross off the list:

Carbs are balanced
New plugs
New air filter

Which leads me to think coils. I don't know if they are gill coils or not (need to find some time to get the tank off and check). Does anyone have any other thoughts? I'm pretty sure it isn't a fueling problem as she runs fine when not at idle. (or should I say attempting to idle)

Further to backup the thought that it is the coils, 2 of the plugs where a bit sooty (middle and right cylinder) and one was fine. Mechanic said it didn't seem to want to rev past 6k in top gear too.

Other than this annoyance, I'm really liking the Trophy - even considering taking it to Spain in the late summer (I'm in the UK) if it decides to be 100% reliable for me.

BlueTrophy · 04-23-2009, 12:10 PM

Most I have seen puts the idle at 1000 or just under. What you have sounds like a vac. leak possibly or something gone wrong with the choke. I just changed out the Gill coils for Nologys this week. I did not have any issues with the idle going up but it would drop to the point the engine would die or it would just die instantly. Check the condition of your vac. line and the plug on the tops of the other two carbs.

craigfortune · 04-23-2009, 12:24 PM

I'm somewhat hesitant to think it is the vac line, as the problem is erratic. A problem with the vac line would be pretty much constant, no?

I've noticed the bike can take a while to "de rev" as well. By this I mean if I'm at idle and I blip the throttle it will take a while to come back to normal pace.

Trophymick · 04-23-2009, 03:53 PM

Take a look at your diaphragms in the top of the carbs, same symptoms. Check carefully they are delicate. A pin prick size hole is all it needs to effect the vacuum effect of the diaphragms.
You can get new ones for less than £10, if I remember correctly.
Hope you get it sorted!

Trophymick

craigfortune · 04-23-2009, 07:13 PM

I think I'll try the ride to work tomorrow with the fuel set to prime (that should override the vac right?) and see if I get any difference in behaviour.

Will report back when I get a chance

Cheers guys.

narrowminded · 04-24-2009, 05:20 AM

Don't see how the coils could draw more fuel into the carbs to make it rev higher. Mis-fire, yes, increase rpm, I don't know.
My 900 idles fine at a hair below 1000rpm.
If the idle is too high these bikes won't de-rev properly.
If I had to guess, I"d say your idle is set way too high because at idle the fuel system isn't free flowing and she's starving. Intermittantly gas flows as it should and she races up.
Check the fuel tank vents, over flow tube, tip-over valve, fuel line filters, petcock etc.
Rather than setting her to prime, try opening the gas cap and see where she idles.
A 12 year old bike, probably the filters, vent or petcock, or all three.
Just my thoughts at 4:25 am.

Carry on!

craigfortune · 04-24-2009, 11:29 AM

Fair point.

Running with the tank cap open wasn't an option today (quite a full tank at the moment) so I had to put it to prime. Bike seems to be running much better at idle, still bouncing around a bit, but a marked improvement for sure. I'll try getting the idle a bit lower and see if she likes it.

Should running on prime totally bypass the valve in the petcock? (It should if I understand the system correctly)

narrowminded · 04-24-2009, 04:39 PM

Yes,
Make sure you turn it back to run!

Carry on!

Mark62 · 04-25-2009, 05:19 PM

Any chance the petcock diaphram is leaking and sucking fuel through vacuum line?