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2003 thunderbird sport
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Discussion Starter · #1 ·
I have just bought a 2003 thunderbird sport, it seems well maintained but I have come across two things which I would appreciate your views on. I have searched the site which mentions some of the issues but I have not seen a suggested cure.
1. I would like to adjust the front suspension but the fork leg adjusters at the base of the forks are seized and a bit chewed up. I have tried soaking with releasing fluid for two day and a bit of heat but the brass adjusters are so soft i don’t want to make things any worse. I was also thinking of drilling a hole in it tapping it and inserting an Allen head bolt coated in jb weld, but I can’t find a schematic to see how thick the brass screw is to see if this is possible?
2. The bike starts and runs nicely but there is very noticeable vibration between 3500 to 4500. I was thinking coils, but why isn’t it there all the time?. I am thinking carbs but I don’t know what would affect this rev range. It accelerates to 8000 rpm with out a problem.
I would appreciate any point of view as I don’t really know where to start.
 

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I do not have a Sport so cannot give any advice on the forks. The vibration very well could be the normal harmonics of this engine that typically shows up around 3500 rpms. Without riding your bike it’s hard to say for sure, let your conscience be your guide. Many new owners report the vibration
 

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As Brg-bird already stated with the vibration, my bike does it around 3000-3200rpm. If your bike is doing it up to 4500rpm make sure your not shifting to soon and lugging the engine. I realize that RPMS are RPMs no matter what gear your in but try winding her up a bit more on the tach before shifting and see if that helps. I know you said vibration is coming from engine but maybe take a look at your tires, how old are they? could be slightly out of balance or flat spot causing a slight issue at certain rpms then smoothing out. Hows the bearings on your headstock ( steering ). Just throwing these out there being its a Triumph and ( speaking from experience ), the problem never seems to be what we think it is! ;)
 

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4000 -4500 rpm's should be in the engine's happy spot. Maybe a cylinder is not firing as it should. I look at the spark plugs, are they a toasty brown as they should be. Maybe one has a different color than the others. Do you have an infrared temperature sensor (non-touch). Is one exhaust header a much different temperature than the others at idle.
 

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Discussion Starter · #5 ·
I do not have a Sport so cannot give any advice on the forks. The vibration very well could be the normal harmonics of this engine that typically shows up around 3500 rpms. Without riding your bike it’s hard to say for sure, let your conscience be your guide. Many new owners report the vibration
Thanks BRG-BiRD I’m sure I’ll get used to it when I ride it more often, I’ll just do the routine service checks and put my mind at rest.
As Brg-bird already stated with the vibration, my bike does it around 3000-3200rpm. If your bike is doing it up to 4500rpm make sure your not shifting to soon and lugging the engine. I realize that RPMS are RPMs no matter what gear your in but try winding her up a bit more on the tach before shifting and see if that helps. I know you said vibration is coming from engine but maybe take a look at your tires, how old are they? could be slightly out of balance or flat spot causing a slight issue at certain rpms then smoothing out. Hows the bearings on your headstock ( steering ). Just throwing these out there being its a Triumph and ( speaking from experience ), the problem never seems to be what we think it is! ;)
Thank you landlocked you have given me some pointers which I will tryout/ check out. I know you have to get used to a bike and I’ve only riden it three times so I could well have to review my great change times. Enjoying checking out the mechanicals for next years riding and getting used to the bike. Many Thanks.
 

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Discussion Starter · #6 ·
4000 -4500 rpm's should be in the engine's happy spot. Maybe a cylinder is not firing as it should. I look at the spark plugs, are they a toasty brown as they should be. Maybe one has a different color than the others. Do you have an infrared temperature sensor (non-touch). Is one exhaust header a much different temperature than the others at idle.
That’s a thought I’m going to change to stick coils and ilI pull the plugs first to see if there a good colour. I’ll also get a temperature checker too. Many Thanks.
 

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Hi John, I'm using stick coils that came from a big twin Thunderbird. Three years now and no problems. I just added a big o-ring at the top of the stick coil to seal up the gap in the valve cover opening for the spark plug.
 

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Discussion Starter · #9 ·
Hi John, I'm using stick coils that came from a big twin Thunderbird. Three years now and no problems. I just added a big o-ring at the top of the stick coil to seal up the gap in the valve cover opening for the spark plug.
Hi Greg I bought some Honda 600rr coils and a Honda coil harness which I’m going to adapt and retape to suit the Thunderbird. I hoping for an improvement but reliability will be a sufficient bonus. I’m pleased to hear you have had no problems in three years. I like the o ring idea and I have a few which might do the job. I followed a post on the sight for the information to do the coils.
 
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