Triumphrat

Rainman9 · 01-23-2008

Friends:

I've noticed over the last year that my Trophy just doesn't have the top speed that it used to. I remember when my bike was new occasionally running it up to about 135 mph. I notice these days that it maxes out at about 110. This is with a top box and some gear in the side bags.

I recently decided to have my local dealer put my bike on his dyno. The results of the dyno comfirmed my suspicion. The max hp reading at the wheel was 64 hp. They wound it out and got 147 mph without any aerodynamic drag on the bike. As you know, the factory hp rating on the engine is about 104. My bike has 60K miles on it.

I have been meticulous about the scheduled maintenence on my bike. I do my own valve shim adjustments and follow the procedures in the shop manual. However, since I do not have the Triumph valve tool I am force to remove the cam shaft(s) each time I have to R&R a shim. I take my time and pay a lot of attention to getting the cams in-time. Of course, I am not a Triumph trained mechanic. Like everyone, I occasionally make mistakes. Oviously, I have already considered to possibility of having a cam out of time. Since the problem has been going on over at least two successive valve adjustments, I would have had to have made the same mistake more than once.

What other issues could cause this loss of power? I appreciate you taking time to help me out.

Wayne

sailfish · 01-24-2008

You might end up having a long list to eventually check, but the very first thing that I would check is compression. Gauges are cheap to buy, even cheaper to borrow. Remember to open the throttle to wide open when you're cranking it over to take a reading.

After that I think that I'd check the fuel system, filters, hoses, etc. Maybe pull the bowls off of the carbs for a look and a cleaning, reset the float level. If you have Mikuinis, your main jet holes won't be round anymore. Balance the carbs to each other. Does the throttle open the carbs to wide open? I've been fooled by that one before. Are the CV diaphrams in good shape? Have a look at the air intake to make sure that a mouse didn't move in upstream from the air filter. Maybe a coil is dying but I would think that you would notice a miss.

Did your fuel milage change in this period?

Here's to it being something simple and inexpensive.

Rainman9 · 01-24-2008

Thanks Sailfish. I will add the carbs to my list. The fuel economy is the same as always. If I drive 65 - 70 mph I get around 38 mpg. If I dog it, it goes down to about 25 to 30 mpg. The dealers mechanic said the exhaust gasses looked normal when he had it on the dyno. I've heard that some times the ignition starts to degrade on these bikes. The carbs could be the problem. Also, I've only changed the air filter once in 60K. The filter is a booger to get in and out. Last time I did it I invented a few new four letter words.

sailfish · 01-24-2008

Quote:

Originally Posted by Rainman9

Also, I've only changed the air filter once in 60K. The filter is a booger to get in and out. Last time I did it I invented a few new four letter words.

I would move cleaning the filter up the list. It is an unpleasant job, but a necessary one. The recommended service interval is high at about 25,000 mile. That might be fine in the UK where there is most likely more mud than dust (just guessing, never been there, UK residents feel free to correct me) but where I live, I can't go that long. I do a valve adjust and air filter service every 10,000 miles.

Rainman9 · 01-28-2008

I'm going to start with a compression check. As I'm doing the compression check, I'll pull the filter and replace it. I am starting to think the culprit might be the igniter.

Wayne

F4sSprintST · 01-28-2008

I think I'd have the SHOP a valve adjustment and timing check.

If those valves aren't closing just right, they leak. Leaks = lost HP

Have them adjust things, redyno

Bear in mind the factory HP rating is at the CRANK, not the REAR WHEEL. Figure a 15% loss, so about 88 rwhp stock