[Chilly]

96' 900 with 22K. Starts and idles normally. Runs up to 4K still OK. But at 4400/4500 there is a subtle loss of power along with slightly more vibration in the bars. It feels like I'm losing a cylinder above 4K. It still runs with no signs of quitting but something is not right. I was forced to buy some generic fuel on a trip a week or so ago though I still used 92 octane. Felt guilty about putting that crap in her so I ran it until I thought it was pretty much gone and filled with Shell 92. After about half the tank of Shell was gone I ran her full throttle to around 7K a few times thinking it would help clean whatever was deposited (if anything) in the carbs and valves from the previous tank. Soon after, maybe two or three days, the loss of power began to show up. So what do you think? Where should I start? New plugs and wires? She's due for valve adjustment. What else? Could it be a coil? Carb? Both?
Thanks in advance
Rick

 

[narrowminded]

I used to use Shell 92. Now it's whatever is available and 87 octane. No problems yet. Hard to believe that cheap gas would cause one cylinder to cut out only at a certain rpm. She would be idling bad if the plugs were fouled, no?
I'd start the process.
Check hoses, wires, plugs,,,,,,,,,
Revving to 7k with no load can't be good.

 

[Chilly]

Narrowminded, Thanks for the reply. I took her to 7K under full load and also failed to mention that I usually run Shell or Chevron in her so I don't think Shell gas caused the problem either. Rick

 

[Mark62]

A loss of power with a load on usually indicates an ignition problem. If you go to the trouble of looking at the plugs, you should go ahead and replace them. To check the plug wires-start up the bike and mist water on the wires and look for arcing which will cause poor running or start bike in the dark and look for arcing. This will tell you if there is a cracked wire (that cannot be seen). The 900 usually does not have the coil issues of the 1200, but that would be the next place to look.
Hope this helps
Mark

 

[Chilly]

Thanks Mark. I'll replace the plugs and most likely the wires. Since I bought the bike used I don't know if the wires are stock. If so they are 13 years old. The other thing I noticed is the smell of unburnt fuel coming from the engine area. No leaks and not strong but more than I remember. Forecast calls for rain through the weekend so its a good time to get my hands dirty.
Rick

 

[macmotor]

HAve you resolved this problem?
if not check your carb slides do they operate freeley? somtimes they gum up or diphrams go bad. are your gloves in the way of the air intake? sounds stupid but i've seen it happen. I have also had a similar issue on a non trump that ended up being the vacuume pet cock diaphram. Please let me know what you find.
Oh the unburnt fuel check your oil if it is fuely your float needles are prob not seating (shuting fuel off) that could deffinatly cause this and is very common on triumphs of this era