Hello Tony:

Thanks for the suggestions - I'm leaning towards your "to lean" idea also. Answers to you points:

1. Stock jetting according to previous owner.
2. Stock airbox & snorkel in place. Previous owner had removed the snorkel which I reinstalled.
3. Sprockets -14/45 (I finally counted).

I bought the bike from the previous owner in Kansas with about 670 miles inlate February. Bike has 3500 miles on it now, mostly above5,000 feet (missing occurs at that altitude on my commute to & fromAlbuquerque). Valves were adjustedat 800 mi.

This weekend we had high warm (80's) winds on Saturday. When I rode into the 20 - 30 mph winds the missing developed, if I turned and rode downwind the missing stopped. Basically it seems to miss when I'm working the engine by riding into a head wind in 6th gear on the flats. Once the missing starts it will persist even if I drop the speed a bit and ride slightly slower but at a higher rpm in 5th. Rarely misses in the mornings when it's cool, more likely to develop miss when it's hot. I'm hoping to get this sorted out before summer really gets rolling!

I'll try your high rpm tests - that's more abuse than I usually subject the engine to (usually shift at 8k, occasionally 9k when accelerating quickly).

One thing about jetting that confuses me - I assumed that going to a higher altitude would usually require a leaner set up dueto less oxygen?

Thanks again,

Howard

 

+1 with Tony on the too lean.

My bike would act like it was fuel starving (missing) and losing power during hard high speed or WOT rides at higher temps (90+), it was bad enough one time that I stopped on the side of the road 150 miles from nowhere to check the fuel filter screen for blockage and fuel lines for kinks I was so convinced that I had a fuel flow restiction.

After I richend up the jet the problem vanished.

 

It's been over a month since the missing problem developed. I'd purchased a slightly larger main jet to richen the mixture, but while I was getting around to installing it I continued to ride the bike. To make a long story short - I also changed my riding habits a bit and generally rode at a higher rpm, never falling below 5k if there was any load in 6th, generally above 4.5k if the engine was loaded in 5th, etc. I think that I had been slightly lugging the bike before when running as low as 4k in 6th. Anyway, the bike hasn't missed once in 6 weeks and 2,000 miles. Eventually I went back to the stock gearing (I'd been running 14/45) because I'm mostly commuting now (80 mi / day) and the higher gearing works great as long as I keep in that 5 - 7 k "sweet spot" for 6th.

In another post I read that some owners had problems with missing & running poorly after overfilling the tank. That could have contributed to my initial problem as I'd filled the tank completely and then trailered the bike on a hot day - the expanded gasoline overflowed the tank quite a bit and may have started my initial series of missing episodes.

Thanks again for all the suggestions - if it starts again I'm better prepared.

Howard