altitude is a pain to adjust for: bike was running rough.

[Guest Vermincelli]

Last year after building the bike it was running smooth but I've been wondering why it felt a little sluggish. Figured it was just the weight.

After letting it sit over the winter I had a hell of a time starting it which a bunch of you gave a bunch of suggestions and with those I got it running again.

 

Well yesterday after running a few blocks and shutting down for an hour, it didn't want to start again. So I pulled the plugs, which looked like they were soaked in oil. I cleaned them and tried again. It ran for a little bit then got really rough.

Yanked plugs again, cleaned them, repeat. Pulled them a 3rd time, cleaned them and still the same thing.

 

So finally called a buddy here in town and first thing he said was "did you swap out for hotter plugs? Don't forget, you have altitude to adjust for up here". So got a set of hotter plugs and that was it. Thing not only runs like a bat outa heck, but it's running way better than it was last year.

 

So just a reminder, if you live at high altitude, don't forget to take into account altitude/air pressure when you are tuning.

[dkaiser]

Im' in Wyoming at about 4400 feet, about the same as Carson if I remember, Can you tell me what plugs you put in that worked well?

 

D

[Guest Vermincelli]

Im' in Wyoming at about 4400 feet, about the same as Carson if I remember, Can you tell me what plugs you put in that worked well?

 

D

 

Was using the standard DPR8EA-9R NGK plugs so went with a set of DPR7EA-9Rs

I took it out and ran it up and down the highway tonight, pulled the plugs and they are all nice and clean. Hopefully that will end the problems. Before I was getting that lag starting off from a standstill and had to wind it up pretty good to pull away. With these, no winding up, pulling away was smooth and strong and acceleration was clean with no hesitations.

 

It does make the engine run a bit hotter though so when the temps get into the 90's in the summer I might switch back to the 8's if the temp gauge gets too high.

[Gearhead]

Not to be contrary, but hotter plugs shouldn't make the engine run hotter unless they cause ping (pre-detonation). The plug tip needs to be in a certain temp range to work right. Hot enough to burn off the carbon, cool enough not to cause ping and meltdown of the plug. A cold plug has a big heat path to the threads so it can transfer heat to the cylinder head faster, thus keeping its temp down, while a hot plug has its tip more isolated, so it retains more heat and runs hotter. The higher altitude means you are running a little rich which causes more carbon and a hotter plug can help in burning that off, as you found. In a sense it's a band-aid, but it's alot easier than rejetting. But those plugs don't make the whole engine run hotter. If you start hearing ping, that would be a good time to put the colder plugs back in.

 

Did you ever try it with new stock plugs? Sometimes cleaning them doesn't do it. I've seen plugs that look fine but are bad.

 

I recently rode my stock VR from Tucson (2500 ft) up Mt Lemmon (9000 ft) and it ran fine the whole time. However, I didn't spend enough time on the mountain to have cumulative rich-build-up like you might get driving all the time at your altitude.

 

My 2 cents.

 

Jeremy

[Guest Vermincelli]

I used 2 different sets of new plugs with similar results.

So far things are running good. No pinging either and will keep my ear open for that as the outside temps get warmer.