Hi, i have a weird problem when riding in the cold (40F). The bike warms up on the temperature gauge just fine but when i take it out for a ride the temperature gauge just drops and the bike starts running like its cold, (stuttering and bogging at higher rpm) could this be a thermostat problem? Thanks

 

Not sure, but when i'm riding my bike in 40'ish degree weather, the temp gauge is usually always "hanging out" in the bottom area and runs just fine. I don't believe this would be a thermostat problem. If the bike is running and moving, it should't be enough to make it bogg and stutter in and of itself, even if the thermostat is stuck open (?). However, if it is a thermostat problem, it may exacerbate an already existing problem, that may not be as noticeable at higher operating temps.

 

Does this stuttering and bogging occur when the weather is hot? Or does it run just fine then?

 

I haven't had a chance to ride it in a hotter temperature range, just picked the bike up about a week ago. Could this just be the carburetor needs adjustment?

 

The weird thing is, it won't stutter after you sit and let the gauge get to about the middle of the temperature gauge. You can slow cruise too, but when you really get into it and start speeding up you can watch the gauge go down and when the gauge is really low again it starts sputtering just like a cold start crank

 

It could be that your thermostat is stuck open so when you ride the engine is unable to stay warm as all the heat is going to the rad, that's why it could feel like its cold, because it is. That's my thoery, good luck with that

 

Assuming your temperature gauge is reading right, Scorch is correct - you're thermostat might be stuck open, allowing the coolant to flow constantly through the radiator, essentially not letting the motor stay at a "proper" operating temperature... however, this should not so adversely affect the way your motor is running, but it will exaggerate a lean condition in one or more of the fueling circuits.

So you've only had it a week, and haven't ridden it in warm weather, but by chance did you buy it from someone you know, and know if it was running fine before, or know whether or not it's been sitting for a long time? If you do not know for sure that it ran fine before, and if it has been sitting for a considerable amount of time, it's time to give the carbs a very thorough cleaning.

You can get a lot of help here, so keep us posted... oh, and let's see this thing, get some pics posted!

 

It does have a K&N air filter and yoshimura rs-3 exhaust, could it just be that it's not jetting properly? I'm going to check the carbs and i have to adjust the choke cable cause its not working, do you know where i should start on adjusting the jets for a lean condition? Would i need to buy a jet kit? I guess i'll also order a new thermostat if i'm going to be checking the carbs

 

Well, most of those questions are impossible to answer, not knowing the current settings and jet sizes - if it has a K&N air filter, then yes, adjustments would have to have been made for it run right, but, we don't know if the PO did that, or not.

I would start simple, and give the carbs a thorough cleaning - you didn't answer whether or not the bike sat for a long time, not running, but if it did, or if the carbs were even gummed up when the last owner ran it, then the cleaning is your first step... gummed up jetting orifices and passages are the equivalent of having the wrong size, as though they are just "dirty", they still flow less fuel volume than they should.

You can then verify the jet sizes and settings while you are cleaning, for example: everything needs to come off anyway, pilot screws, main jets, pilot jets, and the needle jet holders, which the mains screw into - before you remove the pilot screws, turn each of them all the way in, to lightly seated, count the number of turns it took to seat them, write this down, and report back. When you remove the other items, you can make a note of the jet sizes and brands, that are etched on each piece.

 

Oh yes it will let you add photos. Figure it out. Just to let you know, a few months ago, there was somone in the F2 forum that claimed to have found an F2, that had been "frozen in time", immaculate condition, after sitting unridden for years, yada yada. He hasn't been seen since. Not that i'm doubting you, but the best way to rub me the wrong way is to talk about what you have, with no proof