Hey all, My buddy just got a used 2006 can-o-tuna. It came with a Yosh pipe from the headers back, and the bike wont go above 7500 RPM. I'm assuming that the bike is breathing better with an aftermarket exhaust and thus it is leaning out at higher RPM's... if this is the case than I guess he just needs new (bigger) jets in the carbs? Him and I both are at the learning stage, so any advice or information would be very useful and appreciated. Thanks!
Your conclusion is logical. First step would be to speak with the previous owner and see what other modifications were made. Usually, just a pipe isn't enough to make it do that. If the stock can is still available, install it and see if that addresses the problem. If the bike has changed altitudes, then a re-jet may be in order. Weak coils can do the same thing as can a failed stator or weak battery (but those have other symptoms). I think it was added in 1998, but the throttle position sensor (TPS) could be sending a bad signal to the ignitor box, which adjusts timing based on throttle position.
Every thought of the fuel pump? I've seen this problem on a fuel injected bike. Just wouldn't go above a certain RPM in any gear. Turned out to be a shotty fuel pump.
Katana's don't have fuel pumps. Pull the carbs and clean the main jets, a slip on won't change the jetting enough to cause that.
Thanks all for your input. My buddy does not have the stock exhaust, and the previous owner seems to be a bit of a nim-whit. I will pull the carbs and clean the main jets this weekend and report the results at my earliest convenience. Thanks again for the help; I hope this works!
Sir, that's "Tin-Can tana", NOT can-o-tuna...and don't forget to take the red-rag out of the airbox..or is that a dead rodent in the airbox? I do have to wonder if the airbox inlet (air filter cover) is the correct one for that engine size. I think they were interchangable other than the size of the inlet hole...
Tin-Can tana, can-o-tuna, Cana'tana, it's all the same reference to fairly cheep minced and mashed fish, and it all refers to the same sled of a motorcycle...
does it rev quickly up to 7500, then hit a brick wall, does it rev out if you use any other throttle, like 1/4, 1/2 3/4 throttle. try to find out if its electronic, or fuel related. my guess is that the tops of the carbs are missing an o-ring, or the slide diaphragms are not in properly.
Well, I wasn't in attendance this weekend when my buddy stripped down the carbs, but he said he just took them all apart, cleaned everything real well, put um all back together, and now everything is running perfectly. I'm not sure if I believe him yet... I plan to hop on the bike tomorrow and take it for a spin to see for myself. I'll post up an update tomorrow.
...and to answer the last two posts: @Skinny - It revs to 7500 like a bat out of hell; no problems. It hits 7500 and shits the bed, and wont get back on till 6500 or 6000. @Ricebowl - All gears, haven't tried to rev it that high in neutral.
Here are the promised results: As I expected, all was not well in tunaville. We took apart the carbs this evening (again) and this time blew out the carbs, mains, pilots, and all of those other things that we didn't know what were with compressed air. By the time we put it all back together, it was dark and late so I went home. My bud is going to ride the bike over tomorrow and I'll get to see how she's riding. I took a bunch of pictures, I'll put them up tomorrow.
Many times compressed air won't get a gummed up jet completely clean, you need to run a strand of wire thru it and scrub the orfice with the wire.
You should spray carb cleaner through all the jets (and the circuts they controll in the carb bodies) to verify (AND clean at the same time) that they all flow the same amount. Do NOT soak the carb bodies or any rubber parts or bits in flamable carb cleaner, while it's safe to spray and then hit them with air, don't allow the cleaner to stay in contact with any area that even MIGHT contain rubber parts.. Dragging wire through jets is only called for when they are stone plugged up, you CAN damage the inside of a brass jet with steel wire..better to let the jets soak in cleaner for a few hours to soften the varnish/gel..
Every day we see jets that look ok till you run a wire thru them then all of a suden they are 25% larger. I use a strand of wire pulled out of a wire brush on the bench grinder. While it is possible to damage jets with a strand of wire if you force it into a smaller opening one small strand will not damage a main jet or pilot jet if used with some common sense. Many times carb cleaner won't get the job done.
Here are the pics to the "fix" that we did last night: Bike Apart: Carb Open: Jets/Pilots: Carb case after/before: Now everything is going good. There is a slight bog at 9500 RPM, but it's a Katana so we're not worried about it
