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View Full Version : 85 250R sputtering at WOT



SoCalDesertRider
10-26-2003, 11:25 PM
Alright guys, its been a while since I've been on the board, or chat. Hope everyone is doin good! At any rate, the 'ol faithful R had developed a problem.... the last weekend of riding it ran beautifully, not a problem in the world, untill the last day of the weekend (fortunately). It started sputtering out when riding at wide open throttle. I ran the sand hill probly 15 times the night before blasting up at wide open and no problems, went to sleep, got up early went on a long trail ride and noticed it was running a little hot considering the outside temp still hadnt risen too high yet, then I went to do the sand hill and no go, part throttle was ok, and WOT for short bursts was ok, but holding it at WOT it just sputtered out, like it wasnt getting gas or maybe spark. Plus it was running hotter than I thought it should.

Here's what I changed recently... I used to run VP 110 in it, but the place I go to buy fuel now sells FL 111, so I used that for the first time on that weekend, with the same 32:1 Honda HP2 synthetic oil mix that I always use. Right away I noticed it hardly smoked at all with the FL, even at cold start-up and not when I revved it iether, and that was even with a freshly cleaned and oiled air filter, which usually makes it smoke for a while untill it sucks in the excess oil thats on the filter. It also seemed to run a little hotter than it usually does... maybe I should change the oil mix to 30:1 or even 28:1???

Also I changed the throttle cable and put on a quicker-twisting twist throttle, which I like very much, not sure if that would have anything to do with it. Im thinkin maybe I sucked something in the carb that clogged the main jet, or maybe there's something wrong with the electrics, spark cutting out at high RPM? It has a fuel filter and I havent seen anything floating around in there, and I cleaned the air filter before the ride, as I always do, although it was dirty by the last day of the weekend... It also did suck up a little tranny fluid, which it has always done, nothing more than usual though, I guess thats a leaking crank seal? The engine is basically stock, except for a K&N, Outerwears, no air box lid, and an aftermarket silencer. Before the ride I put in a new spark plug, the fuel and oil were fresh, and the whole bike got the usual maintenence I give it before every ride. Before this the bike had sat in the garage for 3 months without being ridden, or started (shame on me). I expected any carb gumming problems would be apparent right away, but it ran great once I got it started and blew it out with the throttle. Maybe the lack of smoking was a gum clogged jet, and it ran so great because it was too lean from the clogged jet?? But why did it run so great at WOT one day and refuse to run at WOT at all the next??

Im thinkin Im gonna have to take off the carb and clean it out, but before I go taking it apart, maybe someone has some ideas? Thanks guys for taking the time to read my loooong explanation. Hopefully I can fix this before this comming Haloween weekend's ride! :)

SoCalDesertRider
10-26-2003, 11:30 PM
I meant to say "s-u-c-k-s" in excess oil from the air filter, but some how the word "Bites" got in there instead?? Hmmm...

atcmatt
10-27-2003, 02:03 AM
If you write s-u-c-k-s it comes up as bites, Automatically............. ;)

Tri-Z Pilot
10-27-2003, 02:38 AM
It could have to do the new fuel you are running in it, although that shouldnt be the problem. Now you were talking about changing your oil gas mixture. you said that you were running it at 32to1, if you wanted it to run cooler you would go to something like 40to1. The reason being that oil doesnt keep you piston cool, the fresh charge of gas coming in does. If you would go to something like 24to1 you would be adding more oil to a certain amount of gas thus making the piston run hotter. but since you said it was overheating, the cylinder is heating up, and the gas has little cooling power when it comes to your cylinder. Check your water pump, the coolant, any intake leaks maybe, or it could be your clutch or one of your wheel bearings starting to lock up. If your bearings provide more resistence your engine has to work harder to go as fast as you normally would also, did you overfill the tranny fluid? This to can cause the tranny to drag more than it should, or it could be something else, who knows, engines can be really stubborn at sometimes and it is hard to diagnose the problem. Good luck!

md1985250r
10-27-2003, 06:41 PM
you said you put a fresh plug in before the ride.....how does that plug look now???? i had a similar problem a while back...it was the plug!! good luck

SoCalDesertRider
10-29-2003, 09:26 PM
Thanks guys for your replies. So far I checked the plug and it looks like its burning good. The coolant bottle was empty and the radiator was slightly low. Now Im wondering whats happening to the coolant because I didnt notice anything leaking or any areas looking like they had been leaking, but I can smell coolant once it warms up. Im still unsure if I should open up the carb or not at this point to see if the jet is clogged.

Tri-Z Pilot
10-30-2003, 12:36 AM
You say when it warms up you can smell the coolant? Sounds to me like you are getting coolant in your crankcase. Check you waterpump and seal to see if there is a leak.

TimSr
10-30-2003, 10:38 AM
Start it up, let it warm, until it reaches operating temp, and revs good. The the garden hose and spray directly on the plug, and start revving it up. If it spits and sputters, replace the $3 spark plug boot, and you will probably have solved your problem.

Rustytinhorn
08-01-2007, 02:36 AM
Start it up, let it warm, until it reaches operating temp, and revs good. The the garden hose and spray directly on the plug, and start revving it up. If it spits and sputters, replace the $3 spark plug boot, and you will probably have solved your problem.

I know this thread is ancient, but why is this so AtcTim?? Also are you reffering to the rubber boot you slip onto the plug?