Or, squirt.
Do you see that little squirt of gasoline coming from that brass thing sticking up near the bottom of that carburetor opening?
The Keihin FCR37MX carburetor my WR-250FP has uses a system that squirts gasoline into the engine as shown in this pic, and it does it whenever you open the throttle fast enough to trigger the accelerator pump into action.
This gives the bike snappy and immediate throttle response that otherwise wouldn't be there when opening the throttle quickly.
Well, today, while installing the new carburetor needle (that I bought because I have read about guys using it who have also uncorked their WR-250FPs and got better performance), I also checked the operation of the little squirt of gas that is supposed to come out of that little brass nozzle.
No squirt came out with just a very slight ooze of gasoline that didn't squirt from the nozzle, but merely dripped out and puddled at the bottom of the nozzle.
When I first cleaned the carburetor a week ago (last Saturday), I made sure the accelerator pump nozzle and passageway leading to it were clear by squirting first carburetor cleaner and then contact cleaner through the whole thing, but, for some reason, the accelerator pump was not squirting one tiny bit upon today's inspection.
Just oozing a small dribble of gas.
So, I now believe that the accelerator pump wasn't even working for all of last Sunday's shakedown ride on the ol' Pachaug loop, and here I was thinking the bike ran pretty good considering the stock carburetor needle and main jet (and stock exhaust system) were still in place.
Hmmmmm.
So, that naturally meant that as soon as I realized this, the carburetor came right back off for cleaning #2, with special attention aimed squarely at the accelerator pump squirt.
All I did was simply repeat the cleaning I did last Saturday with the parts pertaining to the function of the accelerator pump:
Blowing the passage from pump diaphragm to output nozzle clear, and them simply putting it all back together correctly.
This time, however, once the carburetor was back on the bike and held in place by the forward inlet manifold, I hooked the fuel line up, connected the throttle cables, and put gasoline into the carburetor float bowl before I attached the airbox boot to the rear of the carburetor.
This let me see the view similar to the above pic as I twisted the throttle.
Aaaaahhhhh, a nice little squirt of gasoline was a wonderful sight to behold, squirting straight toward the rear of the intake valves, Lenny.
This is one time where seeing a little squirt near my bike was a welcomed thing. ;)
I then put the rest of the bike back together, started the engine, and could immediately feel and hear that the WR-250FP is now much more snappy in the throttle response department compared to how it was on last Sunday's ride.
I'm not sure how much of this snappy throttle response is due to the new OBEKP needle (the one that came stock with the 2002 Yamaha YZ-250FP motocross bike, a bike that came with no EPA regulations like the WR-250FP did), and I'm not sure how much of this snappiness is due to a functioning accelerator pump, but, I'll wager that the accelerator pump has much to do with it.
And, as said above, here I was thinking the bike ran half-way decent last Sunday, considering it was only semi-uncorked and using the stock needle.
Now, the slightest blip of the throttle has the engine sharply responding and feeling very much like my ol' WR-250FY did after I'd uncorked that one.
So, you can bet your booty that tomorrow is going to be another test ride session to both test the results on the bike's performance with a function accelerator pump, and also (I assume it will be required, although I wouldn't argue if it were not needed) to do a bit of fine tuning to the carburetor settings with the new carburetor needle (and a working squirt).
Now, naturally, I wonder what prevented the accelerator pump from working properly.
A passage that was still blocked or became blocked with a wayward piece of crud still in the carburetor?
Maybe.
Improper assembly?
Maybe, although there is nothing complicated about it, really.
Hmmmm.
This rates up there with wondering how many licks it takes to get to the center of a Tootsie Pop. ;)
At any rate, I'm stoked that all is now well and I'm off tomorrow morning - bright and early - to do some more riding.
I had the bike apart not only to install a different carburetor needle, but also to get the rear shock off the bike and over to Nasin Machine to have the shock serviced.
I decided to do it this past jerk week and get it over with, and that was a good move.
Although Tom didn't make any modifications to the damping settings, he did replace the rubber bump stopper that is at the bottom of the shock shaft since the original one was rotting away from 10 years of sitting in a guy's basement.
So now, the shock absorber is all serviced with fresh oil, fresh nitrogen gas, a good bump stopper, and the bike is put back together.
Weeeeee.
Next stop:
Sunday test ride #2.
-John
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