2002 FX470 stalls

gregb · Sep 9, 2005

Hello all,
I just purchased a 2002 FX470E. The engine stalls when a rapid throttle advance is made from engine idle. I charged up the battery and put in fresh gas which seemed to help. It has a Dell Ortro carb. The guy I purchased the bike from mentioned a lot of people switch to a FCR Kiehn carb. Any thoughts? I understand the "big gulp of air" issue with a mechanical slide carb. Can the Dell Ortro be set up to eliminate this type of stall? Thanks GregB

Husby · Sep 9, 2005

FX470

I think that your problem it's only a matter of carburetor tunning. On the other hand if you find a Keihin FCR at a very reasonable price you should go for it. It all depends on. What is your type of rides, if is only at weekend with the guys with some beers on the midle, the Dellorto is quite enough; if you ride on the profissional way at the MX tracks, then go for the Keihin.

Probably you find one on www.ebay.com . Expect for 300 or more USD just for the carb, then add the cables, the throtle and the delivery.

dsducati · Sep 9, 2005

Richen up the pilot jet as much as possible still allowing the bike to idle clean after adjusting idle fuel screw. Richen the needle as much as possible yet still allowing it to run clean at 1/4 throttle or so. Finally, set the intakes a bit on the loose side. Roll the throttle on a bit easier with the above changes and you may get along ok. Be certain the stator isn't weak before going to all this work.
Dan

husabutt · Sep 9, 2005

Hi gregb:

For general off road riding the Dell works fine. My 01 470fx carburates very good with no bog. It sounds like just a little fine tuning is in order.

Can you post the jetting you are currently running. I am sure the opinions will come flooding in.

If you have not already done so you may want to perform a breather modification to eliminate the oil build up in the intake boot (carb to frame).

Sometimes if the accumulation is great, when you wick open the throttle, it will bog as the engine gets a big blast of oil.

Taffy · Sep 11, 2005

greg

please tell me that this 'blip' isn't when revving the bike at a standstill?

secondly, by making sure the engine is hot and then trying the air screw plus or minus half-a-turn you can dial most of this out.

can't agree with DS about going for the largest PJ you can. try the above first and at the most go up one size PJ.

as i said though-don't 'catch' the engine out on the bloody stand please!

regards

Taffy

70marlin · Sep 12, 2005

Not sure if this will help, but I had to clean my choke plunger and circuit it was all corroded and wouldnÃ¢â‚¬â„¢t let the bike Idle correctly and the old girl would snap pop and back fire?

gregb · Sep 12, 2005

2002 FX470 Stall

Husabutt, thanks for the idea to post my jetting. Haven't pulled the carb out to play with it as I just moved into the house I recently finished building. The previous owner mentioned stalling while off throttle and while downshifting at slow speeds. That was his last ride on the bike which was sometime in July. He chalked it up to the extremely hot weather and humidity. The fresh avgas seemed to help. If I can't get it running right after a good cleaning followed by idle mixture screw adjustments, I'll take it apart and post the jetting info. Thanks again. Greg

gregb · Sep 12, 2005

2002 FX470 Stall

Taffy, there was no abuse to my Berg's engine. I first became aware of the problem when letting my neighbor take the bike for a spin. The bike was idling nicely, he put it in first gear, then apparently, he attempted to give it a short rev prior to letting out the clutch. The engine then quit with his rev attempt. His rev attempt shouldn't have killed it. It was a short 1/8th to a 1/4 throttle twist. If it hadn't died, it probably would have raised the RPMs to 1800 or so. I'm not sure what you mean by 'catch' but the context of your message sounds like maxing out the engine RPMs while in neutral. Not a nice thing to do to any engine unless you're trying to throw a rod.

Thanks for the advice. I'll get'r hot and experiment with the air screw. Cheers! Greg

gregb · Sep 12, 2005

2002 FX470E stall

Marlin, thanks for the advice. A good cleaning of the whole carb is probably in order here. I can see how a blocked choke circuit would cause it to bog out. I think it would be a good practice to use Stabil everytime I fill up the Berg. Thanks, Greg

husabutt · Sep 12, 2005

Some good Dellorto reading:

Dellorto tuning guide

BOSS · Sep 12, 2005

02 fx 470

taffy, check owner's doc, its a fuel screw not an air screw.

i'm watching you!

dsducati · Sep 12, 2005

With no accelerator pump and knowing the pilot design in a Dellorto, a richer pilot does help the stalls. May not be the best for economy and you need to use the choke with care, but it does help with flame outs. EPA would frown as well.
Dan

gregb · Sep 12, 2005

FX470 stall

Dan,
If tweaking the fuel screw (thanks Rick - Taffy, you should know better) doesn't take care of the problem, I'll try upsizing the PJ. It makes sense to have more fuel getting sucked in with the big gulp of air. I took her out for a spin today and found the problem almost gone. It did die a couple of times, but the fresh avgas seems to have mitigated the problem. Next time out I'll bring a screwdriver and play with the fuel screw. I am very impressed with the power of this bike. I sold my last bike in 1993, so I've been away from the machines for a while. But I think this power is on par with my old YZ490. Does anyone know the HP and torque stats for a FX470E? It just rips up my fescue field like a cultivator. What a machine!
Greg

husabutt · Sep 12, 2005

gregb:

I concur with Taffy and DS. One or two sizes up on the pilot jet will probably do ya, in addition to dialing in your fuel screw.

Also try increasing your idle speed a little. At first it seems a bit weird especially coming off a two stroke YZ490 airhammer but you will get used to it and appreciate the increased stalling resistace on tight trails.

dsducati · Sep 14, 2005

More volitile fuel will help as well, if you have access to it. Sounds like your headed in the right direction. Good luck
dan

2002 FX470 stalls

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