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View Full Version : Earned my man card back - Fixing carbs



darkwolf
5th November 2011, 21:09
Riding home from work on Tuesday night, my bike stalled while travelling at 100KPH. :doh: Thought it was odd but pulled over, checked fluids etc, and it fired up.

I then got maybe 800m up the road when it died again. At this point I couldn't restart the bike and before long the battery had gone flat and there is no kickstart. :(

Great! :mad: Push her home - well to the parent's in law's anyway. Luckily it was only about 3km and about 25 degrees and I had no where to put my jacket, helmet, gloves, pants (which are over my work pants). After sweating more than I ever have in my life, I made it to my destination.

Spent two nights trying to get it running again. Each time it would start, run for a while then stall. Ran fine while the choke was on but the minute you touched the throttle, it died. On the third night, I decided to ride the bike home. As had been the norm, the bike started but died shortly thereafter. It then dawned on me to try the reserve tap. Bike fired up no problem and ran like a new one. :Oops: Turns out I learned a lesson.

I understood (though through blind ignorance over research) that the reserve was a separate tank with a separate feed into the fuel tap. It turns out this is not the case. The reserve, actually just allows the fuel from the lower part of the feeder stalk to be drawn through. So when it had died the first time, it was due to not having any fuel in the "main" tank. Even though I could see fuel in the tank - it couldn't feed it. :facepalm:

So I was forced to hand in my man card. :bye:

I thought all was fine, so I decided to take the bike into work again on Friday, with a new tank of fuel. Down to the servo, fill up with fuel. Head off to work. Get 4KM down the road and power just disappears. Can't go any faster on full throttle than 70KPH, so I turn back, drop off the bike, head to work in the car... again. :angry2:

I was determined to make the bike work by Saturday. So now the story is out of the road, I'll explain how I earned back my man card.

I started first with the fuel tap. Took that off, pulled it apart, no fault found.

Into the air box. Pull it apart, check all hoses. No fault found, but notice one carb gurgles spits and farts when I blow down the breather hose, the other doesn't... hmmm... should they not act the same? :scratch:

So take off air box, look into carby. Push back the vacuum piston on front carby, let go, slides back into place. Push back the vacuum piston on rear carb. It stays put... hmmm... should they not act the same? <_<

Disconnect carbs and EVERYTHING else. Pull vacuum chamber apart, find front carb is moving smoothly, rear carb is catching. Clean and lubricate vacuum piston and bore, notice large nick missing from venturi needle. But otherwise it works perfectly. :woohoo:

Call Honda, they've never imported a new carb for a VTR250 in NZ (or at least my model of VTR). Will need to get price from Honda NZ to determine cost of new carb. :wait:

So I decided screw that, run with carb as it is. Extra lubricate and clean both carbs. Reinstall carbs, airbox, fuel tank. Now it runs better than when I bought it. :2thumbsup

So I'll keep an eye out for the carb to crap out and start looking at the cost of a new set of carbs or second hand ones just in case. But in pulling apart the entire fuel system, diagnosing the problem, mending it and reinstalling it I think I earned my man card back. :first:

I will now keep a closer eye on my fuel levels. :whistle:

Sable
5th November 2011, 22:31
You can just buy the needle. You should also be wondering why it has a big nick in it

Flip
5th November 2011, 23:04
Some times there is a little water in the bottom of the fuel tank that gets pulled through into the carbs when you switch over to reserve. I had a triumph that used to dothis from time to time.