Triumphrat

trevd · 07-05-2008, 04:16 PM

Hi,

Helping a friend with his '95 Sprint. He was having trouble starting it when it had been sitting for a few days. Also, he was having a hesitation at speed when he'd get on the gas.

We decided to remove the carbs and get them checked out. According to the guy that looked at them (not a pro - but he knows carbs apparently), they're fine. We put new plugs, cleaned/oiled the K&N air filter, and now we're putting it back together to see how it goes.

My buddy's not here right now, so I'm doing it myself. In putting the tank back on, I decided to drain it to make it easier to place it properly, and not pinch any of the hoses. But the problem is that for some reason, no fuel will come out of the petcock. Doesn't matter which way it's pointing (ON, Prime, Res) nothing comes out.

I've ended up siphoning the gas out, and I pulled the filter out to check it, but it looks fine.

I'm wondering if this was his problem all along... My buddy never really knew which way the petcock should be pointing because the writing is worn off, but I do know that pointing in some directions, it doesn't work.

Am I missing something? What is going on?

Thanks,

Trevor
Ottawa, Ontario, Canada

daytona 750 · 07-05-2008, 06:16 PM

probably got the pipes on the wrong way round,
you should have a vacuum pipe that comes of a stub on the right hand carb, that goes onto a stub on the back of the tap(noticebaly thinner than the others.the next one that comes of the back of the tap is a hose with a curve in it, and the last one by elimination goes onto the stub at the front of the tap.
if you have them routed correctly, and still no joy, make sure all pipes are kink free and in good condition.
i found today that prime doesnt always work immediately if you have an airlock in the tank.
another thing to check is the coils.from reading through here it has become evident that they can breakdown very easily due to the heat of the engine.
you will need a multi meter, to check the primary and secondary windings in each coil.
if you need any help with the values that you need to check for, let me know, and i will dig out the haynes

by the way,if you buy a new knob for the tap, they now have the writing embossed on the plastic instead of printed, so it doesnt wear off

trevd · 07-05-2008, 07:20 PM

Quote:

Originally Posted by daytona 750

probably got the pipes on the wrong way round,

Thanks for the reply Daytona, but that can't be. I don't even have the tank on the bike right now... it's just on my workbench. No hoses are connected.

Do I need to have the vacuum hoses attached in order to drain fuel from the tank?

Trevor

bobbo · 07-05-2008, 08:24 PM

The petrol should run out if it's on prime, which I think is pointing with the thin end up, with on being pointing to 3 and res pointing down (possibly). Just a thought, but is the knob just spinning or does it stop at 12 and 6?

trevd · 07-05-2008, 09:12 PM

Yep, it definitely stops at 12, 3, and 6.

I don't understand why the fuel isn't coming out!

Trevor

KitNYC · 07-05-2008, 11:48 PM

With a properly functioning petcock, fuel should come out on Prime but not On or Res. If it's not coming out on Prime, there's some sort of problem. (I do wish I could be more specific, but I can't.) Maybe vapor lock? Have you tried opening the gas cap?

Cheers, HTH,
-Kit

daytona 750 · 07-06-2008, 02:45 AM

mine prime wouldnt flow at first(yesterday) it seems to get a little air lock in the end of the stub,just give it a shake or something to get it started.
opening filler cap may well help!

trevd · 07-06-2008, 09:33 AM

No vapour or air lock... tried opening the gas cap, nothing.

Can someone educate me, as I've never had a bike with a "Prime" position on the petcock: When do you use the Prime position? Would it be after the bike has been sitting for a while in order to get fuel into the carbs, if the fuel in there has evaporated?

And once there is fuel in the carbs, using the On position would be fine? Would using the vaccum fed On position work on a bike with empty carbs?

Thanks,
Trevor

trevd · 07-06-2008, 09:39 AM

Also, if I remove the tap, like I did yesterday, does anyone know what I should see looking down into it as I turn the knob?

I seem to remember seeing openings in 2 of the 3 positions, but no openings in the 3rd position.... I forget which one though.

Is it possible that the previous owner may have screwed around with the petcock internals and has something backwards in there? I don't even know if that's possible to do...

Trevor

daytona 750 · 07-06-2008, 12:28 PM

im really not sure if it can be put together incorrectly or not.
if you have a small peice of pipe to hand that will fit on the thin (vacuum) stub on the back of the tap, and just suck on it, it should open the tap in the on postion.while sucing on it, squash the pipe in a set of locking grips, to maintain the vacuum pressure while you drain the tank.
then you can remove the tap and inspect it