Carburetor upgrade 82 -> 83

[mbaur]

First I am really happy that I can call myself now a "Rider Of Vision" ;D I am riding the V. to work everyday.

I got the bike almost finished, i.e. except for the lower fairing. The carb situation is troubling me somewhat though.

The bike is an '83 with and '82 engine, carbs and gas tank. The original '83 gas tank is pretty much not salvageable: It has several large rust holes (I can stick two of my fat fingers in) and and the petcock is rusted to the gas tank so badly that I would need to drill out the screws holding the petcock. Anybody want to convince me otherwise?

I would really like to get the '83 carbs overhauled and put on the '83 engine. Do you guys know a way of how to achieve this? The problems I can see is that the '83 carbs have two hoses connecting it to the petcock. And the petcocks don't seem to be interchangeable either as they seem to have different size bases :(

The '82 carbs I currently have on the bike are running fine except for the idle circuit. When cold the bike wants to idle either at 3000 to 4000 RPM with the choke half out or die with the choke a bit less than half out. When warmed up the engine idles around 2000. This seems a bit high, but with the idle adjuster screw a quarter turn more in, the engine will die occasionally. Is there any quick fix for this or do I have to do the full overhaul which I'd prefer to do on the '83 carbs?

And one last question: The oil filler hole on the '82 engine seems to be a smaller diameter than on the '83 preventing me from attaching the hose to the '83 oil filler cap at the lower fairing mount. Does anybody have a solution for that (e.g. an adapter piece)?

- Markus
 

[Lucky]

you might have a leaking YICS on the high idle, worth a check, see my page on testing at: http://www.geocities.com/lucky_142/YICS
also very likley a plugged idle circut in the carb.

on the petcock deal the simplest solution might be to cut the tank out around the 83 petcock and have it welded or braised to the 82 tank.  

the only other way i see of doing it would be to grind off the heads of the petcock retaining screws, remove and rebuild the petcock, kits are avalable, and modify the 82 tank to accept the petcock.  poss you could weld a plate over the petcock hole andcut out an opening to fit with tapped holes.
--Lucky

[mh]

on the petcock deal the simplest solution might be to cut the tank out around the 83 petcock and have it welded or braised to the 82 tank. ?

the only other way i see of doing it would be to grind off the heads of the petcock retaining screws, remove and rebuild the petcock, kits are avalable, and modify the 82 tank to accept the petcock. ?poss you could weld a plate over the petcock hole andcut out an opening to fit with tapped holes.

Even easier would be to use the '82 fuel pump with the '83 carb- I believe the bypass comes out the fuel pump, right?

Obviously, this may lead to the original problem that prompted Yamaha to put the bypass in in the first place, though what the problem is, I don't know and my '82 hasn't seemed to have any problems.

-mark

[Lucky]

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[Lucky]

you mean you want to use the 83 carb on the 82 engine right?

swaping pumps might not work because on the 82 the pump and regulator are one piece and are bolted to the brace.

on the 83 the regulator is integral to the carb body, and although i think the pump itself is removable, i don't think the 82 pump/regulator will fit with the 83 regulator in the way. ?i don't have an 83 to look at so you will have to look.

poss you could find an alternate location to mount the 82 pump/reg with a homemade bracket.

if you plug the bypass i think you'll end up flooding the bowls

--Lucky

[mbaur]

Good guess Lucky!

I had looked at the YICS before and checked for leaks by submerging it in water. After reading up on your website yesterday, I decided to do some more testing on the YICS. This time I took a foot pump, attached it to the YICS hoses and gave it a light squeeze: It would pump straight through unless I plugged the other hose. So I had an internal leak :(

I did the same test with the YICS from my parts bike and it held the 8 pounds of pressure from the single squeeze on both chambers. So I swapped the YICS and voil?! The idling improved a lot: 2000-3000 RPM for the warmup is enough and 1500 RPM when the bike is warmed up.

The idle still seems to fluctuate a bit though (go up and down).

I think I am going to leave it at that until I get to the dipping of the '83 carbs and trying to put them on the 82.

Thanks for the suggestions so far!

- Markus

[Brian Moffet]

Don't forget to check the hoses to the YICS for leaks.  That's what usually gets me.

[mbaur]

I did my testing with the hoses left attached (with clamps) to the YICS. So I am pretty sure the I don't have a YICS leak anymore.