carb synching

[cell_491]

ok temporarily back on the valve adjustment issue...i got everything taken off and measured the clearances they were all WAY too tight. So I removed the shims by loosining the cam shaft holders (only one side at a time) and prying them out with a small knife, then I measured them with my new digital caliper and all but one seemed to have zero wear. Anyway I ordered some new shims they should be here by next wednesday (urrg). But i have to ask... how do the clearences decrease over time...i can easily understand them increasing but decreasing is weird, would this be why my bike is sucking down so much GAS-0H-LINE!?!?!

[robinm1]

ok to answer your question about valve clearances decreasing, thats what they do, they very rarly increase, the decrease is brought about by sealing area of the valve wearing and the valve seats in the head wearing, letting the valve come up further than it once did, thus the clearance decreasing.

[cell_491]

hmm interesting, so is it better for the clearences to be tight (.03-.04mm) or loose (.05.08mm)...i ask because one of the valves barely fit the .04mm guage and its shim was 2.57mm so i ordered a 2.55mm to bring it higher in the range (should be .06ish after i put the new shim in).

[MarkusN]

Especially on the exhaust side a little bit loose is better than too tight. A tight valve may not close completly when hot; the hot blowby will quickly erode your valve seats.
To loose OTOH is hard on the valve drive (excessive impacts.)

[cell_491]

ok now that i have the valve adjustment pretty much figured out could somone explain how exactly to hook the manometer up to the carbs... i know it involves hooking them up to some port on the top of the carbs...but can some one be more specific

[scratch]

'Stage' the caps halfway on, so they'll be easy to take off, but still seal.  Start the bike.  Take off one cap and quickly attach one of the tubes of the manometer.  Repeat for other side.  Balance carburetors.

Oh whoops, ok, the vacuum towers, or spigots, are on the forward, right corner of the plastic caps on the carbs.  Hope that helps.

[cell_491]

ok thanks for all the help guys...ill let you know how everything goes 

[makenzie71]

How I sync carbs is using a cheap 2 1/8" vac guage I bought off ebay ($4) and 4ft of vac tubing.  Plug the guage into the #1 carb vac nipple on the manifold, idle the bike, mark the reading.  Repeat for the #2 carb.  Adjust them to match.

Someone I spoke to recently told me about a real ghetto method...take about 6ft of clear vynil 1/8" tubing, put one end in some dish soap and suck up about 12" worth, plug both ends into the carb manifold nipples, idle the bike and adjust until there isn't a greater pull to either side.


ooops...I meant the niples on the towers like Scratch said...I've been playing with those manifold boots lately and got them stuck in my head...

[MarkusN]

Someone I spoke to recently told me about a real ghetto method...take about 6ft of clear vynil 1/8" tubing, put one end in some dish soap and suck up about 12" worth, plug both ends into the carb manifold nipples, idle the bike and adjust until there isn't a greater pull to either side.

Hey, that dish soap thing is a good idea.

1st it's heavier than water, so you need less height
2nd it's very viscous, so it attenuates out the heavily oscillating vacuum

Nifty. Gotty try this some time.

[Egaeus]

Someone I spoke to recently told me about a real ghetto method...take about 6ft of clear vynil 1/8" tubing, put one end in some dish soap and suck up about 12" worth, plug both ends into the carb manifold nipples, idle the bike and adjust until there isn't a greater pull to either side.

Hey, that dish soap thing is a good idea.

1st it's heavier than water, so you need less height
2nd it's very viscous, so it attenuates out the heavily oscillating vacuum

Nifty. Gotty try this some time.

And if you suck it into your engine, it'll blow bubbles out the exhaust!

[MarkusN]

Someone I spoke to recently told me about a real ghetto method...take about 6ft of clear vynil 1/8" tubing, put one end in some dish soap and suck up about 12" worth, plug both ends into the carb manifold nipples, idle the bike and adjust until there isn't a greater pull to either side.

Hey, that dish soap thing is a good idea.

1st it's heavier than water, so you need less height
2nd it's very viscous, so it attenuates out the heavily oscillating vacuum

Nifty. Gotty try this some time.

And if you suck it into your engine, it'll blow bubbles out the exhaust!

Sounds fun. Gotta try this...

[scratch]

Igniting mercury as it gets sucked through your bike is way more fun.