Topic: All praise to the gods of the tune-up......!!

[nickjtc]

Yes, I know all of these observations are blindingly obvious, but this was my first ever post-sohc tuneup epiphany.

Did a valve adjustment, oil/filter change, carb balance, adjusted the timing, and changed the rear tyre on the 650 on Saturday. WOW, what a transformation; it's like riding a new bike!

On the ride home on Friday (440km), pre-tuneup, the bike would wander and squirm whenever I crossed over the centre lines when passing, vibrated to the point of numb fingers and toes at anything over 5,500rpm, and generally sulked if I tried to rev it out.

On the ride back today (also 440km) the bike feels really planted on the road, actually revs willingly (took it up to 9,000rpm through the gears for the very first time since I have owned it), and is smooth as silk at my usual cruising speeds.

What makes it all the more satisfying is that it was all my own work. It reinforces again how great these bikes are and how 'user friendly' they can be.

Incidentally, the carb balancer I use came off eBay:

http://cgi.ebay.com/NEW-Motorcycle-Carb-Balancer-Synchroniser-Vacuum-Gauge_W0QQitemZ230013006463QQihZ013QQcategoryZ25623QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

I was sceptical when I first saw it since it's only a few lengths of tubing, two small ball bearings, and a couple of screw-in adaptors for the vacuum outlet in the carbs. You can only adjust one carb at a time along with the 'reference' one, but even so the whole job only took me 15 minutes.

[cbjunkie]

i've been wondering about these balancing tools...

how hard would it be to fabricate something like that? they are all pretty expensive from what i've seen, but they don't look like complicated paraphenalia...

thoughts?

[theunrulychef]

Congrats, nickjtc, on getting your bike running right.  It is indeed a great thing. 

i've been wondering about these balancing tools...

how hard would it be to fabricate something like that? they are all pretty expensive from what i've seen, but they don't look like complicated paraphenalia...

thoughts?

I remember reading somethhing on one of the BMW forums a while back on how to make one from 4 clear plastic tubes filled with ATF.  I beleive they were connected at the bottom & had flexible tubes that went to each carb at the top.  Unfortunately, when I went to go build one, I couldn't find the page again so I just spend the $50 & bought one.

[cmorgan47]

i borrowed the "morgan carbtune" off a friend to do mine last week and it was dead simple.  for the $100, it's a pretty good solution.



ps, theunrulychef, your 750 is looking nice.  where'd you get the tank?

[cbjunkie]

check this out...http://www.ronayers.com/catalogs/pu/parts.cfm?topsecid=3&subsecid=28&secid=105&type=582

this doesn't look like the same tool at all...is it a modern version? can we use this???

[cmorgan47]

looks like the mercury version of the carbtune to me.

[OldSchool_IsCool]

As I understand it, balance is the goal, not a specific vacuum value, correct?

If that's the case, then 4 plastic tubes with air tight connections to the sync ports with the other end in a common pool of liquid should work.  Carbs would be balanced once all are adjusted to pull the liquid up the tubes the same amount above the surface of the pool. 

One would need to be careful that the tubes are long enough so as to not suck the liquid all the way up the tube and into the mixture stream.

Does that sound about right?

[Bob Wessner]

check this out...http://www.ronayers.com/catalogs/pu/parts.cfm?topsecid=3&subsecid=28&secid=105&type=582

this doesn't look like the same tool at all...is it a modern version? can we use this???

This variety is commonly used and has been around a long time. The  Carbtune is more at take-off design to get around the issues associated with long, fragile glass tubes filled with mercury. There are some plans on the Web somewhere to make your own version using colored water.

[cbjunkie]

i've been looking online for a "how-to-build-it" but no luck yet...

anybody got one???

[nickjtc]

Apart from the fact that you can only balance one carb at a time the unit I used is pretty straightforward.....and, dare I say it, cheap!!

[Bob Wessner]

i've been looking online for a "how-to-build-it" but no luck yet...

anybody got one???

Though I ultimately bought the Carbtune, while researching, came across this. It's for a twin, but either two side-by-side, or all four drawing from a common reservoir should work..I think. 

[cbjunkie]

damn, that's rough...
thanks bob.

[OldSchool_IsCool]

That setup could be made to work on a 4-carb setup.  Just balance 2 against 1 - 1 is now your reference.  Adjust 3 to balance against 1 (don't change 1!) then 4 against 1.

[cmorgan47]

That setup could be made to work on a 4-carb setup.  Just balance 2 against 1 - 1 is now your reference.  Adjust 3 to balance against 1 (don't change 1!) then 4 against 1.

i don't know.  when you have all 4 hooked up, it seems like a little change to any one of them affects all of the others somewhat.  i know i spent a fair amount of time tweeking the other 3 after changing any given one.  not saying it can't be done, but when you watch all 4 at the same time it's a lot easier, and i'd think more accurate.

that's not even including how much i screwed them up with the locknuts.

[OldSchool_IsCool]

You're probably right (not that I've ever synced a bank of carbs!).  To make it a 4-tube system, plug all 4 tubes into an aquarium valve manifold that has 4 tits on it.  Tape the whole half-spider to the ruler/yard stick, open all 4 valves and fill the tubes to the black tape.  Connect it to the sync ports (somehow)?? and you're golden!

[techy5025]

Believe me guys.....dispense with a few six packs and get something that lets you look
at all four carbs at once......and leave it attacked until the last screw or nut is tightened
down and then check it once more.  Minor changes in the carb slide positions make a big
difference in the balance. 

Bob, your version of the two cylinder balancer can use water because the water is only
displaced by the difference in vacuum....not by the absolute amount. This allows the use
of the shorter water column rather than mercury which is obviously much heavier.

Jim

[cbjunkie]

how bout a sketch of that, oleskool?

[Bob Wessner]

Bob, your version of the two cylinder balancer

Not mine, found it on the Web. I'm not that clever.  I cheated and went with the Carbtune. Pricey compared to other alternatives, but save your pennies, you won't be disappointed with it.

[grumburg]

I have never seen such a dramatic difference that a good ignition tuneup and cab sync can make!!

[OldSchool_IsCool]

Gime a few days and I'll try to build one.

[cbjunkie]

thanks, old school...

i'm sure it's nice to buy a shiny new one, but i feel like it would be like paying someone to tie my shoes every morning...

give us a photo tutorial if you go through with it - non-mechanical geniuses like me will be very greatful!

cbj...