Borrow carb syncher?

**XV8Crisis** · 18th March 2012, 14:59

Hey guys,

I'm relatively new to bikes, on a reasonably tight budget, so am looking to save some money by doing as much as I believe I can by myself.

My bike pretty certainly needs a carb rebalance, yet I don't have the tool to do so, and at the moment it's outside of my budget to spend the rougly $150 for a one-time job, considering I'll sell the bike within a year (and be looking at dropping more $ on a better bike in roughly the same time...).

Could anyone in the Wellington region let me borrow their sync tool for a weekend job?

My bike is a 1991 CB250FM Honda Jade, but it get more interesting: its history is murky at best, and the bike itself borders on rat. The instrument cluster (amongst other parts... hah) is not original - in fact, I recently figured out that some previous owner got one off of a VTR and that's now what I've got... minus a tachometer. That's right, I shift by ear, and have no idea what my idle speeds are. So in addition to that, I'm probably looking at borrowing a tachometer cluster if anyone has one laying around...

I know it's a long shot, but it's worth a go. In the meantime, I've set out to just clean the carbs and hope it at least improves my symptoms, but it almost undoubtedly won't fix the whole picture, if any of the idling and varying RPM problems. Or shit, barring all the above, I'd love it if someone could balance them for me for some sort of trade! I've heard some can do it by ear.

Many thanks in advance!

**unstuck** · 18th March 2012, 15:04

How about a bit of DIY.

**XV8Crisis** · 18th March 2012, 15:15

Originally Posted by unstuck

How about a bit of DIY.

Could do, doesn't look too hard. It's a 4-cyl, but as I understand you balance 1 and 2 together first, the 3 and 4, then make sure the 2 pairs are balanced, and away you go.

Cheers

**ducatilover** · 18th March 2012, 15:27

Are your valve clearances in spec? I'd be cleaning the carbs, setting the floats, pilot screws to 2-1/2 turns out etc and then I'd think about synch jobs.

**XV8Crisis** · 18th March 2012, 15:43

Originally Posted by ducatilover

Are your valve clearances in spec? I'd be cleaning the carbs, setting the floats, pilot screws to 2-1/2 turns out etc and then I'd think about synch jobs.

Not sure yet - am looking at cleaning the carbs here in a few hours. Not 100% sure what the specs are for my bike as I don't have the manual and the only manual is in Japanese, but if my logic is right then since it's the exact same engine as a CBR250, albeit tuned a bit higher, then I can use the valve clearance, float, and idle speed specs for the carbs. I have a CBR250 manual.

**ducatilover** · 18th March 2012, 15:47

Originally Posted by XV8Crisis

Not sure yet - am looking at cleaning the carbs here in a few hours. Not 100% sure what the specs are for my bike as I don't have the manual and the only manual is in Japanese, but if my logic is right then since it's the exact same engine as a CBR250, albeit tuned a bit higher, then I can use the valve clearance, float, and idle speed specs for the carbs. I have a CBR250 manual.

Should be similar specs to the MC17/19 CBR250 for the carbs. From memory the CB250 Jade made less power (softer cam profiles, diff ignition and lower compression) but I imagine the float heights are the same if you have the same carbs.

If you're having horrid rough idle issues it might pay to check the intake rubbers and vacuum lines.

**XV8Crisis** · 18th March 2012, 16:18

And when you're talking about valve clearances, are you talking about the guillotine and butterfly valves in the carbs, or the cam valves in the engine?

**ducatilover** · 18th March 2012, 16:45

Originally Posted by XV8Crisis

And when you're talking about valve clearances, are you talking about the guillotine and butterfly valves in the carbs, or the cam valves in the engine?

The cam to valve clearance in the motor.
The butterflies in the carbs are set when you sync them (that's what the sync does)
There's no point doing a carb sync if you haven't checked your valve clearances, the CBR250 manual should be a big help there, not a hard job, just requires careful thinking and it pays to double and triple check everything.

**nzvlogger** · 18th March 2012, 17:16

lol that carb sync thing is awesome, im gonna try that! You could probably just hook up 4 bottles i guess?

**XV8Crisis** · 18th March 2012, 17:39

Aw man, seriously? I was hoping to not mess with the engine at all. Checking cam valves clearances sounds like a careful, serious job! And it's a 4 cyl... That's definitely a different weekend and a whole lot of self encouragement...

Originally Posted by nzvlogger

lol that carb sync thing is awesome, im gonna try that! You could probably just hook up 4 bottles i guess?

Yea but wouldn't you have to have tubes running from each bottle to every other bottle? In the vid he's using rubber stoppers from what looks like a science kit/supply, which is ideal, but... other ways of jimmying it? Punctured rubber diaphragm or foam? That's sorta what I meant with the balancing carb 1 and 2, then 3 and 4, then rigging it up right to measure the pairs in balance.

**ducatilover** · 18th March 2012, 17:42

Originally Posted by XV8Crisis

Aw man, seriously? I was hoping to not mess with the engine at all. Checking cam valves clearances sounds like a careful, serious job! And it's a 4 cyl... That's definitely a different weekend and a whole lot of self encouragement...

Worth doing it though

has always made my bikes happier (probably because none had any history of real work...

)

**XV8Crisis** · 18th March 2012, 18:10

And with the states of my bike in general... ugh. Not looking pretty.

I mean, that's 16 valves, and to get to those (to even just inspect valve clearance!) I need to remove the cylinder head, which starts to get serious. Beyond that, if they do actually need adjustment, the CBR engine uses shims... meaning I have to get the valve cover off... all very internal, careful, serious, clean, organized, tender work...

I'm scared.

and don't wanna...

I'll just pray that everything works well enough after a carb clean and idle speed adjustment, right?

Yea, right... hah.

**ducatilover** · 18th March 2012, 18:13

Originally Posted by XV8Crisis

And with the states of my bike in general... ugh. Not looking pretty.

I mean, that's 16 valves, and to get to those (to even just inspect valve clearance!) I need to remove the cylinder head, which starts to get serious. Beyond that, if they do actually need adjustment, the CBR engine uses shims... meaning I have to get the valve cover off... all very internal, careful, serious, clean, organized, tender work...

I'm scared.

and don't wanna...

I'll just pray that everything works well enough after a carb clean and idle speed adjustment, right?

Yea, right... hah.

No cylinder head removal.
Just under the valve cover.

Valve cover off, measure clearances, pull cams out, pull buckets out, record shim sizes, work out what new sizes you need, put new shims in, cams etc etc, done.

I tend to at least double check all clearances before pulling the cams out.