Purchasing xj650

Thanks both I have a pedal bike torque wrench rated 4-24nm so it should cover me

 

Nice bike.

 

Could I ask someone to check my valve spec numbers? Its 11.20pm here and I feel my tiredness may make for bad judgement ha ha.

I want to query the exhaust 2 shim. It measured at 0.203mm with the feeler gauge so would technically be just out of spec by 0.003mm. Am I correct that I need to change the shim to get it back into spec or is 0.003mm minimal?

On top of this, if I do end up replacing exhaust 2 with the 280 shim, can I use the 280 from exhaust 1 and put the 275 from exhaust 2 into exhaust 1?

 

exhaust 1 correct 2 spec 3 spec 4 correct

intake 1 correct 2 correct 3 correct 4 correct
I would suggest getting metric feeler gauges as the conversion is not quite accurate

 

The only bad news is that you can't swap any of the shims around.
Maybe that will work out next time.

 

note overlapping specs when inches is used 0.006= 0.15mm and 0.16 mm

 

This is the feeler gauge I have

 

Sorry if I'm overlooking something but are my measurements not in metric?

 

Tighten till they make contact then just a little snug. Thin bolts + aluminum + rubber.. they don't need to be tight at all. If they are a bit loose just snug em a bit more.

Your measurements are also in inches. Though that .0025 seems WAYYYYYYYY off.

 

Your gauges are imperial, with metric equivalents stamped. They are fine, but actually a tad less convenient than using proper metric feelers.
The tendency when using imperial/SAE is to read the metric stamp as-is, which actually provides too fine a resolution. You only need to read to the nearest 0.01 mm in order to use the chart and set clearances.

 

yes they are in metric but based on mfg doing math to convert . best way is a feeler for each spec 4 in total base it on go no go only becomes a problem if gaps are way tight or way loose.

if you look at the Yamaha spec I posted you see that the inch scale = 2 metric standards
0.006= 0.15mm and 0.16 mm
so you could end up wirt 0.16mm on intake or .015 mm on exhaust making a tight shim a passing shim on exhaust or a loose shim pass on intake.

it is just how my brain works worry worry about nothing i see 3 shims at that measurment . and is your decmil point in the correct place on inch measurments?

.006=.1524mm where 0.06=1.524mm
you can see how this makes exhaust shims tight and will need to be changed next time around or changed now if you went by mm

not a big issue in the end

 

He has the metric equivalent listed too.
0.0025" is only one shim tight. Wayyy off would be 0.000"


@XJ550H good catch on the decimal. That makes for a huge difference, and it would be really odd to have one set of valves that far off from the others.
I'm betting it's just a transcription error.

 

Thanks both, it was getting late when I took the measurement, however I do remember checking intake 1 twice as I thought it couldn't be correct.

I'll check all clearances again after work today before ordering new shims.

 

Thanks firebane - I don't suppose you know the torque value? I have a wrench that starts at 2nm

 

IIRC 7.2 ft lbs. If I'm wrong it's not far off from that.

 

Thanks k-moe

I don't think these shims have ever been tended to. There were no scratch marks on the crank bolt from where the 19mm spanner cranks.

 

Rechecked the valve clearances, good job I did too!

Exhaust 2 is definitely in spec and intake 1 measurement was way off.

On a side note, I don't suppose anyone knows the official name for the yoke cover thing that says 'Yamaha'? I've just realised mines missing!

 

For the steering assembly.
emblem


ASSEMBLIES WHERE 4H7-23395-00-00 IS USED

• 1980 XJ650 (XJ650G) - Steering
• 1981 XJ650 (XJ650H) - Steering
• 1982 XJ650J - Steering
• 1983 XJ650K - Steering
• 1983 XJ750K - Steering

 

I dont know what I'd do without you k-moe!

Sorry for another question but I'm just buying all the final bits I need to get the xj road worthy. The carbs I'll be ultrasonic cleaning and replacing fuel o rings and butterfly seals but now that I've sorted/sorting the shims, once done I'll need to sync the carbs.

I'm thinking of either colortune or vacuum gauge syncing but unsure which is more accurate/better to do.

I've found a set of gauges relatively cheap on ebay.

Let me know your thoughts...

 

Cheap vacuum gauges are just that. You might get a set that's consistent across all of the gauges (they can be calibrated to each other at baseline, but may not all read the same throughout the range). If you go that route and find that they do not agree with each other you can build a manifold from tubing and just use one gauge, or swap that gauge between vacuum ports.

I use a set of stick gauges which use a liquid substitute for mercury. Other members like the Morgan Carbtune which uses a set of calibrated stainless steel rods.
The advantage there is that the readings are only dependent on the laws of physics, and not a mechanical assembly. They do cost more, but I think they are worth it.