Tuning.....Where the hek to start!

[Paul75]

So...I went back to the points and started over, setting the gaps at 0.40mm and set the static timing with a new lower wattage bulb. I must have spent 2 hours really figuring this out but it was worth it because I managed to really fine tune it and was happy with the results.

Next day, fired it up. Wow! Running even better, adjusted the idle and got the strobe onto it and blow me it was absolutely bang in range, just over very slightly to the right of the F, within the brackets so a tad retarded but no need to adjust again or play with anything else. Advance in range too.

Really surprised with how well it sounded on tickover, these motors really do produce a lovely sound. Will be doing a test run hopefully over Xmas so will then start the carb challenge! Thank you for everybody's help again with this....

Paul

 

[Paul Sutton]

Great News! Let's hope there is a break in the weather for that test run. At the moment the forecast is not looking brilliant.

 

[MaxPete]

Good for Paul - nice work!

Pete

 

[mrtwowheel]

Great job Paul. You are way advanced on the understanding of your points and timing after doing the procedures till perfection. After you get the carbs tuned in you'll have a bike that really purrs, with great throttle response.

Scott

 

[5twins]

You did clip the timing light to each plug wire and checked both cylinders, right? Remember, this set-up is like two separate little ignition systems. You have to check the timing individually for each cylinder. It can be different.

You've done good setting the timing towards the right side of the range, a bit retarded. As I mentioned, I think these bikes run better that way. But actually, you really haven't set the timing retarded at all, at least not according to the timing spec these bikes used when they first came out. The idle timing "range" spec for your model is 13° to 17° BTDC. Full advance is 40° BTDC. When these bikes came out, it was different, a little more retarded. Idle spec was 10° to 15° BTDC and full advance was 38° BTDC. On your bike, the middle of the range, where the "F" mark is, would be 15°. Setting it over towards the right side of the range would put at around 13°, and that setting is pretty much right in the middle of the old timing spec.

 

[Paul75]

Oh hell.....no! You are right.... I only checked the right cylinder (I feel such a fool) Will hopefully fire up again tomorrow and check the left....will let you know how I get on....

 

[TimeMachine]

Oh Dang on that not checking both sides.. I was just about to award you the Gold medal on points setting !! You still get a huge congrats but you have to go for the gold !

 

[MaxPete]

this set-up is like two separate little ignition systems. You have to check the timing individually for each cylinder. It can be different.

5Twin has put his finger on a key realization IMO.

The XS650 really is a very simple machine - except that the points ignition for the two cylinders is actually two separate systems and it is possible to have the points gap and dwell, and the timing be quite different between the two cylinders.

Once you realize this - and it becomes crystal clear when you look closely at the points plate and how the two sets of points are mounted - you will be able to deal with the complexities of the points system much more easily (in my view). Last year when I got Lucille running I finally got around to setting the points and it was only after staring at the points plate for a few minutes that I recalled (from earlier bike in the 1970s) that the two points are mounted separately.

 

[Paul75]

The thing is I actually do understand the plate mounts both left and right points, I hooked up the right to the strobe and was so happy that it was in range that I forgot to check the left!! A schoolboy error!!

Going to squeeze in some garage time today as there will be no time tomorrow....!! Have a great Xmas all!

 

[Paul Sutton]

You have done the hard part by setting the advance and right points. The left is easy as it just needs a points gap setting and fine adjustment. According to the forecast, today should be OK for a quick test ride this afternoon.

 

[motorbikerx]

ok after much perusing of points timing etc topics on here I chance on this thread that seems to cover everything!
woohoo!....set my points to .014"...loosen big phillips to time right cylinder, now all screws have chewed heads but the lower of the big phillips has been stripped presumably my the gorilla that last worked on this bike...
I have a feeling the hole that the lower big screw goes into is actually in the head not the points cup (for want of a better description)
So Ive managed to hold the timing to the righter side of the variables, though checking with a timing light running theres a small variation left/right at idle.
Tomorrow Ill check full advance....or maybe Sunday as Im off to the drags at Willowbank on Saturday arvo (Top Fuel, Top Alcohol, Top Bike, Doorslammers, SuperCharged Outlaws, Super Street....off for my Nitro fix!)

 

[Paul75]

Sounds like fun! This thread certainly helped me get mine running like a charm I'm sure yours will in no time too ;-)

 

[mrtwowheel]

Points aren't so bad. That spring on the points is an important part, it's got to be a strong spring. Mostly that spring strength was the difference between "high performance" points and a set of regular points.

Scott

 

[Paul75]

Guys Hope you are all well!! Ok so I've been off here for a few weeks....but

had to come back because I miss you

Now the weather is perking up a little I've been firing up the bike getting ready for a proper test ride. Upon firing it up (from cold) it is running really badly, popping, banging etc etc, once warmed up though after several minutes it runs perfectly. I remember reading in the past that the float bowl can be clogged/blocked somewhere - is it the pilot jet that I need to check? I did do a carb rebuild but figure that it may need pulling apart and checking again - apart from this the BS38's have not had any alterations.

Would this action be a good starting point? Which part of that carb is the pilot jet?

 

[MaxPete]

Hi Paul - first of all welcome back!

It does sound as though your carbs may be gummed up and need to be cleaned.

The best advice I can give you is to download the excellent XS650 Carb Guide which has been compiled by a couple of forum members. It is essential to any carb work and more than just an assembly manual. It actually explains how the carbs work and so you wind up understanding what’s you are working on as well as which adjustments will solve a given problem and why.

I’m sorry, I don’t have the linky but if you just search for “carb guide”, it will come right up.

Cheers,

Pete

 

[5twins]

On the BS38s, the pilot jet is mounted in the top of the float bowl. The bowl will need to come off to access it, but the carbs don't have to. If you can reach in under there with a stubby screwdriver and get the bowl screws out, you can drop the bowls with the carbs still mounted. Your '79 carbs should have a VM22/210 type pilot jet .....

Remove it and blow all it's little holes clear. Also blow out the passageways leading to it. It gets fed it's fuel supply from the main jet. If you look down into the bigger hole over the main jet, you'll see a cross port going to the pilot jet.

 

[Paul75]

Good info as always. Ah ha, now I remember, these little flat headed jets are the ones I couldn't get out when I had the carbs apart. I think I ended up blowing them out with carb cleaner. I will try again to remove them with a good fitting ground screwdriver and report back......

 

[MaxPete]

The good fitting screwdriver - firmly pressed into the jet is absolutely essential. If the driver is at all loose - you'll simply ruin the slot in the jet and render it darned near impossible to remove.

Don't ask me how I know....

 

[Paul75]

Guys I pulled the bowls out and sure enough there was a bit of crap in one of the pilot jets.....fired it up and bingo! Perfect running bike!!! Thanks all....

 

[aldo5468]

Guys I pulled the bowls out and sure enough there was a bit of crap in one of the pilot jets.....fired it up and bingo! Perfect running bike!!! Thanks all....

From the pic's you have posted I couldn't see if you have an inline filter in the gas supply to your carbs. FYI RonAyers.com has a small nylon mesh one that fits into fuel lines, Kawasaki P/N 49019-1085, as shown in carbs fiche for 2005 Kawasaki ZZR600 (ZX600-J4).