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i think xs 250 has beaten me


Jeremiah+Josh
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Makes things easy on yourself on the ignition. Set the points gap exactly the way it says in the manual. Then set the static timing the way it says here:

Now, once you get the thing idling on both cylinders (I have some thoughts about that, back to that in a minute) and after the static timing is set, with the points cover off, advance the timing slowly turning the points plate clockwise and the idle speed should increase. if it decreases, turn it the other way. When the idle speed is as fast as it gets, back it off a bit and tighten the plate. An engine with some wear will run better with a little bit more advance than stock. Based on your compression numbers, you have enough wear to benefit from this. After you set the timing this way, ride to make sure it is not pinging and check the plugs to make sure there is not too much heat. If there is, back the advance off a bit and ride again.

As for cleaning the carbs, if they are like those used on the XS400, the idle circuit passages can be finicky. Here's how I clean them (this is for BS34s, hopefully yours are similar). With the carbs off (you can leave them attached to each other) take carb cleaner and spray it through the air jet at the mouth of the carb. With the idle mixture screw in, but at the setting for running (try 3 turns out to start) a strong stream should spray out from the hole beneath the idle mixture screw. Turn the carb over and take the idle jet out and clean it and shoot carb cleaner up through where the jet was. You should have a strong stream out the same hole. Then screw the idle mixture screw in and lightly seat it. Spray the carb cleaner in the air jet while holding the carb butterfly open. You should see 3 strong streams coming out of 3 small holes just above where the butterfly rests. Turn the carb over and spray carb cleaner up the idle jet from below and you should see the same thing.

Spray until you can see the carb cleaner flowing in strong streams as noted above. If you can't see that, you may need to strip and boil the carbs (my preference...'cause it's cheap) or have them ultrasonically cleaned. If you can see the carb cleaner spraying out basically unimpeded, then the idle circuit is clean because you have cleaned it from both directions.

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Makes things easy on yourself on the ignition. Set the points gap exactly the way it says in the manual. Then set the static timing the way it says here:

Now, once you get the thing idling on both cylinders (I have some thoughts about that, back to that in a minute) and after the static timing is set, with the points cover off, advance the timing slowly turning the points plate clockwise and the idle speed should increase. if it decreases, turn it the other way. When the idle speed is as fast as it gets, back it off a bit and tighten the plate. An engine with some wear will run better with a little bit more advance than stock. Based on your compression numbers, you have enough wear to benefit from this. After you set the timing this way, ride to make sure it is not pinging and check the plugs to make sure there is not too much heat. If there is, back the advance off a bit and ride again.

As for cleaning the carbs, if they are like those used on the XS400, the idle circuit passages can be finicky. Here's how I clean them (this is for BS34s, hopefully yours are similar). With the carbs off (you can leave them attached to each other) take carb cleaner and spray it through the air jet at the mouth of the carb. With the idle mixture screw in, but at the setting for running (try 3 turns out to start) a strong stream should spray out from the hole beneath the idle mixture screw. Turn the carb over and take the idle jet out and clean it and shoot carb cleaner up through where the jet was. You should have a strong stream out the same hole. Then screw the idle mixture screw in and lightly seat it. Spray the carb cleaner in the air jet while holding the carb butterfly open. You should see 3 strong streams coming out of 3 small holes just above where the butterfly rests. Turn the carb over and spray carb cleaner up the idle jet from below and you should see the same thing.

Spray until you can see the carb cleaner flowing in strong streams as noted above. If you can't see that, you may need to strip and boil the carbs (my preference...'cause it's cheap) or have them ultrasonically cleaned. If you can see the carb cleaner spraying out basically unimpeded, then the idle circuit is clean because you have cleaned it from both directions.

Hi thanks for input done all that a couple of weeks ago

the bit about advancing the timing plate may be handy

as above now idling and ticking over a treat need to balance carbs next and put check main jets and neddles as the carbs are made up now from random bits so to change one part at a time

NEED TO WORK OUT HOW TO REMOVE A BROKEN NEEDLE TIP (I BUST IT OFF YESTERDAY)

where's Drewpy Im interested in this plug gap anomaly

Jeremiah !

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  • Moderator

I wonder if your getting a weak spark and closing the gap is just compensating for it. I am running points, but only as a trigger for electronic ignition which was homemade from an enthusiast in germany!

I have those iridium plugs and haven't changed/adjusted them for a few years and still going strong. ;)

I did have some coil issues but replaced them with a set off ebay with a 3ohm set. £13 each they were and bolted straight on.

which tip did you break off? mains or pilot?

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Hi

new coils from rex count

it feels retarded on the throttle but i have only balanced on rev counter 1 pot at a time need to put vac Guage's on

ill re time with fag paper and then strobe it

a whole new world of tricks is availble now its starting

the tip i broke was pilot mixture screw ...i found some more carb bodys in the basket case and the mixture screws were different (stepped rather than tapered) anyway i tried those in me bestest bodys and one broke ... i have yet to try airline up pilot holes to blow out

thanks for help

will keep it posted

Jez

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  • 2 weeks later...
  • Moderator

adjusted points gap to tad over max now have fat spark bike pulled well

now in bits ready for next stage ... electrics

...

doing well, keep going.......

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  • 2 weeks later...
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Is the battery going under the seat with the reg/rectifyer?

I went to fit my cyl head in the tracker the other day and the fekker wouldn't go on. Had to take the motor back out of the frame and build it off the bike. :(

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