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mbeers6

Softer Dellorto carb spring?

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Looking to make the throttle easier/softer on my 2010 TXT 250 which has the PHBL26 carb. Put a new cable on and lubed the throttle tube properly but I believe the return spring is the issue. 

I also have a 2017 TXT 250 with a Keihn and it requires much less effort to open the throttle. Trying to get the amount of effort on the Dellorto to feel more like the Keihn which is very smooth/low effort.

So, has anyone gone to a softer spring? If so where did you get it (hardware store?) and did it effect the closing of the throttle at all? I don't want to modify the stock one, but what about cutting off some of the coils?

Cheers

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Cut off 4 to 5 coils from the original, always worked in the past. Bye, Peter B.

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Best way and ive done this several times, run the spring up and down a grinding wheel, removing a bit of the thickness, if you apply a little pressure it winds itself in and removes a consistent amount. It can be done in stages and also you maintain the closed coils top and bottom. @mbeers6

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2 hours ago, peterb said:

Cut off 4 to 5 coils from the original, always worked in the past. Bye, Peter B.

i wouldnt do this

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NIGEL DABSTER is correct, whatever you do don't shorten spring. 'THINNING 'the coil with a grinder is only way to modify a spring, otherwise you risk slide sticking open..........trust me I know to my expense.!!

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No, grinding a spring. That is more likely  to leave you in a fix. People have been shortening springs for decades. Just start off small. Another problem with soft throttle springs is they are harder to control. Just a little movement from the throttle hand or hard hit causes some in put to the carb. You could also lube the cable and tube.

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Disagree mark I have cited 2 reasons why its the preferred method. I always did this on my shercos, done 4 with complete sucess, method was shown to me by ace mechanic and tuner who has helped riders win two world championships in seperate disciplines of motorcycling, so imho the best way!

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I agree with Nigel, cutting coils off of a spring increases the spring rate (force required to compress the spring a certain distance) while reducing the initial force to lift the slide off the idle stop. The method I've used in the past was to turn a wooden dowel to just a bit larger than the spring's I.D. Slip the spring over the dowel by turning it in the direction that opens up the coils, then lock it in place by turning the other way. Clamp the dowel in a vise and then use a length of emery cloth pulled between  both hands to remove spring material. This method slowly removes metal and reduces the chance of suddenly overdoing the grinding with an aggressive wheel. You may be surprised how fast this cuts down the wire thickness, too. 

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22 minutes ago, arbutus said:

I agree with Nigel, cutting coils off of a spring increases the spring rate (force required to compress the spring a certain distance) while reducing the initial force to lift the slide off the idle stop. The method I've used in the past was to turn a wooden dowel to just a bit larger than the spring's I.D. Slip the spring over the dowel by turning it in the direction that opens up the coils, then lock it in place by turning the other way. Clamp the dowel in a vise and then use a length of emery cloth pulled between  both hands to remove spring material. This method slowly removes metal and reduces the chance of suddenly overdoing the grinding with an aggressive wheel. You may be surprised how fast this cuts down the wire thickness, too. 

By the time you've done all that, your hands will be strong enough to overcome the massive force required to compress a standard spring.  😳😳😳

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Or just leave the spring as it is and buy one of these, to be used an hour or so, daily. Then use your other hand, too.

No problems whatsoever riding any bike a couple of weeks after that .....

5ae46e2150c3a_2018-04-2814_42_10.thumb.jpg.83dcbc8b26684112912568e009f51f24.jpg

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