South West Bikers | Motorcycle Forum

I'm putting together a part-built ZXR400 for race/trackday use and have stumbled upon a slight problem...

... The throttle cable won't spring back after I attached it along with the return cable to the outside of the carbs. Isn't there a spring in the adjustment screw near the throttle assembly that should help it spring back into place? I'm checking so that I don't have to take the throttle assembly apart unless I really have to.

Anyway, I tried just with the throttle cable attached and it sprung back, as soon as I attached the return cable it didn't spring back. Help!

Bin the return cable
If your doing track days you DONT want it.
I dont run it on mine, as this one time going towards a roundabout my return cable jammed. Thus leaving me with a wide open throttle. Ever since I havent had one.
Better throttle response too.
Get a pic if your still stuck, I know my ZXR's!
Any parts, let me know ;)

Little Loris wrote:I'm putting together a part-built ZXR400 for race/trackday use and have stumbled upon a slight problem...

... The throttle cable won't spring back after I attached it along with the return cable to the outside of the carbs. Isn't there a spring in the adjustment screw near the throttle assembly that should help it spring back into place? I'm checking so that I don't have to take the throttle assembly apart unless I really have to.

Anyway, I tried just with the throttle cable attached and it sprung back, as soon as I attached the return cable it didn't spring back. Help!

If you need a help sorting it mate I am only next door in Wellington.

Age

Probably find one of the cables are too tight even if theres a little slack at the throttle grip, try backing off one of the adjustors and see if it springs back when theres play in the system. You might find the bar position also affects the slack in the cable.

Happens quite often with my XR400 which has 2 cables, I like to run very little slack in the throttle but when you turn the bars the throttle does stick (wide bars probably don't help on this).

I'm going to check it out again this weekend and take some pics.

I must say I love being able to blip the throttle and it flick back to normal. I have thought about disconnecting the return cable altogether but I couldn't ride it with confidence.

I'm pretty sure it's missing a spring between the cable threaded end and the stop on the carbs itself.

why couldnt you ride it with confidence? the return cable is just another cable that will cause fricton and drag meaning it'll be hard to spring back.

try it for a ride and see?

So the bike doesn't necessarily need a return cable? So what is it there for?

I was thinking about the confidence thing, the return cable is NOTHING! My MX bike dont have it.
I think it makes the return less snappy, as obvious with only the Pull cable as soon as you let go, the big spring under tension from being pulled just shuts back,
I doubt many/any race bikes have 2 cables

How much freeplay have you got on the throttle. You should have about 5mm or the throtle could open when you turn the bars. I get a lot of bikes with a sticky throttle and its usualy a bit ofcorrosion on the cable, bit of lub sorts it. Sometimes it's just the twist girp rubbing on the bar end or switch gear. Disconect the cables from the twist grip to rule htis out.

Ok, had a look at the ZXR again at the weekend and it's definitely the spring at the threaded end nearest the carbs on the throttle cable. I've looked at the microfiche and still don't know how I'm supposed to fit a spring in there! However, I'd feel safer knowing I could shut the throttle off if it ever should/would/could get stuck open.

Couldn't take any pics though as the missus forgot the camera So, for payment I'll try and get some of her draped over the bike in a 'kini I'll have to clean it first of course, and the bike.

Pics of the ZXR should be happening this week,

The return cable is there to allow you to close the throttle by rotating the grip towards the bars, it is there as an extra function only. If all is well and the springs are correct then the butterflies/slides should return to idle if the cable breaks/or is released.

All sorted now. Throttle seems to snap shut. Just needed to bend the clip that help the cable in place towards the carbs and it moved more freely. I oiled it 'til I could oil no more but that seemed to do the trick...

... I still have a throttle adjustment spring going spare though