Free up your throttle
Get your twistgrip snapping back and forth like new
1 Sticky situation
A sticking throttle is a problem that creeps up on you and it’s easy to learn to live with it, but it’s a huge safety risk as well as an MoT fail. The problem can often be traced back to a few basic things: the throttle tube rubbing on the handlebar, old cables, poor routing, or the grips binding on the bar end weights.
2 Need a new cable?
To replace the throttle cable you’ll first need to remove the tank and airbox from the bike. Carefully detach the vacuum pipe and fuel line from the fuel tap, as well as any electrical connectors and breathers. To remove the airbox, undo the clamps that secure it to the carbs, as well as any breather pipes.
3 Open housing
Undo the screws that secure the throttle grip, often these will also hold the switchgear in place. Once undone, loosen the cable adjusters on the body of the housing; our Suzuki SV650 is fitted with two cables, one to pull and the other to return. Before you proceed, make sure the replacement cables are correct and identify which is which.
4 Get some slack
Turn your attention to the carb or throttle body end of the cable. Undo the lock nuts then screw in the adjusters far enough so that the cable nipple can be popped out of the linkage or pulley. The other end of the cable can also be popped out of the plastic throttle tube on the handlebar. Repeat for the remaining cable if fitted.
5 Time for the tube
With the cable removed, the throttle tube is almost free, but the bar-end weights need to be removed before it can be slipped off. This SV650 has some aftermarket anodised weights which have deformed the throttle tube over time. Replace them with new OE end weights.
6 Rolling free
Clean the handlebar with contact cleaner and slide the new throttle tube into place. Make sure it rotates freely. If it does bind, remove it and find out why: it could be that the bar is bent from a low-speed tumble in the past or it might just need a more thorough clean.
7 Remove and reroute
Remove the throttle cables one at time and make a note of the routing as you do so. On older bikes don’t always assume that the routing is correct as it is. Check against a workshop manual to be 100% sure the cables won’t foul or snag. Install the cable on the carb/throttle body but keep the adjusters loose.
8 Connect the tube
When both cables are fitted to the carb/throttle body, fit the other ends to the correct side of the throttle tube. In the case of this SV650, the open cable is at the front and the return cable is fitted to the back. When they are located, screw the housing back together making sure that the handlebar location dowel is lined up correctly.
9 Adjust freeplay
When the throttle housing is tightened up, turn the throttle tube to make sure it moves freely then assess how much slack is in the cables. First, tighten up the locknuts at the carb end then adjust the play at the grip end using the adjusters just before the throttle housing. Play on the open cable should be 2-4mm; the return cable should have no play.
10 Refit and check
Do a final check, making sure that the adjuster locknuts are tight. Refit the airbox and tank, ensuring that all the breather pipes are fitted back in place on the airbox. Fit the tank, making sure the fuel gauge sender, fuel line, vacuum, and breather pipes and connections are all in place. Check that the idle speed is correct and the throttle action is smooth.