OzVMX Forum

Clubroom => General Discussion => Topic started by: smartie on August 09, 2013, 09:27:32 am

Title: IT490 gear box problem
Post by: smartie on August 09, 2013, 09:27:32 am

Hi all,
 i'm having gear box problems with my IT490 it is locking the back wheel up in neutral when you spin it on the stand and when you push on flat ground. it broke some teeth off the 4th pinion and 4 wheel gear from the wheel locking up some time ago after about 2000 klms from rebuild .i have change all washers circilps and 4th pinion gear and wheel gear also the number 2 fork ,it rides and changes all gears like a new box as there is nothing wrong, but when it is on the stand you spin the wheel around it locks the wheel , has any one had an issue like this before help needed.

thanks smartie. :( :(

Title: Re: IT490 gear box problem
Post by: crossedup2 on August 09, 2013, 10:20:30 am

Smartie

Does it stay locked up with the clutch in?

Check the sprocket nut is tight. End float of the output shaft sometimes allows it to engage two gears.

Otherwise you may have bent a shift fork.

Good luck!

Peter B

Title: Re: IT490 gear box problem
Post by: smartie on August 09, 2013, 12:13:50 pm

yes,
 spinning the wheel forwards it locks, clutch in still locked, spin the wheel backwards it frees up. not all the time you spin it locks, every now and then it will do it.

smartie.

Title: Re: IT490 gear box problem
Post by: smed on August 09, 2013, 07:47:30 pm

Bent counter or mainshaft?

Title: Re: IT490 gear box problem
Post by: ARN on August 09, 2013, 07:55:51 pm

could be of track ,check the kick start is not getting engaged  not sure it would give the same result, but it would be easy to check ,the 465s have problems with kick start ,490 was improved.

Title: Re: IT490 gear box problem
Post by: smed on August 10, 2013, 05:45:05 pm

When a bike is in neutral on a stand spinning the rear wheel or being pushed with a dead motor only the countershaft is turning,the main shaft will only turn if a gear is selected,Which then will turn the crankshaft,remember this is backwards to the way it works when the motor is running,then only the mainshaft turns,the countershaft will only turn if a gear is selected,there will also be some gears opposite the given shaft that is turning that also will be turning but freewheeling if in neutral, I would pull it apart again & Carefully check all gears for bent or cracked teeth and both shafts for trueness & the shift forks that were not replaced,If the clutch ain't turning at the time you are having the problem which it shouldn't be, it is nothing to do with the clutch or the kickstarter gear :)