SOHC.co.uk Forums > CB500/550
550 K1 : up-shifting issues (mostly low RPMs)
matthewmosse:
That is a sweet looking bike.
Erny:
Coming back to this topic - is there reliable way how to ensure issue comes from bent/work shifting fork or other issue that will force me to split cases?
I want to go maximum avoiding that.
Just thinking, maybe inspection camera?
Bryanj:
Unfortunately not, the tips of the selectors is where you will see wear and they are hidden in the grooves of the gears so not visible till removed, if poor selection is only one way i would suspect mechanism more than selectors.
K2-K6:
Thinking further about this, it's worth splitting down what happens inside to give a better picture of the problem.
I can quite understand not wanting to split a factory built motor, it's nice to have something very original.
To make a statement of the problem :- the second gear engagement dogs are either not fully in position when applying torque through the gearbox or the dogs themselves are worn rounded at their edges, both of which can force the gear back out of engagement and give that false neutral.
Discount the worn dogs for now, just set aside as they shouldn't at that mileage be compromised.
Positioning is achieved by completing the selector drum rotation until it locates the drum in its detent. At that point the gear should be fully engaged. If you don't fully rotate the selector drum the gear is left partly in full engagement, resulting in the gear being forced back out when you apply throttle.
This would be either something wrong with the mechanism that rotates the drum, or the detent that should hold it where you left it after moving the lever.
The operation of this can be inspected after removing the clutch on this engine, without removing or splitting the engine. But you need to make sure that your foot is moving the lever fully when changing up to second to ensure you are not missing something simple here before going inside to inspect.
If the selector drum completes it's rotation and is held by detent but the gear still spits out under load, then it would point to more internal parts that would need a split.
A road test like this will help seperate the two areas :- get out and up to third gear, then change down into second, now leaving it in second gear use full throttle to accelerate, don't change any gears now, shut the throttle and let speed come down again, now repeat. You need to be quite violent in doing this in second gear and then go further by opening and shutting the throttle in quick succession.
What you are testing for is the correct position of second gear location under more extreme loading. It shoukd not pop out of gear if you subject it to this as you are testing both the forward and reverse torque capacity of that gear set. It should just stay in that gear without question.
If this checks out ok, it shows the ability of that gear to operate correctly, confirming that the gear is placed fully and it's dogs are in good condition.
It's quite possible for low mileage gearboxes that have been used very gently to be obstructive, which is probably move related to the machining quality on the shift drum. If that's the case, then very close attention to placing the gearlever as close to your foot as possible will definitely help you. The change from 1st through neutral to 2nd is the longest travel required on these bikes. If you don't make full and positive travel right at the end of the movement it can leave the selector drum short of its detent position.
The clutch on bikes makes almost no difference to gearchange operation, unlike a car they can be helped by not pulling the clutch all the way in, as John mentioned earlier.
All of them should change without clutch at all if the throttle is well set up to allow rider to accurately control torque.
Erny:
Thanks for the feedback
I did road test many times already when riding in my favorite track (uphill, many curves) - so full trottle, shut, full again on 2nd gear many times (believe me I was violent enough) no single issue, 2nd stayed engaged all the time. And as I said before, shifting on higher rpms is all ok.
Concerning lever travel - fact is that I dont have dot on shaft to know exalt position of lever (on lever dot is clearly visible), so I set to my best guess. Not sure if eventual shift by 1 tooth can cause this.
It simply behaves the way when i shift up that I feel something blocking lever to go up more. Either I keep it lifted all possible way up longer and it enegages (lever moves more up) or release it and do second lift to engage it correctly.
I'll open clutch anyway to check it.
Practical question here - is it enough to lay bike on left side to avoid draining oil?
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version