SF1 won't select 5th

C

ColinJ

New member
Location
Aberdeen
Folks,

I posted a few weeks back about my SF1 stuck in neutral and 1st. Since then I have had many adventures with gear selection and have got very oily. My SF1 will now select 1,2,3, and 4, but it goes into a false neutral when I select 5th. I have adjusted the eccentric many times but it I can never get 5th. I have turned the selector drum with a mole grips and I can easily select 4 gears but when I turn it to select 5th the drum turns but it does not select the fifth gear.

I tried riding around for a while in the hope that whatever was stopping selection would get dislodged or wash away when the engine was hot. Still no fifth gear.

Has anyone had this problem? Any thoughts on was I should do next?

Regards Colin
 
It might be worth getting one of those camera adaptors on a flexi stick things and having a look inside. Maybe something is sitting in the bottom of the gearbox impeding the selector drum. The motor hasn't been apart and been assembled with fifth the wrong way around?
 
If the engine has been apart the usual reason for not getting fifth gear is that the selector ring has been put in the wrong way round. I hope in your position that is not the case.
Alan.
 
I once made the mistake with my Suzuki T20. Mounted the 6th gear sproket the wrong way and had an other neutral after the 5th. Hope you problem is outside the gear box.
Andre
 
This selector system is very simple and adjustment probs are usually similarly simple to resolve. Make sure no pins have fallen out of the outer 'drum' that the fork rotates either up or down. If it selects 1. 2. 3 and 4 then it really doesn't sound like adjustment. As already mentioned, if the motor has just been reassembled it's highly likely to be the 5th gear selector ring in the wrong way round (DAMHIK!). Or as Tippie says, something may be preventing the intenal shift drum/plate from rotating to its full extent 9where it's edge will come close to the base of the lower case). Good luck - report back.
 
Thanks for all your suggestions. I drove the bike from Italy to London in 1990, the gears were fine on that trip. Since 1990 the bike sat in my garage until 2006 when I sold it to a friend at work. He started to restore it but as far as I know he did not split the crankcases or in fact do anything to the engine. My friend became very ill and ask me to take the bike back. Sadly he has passed away.

Over the last year I have just reassembled the bike. When I first started the bike it was stuck in neutral and first. This was solved by cleaning the neutral switch and adding another shim. I set the selection mechanism up as per instructions in the green book and this forum but was unable to get into 5th gear. I can see from the diagram on P84 of the green book that 5th gear is selected by a fork which is pegged into the selector drum. The fork closest to the drive sprocket. As Tippie said something may be restricting the movement of the drum. I will get a boroscope and have a look inside.

So my plan is
1) take the cover off and try adjusting the selection mechanism again.
2) have a look inside with a boroscope.
3) Take the engine out and split the crankcases. 😭😭😭😭

Thanks again. Any other advice is most welcome. i will keep you informed of my progress.
 
Try loosening the sprocket cover and wiggling it to another position... a firm whack with a plastic mallet towards the front of the bike often affords the meshing gears of the selector mechanism a little extra play. Suddenly, the selector drum is able to rotate, and, hey presto, 5th gear is back! 5th is the most affected, sometimes the selection stops at 3rd.

Especially the triples show a tendency for the selector shafts to bind at the meshing gears, give them a tiny bit of slop and all is well. The selector drum should have noticable rotary play in all gears.

piet
 
Yep, usually 5th that goes AWOL. The shafts simply bind at some point, using up all tolerances in the wrong direction.

I once removed, opened and replaced my triple engine 3 times in an afternoon because of this... was young and stupid, but mighty strong! :rolleyes:

Wasn't aware of being able to test the gearbox shifting before fitting the sprocket cover at the time (young and stupid, see above).

piet
 
I was just typing the second half when a mate turned up and I had to go out.
Piet beat me to it.
Once the case is just loose enough to ease it around, try, using the selector not "grips", to change up to 4th (or, possibly, 5th).
Then, having removed the gearchange mechanism, gently pull out and push in the drum shaft, finessing the position of the outer case until the drum shaft does not bind.
Tighten case and see if you can get all five.
 
I once changed the selector springs and ended up stuffing around with the gaskets and washer to get every thing working correctly again.
Short story, the gaskets were either to thick or to thin [I was making my own] eventually I got it right.
Just saying, could it be that simple.
 
was there any forcing (on your part) when the bike was previously "stuck in neutral and first"
difficult to see how it was stuck in two positions, so I will assume that you could only get first and neutral, if you have been stomping/stamping on the shift pedal out of frustration (we all have been there) then maybe you have bent a selector fork, if the bike rode well before the lay up, then nothing should have changed while it was idle, so what did you do to cause the first or neutral situation, was it removing inner and outer covers, perhaps to change the gearbox sprocket, was there any hammewrring involved in fitting the new sprocket? this can only be an alignment or adjustment problem, alignement of the two marks as Hamish's picture but also the inner and to an extent, the outer case, as (ususally for motorcycles) those covers are not dowelled, which they should be, they can move around a fair bit to get a sweet spot, always adjust the eccentric with the box in fourth gear, but for testing purposes you can take the spring loaded fork and screw out completely, and see what you get, there is a tee handled factory tool for slipping over the teeth of the small selector barrel to facilitate changing the gears while experimenting, sounds like you need to borrow one, the club has one, as do I if you are near.
CLEM
 
To answer all your questions.
I don't think I used excessive force when it would only sect first and neutral. Clem thanks for the offer of the factory tool but I am way up in Aberdeen.

To simplify things I took the sprocket cover off to expose the inner pinion. This can be turned relatively easily to select gears 1-4. When I move the inner pinion from 4 to 5th it doesn't engage the gear. I marked the positions of the pinion in each of the gears and it does not appear to move as much 4-5 as say 3-4. Although the markings are not very accurate and may be wrong about the lack of movement. The pinion also seams to come to a hard stop as if it is hitting some metal. I don't think it is an external selector mechanism problem.

The end face of the inner pinion looks like someone has been rough with it. It is marked by possibly hammer blows. I've attached an image of the pinion in the 5th gear (almost) position. There is also a ding on part of the casing again consistent with a missed hammer blow. So this leads me to think I bike had a problem in the past. It has <30K on the clock so it is not high mileage. The engine also sounds healthy.

I bought a boroscope from tool station and had a look through the two holes below the pinion.
IMG_1112.JPEG
 
The boroscope images are really difficult to understand. I could see the selector drum which does not seem to be obstructed. The images are reversed left to right below is the left hand track for the selector fork. It seems a bit scuffed but it is difficult to tell.

IMG_1106.JPG
 
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