Maico not shifting down gears AW - now with an answer !

[Husabergpete]

Gents,

On behalf of a mate who intends racing the 250 AW next year - I have spoken to several guru's and we could be headed in the right direction. But I have decided to put this subject to maybe get an answer and help someone coming behind us.

Bike is an original 77 AW 250 5 speed. Motor completely split, cleaned, all new bearings seals, rod etc. We changed the longer 400 shift shaft for the correct and same shaped 250 shaft (bit shorter on the shaft to compensate for clutch width). 

Bike now running and will change up gear very well, but is sticky or down right difficult to go down gears. all but impossible to 2dn or 1st. What we have noticed is on my AW the shift lever moves about 15mm both up and down before it starts to engage a gear. Marks one moves about 10mm down and about 40mm up.  We also flipped the shift shaft return spring over, which actually made a difference even though it looks identical each way. This causes he Shift shaft to rotate very slightly towards the direction of the front wheel. the Shift shaft lever ends up moving about 5 to 6mm. the hole in the end of the level fits into a pin which then is slide back and forward to select gears through the selector plate (not a drum)  We have been told it hard to mis align the teeth between the selector plate and pinion segment gear that is pulled around which then drags the selector plate back and forth which pushes and forces the selector forks to get another gear. hope this is making sense. I didn't check if the selector forks were straight but all the box and selectors look like new. Famous last words. 

Any ideas for the record???

Thanks Pete for Mark

[3858]

  We have been told it hard to mis align the teeth between the selector plate and pinion segment gear that is pulled around which then drags the selector plate back and forth which pushes and forces the selector forks to get another gear. hope this is making sense.

If it is the same as a '81 model in the gear change mech I found it easy to mis-align the timing of the shift plates..... Re-check the indexing...

[Husabergpete]

Could be right. The 77 has a flat shift plate on the top of the box instead of the usual shift drum. We may have allowed the shift pinion or segment to be a tooth out. I take it you had the same issue of not being able to shift down (or up).

Pete

[3858]

Yep I was changing mains and had it mis-align by a tooth.  The result was a change up but not down...  There is dots on the segment that have to align with a certain number tooth..?

It was a while back but I am sure that will be your issue.  Good luck...

[firko]

Hi Pete....Can Mark find neutral with the engine running? Is the clutch set up for just a little drag but idle with the clutch pulled in? Does the bike downshift OK without the clutch? (something early Maicos do with little or no ill effect).This might just be a clutch problem other than anything in the selectors. Have you checked the shift plate for wear and possible "dag" hangups?

[Husabergpete]

Mr 3858 and Mr Firko,

Well,,,,  I can say the bike is suppa difficult to find The Neutral running or not.  I/we didn't check the shift plates too carefully other than they looked to be in excellent nick  and the gear box is really good too. So the selector forks didn't get a real close look in either.
.
One change we did make was to fit a wound clutch spring from Les. That went it well. Clutch action feels like my cup spring model and working well.  The main difference between the two AW's at the moment is my gear lever seems to move the same amount of travel  both up and down but Marks only goes down about 12mm and up about 40mm.

Looks like it is coming apart. I will report back on the outcome. In the mean time any other things to look for are welcome.

PS for the record we did have a small hiccup during the gearbox install. We couldn't get the top side case to fit down, it was rocking on the output shaft and hung up by about 2mm. Ronny the Engineering guru Thunk it out.  Turned out the PLUG in the end of the output shaft - near the front sprocket and outside the cases was pushed in around 2mm. It is like a welsh plug. Had us stuffed for a while.

Pete and Mark

[Husabergpete]

Motor out and will come apart

[reg]

motor has been pulled apart again and everything inside seems good, seems to be all lined
up correctly according to stuff i found on the web.

i rode the thing again yesterday and it changes up very smoothly but changing down i need
to lift the lever a smidgeon, cupla mil, before it changes down.

i also tried turning the shift shaft return spring around, no good, made things worse.
would any of you maico gurus have any ideas as to what the problem may be.

thanks mark
 

[Husabergpete]

More progress.

Problem - Up gears no issue, get to to 5th gear then select down to 4th, no issue. Then select down again, NO GO. it is as if you are in 1st gear and trying to shift down again. Then we found that if we lifted the folding gear shift lever up about 2mm at the tip the Selector Pawl/ratchet who move to the rear of the motor and clip over the dowel pin on the selector plate.

With the help of Paul Chippendale we look like we are on the right track.

Turns out the length of the flat bar that runs from the end of the gear selector `boomerang' to the flat bar that in turn ratchets round the gear selector plate (dowel pins) is critical. Paul checked about 8 of his spares and they were all different lengths. The length we are talking about is from the pin that goes into the boomerang back to the square notch that mates up with the flat bar that pulls on the gear selector plate. Hope this is making some sense.

By adding bend to the flat bar we were able to shorten the mentioned length by 3mm - that resulted in a huge improvement to to so that instead of 2mm of up lift to get the pawl to grab the dowel pin we ended up with only having to lift it a bees dick. Motor to be now put back together fully - oil add and test run.

See how we go.

Pete, Mark, Ron and now Paul

[JohnnyO]

I had the same problem with my 490, turned out to be the flat bar that runs vertically connecting the lower shift mechanism to the top sliding bar had a crack in it at the hole in the middle where it pivots, the crack allowed it to bend slightly and it would shift up gears but not down!

[Husabergpete]

Johnny,

Looks like we HAVE got to the bottom of it.

The bend in the horizonal bar that runs from the shift shaft to in behind the clutch - connected to the other flat bar that rotates the shifting plate (hard to explain these maicos)

Well we put more bend in that resulted in a length of I think 130mm.  Then the other main thing was the little spring inside the motor that pulls the bar that in turn Hooks over the pin in the shift plate Had Very Little tension. So it wouldn't hang onto the pin.  Upped the tension and now on the bench it is a goer.

Ride time this arvo as a final test.

Mark now selling his RM 125 A - see for sale in forum ta Pete Ron Mark Mick De Paul Chippendale and the Maico Gods