Super Jet bendix rattling - please help

jetfreak78

jetfreak78

Location
north east germany; island "usedom"
Hi,

please watch the vid.

im fighting with this for a year now and cant get it. Please help me.

what makes the bendix to shake/rattle like that? when engine is runnig the bendix extends a bit and its gear grabs partially into the flywheel, so the bendix partially rotates (unfortunately hard to see in the vid) and makes this horrible rattling sound.


engine is newly build (overhaul) (805ccm; ported; fresh bore, hone, pistons, etc.; trued, overhauled oem crankshaft; b-pipe; fp waterbox; 46mm single carb; ada head; vforce 2 reeds; 62T crankcase; 6M6 elektronics with rev-modded 61X cdi ......

this is a used jetmaniac tested oem bendix. it does the same as the 20 year (fresh looking and acting) old bendix i had in there before.
the bendix bushing are new, the starter is new.
bendix has washer/spring/washer on cover side and one big washer an crankcase side.

should i by a new oem bendix and test?

i have one last idea. the b-pipe headpipe and chamber are sitting directly next to the hull (absolutely no space, heavily reinforced). could it be, that the running engine converts his (from the hull) restricted vibrations into the hull and the hull sends the vibrations back to the engine, making everything harlem shake?

i rode the ski once (brake in) but am afraid to do it again. when you let off the throttle the holy ski vibrates.

hope this is understandable ;-) any suggestion is appreciated.

Thanks, Georg
 
Last edited:
BruceSki

BruceSki

Formerly Motoman25
Location
Long Island
Try adding an extra washer of two on the front cover to increase spring tension/pressure.

Is the spring in the front cover new?
 
SJdippin

SJdippin

BruceSki said:
Try adding an extra washer of two on the front cover to increase spring tension/pressure.

Is the spring in the front cover new?
Click to expand...
Yes it sounds like the bendix is slightly shorter than what was intended adding a little length, via washer into the holes that except the bendix will hopefully get rid if that rattle.


Sent from my iPhone using Tapatalk
 
jetfreak78

jetfreak78

Location
north east germany; island "usedom"
BruceSki said:
Try adding an extra washer of two on the front cover to increase spring tension/pressure.

Is the spring in the front cover new?
Click to expand...

No, the ski is (was) a SN 1991, so the spring is ;-) Do they wear out?

i have tried 2 different (bendix)springs i had in my spare part boxes, but they are all from 1991-1993 and ended up in the same result (rattling).

Good idea with one or two extra washers in front. I will try that in the evening.

Thank you
 
yamanube

yamanube

This Is The Way
Staff member
Location
Mandalor
I would try a different bendix, it could be that the spring in the bendix is weak allowing the gear to move forward slightly from the vibrations, it would be tough for JM to inspect for this.
Also check to make sure the bushing you put in is seated all the way and not pushing the bendix out away from the cases more than it is supposed to.
 
jetfreak78

jetfreak78

Location
north east germany; island "usedom"
installed two extra washers in the front cover, that helped a little, but the bendix is still partially engaging into the flywheel (and then rotating). it is not the bendix itself, which moves forward, it is the gear of the bendix.

yamanube said:
I would try a different bendix, it could be that the spring in the bendix is weak allowing the gear to move forward slightly from the vibrations, it would be tough for JM to inspect for this.
Also check to make sure the bushing you put in is seated all the way and not pushing the bendix out away from the cases more than it is supposed to.
Click to expand...

i installed the bushings like the old ones were installed. they stick out maybe 0,5mm on the crankcase side. Dont know if this is correct.

i ordered a new OEM Bendix and spring/washer. Hopefully it will be delivered fast :-(

Whats the Problem - the Bendix, or the Vibrations???

i wanna ride!!!!

20150623_191123 klein.jpg
 
Last edited:
Harbor

Harbor

Location
Stockton
The bendix gear to flywheel gear clearance spec is .140

I've got a billit case here with the bendix pocket not machined deep enough by .100 Iam sure you don't have this issue but thought I'd post the spec I case you need to check it. I used a dial indicator on the tip of bendix to check the gear to gear gap
 
jetfreak78

jetfreak78

Location
north east germany; island "usedom"
i set the bendix bushing flush with the case, bought new oem bendix with spring and washers, installed everything, checked the bendix gear to flywheel gear clearance (~3,5mm wich is equal to .140 inch, so ok, thanks harbor)

But that did not help, bendix is still rattling like before. Any other ideas?

What about the vibrations like written in my first post (headpipe sitting against the hull)? i will disassemble the pipe again and grind a bit to make more space for the headpipe. This is my last idea. Hope this helps.

i have dis- and reassembled anything on/in the ski maybe 30 times for over a year now, checking everything, but all seems to be normal, dont know what to do/check next.
 
jetfreak78

jetfreak78

Location
north east germany; island "usedom"
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