Noisy motor RRR--rrr--rrrr.

[Bevel bob]

My 250 has always been noisy and now that i have got the bevels and crank sorted I hoped it would quiet down, no such luck. the noise is only under load condions and in all gears, it seems to be amplified by the tank,the primary gears were run with a out of true crank and i'm thinking uneven wear,can't see anything wrong and there is a little play all round so no tight spots.All the bearings renewed except the clutch races.Any thoughts??.

[Jordan]

I tried to fix a friend's single that had a persistent noise from the cam drive system. Everything I could think of was checked or renewed, but it eluded me.
Later, I read a report that the top bearing of the vertical shaft can sometimes work loose in its housing. It wasn't evident in my case but who knows, might be worth checking.

Jordan

[Bevel bob]

Hi Jordon, what i need is a rolling road so i can listen while its pulling, I will look at the cam drive but the noise under load seems to point to the primary gears, the motor goes well enough and revs to 10 freely but is a bit down on power.

[DewCatTea-Bob]

" All the bearings renewed except the clutch races.Any thoughts??. "

____ Of course it's super rare but still not unheard-of that a new bearing may have an issue.


" the motor goes well enough and revs to 10 freely but is a bit down on power. "

____ How do you know that for sure, have you recently compared yours to another 250-Duke ?
__ BTW, where exactly did you finally end-up setting your max.advance ign.timing at ? - 36-degrees BTDC (like a Monza), or 41-degrees BTDC (like a n-c 250Mk3) ?
Cuz retarded ign.timing could be your reason for feeling that power is a bit down.

____ Has your current issue of concern been evident since you got your Duke back on the road, or has the issue been in a state of gradually developing ?
In either case, since your insight is drawn toward your primary, try this test...
While easy-cruising in 2nd or 3rd under 35-MPH and with your fingers very lightly tugging inward on the clutch hand-lever (just merely enough so as to only draw-up all of the normal cable-slop), then vary your throttle-setting between (about)- 3/4ths-throttle & fully shut-down, and note whether or not the clutch-lever wishes to tighten-up outward whenever your throttle-setting goes from fully shut-down to back towards full-throttle...
If while varying your throttle-setting (under said conditions), you then note that the clutch hand-lever's play-slop also varies (in sink along-with your varying throttle-setting),
then you can be fairly certain that your primary is suffering from a common-problem.
__ Please let us know the results of your testing.


Hopeful-Cheers,
-Bob

[Bevel bob]

Thanks DCT Bob, I'll give the clutch test a go,( suspect box shimming?), yes the timing is retarded a bit 35/36 which allows me to start without too much kick back, it still kicks though!!,The rythmic noise has reduced after the rebuild but is still there and is quite noticable from the saddle at town speeds when pulling.To get 40 degrees advance the static would be 12 degrees, a bit too exciting, time for an AAu mod methinks.

[DewCatTea-Bob]

" I'll give the clutch test a go,( suspect box shimming?), "

____ No, shimming is not a "common-problem", but what is common is for the clutch-hub's nut to come loose, which then in turn allows the drive/pinion primary-gear to pressure the (loose) clutch-drum/basket outward & inward depending on whether the rear-wheel is turning the crankshaft or the crankshaft is turning the rear-wheel.
And in the case when the crankshaft-pinion is driving the clutch-basket inward against it's main-support bearing, the 'primary-meshing' is then sunk into the case (through the bearing), making it carry throughout & become pronounced & noticeable, especially if that bearing has any issue of it's own.


" The rythmic noise has reduced after the rebuild but is still there and is quite noticable from the saddle at town speeds when pulling. "

____ That which you're aware of may be merely normal. _ Too bad that you don't have another Duke to compare against.


" yes the timing is retarded a bit 35/36 which allows me to start without too much kick back, it still kicks though!!,To get 40 degrees advance the static would be 12 degrees, a bit too exciting, time for an AAu mod methinks. "

____ Perhaps you could get good at using a kill-switch to avoid getting the kick-back.
__ Have you considered the electronic-ignition which was recently posted about ?


Hopeful-Cheers,
-Bob

[Bevel bob]

Most unlikely to be a loose clutch nut, I have a fancy lockwasher that holds the flats and mounts on one of the spring posts, that problem is sorted.None of my other contacts recommend timing so far advanced. I understand that todays fuel mix burns faster than of old ,perhaps thats the reason for less advance. I'm of the opinion that 38 degrees is the optimum, certainly after a speed run with a new plug the heat banding on the outer electrode is right up there by the bend, this is an indicator that the motor has enough advance. Still having some richness issues due I think to vibration (plenty of it) affecting the fuel level.I'm working on a remote set up .I'm happy with my sparks ,just need to increase the range of the AAU by 5 degrees to allow a 5 degree static setting and 38 degree fully advanced figure.And maybee fit a head steady.