13 replies to this topic

[B40RT]

Now that my SWM is running reasonably well (still needs cosmetics)
I have noticed, or imagined, that it does not pick up a quickly as my Aprilia did,
is this entirely down to flywheel weight ?
I suppose the sensible thing would be to take them off and weight them, but if some one knows ?
Were there any other differences between the two Rotax engines, apart from clutch covers on the later Aprilia's ?

Thanks

Ross

[NicolasVasic]

Hello

I own a 320 TL with an Aprilia clutch.

The clutch cover is not the only difference, all the clutch system was updated by Aprilia. I think the main advantage of the Aprilia is that, when you work on your clutch, you don't have to remove all the carter, but just the plate. Also the set up is easier to do.

For the flywheel, you'll find an old receipt bi Gilles Burgat: take off 800 grammes (it's on the Continent).

I removed 3 mm from the radius of mine, (± 500 grammes) and I think it's a good compromise.

Cheers
Nicolas

[B40RT]

Thanks Nicolas, just back from holiday so hadn't seen your reply till today.
Thanks for the info on flywheel weight.
My Aprilia has the same clutch cover as SWM, I think it was the Purple ones with discs back & front that had
the modified clutch cover, which is a good mod if you can find one.

Ross

[jumbostu]

Hi

Good thread

Not posted on here for yonks - but couldnt resist this one. I have lots of SWM bits but couldnt find any spare flywheels so I bought one from ebay with the idea of lightening it. Then my mate returned one of my spare flywheels that I had inadvertantly given him in a box of Gori bits. As soon as he handed it back to me I realised that it seemed VERY heavy! the last flywheel I had held was the ebay one.... Putting the 2 together I instantly realised that the one I had bought to lighten had already been done!!!! VERY strange indeed. It has had a couple of mil taken from both its diameter AND its face so is a fair bit lighter than STD. I rode the superb Cumberland County 2 day classic at the weekend and after a dothery Saturday decided to test me new flywheel on the Sunday WOW what an amazing difference - felt like riding a Fantic!!! LOL will endeavour to weigh it and compare to original next time I am in the garage. To be honest it was a little too whippy and seemed to rev out far too quickly - reckon a bit of re jetting and or exhaust work and it will feel more like a "340" Fantic (which isnt always a good thing)

Best wishes

Stu

[B40RT]

Hi Stu

Your info along with NicolasVasic gives me plenty to think about.
On a slightly different note I have just registered the bike which is a TL320, which I thought made it a 280cc. The plate on the steering head said 250cc, which seamed a strange size.
It turned out it have been registered back in 1981 as a 280 so I will have to take the head off to find out the truth.

Ross

[MartinM]

The very early red/white SWM used a smaller flywheel that the yellow models.....Sammy Miller used to list a bolt on flywheel weight in his catalogue many moons ago.

While in the flywheel area.......one of my talented SWM contacts has converted his bike to electronic ignition, with some very good results. It is utilising a kit thats already available on the market, and I have one winging its way to me shortly, to see if its as easy to install as he makes out..and whether the improvement is significant enough to warrant the money.

Will let you know the findings soon.

Martin

[jumbostu]

Hi


The 320s are 276cc

Flywheel I bought seemed to be a home engineering job tho hard to tell with passing of time.

Is it the Dave Renham Bultaco kit slightly modified?? I thought about this but wasnt sure how to trigger signal from a std flywheel?? Would LOVE to lose my points

Cheers Stu

[B40RT]

jumbostu, on Sep 14 2010, 07:30 AM, said:

Would LOVE to lose my points

Cheers Stu

I to would be interested to see what electronic ignition would do to the performance having changed a B40 and found a vast improvement.
That said, I have never had any real problems with the points on a Rotax motor. FWIW.

Ross

[jumbostu]

Hi

Must admit I would only mod my main riding SWM for reliabilty / maintenance reasons - really like to keep em as original as poss - and wouldnt dream of changing me "Bernie Jumbos" from their "standard works guise"!!
Not that I wouldn't ride em in anger - far from it - just that they both STILL have broken kickstart shafts that MUST be fixed before next years Bill Pyes 3 day as I promised me mate Scrumpy that we both ride one each at this event..

Need to sort some motivation, space and ££££'sss first like!! Must have another thinout LOL Any kicks up the ar5e most welcome!

Stu

[t-shock 250]

Hi Martin, do you have any more details on the ignition kit for the rotax?
I would love to ditch the points setup & we tried an electronic ignition a few years ago which ended up with some very strange power delivery issues!
P.S. Your PM inbox is full!

[B40RT]

A picture is worth a thousand words !









Which is SWM and Aprilia, guess.

Edited by B40RT, 09 October 2010 - 04:29 PM.

[jumbostu]

Some pics of my flywheel findings - with further mods this weekend Carb, timing and ignition "settings" bike now revs out much better and am liking the lighter weight much more than last time I rode with it. Was too stally and weak feeling. Am still going to make one with in between weight (I like the sound of Burgat recommendation of 800g? removed in a previous post I read) Grip is affected but nothing that throttle control and body engish shouldnt sort.








Best wishes

Stu

[B40RT]

Will need to weight my flywheels sometime.
Re "Grip effected" I always felt that it gripped better when running slightly rich, if it was lumpy just off tick-over it was about right.

[B40RT]

B40RT, on 09 October 2010 - 04:28 PM, said:

A picture is worth a thousand words !

flywheels 001.jpg




flywheels 002.jpg


Which is SWM and Aprilia, guess.

Another difference flywheel wise is the Aprilia Rotax doesn't have the weight on the clutch side.