Sprag

Well I thought by now I would have got an answer about the new type Jap starters . I was just interested to see how long sprags who ever make were lasting with the faster spining motor and greater out put torque . As I said this is a great sight , but some people like to procrastinate . Just was looking for a short answer , and thought I could offer a much cheaper alternative , but give you the integrity , by the way my new sprag has an extra roller and a heavy duty cage that self centers in the drive sproket bore . I think every one knows the colder the ambient temp the less crank a battery standard (acid filled type that is) works . Ok hope next week can give out all the info and prices to those interested in replacement sprags that just want to ride not tell old glory day stories . I have been riding Norton Commando "s for about 35 years now so any new type parts that work better than the old bits did has to be a bonus . Makes me laugh inside when I see 6 year old bikes being wrecked love my Nortons, Dave .

Norton Dave said:

Well I thought by now I would have got an answer about the new type Jap starters . I was just interested to see how long sprags who ever make were lasting with the faster spining motor and greater out put torque . As I said this is a great sight , but some people like to procrastinate . Just was looking for a short answer , and thought I could offer a much cheaper alternative , but give you the integrity , by the way my new sprag has an extra roller and a heavy duty cage that self centers in the drive sproket bore . I think every one knows the colder the ambient temp the less crank a battery standard (acid filled type that is) works . Ok hope next week can give out all the info and prices to those interested in replacement sprags that just want to ride not tell old glory day stories . I have been riding Norton Commando "s for about 35 years now so any new type parts that work better than the old bits did has to be a bonus . Makes me laugh inside when I see 6 year old bikes being wrecked love my Nortons, Dave .

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I've been using one of Dyno Dave's electric starters for several years now on my street Mk3, and no sprag problems so far, even with the old analog Boyer. That's at least one data point for you. Still, I'll be interested in the final info on your sprag, when you're done. I'm planning to rebuild the bike soon, and have no idea what condition the original sprag is in, except that it still works.

Ken

I have a Dyno Dave starter fitted, AGM battery, upgraded leads. I used to run Boyer, but now Trispark.

I have had one complete failure of a sprag clutch, and have also had a second sprag going over centre and then righting itself (at least I think this is what was happening...it would just whirr and not try to turn the engine over and then suddenly work again :?: ) and this was after fitting a new starter drive gear as well. I lost confidence in this sprag as I was always waiting for it to disintegrate and so fitted a third sprag.

I do start mine 99% of the time on the button, and it is now 920cc running a compression ratio of 9.8:1, so maybe a bit more effort required of the sprag.

Hi there
I have had problems with my starter also done just about everything,4 pole largest battery I can fit in,and replaced sprag,worked for a short time then sprag overcentred and locked up primary,I took it out in disgust and ran without starter for a while,then I saw an article in roadholder 279 re starter problems here it said both surfaces where sprag contacts wear hence giving too much clearance,solution basically machine out the inside of drive sprocket and turn down inner that the sprag runs on and fit a hardened bush onto this with locktight closing the clearance so the sprag can't overcentre,I'm sorry I can't be more technical about this,I had an engineer do this for me but I'm sure you can get the idea.Since doing this bike starts easily when cold although we dont experience some of the temps some of you have to deal with,anyway hopefully we have many miles of trouble fee riding from now on ,last thing attack bush inside and out with dremel or similar inner so locktight has a good key and outside so sprag has something to bite into.cheers for now

My sprag has played up first about four months ago when the starter engaged at tick over i rocked the bike and the stater disengaged and was fine till last week when it happned again i have striped it out and found the cage in the sprag had broken i have checked the gear and sprocket for wear as i got the dimentions from Mick Hemmings a very helpfull man .The bearing has now been replaced and all is well