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dan williams

Another crazy idea?

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Kudos to TRS for thinking outside the box and designing an electric start that drives the ignition side of the crank. My question is why do we need a separate starter motor at all? Current designs use a high speed starter motor geared down to provide starting torque which is engaged and then disengaged becoming dead weight when not in use. With the lighting coils we have an array of coils in a mass of spinning permanent magnets already. If used for a starter motor and then switched to generate power once the engine is started there is no mechanical interface and none of the animal is wasted as the saying goes. The concept of a motor/generator is old. Real old. Starter/generators have been used on aircraft for decades. So is it now time for this to be applied to trials bikes or are we just waiting for the electrics to catch up and not really developing internal combustion any more. I know the margins on trials bikes are pretty thin and most manufacturers have bins full of ignition systems to use up but... For old guys like me that find kicking the beast to be less "fun" than it once was an electric start looks better and better. If it can be done in such a way that the penalty is simply the weight of a LIPo battery and electronics to commutate the motor signal I think it'd sell quite a lot of bikes. The strength of rare earth magnets could make for a very light weight flywheel. Weight could be added to the primary drive side so engine characteristics wouldn't feel significantly different and the twisting force on the crank due to wheel loads would be reduced.

Just throwing it out there.

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"starter motor and then switched to generate power"

1970 Yamaha AT1 125  had that

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23 minutes ago, mcman56 said:

"starter motor and then switched to generate power"

1970 Yamaha AT1 125  had that

Yup and technology has moved on a bit since then? Well magnets are stronger.

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 I'm not saying it can't be done, but I do see hurdles to overcome.

One is the very high static cranking pressure of a big-bore trials bike.  The AT1 (and RD200) had small cylinders with low static cranking pressure.  The snowmobile application has electronic exhaust valves that are undoubtedly in the high-rpm (low static compression) position during starting.

Two is, on a trials bike, there is often little run-time between starts to recharge the battery, and may rule out a super capacitor altogether. 

 

As you may know, the GasGas Contact ES uses a conventional starter with a right-angle drive on the flywheel side. 

You can see KTM's version here: https://www.youtube.com/watch?v=KQTnUxj16nQ

Edited by konrad
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Well that’s a bit harsh. I’m pretty sure the trials manufacturers are not rolling in dough and willfully holding back technology just to spite us. I think it more likely their R&D budgets don’t extend to components they can buy on the open market.  

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Maybe they could fit a lever connected to the engine we could push with our leg.

bet it would be dead simple and light weight .

but then we would not have to spend lots of money on titanium bits to make the bike lighter!!

Now the technology as part of a hybrid system them maybe now that makes sense . 125cc efi 4 stroke with the power and response of 300 cc 2 t  maybe has legs

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15 hours ago, jimmyl said:

Maybe they could fit a lever connected to the engine we could push with our leg.

bet it would be dead simple and light weight .

but then we would not have to spend lots of money on titanium bits to make the bike lighter!!

Now the technology as part of a hybrid system them maybe now that makes sense . 125cc efi 4 stroke with the power and response of 300 cc 2 t  maybe has legs

There's the modern problem jimmyl; it means you have to use your leg. Although they are essential in trials I'm afraid the tendency today is to use them as little as possible. People don't like going places unless you can park your SUV and are slowly losing the ability to use those dangly things that hang from our arses.

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I think the best way to make an alternator/starter work is in conjunction with an automatic compression release.   But if just a compression release made your 300 as easy to kick as a 125, would you still want an electric starter?

Yamaha used a small (3mm?) bleed hole above the exhaust port on the RD400 to make kickstarting easier.  The hole really made no noticeable difference otherwise (as the guys who tried plugging them discovered).

I investigated drilling a bleed hole in a trials cylinder once, but it would have gone right into the water jacket.

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2 hours ago, konrad said:

Yamaha used a small (3mm?) bleed hole above the exhaust port on the RD400 to make kickstarting easier.  The hole really made no noticeable difference otherwise (as the guys who tried plugging them discovered).

I remember reading about that. Of course the RD400 wasn’t meant to spend a lot of time at low rpm so maybe the effect would be more noticeable on a plonker.

I do like the different responses to the post. Your measured engineering response and the inevitable “Just kick it you wuss!”  “We don’t need no steeenking electric start.” Are both expected and entertaining. Though your thoughts are a bit more useful.?

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The problem is more than merely academic to me.  My wife thinks the thing that will eventually cause her to stop competing is repeatedly starting the bike.  I compete on a 250 because it's easier to kick.

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For  trail/ easy trial / older / less physically strong rider I can see all the benefits - trouble is would imagine that is a different market - possibly more niche and therefore production volumes smaller / less feasible financially . The small 4 t bikes already in the market are I presume ideal for what they do.

To have a usp such as hybrid/ regenerative braking that may give a technical advantage to all forms of trials may make a built in electric start economic. But think much tougher emissions or increase fuel economy would have to be imposed on manufactures before that happened - but like the 2 Stoke  ban ??

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Understand that. My wife had a lovely little ttr125l that she didn’t ride because she hated kickstarting it. I could start it by hand? she replaced it with a CRF150f because it has electric start. It also weights 80lbs more than my Beta. She’s added a KLX140g with electric start and I came home Thursday to find her in the garage with the primary drive side cover off installing a Rekluse! 

To be expected when you marry another engineer. We both spend more time redesigning than riding.

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49 minutes ago, konrad said:

The problem is more than merely academic to me.  My wife thinks the thing that will eventually cause her to stop competing is repeatedly starting the bike.  I compete on a 250 because it's easier to kick.

 

 The effort and akwardness of repeatedly kick starting a Trials bike, frequently on uneven terrain, is a significant concern to a gimpy old man like myself as well, even though yes I can start it with my hand if I want to.

 By the way I think I recall seeing the bleed hole in snowmobile cylinders as well.

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