Curvy lightened Flywheel assembly

[millemille]

Suzuki chose to fit the SV650 with a heavy flywheel assembly; made of the flywheel itself and the starter sprag bearing housing.

The Curvy has a very, very heavy flywheel. The Pointy slightly less heavy, but still not light.

Suzuki did this to make the bike novice friendly because the rotating flywheel assembly has massive inertia; so the bike is difficult to stall, easy to launch from a stand and reduces engine braking.

But this has several drawbacks;

It give the crank a very hard time, particularly at high rpm, because every time each cyclinder fires the crank is trying to accelerate but the inertia of the flywheel assembly resists this and is trying to twist the crank. This can lead to...



It blunts the performance and character of the engine because the heavy flywheel assembly is slow to accelerate and slow to decelerate.

It slows the bikes ability to change angle of lean (roll) because you're trying to effectively move the axis of rotation of very heavy gyroscope.

It makes it easier to lock the back wheel of down shifts if you're a bit clumsy with the clutch and revs.

I couldn't find anyone in the UK who sold off the shelf lightened flywheels or would lighten the flywheel on a one-off basis who I trusted to know what they were doing and didn't want an extortionate amount of money to do so.

So together with 2 other engineers we have designed, FEA'd, machined and tested, over several thousand miles, a lightened flywheel assembly for the both the curvy and pointy SV650.

We machine down the Sprag housing on a 3 axis Hass CNC mill using bespoke jigs...



After machining...



That's a saving of between 1/2 and 3/4 of a lb, depending on whether it's a Curvy or Pointy.

There are pictures of lighter sprag housings on the net, but we weren't convinced that going any lighter was a good idea. We've kept the circumference that ensures the sprag housing is accurately located on the flywheel locating studs...



...and we've kept the 6 bolts, rather than reducing to 3, to ensure balance is maintained.

We also machine down the flywheel itself, again using bespoke fixtures.

Here's a lightened curvy complte flywheel assembly...



A total weight saving of 1.27 lb, which is massive when you're talking about rotating engine components.

Here's a lightened pointy complete flywheel assembly....



A total weight saving of 3/4 lb, again a significant weight saving.

We've also done a flywheel with 3 magnets (for TD's or racing if you want to keep a charging system) that weighs ~1,100 grams and a total loss flywheel with no magnets that weighs ~950 grams.

We check the balance after machining, and if neccesary rebalance to with 1 gram, which is better than what Suzuki let them leave the factory at.

The bike is significantly improved with the fitment of a lighter flywheel assembly - faster accelerating, reduced engine vibration, quicker/easier to lean, smoother down changes...all in all it releases the true v-twin character of the engine. There's still enough weight there to not make the bike any more difficult to pull away.

Having thoroughly tested and validated the design we're happy to start selling them and are confident enough that the benefits are immediately obvious we'll offer a money back warranty if you're not immediately happy.

£145 to lighten your flywheel, with a 7 to 10 day turnaround (normally quicker than that).

We can also offer titanium bolts to replace the 6 steel bolts holding the assembly together, these save another 36 grams and cost £40 a set.

Please PM me if you're interested - this has been cleared with Admin.

[maviczap]

Cool sounds like a winter swap over will be on my to do list.

[Davemurphy007]

Definitely interested in getting a set of these fitted!

Are any other parts required to fit these? What's the process to change one of these and what sort of time do you reckon to change them? Are you looking at a ride-in, ride-out service or would you need the bike for a couple of days!

[millemille]

Originally Posted by Davemurphy007

Definitely interested in getting a set of these fitted!

Are any other parts required to fit these? What's the process to change one of these and what sort of time do you reckon to change them? Are you looking at a ride-in, ride-out service or would you need the bike for a couple of days!

Clean engine, drain the oil, remove the generator cover, undo the alternator bolt, remove old flywheel, fit new flywheel, torque up alternator bolt, fit generator cover with new gasket, fit drain plug with new washer, fill oil (either reusing old or with new).

Parts needed are sump plug washer and generator cover gasket.

You'll need a flywheel holding tool and a torque wrench capable of 120NM.

If nothing seizes or breaks it's a ride in/ride out service taking about 30 minutes.

[Davemurphy007]

I'd be bringing it to you to do. Do you have stock of the genny cover gasket and the sump washer or would I need to provide these (along with some new oil and a filter I reckon, I'm not a fan of re-using engine oil).

[millemille]

Originally Posted by Davemurphy007

I'd be bringing it to you to do. Do you have stock of the genny cover gasket and the sump washer or would I need to provide these (along with some new oil and a filter I reckon, I'm not a fan of re-using engine oil).

Gasket and sump plug washer are included in the £30 fitment charge.

I can source oil and filter if needed, at retail prices, or you can bring your own.

[Davemurphy007]

Excellent stuff. Give me a couple of weeks to get back in the country and I will get in touch to arrange fitting

[Nicky S]

I like this post

Would you ever think of just selling them with out having the oem one sent to you ??


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[millemille]

Originally Posted by Nicky S

I like this post

Would you ever think of just selling them with out having the oem one sent to you ??


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Yes.

£145 + whatever it costs to replenish the float with a 2nd hand one.

I'm going to put a post in the wanted section for more flywheels due to the interest we've had....

[Nicky S]

Ok cool what are the prices from Suzuki ??? Or will we all have to get loans ??


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