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General Category >> Rubber Side Down! >> Big bore kit
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Message started by Plymark on 01/09/23 at 06:32:02

Title: Big bore kit
Post by Plymark on 01/09/23 at 06:32:02

I think i've seen a post saying that a 95mm DR650 piston can be used for big bore conversion. Is that right?

Title: Re: Big bore kit
Post by LANCER on 01/09/23 at 09:23:15

The Wiseco DR pistons for model years 1990-1995, come in sizes 95/96/97mm. The compression ratio (CR) of these pistons in the DR650 is 10.5:1 but will only raise the compression in the LS650 Savage/S40 from 8.5:1 to 9.5:1. You may find some on eBay or on the Wiseco website. Cost on eBay is $170-$185, and on the Wiseco site $225-$255. Then you have the cost of boring the cylinder locally which will be $100-200.

I have 94mm Wiseco pistons in “stock” for $229, which is the stock bore for the LS650 so no boring required, just a hone of the cylinder (much cheaper than a bore), and the compression ratio will be raised from 8.5:1 to between 10.5:1 and 11:1…a significant increase over the DR pistons.

My 94mm pistons were custom designed by me, Drag Bike Mike, and Wiseco specifically for the LS650 and are a flat top with a dish design making for higher compression and better flame travel in the combustion chamber producing more power.

You can PM or email me if interested.

Title: Re: Big bore kit
Post by Plymark on 01/11/23 at 11:53:04

Hello Lancer. I can't PM because I have posted less than 10 times. I have been leaning towards a 95 or 96mm Wossner. Your proposal is interesting but I amagine getting it sent to me here in Mallorca, Spain and through customs will be a handful. Can you quote for shipping to non-mainland Spain.

One thing though, you mention 90-95 bikes. Im picking up an '86 for a project on Saturday. I also own a '98. Did cylinder dimensions change through the lifespan of the LS?

Title: Re: Big bore kit
Post by LANCER on 01/11/23 at 18:07:38

526E7B6F637069020 wrote:

**************

Shipping to Spain with insurance is $45.

When I mentioned 1990-1995 models, that was for the DR650 pistons, wether they are Wiseco or Wossner.
For DR650’s of 1996 and later models, the engines were redesigned and so the pistons are different and will not work in the LS650. These newer DR’s have a bigger bore and a shorter stroke vs the 1990-1995 models.

Title: Re: Big bore kit
Post by Dave on 01/12/23 at 02:54:55

The 94mm Wiseco is definitely the easiest and cheapest way to increase power with a piston swap. When you need a cylinder to be bored for a larger piston - you always run the risk of the machinist getting it wrong. Too many bike shops have a boring bar but don't really have experienced folks running it. It is very easy to get the cylinder bore too big and you get a noisy oil burner......or they get it too tight and the pistons seizes in the bore.

The 95mm, 96mm and 97mm DR650 pistons will work in the Savage engine - but they really aren't made for it and the quench area is large and results in less than ideal performance. The 94MM that Lancer has made is a better design and provides better performance than a larger piston designed for the DR650. (You will need to run premium fuel).

Title: Re: Big bore kit
Post by Plymark on 01/12/23 at 13:48:31

Yeah, I can see that Lancer has put a lot of effort into this. I'm picking up an 86 bike on Saturday as i am told its legally easier in spain to homologate bikes older than 30 years. Not seen this thing in the flesh yet but its cheap. I'll have the head off and take a look at the condition of the bore. If its OK, I'll get Lancers piston.

We have good machinist shops here but i was wondering about cold clearance. I thought maybe the piston would come with bore size and tolerance.

Fuel is good here and i want to put either a Lectron or a Murrays VM 36 Mikuni on the bike. Bit torn as there isn't a great deal of info on the Lectron on here. Erik likes his though!

Thanks for your input.

Title: Re: Big bore kit
Post by LANCER on 01/13/23 at 04:49:14

The Lectron carbs function basically the same as Edlebrocks Quicksilver carbs, and both are priced in the $400+ range for the carbs and $7-800 for kits for specific bikes. Lectron sells one for the Suzuki DR650, which is as close as you will get to the Suzuki LS650 Savage/S40. The DR kit comes with a throttle cable made for the DR, but I’m unsure if the cable-to-throttle housing attachment is the same for the DR and LS. You will need to confirm this, and perhaps need to get another cable if they are not the same. Their kit does not mention a new rubber mounting flange so I’m assuming it’s the same size as stock which for the DR is the same as the LS.
Besides the Wiseco piston ($229) I also have carb kits using the Mikuni VM36mm carb, with a custom throttle cable made for the LS, along with a new mounting flange for proper fit, Jet Pak with extra main & pilot jets, Mikuni carb manual, & Uni air filter. Kit price is $429. In addition I have low-midrange camshafts by Webcam Inc. for $329 with your old cam core in exchange. Without a cam core exchange the price is $429. This cam will absolutely wake up a sleepy LS650, and even more so when combined with the piston and carb.
Shipping cost for internationally is expensive, about $80+ for Europe, but if you purchase all 3 from me (piston, carb, cam) then I pay all shipping/insurance costs.
So for just over $1,000 you can get cam-carb-piston compared to $800 for the Lectron carb alone.

Your choice, but either way I’m happy to help in any way can.

Title: Re: Big bore kit
Post by Dave on 01/13/23 at 04:49:30

5A6673676B78610A0 wrote:

We have good machinist shops here but i was wondering about cold clearance. I thought maybe the piston would come with bore size and tolerance.

Wiseco provides the clearance that is needed.....the ring end gap is more of a personal choice based on your riding style. If you ride at full throttle for extended periods you may need larger end gaps. The stock piston specs call for the top and second ring to have identical clearance - Wiseco wants them to be different and provides a chart that with suggested clearances.

I know of 2 piston/cylinder failures that occurred when the users had piston/cylinder clearances that were tight and went on long/fast interstate rides before riding a proper amount of "break-in" miles......and 1 piston/cylinder failure from the bore being too large. It is very important for the machinist to get the clearance correct...and equally important to go easy on the new bore/piston for a while as the piston and cylinder get to know each other.

Title: Re: Big bore kit
Post by DragBikeMike on 01/14/23 at 01:33:33

I would not use the clearance recommendations provided by Wiseco. The Wiseco pistons were designed for an engine that utilizes an oil cooler. The LS doesn't use an oil cooler. I installed a number of these pistons with .0030" to .0035" clearance and never had a problem related to clearance.

Wiseco recommends .0019" clearance for their 97mm pop-top. That always impressed me as being too tight. Being a curious fellow, I decided to try one set up closer to the recommended clearance. So, on my latest project, I spent a great deal of time and effort setting up the clearance right at .0022", just .0003" more that Wiseco suggests. I should have trusted my instincts. After a generous 2000 mile break in, I took the thing up a long 6% grade barging into a stout headwind. The picture tells the story.

Title: Re: Big bore kit
Post by DragBikeMike on 01/14/23 at 01:42:55

I suggest you use the ring gap specifications for "circle track/drag race". The spec is .0055" per inch of bore for the top ring, and .0060" per inch of bore for the 2nd ring. For a 94mm that works out to .020" top and .022" 2nd. Don't skimp on the ring gap, it's painful. This is a picture of a stock piston that I set up with gaps too tight.

Title: Re: Big bore kit
Post by DragBikeMike on 01/14/23 at 01:44:46

The Wiseco pistons work great and are reliable, but they need a little room to do their job. Set em up right and they're good-to-go.

Title: Re: Big bore kit
Post by Plymark on 01/20/23 at 04:32:19

5C515E5355420207300 wrote:

That's got me convinced! Ive got to get the bike started and ready for ITV (spanish roadworthiness inspection) before I can pull anything apart. If the bore is in decent shape, i'll go for the three items. Sending my old cams to you might not be cost effective though.

Title: Re: Big bore kit
Post by LANCER on 01/20/23 at 07:49:48

Just holler when you are ready.