yamaha conrod questions

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tavspeed
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Thu May 28, 2020 12:15 pm

hi chaps what is the best yamaha conrod to use,it will be going in standard ts1,i have some nice rb crank webs so going to have a go at building and it tigging the pin,

dt125 ypvs has the correct big end pin and little end bearing 110 long 16mm wide big end 16mm little end

rd 250 aircooled has same dimensions but different part no,maybe because crank pin is longer

rd250/350 lc is the one af sell but has a 21/16 little end bearing

also are the big end bearings all the same dimension i.e 28 x22 x16 or 29 x22 x16, looking to upgrade to a rb spec big end which are 28x22x16 which af list on there web site,cheers all

Warkton Tornado No.1
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Fri May 29, 2020 6:58 am

Good Luck with the rebuild. Whatever rod you end up choosing is surely not restricted to one manufacturer's rod dimensions, is it?

Unless you have parameters that dictate otherwise, then there are manufacturer's rods that will fit & are in use with tuned Lambrettas.

Personally, particuarly with a reed valve engine, my choice is for a rod with longer centres, because any opportunity to reduce crankcase compression by raising the volume is likely to raise power output purely on it's own. Base packers are available these days in so many thicknesses, that many combinations can be put together.

Have a look @ the KTM conrods...... ;)

tavspeed
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Fri May 29, 2020 12:14 pm

have looked at various rods,and i think i am going to use the dt125ypvs rod as the big end bearing is 28mm o/d and i can get a rb spec bearing from af that is suitable,could'nt get conformation on what size big end bearings are on the other rods and didn't want to mess about sending them back.
the yamaha 110mm rod is ideal as i am going to try it with 2mm packer thus lowering the ts1 barrel 1mm,similar to what mb did with there touring tune,but they machined 1mm off the base.
this should suit my taffspeed exhaust and sx200 gearing better
ideally when funds permit i will try a 115mm rod,probaly a rd 400, with a casa 30mm deck height piston,as seen on steel weasels you tube channel(worth a watch by the way) as this gives a smoother engine and the piston doesnt rock as much due to the position of the gudgeon pin,cheers all

Warkton Tornado No.1
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Fri May 29, 2020 12:50 pm

tavspeed wrote:
Fri May 29, 2020 12:14 pm
have looked at various rods,and i think i am going to use the dt125ypvs rod as the big end bearing is 28mm o/d and i can get a rb spec bearing from af that is suitable,could'nt get conformation on what size big end bearings are on the other rods and didn't want to mess about sending them back.
the yamaha 110mm rod is ideal as i am going to try it with 2mm packer thus lowering the ts1 barrel 1mm,similar to what mb did with there touring tune,but they machined 1mm off the base.
this should suit my taffspeed exhaust and sx200 gearing better
ideally when funds permit i will try a 115mm rod,probaly a rd 400, with a casa 30mm deck height piston,as seen on steel weasels you tube channel(worth a watch by the way) as this gives a smoother engine and the piston doesnt rock as much due to the position of the gudgeon pin,cheers all
Other two stroke enthusiast's have proven the measurable increase in output of an engine modified by only fitting a longer rod.

Anyway, your choice, but the KTM is 118 mm centres.

tavspeed
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Fri May 29, 2020 1:45 pm

hi cheers warkton,do you know what model that rod is off can't find it cheers

Scooterdude
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Fri May 29, 2020 5:08 pm

tavspeed wrote:
Fri May 29, 2020 1:45 pm
hi cheers warkton,do you know what model that rod is off can't find it cheers
KTM 200

10 inch Terror
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Fri May 29, 2020 6:12 pm

Warkton Tornado No.1 wrote:
Fri May 29, 2020 6:58 am
Good Luck with the rebuild. Whatever rod you end up choosing is surely not restricted to one manufacturer's rod dimensions, is it?

Unless you have parameters that dictate otherwise, then there are manufacturer's rods that will fit & are in use with tuned Lambrettas.

Personally, particuarly with a reed valve engine, my choice is for a rod with longer centres, because any opportunity to reduce crankcase compression by raising the volume is likely to raise power output purely on it's own. Base packers are available these days in so many thicknesses, that many combinations can be put together.

Have a look @ the KTM conrods...... ;)
I love reading your replies. You explain yourself very well and are obviously a very knowledgeable fella.

Warkton Tornado No.1
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Fri May 29, 2020 7:48 pm

Thank you 10 inch Terror..... :oops:

Scooterdude, you are also correct. It is KTM200.

I have a feeling there was a (Kawasaki) KE175 (?) rod that proved to be alright.

storkfoot
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Fri May 29, 2020 9:38 pm

Warkton Tornado No.1 wrote:
Fri May 29, 2020 7:48 pm
Thank you 10 inch Terror..... :oops:

Scooterdude, you are also correct. It is KTM200.

I have a feeling there was a (Kawasaki) KE175 (?) rod that proved to be alright.
I run a KE175 110 Conrod in my TS1 and have done for several years (I really need to get a new one at next rebuild). I have had no issues at all. They don’t appear as substantial as the Yamaha ones but I reckon that a KE175 must be able to put out similar power to a TS1, so I never worried.

Scooterdude
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Fri May 29, 2020 9:50 pm

Warkton Tornado No.1 wrote:
Fri May 29, 2020 7:48 pm


Scooterdude, you are also correct. It is KTM200.

.
Thank you sir!

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