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Piston related, Moose Racing vs Vertex. A or B piston?

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I´ve got a Honda rf 250r 2012 wich has around 60 hours on it.

It has been raced a little bit and uses a yoshimura rs4 full exhaust.

 

Im doing a top end rebuld in a month or so and ivé got 2 choices of pistons

 

1. Moose racing 13.5 comp problebly size 76.76 SIze A  : http://www.ebay.co.uk/itm/Moose-Racing-CP-Piston-Kit-w-Gaskets-13-5-1-76-8mm-Honda-CRF250R-CRF250-CRF-/181051288788

 

2. Vertex 13.2 Comp Size 76.77mm B PIston  :http://www.amazon.com/Vertex-23510B-Replica-Piston-Kit/dp/B0031BYP42

 

Wich one would u choose?

 

Is there really a need of size b pistons??

 

If my bike would have done 300 hours i would problebly have gone with a B piston but after 60?

 

Second question: my intake valves are titanium is there a possibility to do some valve lapping on titanium valves or is it just that u shouldn´t?

 

I would prefer a deeper answere with facts around it

 

Thx in advance

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I´ve got a Honda rf 250r 2012 wich has around 60 hours on it.

It has been raced a little bit and uses a yoshimura rs4 full exhaust.

 

Im doing a top end rebuld in a month or so and ivé got 2 choices of pistons

 

1. Moose racing 13.5 comp problebly size 76.76 SIze A  : http://www.ebay.co.uk/itm/Moose-Racing-CP-Piston-Kit-w-Gaskets-13-5-1-76-8mm-Honda-CRF250R-CRF250-CRF-/181051288788

 

2. Vertex 13.2 Comp Size 76.77mm B PIston  :http://www.amazon.com/Vertex-23510B-Replica-Piston-Kit/dp/B0031BYP42

 

Wich one would u choose?

 

Is there really a need of size b pistons??

 

If my bike would have done 300 hours i would problebly have gone with a B piston but after 60?

 

Second question: my intake valves are titanium is there a possibility to do some valve lapping on titanium valves or is it just that u shouldn´t?

 

I would prefer a deeper answere with facts around it

 

Thx in advance

 

IDK who makes the Moose Piston. Its not Moose.  It could be CP as Moose is a reseller of Carrillo rods.

You won't go wrong with a Vertex and using the B piston would be a good choice. The size difference isn't enough to be of any consequence.

Not sure why Vertex sells different size as the typical consumer lacks the precision measuring equipment necessary to know which size is required anyway. 

Probably their reason is that they also sell Cylinder Works cylinders and they can size their pistons to their cylinders for more precise clearances.

 

If you've run your motor hard and depending on the fuel you use, you might find pitting / chipping on the the outer edge of the intake valves.

In which case you should replace them. At 60hrs it would be a good idea to replace them as normal maintenance.

It wouldn't hurt to have the seat faces touched up, if you have the time and money, but if their in good shape there's little to be gained.

You will need to bring the head to a MC machine shop for this service, and that is where the time factors in.

Do not lap titanium valves. The valves have a hardened .002 coating which will cut through if you use lapping compound on them.

 

That's as deep as I'm going for now

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IDK who makes the Moose Piston. Its not Moose.  It could be CP as Moose is a reseller of Carrillo rods.

You won't go wrong with a Vertex and using the B piston would be a good choice. The size difference isn't enough to be of any consequence.

Not sure why Vertex sells different size as the typical consumer lacks the precision measuring equipment necessary to know which size is required anyway. 

Probably their reason is that they also sell Cylinder Works cylinders and they can size their pistons to their cylinders for more precise clearances.

 

If you've run your motor hard and depending on the fuel you use, you might find pitting / chipping on the the outer edge of the intake valves.

In which case you should replace them. At 60hrs it would be a good idea to replace them as normal maintenance.

It wouldn't hurt to have the seat faces touched up, if you have the time and money, but if their in good shape there's little to be gained.

You will need to bring the head to a MC machine shop for this service, and that is where the time factors in.

Do not lap titanium valves. The valves have a hardened .002 coating which will cut through if you use lapping compound on them.

 

That's as deep as I'm going for now

 

 

Yes the moose piston is made from Cp Caparillo and is there projectx piston at 13.5 comp but it´s not there race version wich has 14.5comp and has a different rod.

 

The note on the Moose racing piston only comes woth "deglaze Cylinder" and there isn´t a choice of a size b piston.

 

But my deeper question is there really a need of a B piston? i mean neither wiseco, Cp or honda offers b pistons?? ant the small amount of difference A=76,76 vs

B =76,77 mm isn´t that the Piston rings job ???

 

Vertex piston 13.2 comp B piston=76,77

Moose/Cp 13,5 comp A piston= 76,76

 

Moose/cp more comp wich i want but lacks b piston size

Vertex only benefit is the choice of b piston size and maybe not as super race solid

 

What would u guys choose?

 

Do i really need a b piston or is that just a "sellers way of selling more pistons?

 

The cp piston really looks solid

 

Ok so definetly not lap i titanium valve?

 

Anyway of maybe polish the intake valves or seat if i don´t want to change the valves?

 

If they are done ill just go with solid steal intake valves, but dunno yet the engine isn´t off yet

 

nice forum btw

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New valves at 60 hours? That seems a little overkill to me.

 

How many of these motors have you had apart?

Without knowing how the op motor is ridden it is possibly overkill.

I've seen junk valves come out of race motors with less than 20hrs.

When you run-till-fail you start a snowball effect of bad things and big money outlay's. 

Since I pay the bills, I prefer preventative maint vs run-till-fail. 

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How many of these motors have you had apart?

Without knowing how the op motor is ridden it is possibly overkill.

I've seen junk valves come out of race motors with less than 20hrs.

When you run-till-fail you start a snowball effect of bad things and big money outlay's. 

Since I pay the bills, I prefer preventative maint vs run-till-fail.

Well I'm glad we still have knowledgable people around here like you but I still say if the valves are in spec and it runs good leave it alone at 60 hours.

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How many of these motors have you had apart?

Without knowing how the op motor is ridden it is possibly overkill.

I've seen junk valves come out of race motors with less than 20hrs.

When you run-till-fail you start a snowball effect of bad things and big money outlay's. 

Since I pay the bills, I prefer preventative maint vs run-till-fail. 

 

 

Well im experienced enough to see if there is any damage on intake valves/seat and i will do a leak test.. and problebly just recut the seats.. or go stainless steel.

 

So on about the A vs B piston??

 

i really need someone to chime in here that´s really now there stuff..

 

Does it really makes a difference in perfomance and engine safety with going on a B piston? what i think is that the piston rings will do that job to seal anyway right??

 

That´s all i need to know 

 

i´ve got another question what core does the ignition cable have on the crf?? Copper? im thinking of going with the 8.5mm msd super conductor, have anyone ever tried upgrading to a proper ignition wire?

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Well im experienced enough to see if there is any damage on intake valves/seat and i will do a leak test.. and problebly just recut the seats.. or go stainless steel.

 

So on about the A vs B piston??

 

i really need someone to chime in here that´s really now there stuff..

 

Does it really makes a difference in perfomance and engine safety with going on a B piston? what i think is that the piston rings will do that job to seal anyway right??

 

That´s all i need to know 

 

i´ve got another question what core does the ignition cable have on the crf?? Copper? im thinking of going with the 8.5mm msd super conductor, have anyone ever tried upgrading to a proper ignition wire?

 

Coil on plug sonny, doesn't use secondary ignition wires.

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Coil on plug sonny, doesn't use secondary ignition wires.

its not coil on plug... the coil is about 10cm away and is attached to the frame.. from the coil to the plug is a wire.

have anyone changed there ignition wire and gotten any results?

So no one on the thumpertalk knows if b piston is necessary?

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Is the only difference between the a and b .01mm? I bet the bigger one is for after a hone job and the only ones of us who could measure that would be a machinist with the proper equipment. Try asking this in the town square forum, it seems to get more action than this section.

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Sorry, didn't realize the newer models went to separate coil.

 

Phone Vertex if your that concerned about the piston. The fact that many people use stock or Moose pistons with probably more hours on than your's, with out problems, should tell you something. And besides if your concidering SS valves tells us your not out for ulltimate preformance.

 

 

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Is the only difference between the a and b .01mm? I bet the bigger one is for after a hone job and the only ones of us who could measure that would be a machinist with the proper equipment. Try asking this in the town square forum, it seems to get more action than this section.

  

Sorry, didn't realize the newer models went to separate coil.

I work atnthe industri of military products so ther's no lack of tools.

no im not a high racer and theese new ss valves are really competetive to titanium valve.

 

Phone Vertex if your that concerned about the piston. The fact that many people use stock or Moose pistons with probably more hours on than your's, with out problems, should tell you something. And besides if your concidering SS valves tells us your not out for ulltimate preformance.

yeeh ur problebly right about that there is no need of a b piston.. and my cylinder is problebly not honed.. that moose/ cpnrecommends before installing there piston is to deglaze it..

Please soleone chime in on weither a B piston is needed or not as all sellers recommend a B piston for a used cylinder

im from sweden

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Hi woesner pistons are made in germany I have used quite a few and there great they come in A B C and D size if you want to fit a piston in your motor and go and race fit the A sized piston if you want it to last a little longer between piston changes and you have a little time to run it in the B is a good choice.I have fitted a C sized piston on my CRF 250X which I ride woods trails with no problems and its held up great.With pistons I have found its the piston that wears not so much the rings,measured only 2 thou of ring wear after 70 hours but the piston skirts were worn out.It all depends on what type of riding you do.

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Hi woesner pistons are made in germany I have used quite a few and there great they come in A B C and D size if you want to fit a piston in your motor and go and race fit the A sized piston if you want it to last a little longer between piston changes and you have a little time to run it in the B is a good choice.I have fitted a C sized piston on my CRF 250X which I ride woods trails with no problems and its held up great.With pistons I have found its the piston that wears not so much the rings,measured only 2 thou of ring wear after 70 hours but the piston skirts were worn out.It all depends on what type of riding you do.

 

Ok so what u are saying is that A piston will last me longer?

 

B Piston a little bit better perfomance?

 

cause the moose is problebly an A piston but with higher comp wich i want.

 

yes i know the wössner pistons are good but my 2 choices are the vertex vs the moose/CP

 

Could u please explain a little bit deeper on A/B/C/D pistons and what the benefits are and wich option is the safest? 

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Hi the benefit of using the B over the A piston is a better piston to bore fit as in a tighter fit less clearance this keeps the piston square in the bore resulting in a better ring seal,once the piston starts rocking in the bore due to wear the ring seal is compromised and performance will suffer your at 60 hours now its not new anymore the 13.5/1piston will give you more power the 13.2/1 B size will make a little less but run a little longer before its worn out your call on which one you run.If it was mine I would run a B with 13.5/1 or higher C/R 14/1 would be better.

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Hi the benefit of using the B over the A piston is a better piston to bore fit as in a tighter fit less clearance this keeps the piston square in the bore resulting in a better ring seal,once the piston starts rocking in the bore due to wear the ring seal is compromised and performance will suffer your at 60 hours now its not new anymore the 13.5/1piston will give you more power the 13.2/1 B size will make a little less but run a little longer before its worn out your call on which one you run.If it was mine I would run a B with 13.5/1 or higher C/R 14/1 would be better.

Ok.. ill understand that the b poston = smaller clearences..

But do u really think 60hours will put in in a B piston Spec? Or even C?

Yes of course id rather have a choice in B size moose piston at 13.5 comp but it doesnt exist.

what i do have right now is a vertex B piston with 14.1 comp but dont u think i need race fuel?

I Live in sweden and the best fuel we can get her is 98octane pump gas.

whats the reccomendations when running 14.1comp?

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Hi what fuel can you get,we run Shell V Power pump in the UK its good stuff we run C/R s over 14/1 and its ok.If you can get it you should be fine on 14/1C/R.

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