Any difference between a 2016 300 piston and a 2017?

[JoeMaico]

I went into my local dealer and ordered a Size A piston assembly for my 2016 300 RR Race Edition. I provided them with the 026.02.030.80.0A part number. When I got home I saw that they ordered 026-020328-00A when I looked at the order sheet. Looking this PN up, I see it is for a 2017 300 piston. I also saw that they ordered the 026-110408-200 gasket kit, when I supplied them with the 026.11.113.82.00 part number. I don’t think there is any issue with the gasket kit (other than an extra gasket for exhaust manifold I will not use). But, I wonder if there is any difference between a 2016 and a 2017 piston? I think Beta went to a domed piston in later models, like 2019 or 2020. But, I don’t remember any changes in piston/head/cylinder attributes between 2016 and 2017. Let me know if anyone remembers/knows of any that would cause a concern using a 2017 spec’d piston in a 2016. The piston is on back order from Beta, so who knows when I will see it anyway. But if there is a reason to modify the order, I should do it now.

joe

[wwguy]

The new domed piston was introduced in 2018. Not sure why the piston part numbers changed from 2016 to 2017, as they appear to have identical dimensions and design.

I installed this 2013-2017 300RR top end kit with the 2017 part numbers in my 2016 Xtrainer 150 hours ago, and it's still working great. (Xtrainer and RR share the same top end.)

Here's a pic of my original 2016 piston next to the new one with the 2017 part number:

[JoeMaico]

Thanks. Given the range your kit was designed for, I should have no problems using it in my 2016. Still, I am curious on why the part number change. Perhaps they changed piston suppliers between 2016 and 2017.

joe

[SaulGoodman]

no difference at all. if you want a less expensive forged piston, select one from a 04-16 KTM 300 made by Wiseco.

[JoeMaico]

Still no piston and rings. So, soon I will be asking for my money back (or change to a future B size). When I go to KTM OEM page on RMATV, I cannot order a piston for a 300 XCW. But I do see that you can order the Vertex Standard (71.95mm), or the Wiseco Standard (72mm) from their normal engine parts page for a 2016 300 KTM. Beta Bore Spec's for B size are 71.945mm to 71.955mm. So, the Vertex falls in that range. However, when I go to the Wiseco web page and search for a 2016 300 Beta piston, I get the following part number (886M07200). But the RMATV page for the 2016 300 KTM piston lists the part number as (858M07200). Comparing the two on the Wiseco page, I see that they use the same rings and retaining clips. But, the wrist pins for each piston are different. The KTM piston uses a 13.00mm X 18.00mm X 58.50mm wrist pin, and the Beta piston uses a 12.00mm X 18.00mm X 57.00mm wrist pin. So, I do not know if that means you have to mate the KTM wrist pin to the KTM piston. And, if so, do you also need to to install a KTM needle bearing? If I go with Wiseco - I think the best approach is to just order the Beta piston from Weisco directly (RMATV does not sell it). The other option is to use the ProX Piston (size B - 71.95mm) offered on the RMATV site for Beta's. I do see that ProX offers an A size kit (017393.A - 71.94mm) for Beta's, but RMATV does not offer it. So, i would have to source it from someplace else.

Interestingly, doing a similar analysis on the Vertex website (seems to be hosted by AllBalls) you again get different part numbers for a Beta piston kit and a KTM piston kit. I also find that the KTM piston for size A is 71.940mm, while the size A for the Beta piston is 71.950. So, the Vertex listed Beta piston in an A size does not fall within the Beta spec's for an A size. Decisions, decisions, decisions.

joe

[SaulGoodman]

Still no piston and rings. So, soon I will be asking for my money back (or change to a future B size). When I go to KTM OEM page on RMATV, I cannot order a piston for a 300 XCW. But I do see that you can order the Vertex Standard (71.95mm), or the Wiseco Standard (72mm) from their normal engine parts page for a 2016 300 KTM. Beta Bore Spec's for B size are 71.945mm to 71.955mm. So, the Vertex falls in that range. However, when I go to the Wiseco web page and search for a 2016 300 Beta piston, I get the following part number (886M07200). But the RMATV page for the 2016 300 KTM piston lists the part number as (858M07200). Comparing the two on the Wiseco page, I see that they use the same rings and retaining clips. But, the wrist pins for each piston are different. The KTM piston uses a 13.00mm X 18.00mm X 58.50mm wrist pin, and the Beta piston uses a 12.00mm X 18.00mm X 57.00mm wrist pin. So, I do not know if that means you have to mate the KTM wrist pin to the KTM piston. And, if so, do you also need to to install a KTM needle bearing? If I go with Wiseco - I think the best approach is to just order the Beta piston from Weisco directly (RMATV does not sell it). The other option is to use the ProX Piston (size B - 71.95mm) offered on the RMATV site for Beta's. I do see that ProX offers an A size kit (017393.A - 71.94mm) for Beta's, but RMATV does not offer it. So, i would have to source it from someplace else.

Interestingly, doing a similar analysis on the Vertex website (seems to be hosted by AllBalls) you again get different part numbers for a Beta piston kit and a KTM piston kit. I also find that the KTM piston for size A is 71.940mm, while the size A for the Beta piston is 71.950. So, the Vertex listed Beta piston in an A size does not fall within the Beta spec's for an A size. Decisions, decisions, decisions.

joe

100+ hours on my "ktm" Wiseco piston installed in a 15 Beta 300RR. No problems. Corporate Wiseco emblem (embossed on front of piston at the factory) visible still from exhaust port. Purchased at rocky.

[JoeMaico]

The kit comes with a wrist pin. So, I assume you used the KTM piston and wrist pin in the Beta needle bearing cage. The OD of the wrist pin's are the same. So no issue there. There must be a different machining of the piston's to account for the difference in pin length. The ID of the wrist pin should not matter (except rotational mass).


joe

[SaulGoodman]

The kit comes with a wrist pin. So, I assume you used the KTM piston and wrist pin in the Beta needle bearing cage. The OD of the wrist pin's are the same. So no issue there. There must be a different machining of the piston's to account for the difference in pin length. The ID of the wrist pin should not matter (except rotational mass).


joe

I don't recall but it is likely a KTM wrist pin bearing.

[bzrperfspec77]

Go onto Wiseco's site and order directly there. When Beta couldn't get me a stock piston for my bike (2016 300 RR RE), I went the Wiseco route. They have a specific Beta piston listed.

I got it within 2 days. I've had it in there for probably 10-15 hours now and no issues. It's a work of art, shipped and packaged very nicely and the guy I spoke to on the phone was super nice. As long as I get the longevity out of it, I'll order another from them.