Rev 3 250 Crank?

[mcman56]

Does anyone know if a 250 or 270 crank has more holes in it than this 200 crank? I was expecting stuffers but there are none.

[lineaway]

You are talking a 9 year span. Do you have a 2005 or older?

[zerorev3rev4]

what are you trying to achieve

[mcman56]

This is a 2008 200cc model. After, installing an earlier model (03?) 250cc top end, there is an annoying POP POP POP POP in the exhaust when chopping the throttle. This is accompanied by some surging and the popping basically replaced the normal ring ding ding ding. Otherwise, it runs fine. After leak testing and adjusting all possible tuning variables, the pop remains the same. The bigger bore would raise the primary compression ratio so I thought that there may be stuffers that could be removed. There are no stuffers so I'm wondering if the 250 crank is different. Are there any suggestions?

[lineaway]

Actually your crank looks like the earlier rev3 models. The later ones had quite a bit of plastic. The 250 and 270 always had a good pop to the exhaust on a good running Beta. Have you messed with the timing?

[mcman56]

When you say a good pop, do you mean on throttle, idling along or when chopping throttle? I have not been on a 250 Rev 3 but an evo I rode did not have the pop. It had the ring ding ding. Could the pop be normal? I have heard other bikes do it a little.

I suspect that manufacturers use older model parts on bikes that are not their top of the line...like the Beta 200. But, it does seem odd that the 200 crank would have more metal/ mass.

I have been through all tuning variables I could think of; timing, jetting, compression, squish, etc.

[lineaway]

No, the Beta`s always had a good pop just at idle. And more mas means slower response.