Watts does very nice work and has factory team experience, but one member here had to resort to calling the police in order to get his parts returned from Watts after a lengthy delay. Similar to a Varner type horror story. Plus, Watts was expensive. ... more »

Pro Circuit modifies both the stock cylinder and the stock head as part of their porting package. As you mentioned, they offer a choice of race fuel, or pump gas setup. No other options are available. You would most likely need to purchase a Honda head ... more »

Which CRF 22mm clamp and what about the steering stem?

Agree- do not machine the cylinder base. Pro Circuit has pretty good porting and head specs and they do not mill the cylinder base, and they do not use any epoxy in the transfers or boost port.

The YZ250 transmissions have been a problem for a long time. Weakly supported 4th gear. 3 dog engagement design. Shift forks that are rigidly staked to their pins instead of using a floating design. Gears that can shatter in addition to the usual wear ... more »

Absolutely correct. It was a good era to be on a Honda- right up until the 1997 aluminum frame disaster.

The HPP engines were good. Substantially better than the older ATAC system.

You might as well have just drained the oil out of those forks and filled them with concrete- the end result would have been virtually identical. Plus, the quick chassis made them feel even worse.

43500-KZ4-J42 43500-KZ4-J43 and 43500-MEN-305 will all work. All are still available.

The 03 ignition is reportedly better than the 02 if you can find one. We e-mailed JD ignition in Italy a few months ago and they were offering a double map 05-07 iginition. Didn't inquire about 02-04 but they're worth contacting.

We have sent several 05-07 cylinders and heads to PC over the years and the results have been very good at fairly reasonable prices. They have a cookie cutter engine setup where the only options offered to choose from are a pump gas head, or race fuel ... more »

Gotta love these states with NO state income tax.

Yes, you can use the 07

Agreed, but nothing prevents someone from grinding out the PWK inlet guide vanes to acheive TMX flow if that was the objective.

IMO, this is the real reason why Honda and KTM went to the TMX- it is substantially less expensive than the PWK. The TMX is not a completely terrible carb- it does make good peak power numbers, but the fact that it is so much cheaper had the accountants ... more »

One thing about matching cases to the cylinder is guys frequently forget to also match the base gasket. Spend time matching the cases only to robotically install the base gasket which then protrudes into area you just matched.

What kind of power change does the silencer mod create? Is it possible to modify the older pre-2011 26mm core silencers to achieve the same results? Doesn't appear so.

Highly under-rated machines. Good handling, ergonomics, overall parts quality and durability.

Yes, please post all details publicly. This appears to be a very inexpensive mod which would benefit all YZ operators.