CRF2. 50. X Big Bore. Big Bore Kit v. 1The Thumper Racing 2. Thumper will bore your cylinder and press. The kit increases displacement to 2. Thumper calls it their 2. The new piston has a. The piston skirt is wider. Price. is about 3. Thumper Racing web site. Harley Davidson Twin Cam, Evo Big Twin, Sportster and Buell High Performance Parts and Services. The finest in motorcycle performance products for Honda, Kawasaki, Suzuki, and Yamaha. An Oring, also known as a packing, or a toric joint, is a mechanical gasket in the shape of a torus it is a loop of elastomer with a round crosssection, designed. Im putting the original 305HO back in the Monte after taking the ZZ3 out for my Iroc project. This is mainly to make the car mobile but it may end up. Highly recommended for stock or performance engines. Velva touch antipump hydraulic lifters information and installation instructions important note please read these instructions through at least once prior to. The 350 in Bill Hedekins 1967 Corvette Backfires, Stalls, and Uses Oil. Time for HOT ROD to Fix It. FIY/CYM1/FAKWQ993/FIYCYM1FAKWQ993.RECT2100.jpg' alt='How To Install Cam Seals' title='How To Install Cam Seals' />I ordered the 2. Thumper today, and sent them a new 2. X cylinder, so they. The new cylinder was. I had previously ordered from Service Honda 1. Car Battery Install 55103 Solar Gel Batteries Solar Charged Battery Pack Nicad Rechargeable Battery For Solar Lights. From replacement of hardware to seals, we specialise in all forms of maintenance of windows and doors. Have an older home or building thats in need of an upgradeKRN 6. I didnt have to have the 2. X down while waiting for parts. I got the big bore kit. The piston is made by Wiseco, and the gaskets are from. Cometic. My plan is to install the kit when my 2. X gets to 2. 00. 0. Nov or so. 1. 01. I now have 2. 00. X, and its time to start the big bore work. But, I had a change in plans. I plan to install the 0. CRF2. 50. R. head at the same time as the big bore kit. Tuner on Thumpertalk. The 0. 5 2. 50. R head has a new intake port shape. The. new port shape is an oval configuration designed to boost intake. Tuner felt that it did just that. I will be sticking with the. Honda 0. 4 2. 50. X valves and springs I have had no valve problems. I ordered the head and a few other parts from Service Honda. Now Ill have to just wait a bit until the parts show up. The new 0. 5 CRF2. R head came. in today. I had new valves and valve guide seals on hand from. Other parts are on the way. I found some curious markings inscribed on the new head. Youll. have to click on the picture to see them clearly. The cam holder. clamps have 3. R inscribed on each. The front of the head has R3. GR and 3. 7 on the right. I. think GR are a persons initials, but I have no idea about the. There are also numbers on my old head same pattern. If anyone knows what all this means, drop me. Does that head look trick, or what I did the initial tasks. I. checked the compression 5. Ill pull everything. After a few aborted. I finally managed to take all the top end parts off. Removing. the cylinder requires that you remove the carb, also. And that. means the sub frame at least has to swing up and away. Crack Para Depth Hunter Pc more. Im also. doing a rear shock linkage service, so that means the shock comes. And on and on. Ill be measuring and checking things out for several days. I start reassembling. When Thumper says their piston skirt is wider than stock, which. The front and rear skirts are wider, left to right, than the stock. The Thumper piston is the same height as the stock piston. Notice the blow by on the old pistonIts actually not as bad. I thought it would be theres virtually none below the rings. A rockhound friend weighed the stock and Thumper. Racing piston. assemblies on her very accurate scale. The weights are stock. Thumper. Racing 2. Thats about 1. 5 heavier. Thumper. Racing assembly. The assembly includes the piston. Heres a brand new. Honda intake valve on the left and my right front intake. My valve has about 2. When. my scanning electron microscope arrives, Ill take some really. I can see how much of the valve. Or I may use my atomic cantilever tip. Until then, Ill just look at the valve surface and. It. looks pretty good to me. I can just barely see some very minor. When using my magnifier headband and close up loupe, I can. I call cupping or feathering of. Not much, but its the start of what could be valve. Im thinking my own personal valve replacement. Please ignore the small white specks. They are nearly invisible. I didnt see them until after I took the. Thatll teach me to keep a cleaner engine work areaI dont believe it. No sooner. did I made a wisecrack about a scanning electron microscope when. Captain. J posts on Thumper. Talk that he actually DOES have. Here is an excerpt. SEM picture and component analysis. Just thought Id add a little more to the valve discussion. I work for a medical device company where I have access to a scanning. Granted, most people dont look. I thought I would take advantage. When the Honda dealer first. I was real skeptical. I had heard that the valves were. Titanium. Some were saying that there was only a Titanium oxide. Here. is a picture of the valve and the results of the scan taken to. The readings were. Both readings conclude. Titanium 6 4 grade. It also shows. that there is a slight recession on the face although looking. Im not sure if I would have replaced them myself. Hope. this helps. Oil Squirter Jet. This small oil squirter jet on the left crankcase has changed. The history on the X. The 0. 6 and 0. X cylinder will not work on the 0. X crankcase because of the different design of the oil jet. But. you can modify the newer cylinder to work with the older crankcase. The R oil squirter jet. X. Motocross Action. February 0. 5 issue showing the. R cases with the 0. R cylinder. It is clear that. R cylinder will not work with the 0. R cases. Eric Gorr wrote the Honda CRF Performance Handbook. Honda CRF2. 50. R4. R owners. with detailed do it yourself tips on installing 3. This book combines honest servicing tips. Price 1. 8. 0. 0. See Eric. Gorrs web site for details. A sample of the book is available as a PDF file on his web. The sample shows Chapter 7, How to Install an Aftermarket. High Compression Piston Kit. The last page of the chapter. R cylinder that is. R engine. This relief allows the oil. You can perform this mod on an X cylinder. You MUST perform this modification when installing an. X cylinder in an 0. X engine or when installing an. R cylinder in an 0. R engine. There is an exception. If you update the 0. X or 0. 4 R. oil squirter in the crankcase to the newer design, the newer cylinder. NOTE I read about the cylinder mod on Thumper. Talk, but neglected. I also saw. the cylinder mod in one of the dirt bike magazines, but dont. Lastly, I dimly recall seeing the oil squirter. Unfortunately, whenever I saw the mod, I decided it was not important. I thought Id never put a newer cylinder on my 0. X. How short sighted was thatNOTE The Thumper Racing 2. I have no information on the Athena. Ever wonder what was under the plate on the underside of the. Me too. The bolts came out with some difficulty because. I kinda figured there would. I found. There was absolutely. I will probably never. I DID put thread locker on the bolts. Carb work. I adjusted the throttle position sensor it was off about 1. The improper setting probably did not affect anything to. The bike has always started and idled just fine. I checked the carb interior pretty carefully and did not find. I swabbed the drain hose and the four vent hoses. The hose routing and filters that. I used seemed to be adequate to stop dust intrusion. There was. a very light coating of dust on one small part of the plastic. I did. notice that the cover snaps into place I had not noticed that. I worked on the carb in Feb. I had previously routed the two upper carb vent hoses into. However. I decided to add some filters to the hose ends and get them out. The Du. Bro filters mentioned on a Thumper. Talk thread. come in two sizes. I used two of the smaller size. I put some. air filter foam inside each, pushed them onto the hoses theyre. I tucked. the ends of the filters under the hose and frame in the area. Testing the accelerator. Make sure there is fuel in the float bowl. Twist the throttle. Try viewing one of these short movies. Im trying several formats, so let me know if you have problems. Carb. Squirt. AVI  2. KBCarb. Squirt. MOV  3. KBCarb. Squirt. SC. MOV  5. 97. KB. If you look carefully at the picture above, youll notice the. I removed the stock hot start valve. I have never used the hot.