Goofy Footer 539 Posted June 28, 2013 In my experience full race engines no more than about 6%, play engines up to 10% or so, although having said that by the time you get to 10% you can usually see excessive oil around the breather and/or you will be using oil. Thanks for the info! The original quote of 8% leakdown was with the motor cold. When warmed (proper testing procedure when everything is sealing properly) my DRZe was at 5% or a smidge over 5% so I'm quite happy. I need to learn a lot more before I attempt motor surgery on any bike of mine but I'll do my best stay attentive to maintenance and diagnostic testing. In fact, I just ordered a Motion Pro leakdown tester to check my other bike so if anybody wants to do a Leakdown Party / Maintenance Anonymous Tech Day I'm game! Share this post Link to post Share on other sites
bikeslut 1 Posted June 28, 2013 In my experience full race engines no more than about 6%, play engines up to 10% or so, although having said that by the time you get to 10% you can usually see excessive oil around the breather and/or you will be using oil. Thanks for the info! The original quote of 8% leakdown was with the motor cold. When warmed (proper testing procedure when everything is sealing properly) my DRZe was at 5% or a smidge over 5% so I'm quite happy. I need to learn a lot more before I attempt motor surgery on any bike of mine but I'll do my best stay attentive to maintenance and diagnostic testing. In fact, I just ordered a Motion Pro leakdown tester to check my other bike so if anybody wants to do a Leakdown Party / Maintenance Anonymous Tech Day I'm game! yeah- i wouldn't mind checking out the DRZ... Share this post Link to post Share on other sites
Goofy Footer 539 Posted June 28, 2013 Top end rebuild kits between four strokes and two strokes don't seem to be that much different in parts cost - piston/rings/gaskets. What does seem costly are four stroke valves and the headwork associated with valve failure. So.. if a four stroke is maintained properly (ring/piston and valve checks) how long can the valves last without needing replacement or failing? Is the Yamaha 5 valve motor a good top end design? Mo valves Mo problems? Why do CRF250Xs seem to eat valves all the time? Is the R a different design? A few SDAR guys recently rebuild their RFS motors around 10,000+ miles - did you get new valves/headwork done? I think the DRZ has two piece valves - seems scary no? How're Husky valves? Can somebody give me the scoop? Thank you to those who have posted so far - great discussion and I'm learning a lot. Edit: I realize that is a big question. I'm not trying to start some a brand flame war. I'm just interested in learning about different designs, stainless steel vs titanium etc. Share this post Link to post Share on other sites
Covered in Dust 163 Posted June 29, 2013 At 600+ hours on my RFS motor I had new Kibblewhite valves and hard seats put in. The cylinder was fine so just new piston and rings added. I could have used the old piston but figured for the money might as well add the piston. The bike runs better than new now and with the hard seats no more valve adjustments should be needed. Covered in Dust Share this post Link to post Share on other sites
paulmbowers 236 Posted June 29, 2013 At 600+ hours on my RFS motor I had new titanium valves and hard seats put in. The piston and cylinder were fine so just new rings added. Covered in Dust Are you sure they're titanium? It'd be the first time I've heard of him doing that- he's a Kibblewhite dealer, and those are stainless... Share this post Link to post Share on other sites
Covered in Dust 163 Posted June 29, 2013 At 600+ hours on my RFS motor I had new titanium valves and hard seats put in. The piston and cylinder were fine so just new rings added. Covered in Dust Are you sure they're titanium? It'd be the first time I've heard of him doing that- he's a Kibblewhite dealer, and those are stainless... What u talking bout? (thanks for the correction) Share this post Link to post Share on other sites
tntmo 910 Posted June 29, 2013 Is the Yamaha 5 valve motor a good top end design? Mo valves Mo problems? Why do CRF250Xs seem to eat valves all the time? Is the R a different design? A few SDAR guys recently rebuild their RFS motors around 10,000+ miles - did you get new valves/headwork done? I think the DRZ has two piece valves - seems scary no? How're Husky valves? Can somebody give me the scoop? Thank you to those who have posted so far - great discussion and I'm learning a lot. Edit: I realize that is a big question. I'm not trying to start some a brand flame war. I'm just interested in learning about different designs, stainless steel vs titanium etc. From the research I've done, and the real world of working and living with these bikes...the Yamaha valves seem to last the longest of the Japanese bikes. The Honda Uni-Cam design may be the cause of their intake valves failure since it has an aggressive profile, also the earlier models had poor sealing of the air box. There are solutions to these problems, most common being a change to stainless steel valves and new seats and springs once you get the air box sealed. A lot of bikes use two piece valves, it's not uncommon and it's not scary. Husky valves I don't know about yet, except they are easy to check and adjust. KTM is also nice, screw and locknut. The original valves tend to cup but can last quite a while. And in the end, someone will have a bike with a million miles and no issues and another guy will have the same model that blew up on the first ride. Roll the dice! Share this post Link to post Share on other sites
Goofy Footer 539 Posted July 1, 2013 At 600+ hours on my RFS motor I had new Kibblewhite valves and hard seats put in. The cylinder was fine so just new piston and rings added. I could have used the old piston but figured for the money might as well add the piston. The bike runs better than new now and with the hard seats no more valve adjustments should be needed. Covered in Dust From the research I've done, and the real world of working and living with these bikes...the Yamaha valves seem to last the longest of the Japanese bikes. The Honda Uni-Cam design may be the cause of their intake valves failure since it has an aggressive profile, also the earlier models had poor sealing of the air box. There are solutions to these problems, most common being a change to stainless steel valves and new seats and springs once you get the air box sealed. A lot of bikes use two piece valves, it's not uncommon and it's not scary. Husky valves I don't know about yet, except they are easy to check and adjust. KTM is also nice, screw and locknut. The original valves tend to cup but can last quite a while. And in the end, someone will have a bike with a million miles and no issues and another guy will have the same model that blew up on the first ride. Roll the dice! I appreciate the replies and great info guys - just what I was looking for. The SDAR community rocks! Adding to the thread, here are some videos of a Yamaha 5 valve top end rebuild. Share this post Link to post Share on other sites
robertaccio 412 Posted July 1, 2013 "How're Husky valves?" since 2006 or so all Husky valves have been sourced from DelWest, most are Ti I think some are aslo SS depending on models. I believe made in the Switzerland plant In 2004 they had Ti valve issues (before DelWest), in my 04 TC450 we replaced the Ti valves with SS when the Ti showed signs of stretch. Never had any issues with the SS valves. My 06 TE450 came with SS valves (never any issues) http://www.delwestengineering.com/who_we_are.html My 2008 TXC450 (DelWest Ti valves) was raced and ridden hard for @260 hours and the Ti intake valves were still good, we replaced the exhaust valves, the seats were pitted. FYI/example post. Share this post Link to post Share on other sites
