Hi guys, I'm new on TT. I'd appreciate any helpful advice. Sorry for the novel but I think the better I explain, the better you can help me.

Bought a 2004 crf250x 3 months ago. After supposedly seizing the top-end, the owner had it rebuilt, and has the cyl. head from a 250r, re-jetted carb, FMF Powerbomb header and Powercore 4 spark arrester muffler. Other than that, the bike is stock and in great shape. Went trail riding in late April (about 7 hours), bike started easily all day and ran great with awesome power. Next morning - no start. Cleaned out the fuel tank, carb and installed new spark plug, no luck. Two weeks later, a buddy and I got it started after about 30 kicks (no luck with e-start), and the bike ran the trails flawlessly all day (rode about 4 hours) and would restart easily with kick or electric if the engine was still warm. Same issue next day (many kicks to start, then ran great for 5 hours of trails, no loss in power). Took it to the Honda shop, valves were tight and needed shims. They adjusted valves to correct clearance and went thru the carb just in case, also installed decompressor that was apparently missing from my camshaft - STILL no start. They say a compression test shows only 25 psi and leakdown test shows it's not leaking past the valves, but possibly piston or rings.

My question - considering how well the bike ran last time I rode it (once I got it started), could the compression really be that low? I would think with only 25 psi, it would barely idle. Like I said, 2 days in a row it ran perfectly all day after the complicated start. No stalls, odd noises, smells, or loss of engine power and it hasn't lost any oil. I would think if the piston or rings wore out as I was riding, I would have noticed something. Could there still be an issue with the valves or valve seats, even after they shimmed them? Could the timing chain have jumped a tooth, making starting impossible but okay enough to run warm? I would think the shop would notice that with the valve cover off. Thanks so much for any ideas, -Steve.

Check the valves again. I,ve seen reshimed valves 0 in a very short time.Most likely time for new valves, seats, guides... Doubt its timing,if the chain jumped it would not run at all.

The shop shimmed the valves to spec, and by pressurizing the cylinder in the leakdown test, they said nothing is getting past the valves, but they can supposedly hear oil bubbling down in the crankcase if they remove the oil dipstick/cap. The guy was gonna pull off the head to see what the piston and rings look like - haven't heard back yet. Is it possible that the piston and rings are ok and the blow-by (25 psi compression) is simply a bad head gasket?

Is the compression results 25psi or is the leakage test 25%?

I would re run the leakage test and make sure the valves are not leaking. Way more common for valve problems causing the compression loss.
Compression test results will alway be low due to the decompression device on the cam.
Leakage test results over 10% will start causing hard start problems.

Not sure, that's a good question. Shop told me the compression test showed only 25 psi. They didn't tell me a number for the leakdown. Apparently after the valve shims, they don't hear any air coming thru the carb (intake valves) or through the muffler (exhaust valves) so the valves seem fine. Only that it sounded like it's getting past the piston into the crankcase. Still waiting to hear what they found with the head pulled off. I still find it odd that the piston/rings would be so worn out when I was pulling wheelies in my driveway 3 days before I brought it in to the shop (after 50 kicks to start it). Thanks for the info.

Were you burning oil? That's a good indication that the rings are bad.

When I first bought the bike, the oil was black and really low on the dipstick. Maybe that was a warning sign. I changed the oil and filter before riding at all, and in the 2 weekends I rode, it only used a bit of oil. Talked to the shop Friday, I guess whoever rebuilt it a few years ago honed the cylinder too rough and it eventually wore the rings. It had low hours on the rebuild. They're gonna re-hone it and put in new rings, and said the piston is fine.

steveo250x you should really if you have the time use TT as a resource and do this work yourself. You would save a lot of money and really it's quite simple to do. I understand that some guys don't have the time, tools... to do it at home but really they are very easy to work on. All you have to do is follow the steps and you can rebuild just about anything on the bike with out any special tools.

You are going to be needing new valves and the seats cut on your head here really soon if you had to have them shimmed. One long weekend and you bike will not start again. If you do the work your self you will save a ton of money.

Hit_the_set said:

Yes indeed.

With your symptoms (very hard to start, runs good once started) are classic valve tolerance symptoms. An adjustment should of had your bike starting and running good for a little while. I dont know why they went thru the carb and why she wont start now. I have seen them so flooded the rings arent sealing anymore, a shot of oil in the cylinder and off she goes.

You need to do a top end and while you are in there you need to replace the piston and rings as well. You need to prepare to pay the dealership to do this or do it yourself. My guess is a dealer is going to cost you @ 1,500.00 for a valve job and piston/ring. You could do it yourself for 1/2 or less.

With zero'd valves you wont get much leak down past them. Its not like they are burned and they beat themselves into the seats.

Good luck!

I have an 06 and had to shim the vales put them to speck then rode it in up and down the back yard once wouldnt start again. got an 07r head from ron hamp put in a higher comp piston race it about once a month since 07 have not hade one problem since. awsome bike!

I originally thought it was a carb problem, that's why I had them go thru it at the shop. I took it apart at home and I was skeptical during my reassembly, so I wanted them to see if it needed fine tuning. It's a bit more complex than my previous bike ('89 RMX250).

By now, I know this shop visit is gonna cost me a few bucks. I don't have a repair manual yet and thought all it would take is a carb/valve adjustment and I'd be riding again in 2 weeks (this was June 1st). I'm gonna buy a book and tackle it myself in the future. I'm fairly mechanical and have a garage, time and most basic tools, just not much experience with 4-stroke bikes. Right off the bat, I know I don't have a valve-spring compressor, cylinder bore gauge, and probably some others.

Just curious, why will I need new valves and the seats cut soon? I plan to check clearance after the recommended hours and shim again if needed. The shop told me the valves have alot of length left and I can do a few more shims before they're maxed out and time for replacement. At that time, I'll probably do a steel valve kit. I don't race so hopefully this and the next re-shim will last me a few decent trail rides. Should get the bike back in a few days.

Generally once the valves move a few shim sizes the hardened coating on the ti. valves is gone. The valves will begin to wear and need adjusting very quickly after that.
If you remove trhe valve and lok at it you can see the steped wear on the valve face.
When i still had ti. valves as soon as the needed any adjusting i would replace them after the next ride.

Exactly what shovel said on the valves, once they move get your plan together.

The other thing is this; once you are at the piston, do the valves and visa versa.

If you are mechanically inclined at all it is really not that difficult to work on. With the resources here and a manual you can get it done.

Ok gotcha, thanks for the heads up. I ran across a Honda service manual this weekend and got it cheap, so next time I can tackle it on my own. Any recommendations on companies for steel valve kits and/or valve seat cutting work in the future? Again, I have a 250x but it's got the 250r head, so I'm assuming I'd order valves for the R when the time comes.

Ok, I've decided to do a steel valve kit so I tore my cylinder head off a couple weeks ago. Before this site made the switch, someone told me to check out Ron Hamp, Agent Smith, or MX Time for head work. I emailed Ron, and he replied with "I no longer offer those services". Do you guys have any experience with the other two? Also wondering which valve kit to order, heard good reviews of Kibblewhites. Can the engine shop order the correct valve kit parts for me once I send them my cyl. head?

Contact Agent Smith their number is listed on the web site.

Engine Dynamics in petaluma CA.
they have done all my engine work. alway been very happy.
they are a kibblewhite dealer.
highly recommeded from kibblewhite themself also.
http://www.enginedyn...m/company.shtml

707 763-7519

steveo250x, on 11 July 2011 - 01:32 PM, said:

That little bit of oil you used was probably from filling in the oil filter once it started up, other than that, your on your own

Ok, one small issue before I send out my cylinder head. I'm putting all the components together so they can bench-shim it once the new valves are in. The problem is once I put the cam and cam holders in place, I BARELY tighten the holder bolts with a socket (just past finger-tight) and before the 1/4-inch ratchet is even slightly snug, the cam develops a lot of friction and won't spin as free as it should. It gets a "more than normal friction" slightly gritty feeling, as if there's a slight grinding in the bearings. If I tap and wiggle the holders loose, the friction is instantly gone and the cam has a free-spinning feel again. The bearings and holders are clean of any grit, and I smeared oil on them before putting it together. I can't imagine that much friction being normal, especially when the bolts aren't torqued yet. Is it possible that once back on the bike, the timing chain pulls down on that side of the cam, straightening it out and releiving the friction? The shims, buckets and rocker arm are in place, so obviously the cam only rotates a small amount both ways before the lobes start to contact those parts. The friction just seems way more than it should be. I don't know what to compare it to, because I never tried to rotate it while it was still in the bike. I'm sure Agent Smith can figure it out if I send it this way, but I'd like to figure out what my problem is before, so I know for sure what to expect when I re-install it on the bike later on. Thanks in advance for any advice.