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question about valve specifications

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Hello

I have a few questions about checking and/or adjusting valves on my 04 rmz.

I posted earlier about haveing a hard starting bike, but now the bike doesnt seem to want to start at all.

Anyway, I've went thru the carb, seems to be working fine, except i need to change the main jet, according to fmf factory 4 specs.

I checked the clearences on the valves but i'm unsure how much drag should be on the feeler gauge, they seem to be pretty tight.

The bike was supposed to have had new valves put in just recently, I purchased the bike used.

I also took the top end apart and checked the piston and rings all seem to be fine.

What the bike is doing now is, doesn't seem to hit a lick with the choke on, and doesn't hit at all without it. IF i kick the bike slowly with the throttle wide open and then let off and kick it it will back fire one time.

The timing seems to be set right to specs and there is plenty of spark.

ANY SUGGESTIONS WOULD BE HELPFUL?

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This is what I do for valve specs. Take the feeler gauge for the bottom end of the tolerance (intake is .0039 and exhaust is .0055 i believe, it's in your manual so double check because i can't remember off the top of my head) see if you can fit those gauges in at all. If they slide in very easily, keep going up on the thickness of the gauge until you are met with some resistance, if the gauge doesn't go in at all it is too big. If you can't make the smallest gauge fit, or it is very hard to slide in, the valves are tight.

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So if they are out of spec, then they need to be re shimmed correct?

does anyone know if they sell the shims in a kit, like a bunch of different sizes or do you have to buy each one seperate?

Thanks

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Yes, if they're out of spec you have to shim them. That procedure can be found in the service manual. It's a lot easier than it seems when you read it, don't get discouraged about removing the cams. You can buy kits, but they go for a lot more than the shims. A shim costs around 4-5 bucks.

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like tnt said re-shimming isn't very hard at all, The service manual is very helpful and takes you through it step by step. once you take out the old shim there is a simple equation to figure out the one you need and then just go down to you local dealership and buy it. THe shim kits are pretty expensive and unless you plan on doing alot of reshimming i would recomend buying them seperate. good luck

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If you own a four stroke you should learn to check the valves. It's as important as changing the oil or cleaning the air filter. Most people could do a top end on their two stroke because it was important and they figured it out after doing it a few times. There is a lot more going on in a four stroke but once you get into it you will pick it up pretty quick. I like figuring everything out, when I understand what's going on in the motor I am better able to fix it, or keep it from breaking.

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were in the manual does it say how to shim? i dont see that i only see how to check if there in or out of spec?!? and right after that it starts in on how to put back on the cylinder head cover!? and whats it mean by upper chain guide bottomed?

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http://www.nbsupercycle.com/servicemanuals/04servicemanuals.htm 5mb

Are you looking in the owners manual or the service manual. Different things. Download the service manual and all will be revealed. I think the details are around page 35.

Did the bike get new new valves or was it just re shimmed. Once the valves have closed up completely they are buggered. You can re shim but it won't last long because the Ti coating has been worn through and it will keep wearing.

I've seen a few 2nd hand bikes that have been bought and are running fine for a short time. The shop or previous owner has just re shimmed it to get it going long enough to sell.

If you valves have not closed up completely you probably can re shim and get some good life out of it. Keep an eye on it and if they keep moving then it's time to look at new valves/seat work.

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The Hot Cam Shim Kits aren't that expensive, around 100.00 US. The only problem is they com in .05 mm increments and most of the time you still need to get the half size shims .125mm increments I continue to add to my inventory but it seems I always have to go buy at least one shim everytime. If your not Mech inclined your in trouble the service shop bills are going to eat you alive. If your are good with a wrench get the service manual, a good set of feller gage's in mm, a valve spring compressor Motion Pro makes a good one you'll need an smaller adapter for the exhaust springs or cut a good size notch in a 5/8" spark plug socket. Then pull the head pop out the valves and look at them and the seat in the head I always use a magnifying glass, you should be able to see if there are any problems, if you can't tell take it down the service shop and have them explain to you what your looking for, ie. pitted valve seats, cupped valve head caused from the valve seat being to worn. This all sounds like allot but this is the price of having a four stroke race bike, theres a lot more to check in these engines than the 2-stroke. My new motto is when in doubt replace it all. If one valve is bad do them all, change valve springs every 15-20 hrs & springs + valves every 30-40 hrs if your running it hard in race conditions, you change piston & rings every 30-40 hrs also. One last thing don't let your bike overheat, In my option it's the excessive heat in these engines that kill the valve train. Good Luck :applause:

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Those intervals seem a little intense. I have 70 hours on the top end and everything is running smoothly. I realize that the time to rebuild is near but no way am i replacing springs every 15 hours, heck that's only one good weekend of riding. 100 bucks for a shim kit seems a little steep IMO, a shim is only 4-5 bucks, so basically if you shim all the valves when you do the shim job, you still need to shim them 20 times to get your money back. That takes years for that many shim jobs.

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Hello

I just got thru changing the shims in my intake valves they were the only ones that were tight. I couldn't even come close to getting a .004 gauge in between them and the .002 wouldn't go either but it's so flimsy. anyway I measured the shims that were in the intake valves and they were 2.800 so I figured I would be safe by going down four sizes so I bought 2.700 got them installed and still can't get .004 clearance, it did help though because now my compression is up, I will have to get some more shims, but my question is, does anyone know a good place to order the shims on-line, I was planning on them costing me around 4 or 5 dollars a piece, but at the shop I got mine they were closer to $8.50 a piece.

So if you have a place on line that would save me some money I would appreciate the info.

Thanks

Also thanks for the all the imput and advise I have been getting.

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I got bad news, if you can't get the clearance without using more than 3 shims, you need new valves.

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Just talked to the guy I bought the bike from and he states that he had the top end rebuilt and all new valves put in last month and has the receipts, that he will send me.

and he also states that the bike was used only a couple of times since the work was done.

The exhaust valves are fine, all within specs, I'm just taking for granted that I went down 3 shim sizes, there were no markings on the shims I pulled out, but I measured them with a set of calipers which measured .110 thousands and I just converted that to be 2.794 and I just rounded that to 2.800, but I also could not measure the actual measurement with my feeler gauge, it only goes down to .002 and that one is so flimsy that you cant get it under without bending it.

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you did setup the timing before you checked them right?

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well guys i 've got another problem now.

I changed the shims in the intake valves and got the clearance i needed. put the bike back together and started it, it started fairly easy and was letting it warm up when it all of a sudden just stopped dead, so i restarted it but seemed to have some drag.

I pulled the valve cover off and found the exhaust cam binding, took it apart and it seems the head and exhaust cam are gauled or marred. I don't know if i can clean them up or not.

Anyone had this problem and if so is there any fix besides all new parts?

This bike is beginning to cost me an arm and leg.

I guess I failed to soak the cam with oil before starting the bike, I didn't have the exhaust cam off so it slipped my mind I put oil on the intake cam and it looked fine.

Also if the head has to be replaced would it be better to get an 05 head and all the new valves and springs?

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This is one thing you can't blame on the bike, this is totally your fault. Depending on how bad they are, you may be able to clean them up. If not, you need a new head and a new cam. It's also possible you overtightened the cam caps which led to this problem. Also, how on earth did you reshim the intakes without pulling the exhaust cam?

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Well In my repair manual it says to remove the intake cam first so once I had the intake cam off there was no reason to take off the exhaust cam I left it tightend down, and besides if you over tighten the cam caps the only thing that will happen is you will pull out the threads, they are to be torgued down at 104 in lbs and that's what i did.

Thanks :applause:

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Well In my repair manual it says to remove the intake cam first so once I had the intake cam off there was no reason to take off the exhaust cam I left it tightend down, and besides if you over tighten the cam caps the only thing that will happen is you will pull out the threads, they are to be torgued down at 104 in lbs and that's what i did.

Thanks :applause:

so you didn't touch the exhaust cam and it was the cam that seized? the intake usually seizes but if the exhaust did then you have a problem with lubrication and need to check your oil filter or something else because that means it wasn't getting oil.

also, the 05 head won't fit without mods. the left bolts that secure the camchain side are different on the 05 than the 04.

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