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Maybe Time For New Valves?

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So, i ended up with one of the 2006 250's with valve problems right away and have been shimming them. I think the bike came from the factory with something like 180's or 190's for the intake and the exhaust was 275's. Took the bike to the local honda shop to reshim. They put in 170's for the intake and left the exhaust because it was fine. Well that sucked because the bike hardly lasted 2 hours so i bought the hotcams shim kit and decided to do it myself from there in. I put in 165 for the left intake and 150 for the right intake and dropped the exhaust valves down to 250's. That was pretty good because the bike lasted for about 8 hours before i couldnt get the thing to stay running. Took the bike apart, the intakes were at zero and the exhaust was a bit tight. Calculated the shims and dropped them in, checked it and the exhaust were at 0.010 in. so i called that good, but the left intake was still tight and the right was still at zero. I knew one size down wouldnt make a difference so i went two down on the right and one down on the left. The left was perfect but the right was at 0.003 in. So that all means that right now in my bike i have the following shims, Lft In. 1.50 , Rht In. 1.30 , Lft and Rht Ex. 2.40. Since the right intake is still tight, i need to go down one shim size to a 1.25mm , but my problem is that the shim kit only has shims to 1.20 :thumbsup: , am i shimming it too far, and i need to put new valves in and cut the seats? Thanks for any help

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I would just put new valves in because i wouldent run the risk of having a valve go south and having a monster repair bill.

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You will need to pull off the head and take it apart.

Now send out the head to RHC or MX time and get the seats cut and new guides installed.

Pick up yourself a Faction MX intake SS valve kit, comes with SS intake valves, springs, retainers and cotters. Buy some new OEM seals (4), guides (4), exhaust valves (2), exh springs (2), exh cotters, exh retainers.

Once you get the head back install all parts, do not over compress valve springs, only compress as much as needed.

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Okay, well that sounds like what im going to do. But do you guys have an idea of how many hours i can look forward to getting out of the new valves, because i only got 38 hours out of the stock ones. And will i be reshimming every five hours or so, like i have been doing? Thanks again

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So, i ended up with one of the 2006 250's with valve problems right away and have been shimming them. I think the bike came from the factory with something like 180's or 190's for the intake and the exhaust was 275's. Took the bike to the local honda shop to reshim. They put in 170's for the intake and left the exhaust because it was fine. Well that sucked because the bike hardly lasted 2 hours so i bought the hotcams shim kit and decided to do it myself from there in. I put in 165 for the left intake and 150 for the right intake and dropped the exhaust valves down to 250's. That was pretty good because the bike lasted for about 8 hours before i couldnt get the thing to stay running. Took the bike apart, the intakes were at zero and the exhaust was a bit tight. Calculated the shims and dropped them in, checked it and the exhaust were at 0.010 in. so i called that good, but the left intake was still tight and the right was still at zero. I knew one size down wouldnt make a difference so i went two down on the right and one down on the left. The left was perfect but the right was at 0.003 in. So that all means that right now in my bike i have the following shims, Lft In. 1.50 , Rht In. 1.30 , Lft and Rht Ex. 2.40. Since the right intake is still tight, i need to go down one shim size to a 1.25mm , but my problem is that the shim kit only has shims to 1.20 :thumbsup: , am i shimming it too far, and i need to put new valves in and cut the seats? Thanks for any help

This is a classic example of why you should not reshim your valves once they start to move, just cut your seats and replace them at first sign of movement. Once they move (Mushroom) and you continue to reshim and run them they will continue to move, not to mention you're absolutely destroing the valve seats, you're also running a real risk of a valve breakage and ruining the head, cylinder, piston and so on. Everybody always say "Then what is the shim kit for", it's for setting the lash when you put in new valves, setting the original lash to different specs, setting the lash for different cams, or it's an emergency situation at a race you just have to do…etc.

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This is a classic example of why you should not reshim your valves once they start to move, just cut your seats and replace them at first sign of movement. Once they move (Mushroom) and you continue to reshim and run them they will continue to move, not to mention you're absolutely destroing the valve seats, you're also running a real risk of a valve breakage and ruining the head, cylinder, piston and so on. Everybody always say "Then what is the shim kit for", it's for setting the lash when you put in new valves, setting the original lash to different specs, setting the lash for different cams, or it's an emergency situation at a race you just have to do…etc.

Oh, well i guess i should have learned this before hand :thumbsup: . Im still pretty new to the race bikes and after the first signs of problems, i would immediately take it to my local honda shop to fix. They told us, to keep checking the valves and when they go out, just drop some more shims in there and your good. Well after the bills for the honda shop i decided to start doing the work myself. Thank you a bunch for the info, do you think my head is really damaged? I know my brothers 250x went 100+ hrs and the valves finally started to go out, and the local honda shop did the same thing, shimmed it probably three times, maybe four. Then we took it to another shop further away and they had to replace the head and the valves and the works :thumbsup: . Well im just hoping it hasnt gotten too bad for my bike.

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Oh, well i guess i should have learned this before hand :thumbsup: . Im still pretty new to the race bikes and after the first signs of problems, i would immediately take it to my local honda shop to fix. They told us, to keep checking the valves and when they go out, just drop some more shims in there and your good. Well after the bills for the honda shop i decided to start doing the work myself. Thank you a bunch for the info, do you think my head is really damaged? I know my brothers 250x went 100+ hrs and the valves finally started to go out, and the local honda shop did the same thing, shimmed it probably three times, maybe four. Then we took it to another shop further away and they had to replace the head and the valves and the works :thumbsup: . Well im just hoping it hasnt gotten too bad for my bike.

Your head should be perfectly fine, Just be sure to get the seats cut before you put in all new valves.

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Oh yea, of course, im definitly going to be cutting the seats before putting in new valves. Thanks for your help

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