valve clearance & motor failure

[Trxster]

Just thought I would post some info......I recently took the head off to do the gaskets and like a dummy had a few of my lifters/shims come out. I am pretty sure I got them back in the right holes but....since it happened I decided to check the valve clearance (sled has about 2000miles). Unless I am doing something wrong in checking the clearances my clearances were almost all below spec.

I called and talked to the main R1 mechanic at Lynnwood Motoplex and also talked to my friend MtViper who is a seasoned mechanic and was told that the clearances do shrink as the valves seat and get worn in. Having the valves with too little or no clearance would cause the valves to get too hot and this is how you have valve failure. On a turboed motor the issues is compounded due to the pressures and loading. So, my sled is going in to get the clearances reset to the outer limits this next week. Probably worth the $100.

Just thought I would mention it since Yamaha says you don't need to check valve clearance until 25k or something like that. If your doing your head gaskets it might be worth checking. This could be one of the reasons people or having motor failures after adding turbos.

Rt

 

[black john]

clerance

by putting the valve clerance to max you will be removeing some valve lift as well. ie reduceing camshaft lift.

 

[BlueMax]

I would check the valve clearances and I have found them out of spec on numerous 4 cylinder 4 strokes. I would definitely do it if you are adding turbo/SC to your sled. Documentation is helpful also when checking valve clearance. I usually write down each value (keep on Excel spreadsheet) as I am checking clearances. I keep this information to check against new numbers measured during the next check. I also measure the shims under each follower (bucket) and document where they are located and size. The next time you check valve clearance and find some out of spec you can go down to your Yamaha dealer and get the correct shim to make adjustments. If more than one valve clearance is incorrect, you can use the shim size documentation to shift some around and limit the number required to purchase. By the way, have them check the actual thickness of the shim before leaving the dealer. Sometimes dealers get them mixed up and this will save you a return trip to dealer. The shims are too expensive to keep a bunch laying around for making further adjustments and you don't know what sizes to purchase. Hope this helps.

 

[Skydog]

Boy now we have to adj vavles at 2,000 miles???

 

[BlueMax]

Maybe I should explain what I meant in the last post. I should have said the owner (if you are into that kind of stuff) should check the valve clearances and take a little more time to get accurate measurements. Some dealers tend to just check go or no go with their feeler gauges and if they are close they let it slide. Most dealers will tell you it is not necessary. I would check them once early to make sure you are not going to damage a valve that you expect to run for thousands of miles. The valve clearance does not change much after the initial break-in is complete. If you are installing a turbo/SC, you probably will have the head off anyway so this is a good time to check.

 

[Trxster]

yeah, I guess that was my point that if you have the head off, take 15 minutes to check the clearances before you put it back together. By the way, the shims on my are all numbered on the bottom in MM

The sizes are like 199,196,201 or 1.99mm 1.96mm and 2.01mm

Rt

 

[black john]

valve,s

numbers go to the top. not the bottem so that the numbers do not were off.