Jump to content
CBR1100XX.org Forum

Valve Adjustement


TimXX

Recommended Posts

Last week I came back from a long bike trip to Sturgis, New Mexico, LA and then up the west coast on 101 and 1. I returned home with 27,900 km on my bike and realized it was time to check my valve clearance.

The Honda dealer here found they were EX: .25, .22,.22, .22mm and my Intakes were: 15,19,19,15mm. They decided that the clearances were within spec [Ex: .19-.25 and Int: .13-.19mm] and just left them alone [so it cost me $340CAD for a peace of mind check but no changes]

Question: as the valves wear, does the clearance get larger or smaller? It seems that if they get larger, it would have been better to reduce the clearance to the minimum so it would stay within spec for a longer time. The dealer mech said that with the clearances I had I could go another 25,000km without worry. Does this sound correct?

Any info is appreciated.

TimXX

Link to comment
Share on other sites

clearance will increase, causing powerloss from the valves not opening fully.

I really don't know the answer of just leaving them or why they actually didn't tighten them down to a tighter spec.

Buddy of mine had a rear brake leak on his bird, I gave it a quick fix and he took it to the dealer since the bike was only 2 months old. (might need something replaced)

They told him they checked everything over and it all looked good. But tightened everything up :???: :?: which is it? everything looks good or something was loose for the need to be tightened?

Similar bullshit like checking the valves at the 600 mile service. Have yet to see a stealership mechanic do it. I marked my tank bolts before taking my bike in.. Unless they found a new way to check the valves without taking off the tank mine were never checked. :roll:

Link to comment
Share on other sites

I like that, "marked my tank bolts". Everyone should do that. I wonder how often you bring your bike in for valve checks and they park it in the corner of the shop for a week then charge you $450. :shock:

Another reason my bike NEVER sees a shop. FUCK EM!

Link to comment
Share on other sites

bout every 5K miles) I run a bottle of the STP fuel conditioner which also takes all the carbon off the plugs and probably the valves as well. I tried a bottle running in my ST1100 and checked the plugs before adn after... after running the bottle the plugs came out looking brand new versus some carbon on them so I am assuming the valves would also be better. I have seen many pistons recently, from several different bikes, and know these things get some pretty good build-up, regardless of how hot we may run them.

Steve

Link to comment
Share on other sites

Thanks for the info RMU.

Question: the valve seats are contact points and when they wear it decreases the clearances-makes sense.

However, aren't the cam lobes wearing on the shims, and the shims wearing on the heads [?] of the valves? If this is the case, wouldn't it Increase the clearance?

Which would wear faster?

Looking forward to anwers.

TimXX

Link to comment
Share on other sites

at 52,000 miles my valves were all still in spec, at the deal ship they gave me a very nice diagram of what the measurments on each were.

Shenandoah Honda is the dealship to go if your going to have you work done by Honda. Too bad your all not close enoguh to go there! but if in Northern VA look them up.

It's more inovled to adjust this type of engine comapred to the type of valves in a XR400. I do that my self. Not a chance im doing my XX valves as you need access to a set of shims to pick the ones you need. you dont just get a new shims, you measue and fit a correct size shim.

Link to comment
Share on other sites

^^ no close though, in Winchester VA.

Though I've heard that the shop in Harrisonburg is good too.

I live near Front Royal, right by that nice road that runs through the G.W. Forest that goes by Elizbeth Furnace, the back way to 211. Do you ever do Route 211 or 33 runs through the mountains?

Link to comment
Share on other sites

Yes, the cam lobes wear on the shims.

The shims don't wear on the valves, because they don't touch them. The piece that actually presses on the valve is the bucket. That wears as well.

Wear in those areas would increase the valve clearance, yes.

Actually, the cam lobes ride on the buckets, and the shims are between the bucket and top of the valve.

There is no wear on the underside of the bucket, the shim, or the top of the valve.

My valve clearances at 25K were a little tight on the exhaust side, and good on the intake.

Link to comment
Share on other sites

Thanks again RMU and Northman- it all makes sense now. Also- it feels good to know that my clearances are at max on some cylinders and mid range in the others. This leaves LOTS of room for valve seat wear.

BTW: why are the valves rotating?- is this just because they are cylindrical and some of the explosive force of the combustion process turns them? It seems that the cams moving on the bucket, shims and valve stems wouldn't have much rotation force.

BTW2: how much can the valves or seats wear before they crack [?]. It also seems that as they wear, they actually seat better since they are being honed to fit.

Interesting stuff, mechanics.

TimXX

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

Terms of Use