I know this has been covered before but can't find where it was mentioned...

When adjusting the valve clearences the book specifies 0.15 - 0.20 for Intake and 0.25 - 0.30 for exhaust.

Which way round is the ideal as in which clearance is the more ideal for running....

Just to show what I found earlier on my engine.

Intake	.127	.203	.127	.152
Exhaust	.254	.229	.279	.229

Hi,I am wondering if you had checked this one out before.Have a look.

https://www.youtube.com/watch?v=bFkPnLVkxWQ

Yeah I have seen that video... it shows very clearly how to check the valves, I wish I had a bike stand to raise the height up!

I recall there is an ideal of having the intakes tight and exhausts loose...

But as he says in the video loose is good on both...

Either way I have 2 intake and 2 exhaust valve clearances that are tight.

So the plan is to whip them all out and measure them to see if I can swap them around! Just need to find some 5mm Steel to make the tool...

I can't remember if you are a UK BMW Club member?

If so we have the tools in the Club's Tool Hire facility.

Mike

Hi Mike,

Yeah I am a member..... was thinking about giving the "Tool Holder" a PM Just racking my brain as to whether we have some off cuts in work that I could make one from......

You may recieve a PM shortly lol!

Go for it!

The tools are currently available, so could post first thing Tuesday morning. For our antipodean friends we have a bank holiday in the UK, so Monday is (for most) a day off!

Mike

Most people but not all of us are going to be off

The plan is.... Tomorrow I am going to whip off the camshafts and measure each of the shims... see if I can bring any into spec... That will give royal mail a chance to deliver the tools and means Tuesday morning I can phone BMW and order the shims that I need.

Looking at the numbers I have I don't think that I am going to be able to get them all in spec just by swapping them around

That will give me a chance to let you know Mike if I need to hire the tools as well.

I need to take the camshaft cover off anyhow as there is a minute weep from the top of it! Can't have used enough instant gasket stuff the last time!

Kawasaki use the same shims in many of their older bikes so you may not have to pay the BMW price depending on where you are situated in relation to dealers.

I have taken all the measurements now and know what shims I am going to replace. As can be seen below.... It shows what the final clearances should be.... I know the ideal is to have them all identical... this is possible on the Exhaust side but the Intake side isn't going to be so easy... Should I take the intakes so they are tighter which means I need to change the size shim on cylinder 2 and 4 or should I maintain them as shown below with a looser fit?

Exhaust					Intake
Current Gap	Current Shim	New Shim	New Gap	Cyl No	Current Gap	Current Shim	New Shim	New Gap
0.279	2.55	2.55	0.2790	1	0.127	2.55	2.5	0.1770
0.279	2.55	2.5	0.2790	2	0.203	2.55	2.55	0.2030
0.279	2.55	2.55	0.2790	3	0.127	2.6	2.55	0.1770
0.279	2.55	2.5	0.2790	4	0.152	2.6	2.55	0.2020

Right quick update.... I have replaced the 3 shims that I planned to, the bike was a total pig to start up initially!!! Needed full choke which is never needed.... once she idled on half choke, I took her out for a spin to warm her up properly.

I balanced the throttle bodies which were well out as I would have guessed having changed shims although I wouldn't have thought she would have been that far out!

Checked the tickover speed, She shows as idling around 1100 rpm on the bikes gauge. Using a pick up on the HT leads she shows to be idling at 900-950 rpm which I am happy about.

I checked and adjusted the CO measurement.... First proper test ride this evening going to work! Will post how she feels when I get there.

top work twincarb

Rick G wrote:Kawasaki use the same shims in many of their older bikes so you may not have to pay the BMW price depending on where you are situated in relation to dealers.

Yamaha XJ750/XJ900 too.I harvested a bunch of them from some XJ750stuff I had years ago. I added them to the BMWTCNSW shim kit.

Al

twincarb wrote:First proper test ride this evening going to work! Will post how she feels when I get there.

That was 9 hours ago. You ok TC? or are you stuck on the side of the road? Or do you work a reeeeally long way from home?

Work was busy last night which is a bit unusual! Hence wasn't able to log on.

Report back is the bike is deff pulling a lot better. There were several occasions when I was shooting down the Dual Carriageway that I glanced at the speedo and had to back off! I am sure the engine is running quieter now as well.

This morning I wheeled the K outside and fired her up. No "choke" used and she just purred into life

MPG has shown a slight raise since replacing the FPR she was 43 Mpg now 43.6 Mpg! so there is an improvement.... Replacing the Injectors is still at the back of my mind...

I have got an excel spreadsheet here that I will pass onto CF to put into the downloads section which calculates the size shim that you need to put in to get them back into spec. It also allows you to see what the clearances will be when you have fitted the new one's which is handy.

Twincarb wrote: "Should I take the intakes so they are tighter which means I need to change the size shim on cylinder 2 and 4 or should I maintain them as shown below with a looser fit?"

My mechanic in Manchester, NH says that loose is OK. That is, if the clearance is too tight then shim it, otherwise don't worry about it. This makes complete sense to me.

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On the other hand, I've read posters to this board claim that tolerances closer to the tight end are better for performance. This rational escapes me because either the valve is open enough to do its job, or it is not. Having it open just enough but no more seems a bit sophomoric, especially if one has to go back next year and re-shim because it's become too tight again.

---

I suppose if it's completely out of range on the loose side that may be perceived as inefficient, but I'm not convinced it affects performance to any degree.
So, am I going wrong somewhere here? :pale:

AJ, I pretty much used the logic that you wrote.... I took all the measurements and then measured the Shims that were in place. I then used the excel chart I had and entered the figures.

Essentially what I was then looking for was to have the intake valves as close as possible and the same with the exhausts so all cylinders are allowed to have the same amount of air, even though the difference can be 0.05mm difference it will still throw the air fuel balance off. This will be increased if the exhausts are open for different amounts of time.

There was a link to a video earlier and all the mechanic was checking was that they aren't to tight, this is more essential on the exhaust valves.

I know that if valves are to loose you get the tick tick tick from the top end (I had that on my car which had hydraulic valves - top end rebuild needed!)

It was more by luck that all the figures came in the way they did, with the exhausts being loose and the inlets tight. I believe that some also say it's better that way as exhausts valves only go tight over time. Others say that on our engines the valves never need adjusting! I shall check mine again in about 1000 miles (which is only about 2 weeks riding!) But then it will give me a warm feeling if they are all good!

As for performance, I think that everything is tied in together so when the valves are adjusted the throttle bodies need checking/adjusting... and when they have been done then it's worth checking the CO adjustment as well. So with tweaking all of the above the net gain is there. Of course performance/power is subjective and it may just be a psychological impression that the work I have done has restored any loss of power!

If you are setting up an engine for the next race then yes the clearances are critical. With the standard engine you are best to stick to the factory clearances with any error on tolerance to tight on the inlet and lose on the exhaust.
Any performance increase you get will be very marginal at best and the idle will be easier to get nice and smooth and once you crack the throttle a smooth idle is nothing but that, a smooth idle.

I felt like an Aussie today, checking the valve clearances on the outfit. So I was hanging upside down between the bike and sidecar.:geek:

All the exhausts were spot on, 12 thou no go, 10 thou go.
Inlets, 2 were good at 8 thou no go, 6 thou go; and 2 were 1 thou tight at 5 thou....which doesn't worry me at all.

So if the 2 inlets have gone 1 thou tight in 101,000 miles I reckon I've got a few more miles before they close up completely ( ½ a million? )
I also fitted my repainted spare cam cover so now the passenger doesn't have to look at a scruffy cover.

All good fun and I won't need to borrow MikeP's shim tools just yet.
Paul.

All good results there... I don't expect to have to replace shims for the life of the engine now.

I have to say the shim tools make it a very easy job to do which reminds me need to email Mike to let him know they are back in the post...

Seen the email - thanks.

Mike

sidecar paul wrote:I felt like an Aussie today, checking the valve clearances on the outfit. So I was hanging upside down between the bike and sidecar.:geek:

Easier for me , but when I want to check the oil, this is another story . I have to hang upside down.

twincarb wrote:I have got an excel spreadsheet here that I will pass onto CF to put into the downloads section which calculates the size shim that you need to put in to get them back into spec. It also allows you to see what the clearances will be when you have fitted the new one's which is handy.

If this is this one, it's already in the downloads for over a year



Any other spreadsheet is welcome.

CF

Hi Twincarb

The tools arrived back this morning - thanks.

Mike

Is that guy in the Youtube video serious when he says silicone doesn't hurt the engine?