Jump to content

Exhaust Lash for Terry Miller ST & 40/402

Recommended Posts

I recall reading somewhere in here that some are using 0.004"/0.004" instead of 0.004"/0.005" for valve lash with Terry's ST cams.  Since the 40mc/402 has the same exhaust lobe as many of Terry's ST cams should I be using 0.004" on the exhaust side as well?

The last time I rode it seemed the valves were noisier than usual so I just checked the exhaust side and it is still dead on at 0.005".  I didn't have time to get to the intake side tonight so that will be tomorrow morning.

Generally tighter valve lash sacrifices a bit of low-speed power but I have all I need with what I have.

Share this post


Link to post
Share on other sites

Yes...  I am talking to myself here...

The exhaust side was a perfect 0.005" so I closed it down to 0.004".

The intake side was a very tight 0.005" so I closed it down to a tight 0.004".

I guess this explains the extra noise I was hearing due to the slightly loose intake side.  The intake lobe looks nice and clean so I guess it just loosened up or I was a bit off on the lash setting after break-in.  When I did the valves the last time I did let the engine sit a few hours overnight but perhaps it was still not stone cold.  I usually only set valve lash if the engine has not been run for quite some time.

On to the carb which now has an off-idle stumble again.  I assume that is due to the gas that was left in it for awhile.  Sta-Bil for sure next time...

  • Like 1

Share this post


Link to post
Share on other sites

Yup...  Still talking to myself here...

The carb was spotless inside but I disassembled it and blew compressed air through all the jets and holes.  The was no crud or dirt to be found anywhere and I checked float level again, even though it checked out externally.  The idle mixture screw was two turns out in an effort to combat the off-idle stumble.  It is usually only 1/2-3/4 turns out in the summer so whatever was going on was really throwing it off.

It sure was fun to be working on the old CRF230 again after so much time on the old SRX600.  I just love the simplicity of both bikes...

Share this post


Link to post
Share on other sites
1 hour ago, Baja Rambler said:

Valve noise . . . . do you run 20w-50 in your air-cooled engine?

My valve noise was never as bad as what I seem to read about here.  I use Shell Rotella T6 in all my bikes - From CRF100 to the two 600/650 cc singles.

Share this post


Link to post
Share on other sites
I recall reading somewhere in here that some are using 0.004"/0.004" instead of .005


Generally tighter valve lash sacrifices a bit of low-speed power but I have all I need with what I have.



Sorry, I have not addressed this issue before now until I read this....(but always thought that I should have)

Ok, correct me if I'm not reading this as it was intended or if I'm flat wrong, but if adjusting the intake valve .001 looser or tighter makes a noticeable difference in low speed power on a 230f then why do I get poo poo thrown my way when I suggest that (1) properly degreeing ANY cam for a 230f (2) advancing ANY cam for a 230f by 2d can noticeably enhance low speed power over NOT DOING one or the other or both?

Share this post


Link to post
Share on other sites
55 minutes ago, Confederate said:

It's freaking hot where he lives! All the time!

Not always, but the only reason I would go lower than 20W-50 on an air cooled motor is if the oil is too cold and thick to crank over.. then I would run 5w-40.

I have T6 in the 230 right now but will switch to 20w-50 for major ride.

Share this post


Link to post
Share on other sites
9 hours ago, adnohguy said:

Sorry, I have not addressed this issue before now until I read this....(but always thought that I should have)


Ok, correct me if I'm not reading this as it was intended or if I'm flat wrong, but if adjusting the intake valve .001 looser or tighter makes a noticeable difference in low speed power on a 230f then why do I get poo poo thrown my way when I suggest that (1) properly degreeing ANY cam for a 230f (2) advancing ANY cam for a 230f by 2d can noticeably enhance low speed power over NOT DOING one or the other or both?

No poo poo my friend.  I think anybody with the means and the time should degree his cam but for mild grinds from reputable manufacturers the need is greatly reduced.  However, I completely agree setting the cam advanced during install to combat timing chain stretch is a great idea.  Again I would state the milder the build the less any of this is necessary.  For an all-out race engine or if competing in a Dyno War it is a necessity.

Dyno tests have shown the impact of valve lash on torque curves and the logic makes sense.  The looser the lash the less duration and lift you have so the TQ curve is moved to the left.  Low-speed power is increased at the price of high-speed power with a whole bunch of tappet noise.  I believe FJ ran very loose lash with his 89a cam in an effort to get some low end.  The two Al Baker engines with Mugen Desert Grind cams used 0.006"/0.008" and they sounded like the were going to let loose if you rode them without a helmet.

Nobody wrote "...adjusting the intake valve .001 looser or tighter makes a noticeable difference in low speed power..."  I doubt there is any way a rider could discern +/- two degrees cam timing with an engine making 18-22 RWHP with the cam straight up.

  • Like 1

Share this post


Link to post
Share on other sites

Probably true Paul but I always have subscribed to the theory that add all of the little things together, they start adding up to be noticeable, not like in the Summett Catalog for a small block Chevy, but even for a Briggs and Stratton, if all the tiny things you do are working together in harmony, eventually it shows up as another Ft lb, and/or another Hp.
When your dealing with less that 15 CID, it shows up under your helmet as a grin. A little more here, there, everywhere, it makes a smile.
Pretty soon, after much persistence, your laughing while your riding.
Like Mike Coe told me in the beginning, it's addicting, and drives some people for more and more...
For me at least, Mike was spot on.

  • Like 1

Share this post


Link to post
Share on other sites
6 hours ago, adnohguy said:

Probably true Paul but I always have subscribed to the theory that add all of the little things together, they start adding up to be noticeable, not like in the Summett Catalog for a small block Chevy, but even for a Briggs and Stratton, if all the tiny things you do are working together in harmony, eventually it shows up as another Ft lb, and/or another Hp.
When your dealing with less that 15 CID, it shows up under your helmet as a grin. A little more here, there, everywhere, it makes a smile.
Pretty soon, after much persistence, your laughing while your riding.
Like Mike Coe told me in the beginning, it's addicting, and drives some people for more and more...
For me at least, Mike was spot on.

Agreed 100% my friend and I can not contest anything you have said.  It is the SUM of all the small things that make the WHOLE.  Like Frank Nye often says it is the difference between being Number One and Number Two.

Share this post


Link to post
Share on other sites

On both my St cams yes lots of noise. When we removed 1.0 cam   and installed 2.5 cam. I dont know what the cap is called on top of each valve it a small cap.I think its to use the St cam. That part it getting a beating slightly dished in where valve lash adjuster makes contact. Im sure that is the noise we hear. That part is or is not stock?    Im sure it is only used with the St cam. I run mine at  0.004    I did try .003 cold it was less noise when heated up same.   I may think about replacing the valve lash caps since its very easy. That part Im thinking is a web cam part This true ADN.   Love the performance of this stroker on yesterdays ride we did a short 1 mile pavement to connect trail. We all took off wide open the little shit Crf was right in the pack of big bores.

  • Like 1

Share this post


Link to post
Share on other sites

The lash caps are only used when using Terry's Stainless valves, not required with stock factory OEM valves.

  • Like 1

Share this post


Link to post
Share on other sites

Did you guys ever compare cold and hot valve lash?

The camshaft that I'm using recommend a "hot lash" of .05mm on both of valves. But I was having trouble at cold starts... 

I was tired of burning me at that stupid hot head, so I decided to do the last hot adjustment ever! I thought that if I set up it hot, then wait till everything become cold again would be easy, just jot down the cold measurements, and start using them... 

But for my surprise the exhaust lash keep the same, but speaking of the intake... was stuck!

Speaking of the valves, while for one pass cold mixture, the other one, fire, ok?

So, I realized that the whole head get dilated when it heat (because the exhaust lash keep the same) right? 

Share this post


Link to post
Share on other sites

On a 230f, ALWAYS:
Adjust your valves with the engine dead cold, no matter what cam is used

If your going to insist on adjusting the valves with the engine hot, how hot is correct? 100, 200, 300, 400 degrees?
And what is the correct way to test/check the temperature? Oil temp? Heat gun, remove engine put it in the oven, heat test strips, guessing, etc?

Just use the KISS method. That would be with a Cold engine. Tried and true.

  • Like 2

Share this post


Link to post
Share on other sites
10 minutes ago, adnohguy said:

On a 230f, ALWAYS:
Adjust your valves with the engine dead cold, no matter what cam is used

If your going to insist on adjusting the valves with the engine hot, how hot is correct? 100, 200, 300, 400 degrees?
And what is the correct way to test/check the temperature? Oil temp? Heat gun, remove engine put it in the oven, heat test strips, guessing, etc?

Just use the KISS method. That would be with a Cold engine. Tried and true.

100% agreed and "dead cold" means exactly that.  Let the engine cool down overnight or even longer.  The service manual specially states "below 95 F" and that is pretty cold.

 

  • Like 1

Share this post


Link to post
Share on other sites

Still not used to the valve train noise with my ST2.5 . I will try a (snug) .004 on the intake as that's the noisy valve. Must be vary aggressive ramps.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:


×