Valve Adjustment? By poppabear (Read 3,204 times)

[poppabear]

Just Asking Is A Valve Adj A Mileage Or A Symptom Thing And What Are The Recommendations ?

[Alleyoop]

Valve adjustment can be both but mostly a Symptom Thing. When the motor gets harder to start and does not want to stay idling and or when riding and the motor gets nice and hot and you come to a stop the motor will want to die or die if you do not keep giving it throttle to keep it running.

Recommendations is Adjust your Valves:

If a 50cc set them both to .003 inchs
If a 150cc set them both to .004 inchs
Or if you have a service manual for your model go by what they recommend.

[tvnacman]

I do it as part of service till the engine has several thousand miles. It is quick and easy.



John

[robertwav1]

I've been getting different information on valve settings and finding the .003 and .004 are not quite enough on these engines. The aluminum heats up and expands sometimes causing valves to be partially open resulting in lost compression as the engine heats up. I've found through trial and error that .006 to .010 are a more reliable setting and allows for expansion. These are with the BBK on three bikes now. Not a ton of experience here so this is only my findings so far. We plan on building several more as the days pass, sort of a hobby thing. Constantly tuning and comparing and asking around this is where we are at. One of the 50's we've taken apart had around a .020 setting and it ran fine? I don't want to confuse, just telling other's what we found.

[czmdiver]

Oct 19, 2015 15:29:07 GMT -6 robertwav1 said:

I've been getting different information on valve settings and finding the .003 and .004 are not quite enough on these engines. The aluminum heats up and expands sometimes causing valves to be partially open resulting in lost compression as the engine heats up. I've found through trial and error that .006 to .010 are a more reliable setting and allows for expansion. These are with the BBK on three bikes now. Not a ton of experience here so this is only my findings so far. We plan on building several more as the days pass, sort of a hobby thing. Constantly tuning and comparing and asking around this is where we are at. One of the 50's we've taken apart had around a .020 setting and it ran fine? I don't want to confuse, just telling other's what we found.

This is complete Bunk.
The Head is Cast Aluminum with a % of Silicon for hardness and Control Thermal Expansion. expansion is minimal.
The Rocker Assy and Rockers are a Cast/Iron/Steel Alloy., This Can and Does Expand Much more. This is Factored in to the .004 Proper Clearance.
The Best Cooking is Iron for its Heat Retention Properties. Aluminum is the Worst for cooking, It Rapidly Dissipates Heat.
.004 is Plenty, the Only thing your doing with .010 is Giving Up .006 in Cam Lift? why would i want to give up any cam numbers?
.020 on a Fiddy? now your giving up .017 in Cam numbers. foolish. just because it ran doesn't mean a darn thing.
I have a whole bunch of different material's, Iron Bores (barbaric), Plated Bores, Castings, Forgings,



Iron bore/ Plated Bore.
Raw Forging to First hit Slug
I'm well versed in all the thermal expansion properties of the Cylinder Head/Cyl/Piston/Rod/Crank/pin/ring/valves/valve seats/valve guides/keepers/retainers/valve springs Material's

[Alleyoop]

+1 CZMDIVER, you do NOT set the valve gaps wider just so the next valve adjustment is not sooner. You are setting them for the best performance, better starting and not needing to over fuel the thing due to the intake valve not opening up enough. Also one thing that people do not think about is as you put more miles on motor the metals no longer expand and compress as much as when it was new. So valve adjustment as the motor gets more miles are now far and few between than when it was new.

It takes about 2500 miles for the metals to expand and get compressed with all the banging goes on so you will fine that after around 2500 your valves hold the gap for a much longer period. Mine holds the gap for over 4000 miles. I check them just to make sure everything is all right under the valve cover but I have not had to adjust them for over 4000 miles now.

Now with all that said, IF YOU BUY cheap BBKs and or motor parts the valves will need to be adjusted more frequently. The quality of the metals is what will determine the frequency of valve adjustment until the motor has some miles on them.

.006 to .010 also .020

What are those measurements MMs or INCHS? Because if .010 and .020 are MMs they are tighter than someones butt

And if in INCHS the only one valid is .006 the .010 and .020 if in inchs you can drive a truck through.

So sorry to say your information is flat arse wrong and had to be corrected so some poor soul would not follow those settings.
Alleyoop

[tvnacman]

I go with .004" for both and check them anytime I think there might be a problem.

John

[robertwav1]

Okay guys. Like I said in the post, I don't have a whole lot of experience on small engine stuff so listening to the techs that work on these all day long. Not to say they are correct but figured I'd follow the experience. The way it was explained to me was that on these BBK's, the aluminum has a lot of air injected into the mold, tis why they are so cheap. Yes, there are better kits then others on the market but I use what they use since they tell me they tried them all. I was also told that if you don't hear the valves at all, it's too tight. Again, I'm only going on what I've been told and would rather follow experience of a shop that does two or three mods a week. This is the reason I joined the forum, to get input from all possible sources so, the criticism is well taken.

[cyborg]

they are using mm,,,the valves would be clattering very loudly,,and as the fellows have said performance would be suffering big time from valve lift loss,,,

[Alleyoop]

GEEZ!! Sorry to say but stay away from that shop the ones saying such things are not the sharpest knifes in the drawer, they need some learning

Not only would they be clattering and making a racket having the rocker come off the high lobe on the cam and slapping down on the low end the Rockers could break.
Alleyoop

[jerryscript]

Experience is worth the effort. Try their way for a few days, then try what everyone here says a few days. Then you can make your own decision based on your experience.

I know a mechanic who refuses to purchase feeler gauges, instead he uses a matchbook cover. He has learned from experience what works best for him. Don't be afraid to experiment!

[Alleyoop]

Yea experiment BUT NOT .010 OR .020, huge difference BETWEEN THAT AND .10 AND .20 mm's.

.10 is almost .004 inchs and .20 is almost .008 inchs(which is a little wide and will clatter).

[czmdiver]

Oct 20, 2015 11:59:53 GMT -6 jerryscript said:

Experience is worth the effort. Try their way for a few days, then try what everyone here says a few days. Then you can make your own decision based on your experience.

I know a mechanic who refuses to purchase feeler gauges, instead he uses a matchbook cover. He has learned from experience what works best for him. Don't be afraid to experiment!

I set Allot of Points with a matchbook cover on bikes back in the day, pret much a .020 
Maybe a shmancy match book at .018  got me out of the woods and home.

[czmdiver]

Oct 20, 2015 7:01:08 GMT -6 robertwav1 said:

Okay guys. Like I said in the post, I don't have a whole lot of experience on small engine stuff so listening to the techs that work on these all day long. Not to say they are correct but figured I'd follow the experience. The way it was explained to me was that on these BBK's, the aluminum has a lot of air injected into the mold, tis why they are so cheap. Yes, there are better kits then others on the market but I use what they use since they tell me they tried them all. I was also told that if you don't hear the valves at all, it's too tight. Again, I'm only going on what I've been told and would rather follow experience of a shop that does two or three mods a week. This is the reason I joined the forum, to get input from all possible sources so, the criticism is well taken.

Here is how a Inch/Metric will read.



Bro. I'm not all caught up and star struck with what I do, Its just a Job at the end of the day.
Not to belittle Technicians here as for Me You Are Communicating with a American MFG. Of High End Forgings/ Casting's Big Block Kits (anyone remember the KZ and GS +1,400cc Blown,Nitrous,High Comp Block Kits?) Billet Ice Cube Big Bore Cylinders, Forged Cube Big Blocks. as so much of this was private labeled most don't know how really made it.
I'm well versed on POROSITY in Aluminum Castings and Sand Casting manufacturing. The Only issue I encounter with Cast Porosity is a Occasional Aluminum Cylinder with a plated bore, Rarely I find a what looks like Pitting, very small, No Effect on the engine just looks less than Prefect. A Few Sled's and Dirt bikes in the 70's had Carbs with Cast Porosity Issues, Nothing to do with Thermal Expansion.
Aluminum is Superior in Heat Dissipation and Thermal Expansion. Thats Why its Sucks to Cook with.
Her is almost perfect Example of a Cold Seize, Iron Lined Bore, Alum Alloy Piston, I'm not scared to show I Blow'd stuff up. I was incorrect in thinking my Break In was good.
The Iron Expanded Many Time's the Rate of the Aluminum and the Iron Expanded Into the Piston, Not The Revers as some Feel



Application is Famous Yam, RD,
There is No Whole Bunch of Air Blasted in and somehow that would Lower My Mfg Cost.
I'm More than Familiar with the EPA Logistics in mfg these products, Virtually Non Existent in China. Copied Junk, No Warranty,No Guarantee/No Instructions, Slave Labor.
Sad there seems be More Misinformation around these days with the web than ever.
In the end her I can easily  check my valves at .004 Ambient temp, Ride it Bringinng it up to operating Temp and re-check that valve, No Way it closed to 000 and is Bleeding Compression, I leave the front cover Off on my scoot just to I can easily check this, Even under a At Temperature WOT will Not close to Bleeding Compression, It Does Not Tick Either,

[czmdiver]

Oct 20, 2015 7:01:08 GMT -6 robertwav1 said:

Okay guys. Like I said in the post, I don't have a whole lot of experience on small engine stuff so listening to the techs that work on these all day long. Not to say they are correct but figured I'd follow the experience. The way it was explained to me was that on these BBK's, the aluminum has a lot of air injected into the mold, tis why they are so cheap. Yes, there are better kits then others on the market but I use what they use since they tell me they tried them all. I was also told that if you don't hear the valves at all, it's too tight. Again, I'm only going on what I've been told and would rather follow experience of a shop that does two or three mods a week. This is the reason I joined the forum, to get input from all possible sources so, the criticism is well tak