Jaketab

My Feedback: (2)

Hello - help with engine tuning please.

Getting ready to maiden a Gee Bee R3 with Moki 250 this weekend. Had the plane out in the yard today doing final adjustment to engine with the cowl removed. Discovered that the #5 cylinder is consistently running about 20 to 35 F hotter than 1-2-3-4.

Measured again immediately upon shutdown. Cylinders 1-2-3-4 are 200F range. The #5 is at 239F.

I would like to bring the temp of #5 down to match the temps of the others. The only 2 adjustment variables I know would be valve lash adjustment and plug gap.

Help please – would increasing or decreasing the valve gap produce the results I seeking????

The valve gap is currently at .006. If I increased the intake lash - would this lower the temp on the theory of letting less fuel into the #5 cylinder????????

Any ideas please,

Thanks - Jaketab

Detlef Kunkel

Jaketab,
I would say that a difference in the range that you measured is OK and doesnt cause a problem. Depending on your cooling situaion,and mixture-differencies between the 5 cylinders, values like yours temps seem pretty Ok.

I would NOT recommend to try and manipulate temperatures by mis-adjusting valve clearencees!!! The danger of severely ruining your engine is much too high.
That is NOT the way to solve temp problems! Valve gap is to adjust within manufacturers specs, not more, not less.

kipuetz

Dear Detlef,
your answer to jaketabs question lets me rest a little easier now,I have had the same concern re. my 150.
With regard to to manufacturers valve lash settings of "0.05-0.08mm, [5-8 thou], I am a little confused.
To me the latter is" roughly" double in value then the former!
The dealer I purchased the engine from has not answered my question re this discrepancy in values!
Could you please shine some light on this for me,at the moment I adjust to ,0.005 thou.
Regards, Karl-Heinz.
PS,perhaps I'm to thick to see all this clearly.

Detlef Kunkel

Karl Heinz (Germane Name, eh?),
valve clearence is depending on many feautres; cam profile, extension of all parts when getting warm, valve train type, max rpm etc.
In case of a moki radial, everything is very smooth, meaning this is no race engine with "sharp" cam profile, high acceleration of valve lift curve etc.
Also you can see when adjusting one valve and turn the engine full two times, the clearence migt not be the same. Your need such a range to run the engine properly, and the cam profile allows that range without "hammering" the valves or let them freely fall into their seats. Dont worry about that.
As long as you dont run it on0,2 mm or more, or less than 0,025, your engine will be fine, for a long time.
Adjusting should be done on a cold engine, there is built-in a tendency for more clearence on a hot engine, so dont confuse this. :-)

kipuetz

Dear Detlef,
Thank you very much for the information ,top class info,we are all grateful for it,i'm sure.
Yes,you'r absolutely right with the name, too !
Regards,Karl-Heinz.

Jaketab

My Feedback: (2)

Hello Detlef,

Thanks again many times for your responses.
Just to make certain all are on the same page regarding valve adjustment, my instructions call for an adjustment range of
.005 to .008 thousands - English Standard.

If I convert to metric the range is .127 mm to .2032 mm.
Is this correct?????

Thank you - Jaketab

stivvy

Hi Detlef/Radial users,

Help please from anyone.

I have a used Moki 215 and need 2 new pushrods.
The replacements I have been supplied with are 3 to 4mm too long (originals are 76/77mm length, replacements 80mm).

Can anyone supply the correct length ?
Is it feasible to grind each end of the pushrod down by around 1.5mm, to achieve the correct length or will this destroy the hardening ?

Thanks

Steve D

Straightleg

Hello Steve ! I think a better idea is to remove the hard tip, cut the tube with a Dremel, and put the tip back !


/Straightleg

stivvy

Hi Straightleg,

I didn't know the tips were removable !

Do they pull off and then simply push back in, maybe with some Hysol epoxy ?

Steve

Straightleg

Yes, Steve, just pretend that you are a dentist, and pull it out( carefully)
May be thin CA is as good as epoxy,since it is very tight !!

/Straightleg

stivvy

Brilliant I will give it a go

Detlef Kunkel

Dont worry, I did the same with mine. Its quite easy :-)

Detlef Kunkel

No, not correct.
The values are in millimeters!
0,05 to 0,08 mm!!

URAYASUTTARO

Hi all, I want get information for vibration moki 150(new one).Already I have moki 215 taht like a electric motor no vibration.
But moki 150 will get mderate ~ +moderate vib around 4000rpm.Engine mount and prop is no problem.
Is this vib a typical moki 150. Advice please If you have experience for the improvement of working.[]

kipuetz

Hi Jaketab,
I am glad we'r gettig this valve adjustment sorted out,I tryed to warn people about this before,
[see back page 64 of this forum],All we have to do now is to covince the supplyer of toolkits advertised
for the moki engines to include the right feeler gauges in the kit.[ if they sell it ,it must be right hey!]
Sincerely,Karl-Heinz.

Jaketab

My Feedback: (2)

Karl,

Thanks - I don't want to mention any names, but the initials of the company selling .007" (inch) feeler gages is TBM.
I've been setting my valve lash at .006", which is too much gap. Don't believe it hurt anything other then not opening the valves quite enough.
I'll readajust and test today before my first flight.
If I did the conversion correctly, .064mm = .0025". This is about the thickness of a sheet of paper????? Not much gap at all.
So the correct feeler gage in English Standard is .0025" inch. Yes/No????

Jaketab

wingstrut

Just for your info, My moki 215 came new in the box with .006 clearance between the rockers and the valve tip.

wingstrut

Fella's I just checked my instruction sheet that came with my Moki 215 and it stated the valve clearance should be .05 to .08 mm then it states .005 to .008 of an inch
Someone doesn't know their math, .05 to .08 mm converts to .0019 to .003 of an inch.
I am assuming someone apparently adjusted the valve clearance on my engine before I received it.
If the actual adjustment is supposed to be .05 to .08 mm

Jaketab

My Feedback: (2)

Gentlemen,

First 2 flights on my Airworld Gee Bee R3 today. Before flying, I adjusted the valve lash gap from .006" to .003" - which is closer to .08mm.
I immediately notice the temps were down slightly in spite of an 85F day. I can only guess that opening valves more induced more fuel to enter the cylinder and helped with cooling???? Or, could it be the longer open time of the exhaust valves took more heat from the cylinder?????

Next adjustment I'll set the gap at .025" (inch) = .064mm.

Jaketab

ram3500-RCU

My Feedback: (221)

Move the jam nut on the rocker adjuster to the other side, and they should work.

kipuetz

Hi Jaketab,
congrat's on you first flights.
You'r absolutely right with the conversion on the metric values.
I did as you did,I went half way first time,I run my engine with a 0.03 mm clearance now,I swear it runs more humming like.Beautiful!!
There is one more thing we have to consider with having run the engine with a largish valve clearance gap for a longish time.
The rockerface will have [most likely] small indentation from the valve stem due to the possigility of hammering efect.
I t might be small or,not existend in some engines.
If there is undue wear or inentation present, they will have to be worked off, as the feeler gauge will just bridge the indent.
A diamond faced flat file will do th job nicely. If it's not taken out, it does not matter how carful you adjust
the tappets,the will not be setaccurate.
It does no harm checking,does it !?
Regards,Karl-Heinz.

Benoit

Hello Guys,

Thank you for the valuable infos about the Moki engines in this thread.

I am busy with the honing of my Moki 250cc.
I had around 45° C difference between cylinder (the coldest at 7 o'clock and the hotest at 1 o'clock)

I put the turbulator and a ASP pump. The max T° difference is now around 20°C :-)

What are the maximun acceptable T° of the cylinder?
I saw once up to 146°C on cylinder at 1 o'clock, the hotest

What is your reliable idle speed?
Thank you.
Benoit

TJPro351

My Feedback: (8)

Does anyone know what size the jam nut is on the rocker arms? Stripped mine out trying to adjust valve clearance. I am using the Moki/RCS valve adjustment kit that is sold by TBM. The wrench for the jam nut is 5.5mm but seems to be too big. I have used this size wrench on my old RCS 215 and never had a problem with it. Does the new Moki 250 have different size jam nuts?

Thanks in advance.
Tim

Jaketab

My Feedback: (2)

Tim,

The rocker screw nut is 3mm on my 250. The 5.5mm wrench fits good.
The rocker arrm screws and nuts are getting worn from adjusting. I'd like to find a good cheap source for replacements.
But in the Moki world there seems to be no such thing.
Anybody got Moki rocker arm adjustment screws on sale ?????

Jaketab

GaryM

My Feedback: (14)

Jaketab,

Google, Fasteners, Nuts and Bolts, Charleston West Virgina, and you should come up with Smith Fastener Co., 7500 MacCorkle Ave. 304-925-4787

From the looks of their web page I would be willing to bet they will have what you need. I buy all of my small hardware etc from a similar type busness near where I live in Texas. I even have a spare set of the same nut you are looking for.

I would also suggest while you are there you check the prices of 2:56, 4:40, 8:32 etc in boxes of 50 or 100 count. You will surprised how dirt cheap they are in large quanties.