JAP type 6 photographs

Hello,

I am currently working on a JAP type 6 engine, I am having some problems with what I can only think to be the governor but even though I have the JAP service guide, the 6 isn't covered very well.

Essentially, my question is does anyone have any external photographs of the 6 without the cowling on?

Any help really would be appreciated and I will be putting up some photographs shortly so you can see if I'm doing something stupid!

Kris

The problem I have is I basically have to throttle it manually, or it just stalls.

Hope you didn't mind but I turned your pics so they can be viewed easier. (Stu)

Be a bit careful here, if you get a linkage round the wrong way with a governor it can make an engine race out of control, so make sure you have a good way of stopping the engine before doing any test runs (I expect you know this, but I had to say it, it's the main thing I make sure of when starting any new project for the first time; "Can I stop it?"

Anyway, I'm not too sure about this particular governor, & I've lost my JAP book, but basically, with the governor moving freely & the engine stopped the throttle should be wide open on the carb, with spring pressure keeping it that way. You should be able to push the linkage, acting against the spring, to close the throttle quite easily, & it should spring back to fully open again when you let go.

When the engine starts up it will naturally start accelerating up to full (usually catastrophic) revs, but before this happens the little weights, spinning inside the governor, will fling outwards with centrifugal force, which will act against the spring(s) on the governor (springs can be internal or on the external linkage, this is the same spring we were acting against earlier when pushing the throttle closed before starting) & the force of these weights, acting on the linkage, against the spring, will start to close the throttle.

If for any reason the engine goes too slow (like a load is added), the weights inside the governor will have less centrifugal force, therefore the spring in the governor will pull the throttle open again until the weights are spinning at the correct rate to act against it.

In order to make the engine go faster you usually have to adjust the tension on the spring (which is why most of them are mounted externally, on the linkage somewhere, internally mounted springs are usually non-adjustable for fixed speed engines, although some governors will have a mixture of internal & external springs). You pull the spring tighter to make it faster (giving it more spring tension to work against) & less spring tension to slow it down.


OK, so I'm probably telling you stuff you already know (stating the bleeding obvious again ). But! There is a point to all this, I find, once you understand what's going on with the governor, you can usually put it all together without the aid of pictures or diagrams, as long as all the correct bits are there, & usually get it set up pretty well first time. The main key is to have it set to fully open throttle when the engine is at rest, no further than fully open, no less (you can always tinker with this later on if necessary) & the important factor is to make sure that it is set to close the throttle as the engine gets up to speed & not open it, or it could rev to destruction.

If for some reason you can't set it up like this, then it's possible that either a part is missing, broken or misaligned inside the governor somewhere. The spinning weights usually act against a stationary rod, sometimes this rod can be missing, sometimes a weight can be broken. But if it's a simple case of taking something apart & not remembering how it goes back together then this should assist.

I expect someone will come along with a diagram or something, but in the meantime I hope this helps a bit.

Wow, I didn't expect such an excellent response, thank you!

I did almost rattle this engine to death, though luckily I knew where the stop button was on the magneto! Seemed to work well.

The spring which pushes on the throttle seems to be working fine, but as you said, the governor doesn't seem to be pushing the throttle off. I get the feeling this may be a "remove flywheel, dismantle governor, drink loads of tea and re-assemble/ replace broken parts" job.

I would however appreciate any diagrams, as the JAP book is a bit flaky.

I think (I don't know for sure) that the governor on the model 6 is very much like the one on the model 5, they are very similar engines. Might be worth having a look at other ones in the book to see if they can tell you anything.

(Just thinking aloud here) I suppose, if the spring is pulling the throttle open (as it should be), if for some reason the governor is no longer pushing against the linkage, then it would just continue to rev.

As long as the linkage is set up so that the throttle is wide open for starting, then you know it's roughly set up correctly. If it then fails to close the throttle when the engine runs, we know something is amiss inside the governor.

Have you looked on the engine books/reference section here (can't remember the proper name for this section now, something like reference/download section maybe), someone might have a JAP model 6 manual. Might be worth putting out a call for one there as well. Even if someone only had a hard copy they could either photograph it or scan it & post it up/email it to you, or maybe even photocopy the relevant pages & post them to you.

I've check what manuals I have and I've not got one for a JAP 6, although I do think Kev (kevjhnsn) may have a manual and the same member is experienced with JAP engines so if he hasn't replied to this post in a few days PM him and I'm sure he can help you.

Stu.

Yeah, Kev would be able to tell you if it's the same design as the model 5 as well.

All I've told you above is just general, generic throttle governor systems, which are on most engines. The principles are much the same on all of them, but the methods used to gain the principle are very different from manufacturer to manufacturer.

Generally they all have spinning weights & at least one spring, but some have very elaborate linkages, strange adjustment methods & systems to damp out fluctuations.

It's all part of the fun.

I think it's a JAP 5 I have at the back of the lock up but I can't get near it to have a look sorry. There is a few bits missing also so don't know if it would help or not!

Stu.

Well, we're still waiting for Kev to come along (only joking Kev ) but in the meantine have a look at his thread on the restoration of a JAP model 55 (twin cylinder). It may help you, it may not, but must be worth a look.

Here's a link for it....

http://www.stationaryengineforum.net/t5662-my-new-project-a-twin-cylinder-jap-model-55-petrol-parrafin-engine

kris
nutgone sent me a message to pop on here and see what i do for you
as he says above the guvernor prinapls are almost all the same "in theory"
your engine is stopping with out manual assistance
if you look at the elbow on the bronze gurenoir arm ,there is a streght metal bar pointing to the sky
this is the speed control for the jap range , it should have a coiled spring washer, and be firm to move but if you pull it down the the elbow as above, thiswill stop your engine from"STOPPING" its like a trottle lever on a old tractor ,just more basic
hope this helps
i do have the jap instrial range manual as i have the jap models 2a, 2s ,4/3 ,5 and the 55 , just no 6

kev

kris
if this still dont work ,just message me as it could be the knurled screw sprung piston /plunger the elbow pushes on sticking
just been looking for a pic of the rod to elbow, but the pics on my post jap 55 v/o are out of focus
kev

Cheers Kev, sorry to pester you via PM, but I needed to get in touch anyway.

Kris:
How about doing a google search or images of the bigger JAP engines? That might yield something, you never know.

Nuts you beat me to it, I was going to PM kev he he hadn't shown up before much longer.
Ah well he's here now so he should get it all under control soon.

Stu.

stationary stu wrote: Nuts you beat me to it, I was going to PM kev he he hadn't shown up before much longer.
Ah well he's here now so he should get it all under control soon.

Stu.

I needed to PM him about something else anyway, so thought I would mention it.

Stu.