my v-twin diesel engine cant idle

[iron_monkey]

Hi all, I have bought a v twin diesel clone engine.

Are these things set up to idle out of the box (theres no throttle stop on mine)? I have to maintain some level of throttle to keep it from dying, does this indicate a problem? Otherwise it runs fine, it knocks but runs smooth past idle.

Also, I tried stretching the throttle cable to an extent that it leaves the throttle partially open. Tried starting it next day and found it harder to start and one cylinder is very smokey (I can tell as i made dual exhaust). I need to hold it near WOT to keep it from dying for about 30 seconds. After that the smokey cylinder is back to normal and throttle response is back. What happened here? A large pool of fuel go into one cylinder from having the throttle partially open overnight?

Have not checked valve clearance and if really necessary I will learn. Certainly does not seem like engines you can just turnkey and ride....

[gilburton]

A pic would help??
There must be some sort of idle? Is it by friction? eg tighten up the pivot on the throttle lever??
Sometimes it's just a screw/locknut against the case?
I presume you checked oil levels etc. as they are usually shipped without oil?

[alexanderfoti]

These engines come with an assortment of different throttle arrangements I find. A lot of them dont provide a provision for an idle stop. Idleing on these engines is essentially provided by opening the throttle (governer) slightly.

I would check your ignition timing first of all, its common for these engines to come out of the factory with the syncronisation between the 2 cylinders completely off.

Fuel will only be injected when the engine is turning so dont worry about leaving the throttle open slightly.

What colour is the smokey cylinder?

[iron_monkey]

Yes I put in new oil. The only other thing that may be relevant is that there's little fuel pressure, or maybe fuel starvation. I haven't made the fuel tank yet so im just squirting 10ml of fuel into the fuel line and trying the engine out. I will post photos when i get around to it.

The engine produces grey smoke (maybe blueish, not quite sure), not black. I've read http://www.dieselsmoke.com.au/ Can you direct me to a page on how to check ignition timing?

I think its better that I'll run the engine in first (to seat everything in) and get back to you guys (maybe next week or the week after) if theres still a problem, thanks.

[alexanderfoti]

Yes, you need a proper fuel tank, or a continuous fuel flow, these engines (all diesels) do not like air in the system. The white smoke is unburnt diesel, due to the air in the system.

Sorry, I do not know of a guide to sync these v twins up, but im sure somebody will come along with some guidance.

[gilburton]

Yes you will need a proper fuel flow via a filter and fully bleed the system up to the injectors or as described in your manual.
It will not run properly if there is air in the fuel system and it certainly won't idle using the method you have described

[iron_monkey]

the manual has instructions for how to adjust timing but it tells me there should be a mark on the engine cover when there isn't.


Is it as simple as finding the angle of rotation between the fuel being squirted out? (ie...I just mark flywheel cover of a squirting point, rotate flywheel until it squirts again, measure angle)

[gilburton]

Don't get too involved just yet. Get the fuel supply sorted out first and see how it runs.
An old motorcycle tank on a bench above the engine will do.
Make sure the engine bolted down to some wood or a pallet

Do a forum search for Punsun and you will find plenty of threads about V twins

[iron_monkey]

Just an update:

turns out I need to screw the allen bolts near the fuel inkectors to bleed the air out. Now the engine starts great. Just black smoke now. When idling theres absolutely no smoke.


However when i blip the throttle sometimes it wont idle once I suddenly let go of the throttle, it will die. I can make it idle higher to solve the issue but I'm just wondering if this is a symptom of another problem?

[alexanderfoti]

Just an update:



However when i blip the throttle sometimes it wont idle once I suddenly let go of the throttle, it will die. I can make it idle higher to solve the issue but I'm just wondering if this is a symptom of another problem?

That's pretty normal. You can put some heavier springs on the governor but that will make your throttle harder

[gilburton]

I would suggest,as it's a V twin,not to "blip" the throttle.
Being a diesel you have a lot of mass to overcome so gently open and close the throttle in a smooth manner.It is new after all so give it some time to bed in!
There have been reports of this type engine breaking cranks and my own theory is that it's the constant quick throttle variation in motorcycle use that does the damage. Used as an industrial engine the revs would be more constant.
I've no proof of this and it may be down to poor quality but it can't hurt

[old clunker]

Yes, gently run a new diesel engine in for at least the first 300 to 500 miles when installed on the bike is always a good idea, as well as frequent oil changes initially, again around every 500 miles.
Then it should run and idle smoothly (for a diesel!) and be reliable hopefully

[iron_monkey]

I would suggest,as it's a V twin,not to "blip" the throttle.
Being a diesel you have a lot of mass to overcome so gently open and close the throttle in a smooth manner.It is new after all so give it some time to bed in!

Oh I only blip it a little, like up to 2000rpm or something.


Now I cant kill this thing! Its definately not a gasket air leak, I put a plastic bag around the air filter and it almost destroyed the filter. I put a damp cloth on the intake and all it does is suck the moisture out. This thing wont die. The only thing killing it is the governor slowing it after blipping the throttle.

The solenoid foam plug mechanism I made up is helpless; need something air tight and rigid. What do you guys use to kill these engines? I searched this form and found mention of sewage RV valves, but I'm wondering if there's other methods?

[gilburton]

It must have a stop position on the throttle, a separate stop lever or it has a stop solenoid on the pump.
I presume it's electric start so when you turn the ignition off it should close the fuel shut off valve.
If it has and it's not doing this then possibly it might be sticking so try disconnecting the battery or switching the fuel off manually.
If it's on the throttle they usually have 3 positions eg stop/idle/run
What does it say in the manual re stopping??

[old clunker]

As gilburton stated, it should either have a fuel shut off solenoid, or be shut off mechanically by moving the normally spring loaded engine governor link arm beyond it's normal at rest position. Move the arm one way to increase the engine speed (throttle action) to max. Moving it the other way to max movement should shut down the engine.
Otherwise fit a suitably sized in line fuel tap (fuel cock) like I have done to my bike, and when shut off, shuts down the engine in about 5 secs.
So these are the usual options. Have fun with your engine!

[iron_monkey]

I'm aware of the fuel solenoid, but it doesnt shut it down quickly.

I also thought it was pretty important to have a shut off mechanism that caps the intake of the engine to prevent a runaway situation?

[alexanderfoti]

I'm aware of the fuel solenoid, but it doesnt shut it down quickly.

I also thought it was pretty important to have a shut off mechanism that caps the intake of the engine to prevent a runaway situation?

It should stop it immediately, only the weight of the flywheel keeping it moving for a bit.

You shouldnt need to engineer a soulution to cover the intakes, whilst a runaway is a possiblity, stalling in gear etc is an easier way to stop a runaway engine

[coachgeo]

....

You shouldnt need to engineer a soulution to cover the intakes, whilst a runaway is a possiblity, stalling in gear etc is an easier way to stop a runaway engine

ewghhhhhhhh...... good point......... as in........ if your using a cvt....... you have no gear to stall it with thus must design in a plan accordingly.

[alexanderfoti]

Indeed, a CVT is an issue when trying to stall