650fse Flame outs, Help ?

Bike has always poped and backfired on closing throttle but I notice I now have flame coming out the can as well.
Bike is on standard jets with Rhino Race can.
Just fitted recommended NGK Iridium plug, would that cause problem ?
Exhast Headers have been sealed with good compound and carb fittings all appear tight so hopefully no air leak.
Mixture screw set at 2 turn out from stop. turning mixture screw in or out has no effect on the backfire or flame.
Can you help, does the primary jet need an inrease in size:?

Flame Outs !

Husabutt,
Thanks, yes had read the thread, but have only just noticed the flame outs, after changing to the Iridium plug !
Just been out and played with the idle screw. I can turn the idle screw all the way in and the engine just speeds up and keeps running.
If I turn idle screw in more than one turn from current setting the bike will not start, and if i screw it out more than two turns again I cannot get bike to start.
Confused over where to go with jets ?

What kind of bike is it and are you starting with with choke on and no throttle?

Edit: I can see clearly now. A 650. Sorry.

Flame Outs

Hi,
Bike has always started with no choke, and no throttle, any touch of throttle stops starting.
Only backfires and flames when stood idling and when hot !
Perhaps it might be running to hot, is that possible how do you tell ?

It seems to me that if it only happens when idling the bike is carbureting on the air screw and pilot jet. I would go up one size on the pilot jet and start with that.

Flame Outs

Thanks Husabutt,
I will set about purchasing jets in the morning, once installed I will report back.

You may want to pick up 3 or 4 incrementally larger pilot jets and maybe a main or two while your at it.

Re: Flame Outs !

alancar1 said:

Just been out and played with the idle screw. I can turn the idle screw all the way in and the engine just speeds up and keeps running.
If I turn idle screw in more than one turn from current setting the bike will not start, and if i screw it out more than two turns again I cannot get bike to start.
Confused over where to go with jets ?

Click to expand...

Lets just clarify:

Have you got the Keihin or Dellorto carb?

Which screw specifically are you turning, the idle speed or the idle mixture?

Oh, and what does the flame look like, the blue sharp type of a blow torch or that of something like the Foggy Petronas Racing superbike?

Simon

Flame Outs

Hi Guys,
Dave Clark Racing sending some jets in the post both pilot amd mains.
In reply to questions its a dellorto carb and the flame is a yellow foggy style .
To clarify this happens when you blip the throttle from idle and only when at full temp, not before full temp !
Starting is perfect at present both hot and cold on the button. O2 model with 04 battery and iridium plug. That battery and plug make all the difference !
Mixture scew makes little difference unless screwed out to far and then engine cuts, it can be screwed all the way in with no change to revs.
If the idle srew is moved more than one turn in any direction I loose the perfect starting, screw it in more than one turn and the engine will not even fire !
Bike starts well and idles. After a run the plug comes out black but not sooty black !
Husabutts idea of running a slightly larger pilot sounds the way to go for now, then if that improves matters move onto a slighty larger main and see if it improves the problem or gives better performance.

Hi Alan:

If going up a size or two on the pilot cures 90% of the problem you may want to try lowering the needle clip a notch or two (from the top thereby raising the needle) before going on to the main. This will fatten up the midrange. I suspect though that increasing
your main jet size is probably warranted due to the increased air flow of the aftermarket exhaust. Just change one thing at a time and document the results.

Flame Outs

Husabutt,
Had a friend who has been a bike technician check the bike last night and confirmed the pilot needs upping.
His way of diagnosing the problem was as follows:
Warm the engine up to operating temp, then very gently and very slowly just open the throttle perhaps quarter of a turn. Do this three or four consecutive times immediately followed by snapping the throttle fully open.
On my bike this killed the engine due to the rush of air into the carb, with the correct pilot jet the engine should make this transition without cutting even if it just splutters through.
Hope this may be of help to others

alancar1,

I hope the idle jet is the source of your problem but I've not seen a small idle jet cause flaming out of the exhaust. Neither does it cause a black plug.

Hopefully I'm totally wrong but I suspect you may have oil or excess fuel getting into the exhaust system (although fuel would normally cause a big pop and bang).

In my personal experience you actually need no larger than a 35 pilot jet on a 650 even with a race system. Regarding the main, I would hazard a gues at around the 190 mark for your system.

Change out your pilot and let us know the results.

Cheers,
Simon

My stock husa 650,is also way too lean at low rpm,+- 16:1 Air-fuel,
So i ordered a 50 pilot jet,my main may lean out to 172- 175 from 180,with 24degrees C.
When is hotter than 20degrees,no real problem ,but in morning-or evening ,-20degrees the popping start on deceleration.
Future plan;
work on the cylinder head+DOMA exhaust.
Mathieu

alancar1 said:

Bike has always poped and backfired on closing throttle

Click to expand...

Alan:

You stated that the bike had always popped but just so you don't waste any time you may want to make absolutely sure that no exhaust leaks are present. Especially at the headpipe area. Also fresh repacking in your silencer would be a good idea before the jetting ritual begins.

Flame Outs

Husabutt,
What packing, the Rhino Racing end can is straight through from what i can see !, from the amount of heads that turn from great distance when Im riding, it must be straight through !
Still waiting on jets in the post.

Alan,
Would you go into 'your account and update your info? It helps if we know your locale when discussing jetting. As you are aware, elevation, temperature, and humidity play a major role in proper jetting.

Several of us in the dry regions around the world have increased our pilots upto and greater than 50, while guys in very humid areas find a pilot around 40 to 45 is best. Where do you live?

As far as the black plug readings, I would guess that your needle is already too rich, as an attempt to compensate for too lean of a pilot. That is how they ship from the factory. Mine, and a few others that I know had this same set-up. I would recommend raising the clip 1 notch, thus lowering the needle and leaning the midrange (throttle opening). Most riding is not wide open throttle. Most riding is in the range of the needle, so if your plug is jet black, your needle is probably too rich.

My bike was finicky starting when new. Berger suggested (while we were out riding) that I try lowering the needle 1 notch. He had a similar starting problem with his bergs, which the needle affected. So I figured 'Why not try it?' I raised the clip (lowered the needle) and the next day the bike did start better. I know it contradicts all logic. But it worked on Berger's bikes and it helped on mine.

Now my jetting is 48 pilot, clip 1 notch higher than stock, 192 main.
Mixture screw 1/2 turn out.
Elevation 1500 ASL Temp >105F

Choke on, 2 kicks, choke off, starts on the button.
Maybe when the temps drop, I'll leave the choke on to start.

This jetting worked flawlessly at 6000ASL @ 72F
Great bottom end grunt, no hiccups, which is good. We were rock crawling and riding very tight and steep single track. Can't afford any hiccups there.

A little rich on the main at 9500 @ 75F,
but starting and midrange were flawless.

Here are a couple of must have links to help you in your quest for jetting nirvana:

Maharishi Mikuni Natural Law Jetting Secrets

The Secret Order of the Dellorto Vergasser

True enlightenment is merely a click away. Don't worry be happy :wink:

Flame outs

Gents,
Great info, i think with your help I am confident in getting the jetting correct. At least i now understand what I am doing and why.

Flame outs

Gents,
Just put in new 48 pilot and raised needle clip one position of standard.
Starting not great , Do I need to adjust the mixture screw, idle scew or both?
Have not had chance to ride but have tried snapping the throttle open from idle and the pick up is instant.
Still getting the popping and small yellow flame when letting the throttle snap shut from open but it is far improved.
Would like to get the starting back to perfect as it was, before test riding !