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Dellorto 38 CD1 jet - FE600 -94

I don't have the cam/spring auto decomp. My bike has the kickstart lever cable actuated decomp. It's fairly easy to kick around with the decomp adjusted as per manual (3 mm play at tdc, lobes down).

With the cd1 jet installed it pops on deceleration. Flames out of the exhaust.

I can turn of the choke more or less immediately (like 10 seconds or so) after starting it cold.

It runs when hot, everything OK, it pulls great, lots of power. But when I turn it off, I can't restart it. Wait an hour or so until it's completly cold and then I can restart it with the choke.

Away for work now until friday. I'll check ignition with a strobe light and ohm-measure the stator.
 
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OK let's get two things going right here.

you need to be sure that you have a spark under pressure in the combustion chamber. the best you can do i suggest is a strobe for ignition timing on the HT lead. plug caps can break down so perhaps a new plug cap BUT, like you, I believe it is carb related.

basically, your bike is running rich and needs little choke.

try and keep the same idle but turn the idle in until either the idle starts to fall OR when riding you have a poor response.

how many turns out is this? i bet it is just about 1-1.25 turns out from closed?

what size were the jets and the clip position in the carb?

I guess if i look back to the beginniing it will say the year, model and CC right?

Taffy
 
FE600 1994. Roundslide 38 mm dellorto.

Again: Pilot is 52, needle K32, emulsion tube AB265, choke jet 45 and main jet 180, round slide no 50. Needle in pos 3 from counted from top.

Fuel screw 2 turns out has highest idle and smooth response. Idle screw one turn out for start, then back it out another turn after started for a more normal idle.
 
Hi

So obviously you have a pilot jet too big.

Your carb it's not the same as mine (600-98) and you have there some strange things, but for mine the std PJ is 40, and usually you go to smaller one.

:cool:
ZAGA
 
I think my bike had pilot 38 original, I changed to 52 many years ago, were hard to start warm the first years but got better with other adjustments.
I think the biggest flaw with a really small pilot is that its extremly sensitive when it comes to dirt and it could stop the engine.
 
Zaga: why do you mean the pilot jet is obviously too big? Two turns out and a smooth idle and response (once it starts) sounds just about right I think. And it's standard jet according to the 89-96 parts manual.

I'll check the timing with a strobe, should be 33-34 deg advanced right? But wouldn't a slighly ******** timing make it easier to start even if it maked it more prone to pop/ping/flame and have a little less power?
 
Hi
I say too rich because you say you need to go to one turn out to start the bike.
Only after star you go to 2 out
If the bike is idling and you start to screw in the ps, how much can you go before the bike stops?

With the strobe, at idle speed, go to 6deg of advance
You can also check max advance
Watch out this CDI will jump very fast from idle to max advance, that is one of it's flaws.

Cheers
ZAGA


Enviado do meu iPhone usando o Tapatalk
 
Ok. By idle screw, I meant the screw that sets the slide height stop position and thereby the idle speed. By fuel screw I meant the one on the pilot jet circuit. Maybe that's not the right words then. The screw on the pilot jet circuit I have two turns out all the time.
 
Hi

Sorry, I call it pilot screw or PS.

It is strange that your PJ is a 52, I would say it's too big anyway.

Again, try to screw in your PS, to see when the bike stops

:cool:
ZAGA
 
Thanks for that link Jampe. I have some reading to do this weekend.

Latest status:

1. Checked the stator DC resistance values. 1690 ohm cold red/black and 21 ohm cold green/black. 1860 / 23 ohm hot. This is well within 10% tolerance.

2. Spark test shows I can get a blue nice spart for at least 10 mm distance hot and cold.

3. Ether based starting gas used for testing for air leaks at intake boot, fuel screw, idle screw, slide top cover. No leak.

4. With fuel screw (Pilot jet screw) out about 1,5-2 turns I have the smoothest idle. Engine still runs at about 0,5 turns out but beyond this it stalls.

5. Strobed the timing. Have 33 degrees advance at high idle/throttle and it drops to about 6-7 degrees at low idle. The difference is very noticable.

6. Starts fairly easy when cold (usually not more than 10 kicks or so) using the choke and idle raised to one turn out from bottom. PS at -1,5 to -2 turns. I don't even have to kick it that hard. Just a nice smooth kick thru the whole motion starting at "lobes up".

7. Impossible to start hot. Can get it to just ignite a pop or two but then nothing. Let it cool and it starts again, with choke.

8. Needle position in second from top but this shouldnt have much to do with the starting abilities, right?
 
Smaller pilot jet is still my advice.
Try this... Hold in the kill button, open throttle and do 3-4 full kick and then release kill button,throttle and try to start it again.
That worked fine for my 501 when it stalled before i changed the pilot jet.
Regards
Jampe
 
Yes I would start with 40
[emoji106]


Enviado do meu iPhone usando o Tapatalk
 
A theory of mine is that the mixture becomes richer on a bike when its hot.
Cold air has more oxygen than warm.
When you kick a warm engine the engine-rotation goes so slow that the air that goes into the engine warms up so the amount of oxigen decreases therefore, I think, many have problems to start warm bikes.
 
That is why you have the choke, as the engine gets warmer the less oxygen you have
And 4 strokers runs very hot
Also the hot star was invented for a reason
A hot start is no more than fresh air directly in to your intake


Enviado do meu iPhone usando o Tapatalk
 
about a 42 I would think. but something isn't right because stalling with less than 0.5 of a turn indicates that the PJ is fine!

so the problem could be elsewhere. not a problem a such but something that isn't spot on.

on a dell orto it is a fuel screw, on a keihin it is a pilot screw.

regards

Taffy
 
I've ordered some pilot jets - 40, 46 and 58. Together with my current 52 that should cover the whole possible range for a 600 with the PHM38 don't you think. I also ordered som choke jets - 40 an 50 which together with my current 45 also should cover most of the range? Ordered new gaskets and o-rings although I didn't identify any leaks with the starting fluid.

Tried another method, took off the side mounted air filter and blew som cold air in with the compressor (evacuating the hot air from the crank vent). Could actually get it to start once hot (no choke) though it took some kicking.

Lets see what above combinations can give.
 
I took the bike for a ride in the woods today, 20degrees, cloudfree, much deforestation overall good speed, clean airfilters but the idle was weak, so close to stalling several times but made it without.
In the end of the run I turned the fuelscrew(must be an airscrew) in a bit and it almost stalled, I screwed it out 2and a half turn and the idle was back to normal again.
Someone here said it was a fuelscrew, in other words the screw in that case would add fuel when I screw it out and the result would be a lower rpm on idle.
But this could not be the case, it has to be an airscrew because adding air to the mixture will result in a higher rpm.
Husaberg 600fe 1995 with dellorto
 
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