Cold start issue T3

[RKS_DK]

Hey guys,

Could use some advice here, I got a T3 but with a newer cali 1100 engine, PHF36 carbs.

I can always start it easily, but while using the choke the idle speed is unchanged vs normal, which means it can't keep itself running without having to be on the throttle until its warm..

This engine was fitted while I had it, and before the engine swap I had no issue, when I pulled the choke back on the old engine it would go around 1800-2k rpm (same carbs)

I can't find any info on adjusting the idling speed with choke on, if at all possible..

Any ideas ??

[Groover]

Hmm.. this is an interesting one. Perhaps the jetting needs changed to compensate for the bigger engine? I think there is a choke needle circuit in the dellortos but I've never messed with that circuit. I think you may need to look at a carb diagram to see which. I think there is a dellorto manual floating around out there. I'll see if I can find it.

That's my guess. How does it run otherwise (once warm)?

[Groover]

Here you go. I just uploaded one I had on my computer. It's item 13 in the diagram. You may need to change that one. Up or down in number, not sure. Sometimes going larger on certain circuits in the dellorto carbs means leaner (where you might think it would mean richer)



Hope that helps

[RKS_DK]

Hmm.. this is an interesting one. Perhaps the jetting needs changed to compensate for the bigger engine? I think there is a choke needle circuit in the dellortos but I've never messed with that circuit. I think you may need to look at a carb diagram to see which. I think there is a dellorto manual floating around out there. I'll see if I can find it.

That's my guess. How does it run otherwise (once warm)?

Forgot to say the engine before was 1000cc.

It runs great when warm, never had carb issues otherwise.

If I adjust the cable on the carb (so it pulls more on the choke) it starts smoking black alot, so I'm not sure if changing the jet does much.

[Tom]

Adjust after reaching operating temp.  Check plugs then live with it.

[Groover]

It could still be. My guess is that item 13 then probably needs to be smaller for the 1100 engine. I'm thinking this engine is drawing stronger pulling more fuel through 13 (hence the heavier black smoke), so to balance you would need to restrict the fuel by making 13 smaller) that way when the choke is pulled, the idle would raise because it has higher air ratio like opening the throttle a bit.

That's my guess. Hopefully someone else can help if that's not it.

[Triple Jim]

My Mille might behave similarly to your bike.  When the engine is cold, using the enricher gets it running, but I can't take my hand off the throttle or it will die.  Pushing the enricher farther makes it run richer and it blows smoke and starts misfiring.  Using less enricher eliminates the smoke, but there's not enough throttle to keep it going without twisting the grip.

I've thought that it would be nice to have a fast idle feature other than giving the idle speed screws a twist, but I've learned to work around the problem by riding off gently right away.  By the time I'm a mile up the road, it will idle OK at stop signs.

[Groover]

I hate to sound like a broken record, record, record..  but I do think that's where the problem is in both those cases. The jets are there for a reason, and 13 is specific to the choke circuit. They're not a 1-size fits all, otherwise they wouldn't put them there.

Maybe it's something else, but 50cc per side on the engine is a whole moped increase per side 

[Testarossa]

Dellorto manual is here: http://www.ask-ancenis.fr/documents/Rotax/DellOrtoMAJ01.pdf   

Section on the enrichener begins page 25.

[RKS_DK]

Yeah read thru the manual alot, but I can't find anything about idle speed under choke circuit.

Btw. my carbs are PHF 36 DD - the diagram seems to for PHB's - not sure if it matters tho

[Testarossa]

And the exploded drawing at the top of the thread is for a VHB. 

[Guzzi_Don]

You could use the friction screw at the base of the twistgrip.

[guzzista]

Choke System is pretty much the same on VHB as on T3 and PHF carbs. Make sure you don't have any air leaks ( that includes the rubber spigots to manifolds and manifold gaskets), +1 as the other posters in as check your choke circuit.  If you pull your  choke when the engine is warm ,  the engine should chug and bog down otherwise the choke is not working at all.