Typhoon Starting issue

[sdillon]

Hi all. ( Typhoon almost impossible to kick-start)
This one is tricky.
I have matchless typhoon recently aquired. It has original Gp5 carb and Lucas comp magneto. once started it runs great strong and keen riding it.
It doesn't have any tick over but thats fine I don't have a problem with that.
The issue is.
It's v difficult to start. It's almost impossible to kick start. but bump start works fine.
This is the list of stuff I have have done to try and figure it out
1. Cleaned and air blasted the carb. Particularly the pilot and air hole.
2. Tried adjusting the idle screw in and out ie richer or leaner.
3. Tried different advance, retard has to be a bit retarded to start not full advance.
4. It's often almost OK on kick start on first or second kick but after that gets virtually impossible.
5. I have the (choke) at leanest setting but also tried richer, makes it worse.
6. Best chance I have is the idle screw turned all the way in (ie lean as possible) on idle.
7. If I richen say standard 10 clicks I might be lucky but it's almost no chance dispite my best kick.
8. If I turn the idle screw 10 clicks out then petrol dribbles put of the air hole. Not sure if thats correct.
9. Spark is good and checked ht leads connections all sem OK.

So main symptoms are it nearly catches, after leaving it 15 minutes or so but after that is virtually impossible to kick start. It's like it flooding but when I take the plug out it feels and smells bone dry. But as I said bump starts OK.. I really want to stick with the gp5 carb if possible.

Any idea you experts out there, happy to answer more questions.. Cheers fingers crossed.

[mdt-son]

Hi sdillon, I have no experience with the 5GP3 carb, sorry. You didn't mention the model year of your bike. Pre-60 models will have the slot firing cylinder head, which by itself makes starting much harder. Then there is the racing carb, which is infamous for hard starting. Have you tried starting fluid? If your ignition timing is correct, I suggest starting at full retard.

- Knut

[sdillon]

Cheers Knut, it's a 1960..

[SPRIDDLER]

I've no experience with the Typhoon (and seen only two in the flesh) or the GP carb but FWIW........

It's v difficult to start. It's almost impossible to kick start. but bump start works fine.

When retarded for starting is the mag producing a good blue spark at kickstarting speeds? The spark will be weaker when ign retarded than when advanced. Maybe a 1960 mag does have manual A/R but I would've thought it would be auto and if so the Advance/Retard mechanism may be gummed up and sticking.
No matter how new is the sparkling plug my first step with starting issues is to fit a new one. Cleaning a plug with anything coarse (e.g. even a brass wire brush or Emery cloth) can leave scratches on the ( nowadays unglazed) insulator which will cause tracking along the insulator instead of the required sparkling at the electrodes.

I really want to stick with the gp5 carb if possible.

If you don't have them there are 5GP tech details and tuning instructions here:

http://reocarchive.byethost31.com/Amal/amal.html

[sdillon]

Hi all many thanks for the update. After leaving over night tickled the carb and got it started second kick but after stopping and trying again no joy.
I have found something that's I don't think is correct. With the carb tickled and kicked over a few times there is petrol dribbling from the permant leak air hole at the front of the carb. Thoughts, pilot circuit jet allowing flooding..? Pilot screw issue?

[SPRIDDLER]

With the carb tickled and kicked over a few times there is petrol dribbling from the permant leak air hole at the front of the carb. Thoughts, pilot circuit jet allowing flooding..? Pilot screw issue?

Well out of my depth with the GP carb but with the cooking carbs it happens when the fuel level in the float chamber is too high - wrong or punctured float/wrong needle/wrong needle clip position or the needle isn't sealing off the fuel to the float chamber. But I guess you know that.
Dunno.

[sdillon]

OK folks some real progress found two issues. One fixed easy the other I have done a temporary solution.
1. If I depress the tickler till fuel spills over it has a tenancy to flood the whole carb, so I don't use it unless standing overnight.
2. This is the main issue.. With the throttle not twisted there is no air gap between the throttle valve and the carb body. This means on kick over there is no air getting through the carb. I have done a test temp solution by tensioning the throttle cable so there is a gap of about 1.5mm at rest.
I can now easily start the bike via kick start and even better I have adjusted idle screw so I have a nice tick over... What a result
The remaking issue is because of the cable tension when I turn the handle bars left the tick over lowers slightly and right it raises slightly.. So a bit sub optimal but taking a rest now

Thanks all
any thought on raising throttle valve without using the throttle cable?

[Duncan]

any thought on raising throttle valve without using the throttle cable?

Starting with the disclaimer that I have never had a bike with a GP carb, my understanding is that they do not have a throttle stop to set a tick over as in competition they are supposed to kill the engine when the throttle is closed, that is why Goldstar owners are constantly blipping their throttles while waiting for their mates to get started, therefore if you are setting tickover on the throttle cable it will always vary as the bars are turned and the cable moves. I think you may be referring to the pilot jet screw as the idle screw. Apologies in advance if I have misunderstood.

[sdillon]

Thanks Duncan, I believe you are correct...
Cheers.
This forum is great such a broad and deep knowledge pool...