Triumphrat

ColdBlooded

Hi, I just purchased a 66 bonnie this past weekend. I was told it has a 650 out of a 75' in it. Anyway i cant get the bike to fire cold. It has a mikuni on it. After about 15 minutes of kicking and trying different things i usually get it started. Ive come to the conclusion its not getting enough fuel to start. Ive pulled the plugs after kicking it for a while and theyre always dry and clean. I pulled the carb off and cleaned it and am still having the same problem. The guy i bought it off of said the carb is fairly new. Which i belive because when i took it off it wasnt dirty at all inside really. I drained the tank and put new fuel in. I checked the spark, its great. New battery also. Once it does fire it runs fairly well. Idles great, and revs right up. Ive only ridden it around a small parking lot (not registered) and it seems to run alright, although i do feel a bit of low speed surging and flat spots. After its warm i can shut it off and fire it up on one kick everytime. But i go to start it the next day and i go though the same not starting problem. So anyone have any ideas? should i try to just get an Amal to put on there instead? It really feels like it needs the "tickler" on there.

peterocket

For starters you say it has a 650 from a '75 model.
They stopped the 650 in 73 and went to 750, so...
Also you say it's a Bonnie yet by your wording it only has one carby.
Bonnies have two carbs. So, it's either not a Bonnie or it has a different head.
If it runs OK once it starts and starts first kick once it's warmed up, here's what I think.

Cold start sequence:
1. Slowly depress and turn kick starter until solid resistance is felt.
2. Let it gently spring back to it's high position and just check again that the resistance is still there.
3. Pull your air lever (choke) all the way on
4. DON'T TWIST THE THROTTLE AT ALL
5. One big jump down on the kick starter.
6. Once it has fired, THEN you can give the throttle a twist.
7. Run for about 30 seconds to a minute and turn your air lever off.

If you don't have an air lever, ...there's your problem.

ColdBlooded

lol, well as you can see i know nothing about what i have. Its a bonnie frame but the whole bike has been done over into a bobber. I have tried the "get the motor to the bottom of the compression stroke and kick the crap out of it" technique but that hasnt worked either. And like i said its a mikuni carb so all it has for a "choke" is an enrichment lever. Thanks for the help so far.

peterocket

An air lever or an enrichment lever.
Shouldn't matter. The sequence should be the same.

t100rc

Get rid of the Asian carb and replace it with an Amal. It's simpler and looks 'right' on the bike. I've said it before ... you could modify the frame to accept a Honda motor, but you wouldn't, would you?

Anyway, it sounds to me like there isn't fuel in the carby when you first try it. Is there a 'primer' of some type on the Mikuni? Does the Mikuni have an accelerator pump so you can twist the throttle and get it to fill up?

I have no choke and STILL start right up when cold. I start cussing if I have to kick it a second time. But ... I do 'tickle' the carb until I see fuel.

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RC
'70 T100
'57 T110 (in a pile)

ColdBlooded

Any body else think it could be from the straight pipe exhaust. It looks like its got 1 3/4" head pipes with 24 inch straight tail pipes. Im thinking that exhaust dosent provide enough back pressure to suck the fuel into the motor when cracking.

happyray

Hi,

which Mikuni is it ?
Single or 2 carbs ?
Jet-sizes ?
Needle-settings ?

The Mikuni carbs wether they are flat or roundslide aren`t that easy to comprehend (at least not to me )
As far as I am concerned the choke doens`t limit the air-intake it opens another fueljet.
This way Mikuni`s enrichen the mixture.
If you open up the throttle while starting...the choke will NOT work !

Once you take the float-bowl off you might see a small pipe sticking outta the bowl.
This is the passage for the fuel to the choke.
An air-compressor is doing a good job on this tiny pipe (usually I never use an air-compressor
at a carb but here there is no other way)

BTW: I trust that you`ve checked the ignition already lol

ray

Emanthehorse

That wouldn't make much difference on startup.
Personally, I'd go find a good AMAL 930 and throw it on for comparison, I'm not like some of these "If it's stock it has to be right" guys, but the AMAL just works really well.
How is the bike titled?
Got any pictures?

GrandPaulZ

Mikunis don't have choke/enrigher levers with cables.

Toss it and put a new Amal 930 on it, jetted for single carb Triumph. it WILL run right, right out of the box.

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GrandPaulZ
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ColdBlooded

Alright well im looking for a Amal to put on it now. Thanks for the help.