[Desert Rat]

I bought this 1973 tiger 750, pretty stock but with a typanium unit, it did fine on the test drive but have been having problems ever since. Fix electrical, carb and now this: It'll start and idle fine but once Im on it and starting down the road it feels bogged down, misses, blows back from the carb intake and eventually dies after around 10 min rolling. Ill tickle it, start it and once moving again same thing. Repeat until it eventually wont start at all. I have good spark, The carb has been cleaned, theres gas getting there... So I broke down and brought it to a dude who's worked on Triumphs ( has and older one of his own). He goes through, cleans the carb, again, adjusts some electrical fittings, says the carb doesnt need tuning and charges me $40. I pick it up and same story.
Im convinced the air/fuel mix in the carb is off. I've tried to tune it myself but havent the time or patience lately, especially if Im not sure its the problem. What do ya'll think?
Chris

 

[hatch]

the idle passages are a bitch to clean....and that is what I think your problem is. An ultrasonic cleaner would help.

 

[Desert Rat]

whoa, that sounds interesting. What the hell is it and how can I get one?

 

[Cosmo]

Crap inna tank?? A filter can be fabb'ed with fuel sock material cut and formed around the fuel pipe. Done this on older (40's) M20's to good effect. Usually add a short pipe to the reserve hole, so all is filtered. Shortens your reserve, but so what??

Cosmo

 

[Desert Rat]

this afternoon I drained all the gas, pulled off the petcocks and they were both fine. The little screen in the carb being clean too. There is gas getting to the float bowl just fine, So my problem must be between the float bowl and the spark, right? It idles fine so couldnt be the points or timing, right?

 

[Desert Rat]

whoa, that sounds interesting. What the hell is it and how can I get one?

Looked it up, these things sound pretty cool. Worth buying one or is this a common tool found in your run of the mill mechanics garage?

 

[Tony the torch]

check the air bleed hole in the gas cap, if it's clogged it will starve the gas until the vacuum in the tank is released,
try running around with the cap on there loose and see if it makes a differance.

 

[gsand]

Looked it up, these things sound pretty cool. Worth buying one or is this a common tool found in your run of the mill mechanics garage?

Pretty expensive for one big enough to call "usefull"

Most shops that specialize in carburetors should have one, or access to one. Other side of the world, but ive been quoted $70 to have a bank of 4 carbs ultrasonically cleaned

 

[Glider]

There's a lot of information here and on the web on how to properly clean the idle circuit on the Amal--if that's your problem.
Start with a comprehensive tune-up as per the manual. Timing, valves, carb air screw set at 1 and one-half turns out from bottom. Make sure the carb is jetted as per the manual. Etc., etc.
Battery must be fully charged.
Plugs clean, or checked in plug tester. If you can't test the plugs or bead blast them clean, get new ones.
There are no short cuts. Depending on other people to keep your classic bike running is a losing game. You have to learn how to do it yourself.
Have fun.

 

[jdreich]

Looked it up, these things sound pretty cool. Worth buying one or is this a common tool found in your run of the mill mechanics garage?

Many carpet cleaning companies use ultrasonic cleaners to clean blinds, etc. May be worth a call to a few to see if they would dip your carb. It takes such little time they could probably do it while you wait. This process really turns out a clean carb.

 

[Desert Rat]

Tony, had that thought myself about the gas cap but thats not it.
I'll go through the carb and tune up as per glider and see if it helps. Im trying to do this all solo but sometimes time and expertise simply gets maxed out and I live on a major motorbike tour route so jealousy is a daily event. Patience...

 

[Loffer]

You said fix electrical and carb? What did you do ? What electrical did you fix? Before or after it was not working. Sounds like maybe its losing spark while your running higher rpms . Just trying to help.

 

[Mr.Pete]

Take out the air mixture screw.A wire,0.016" diameter or less,should push at least 1-1/2" into the carb body if the pilot jet behind the screw isn't blocked.
Take out the float bowl drain plug and turn on the fuel.At least 300ml/minute of fuel should flow through.
If that's all OK,suspect the condensors or the kill-switch.You could by-pass the ignition switch and kill-switch to test it.

 

[Desert Rat]

Ill give that a whirl too, Mr Pete. None of the wires leading to the handle bar controls are connected anymore, no blinkers, horn and IM assuming the kill switch is also disconnected. The PO pulled out the zener diode and added the typanium and cut and pasted a few more times making connections with twist on caps like you use in home electrics making something already bad, worse. I pulled and cleaned the carb before the mechanic did, and attempted a tune but failed. The carbs on my bonnie are really sensitive and I can hear the difference in a half turn of the screws. I screwed with the tiger carb and cant hear any difference in running so gave up and brought it to homeboy. For some reason Im convinced its the carb...

 

[Tony the torch]

gas cap...

 

[70TR6R]

Just a thought, but have you checked the coils? My bike did the same thing, run fine at first and start crapping when it got hot. Changed coils, problem went away. Just my 2 cents.