oilly deposit in inlet port
 

Hi
My Bike yamaha TTR 600 (same engine as XT 600) started cutting out usually while at lower revs,at first it would kick start stright away but got worse and now if it will start it will either die stright away or after a few hundred yards and wont start again.
So far I have changed spark plug,HT cap,petrol,cleaned carb there was quite a bit of yellow stuff in carb a bit like rust ( I have a plastic tank)and i assumed this was the problem but still no good I have disconected and tapped up wires to side stand switch and had a look for any loose wires,also checked tappets.
Spark plug is rather black but when the bike has been runng it usually has not warmed up and choke is still on before it cuts out.
When I took carbs off I noticed there was some black oily sludge deposits in one of the inlet manifold I dont think this should be there any suggestions? and could this be my problem

Hi, bolla,

Your problems sound to me like they carb are carb related. First the oily deposit sound like blowback thru the inlet valve, I wouldnt worry too much, its cured by regrinding the valves, and blowback can happen to some extent if the valves are OK. Any deposit in the float bowl is bad news, a yellow rubbery deposit is from evaporation of petrol, and gums up your jets and inlet stop valve (has the bike been standing unused for a long time?). Any grit in the float bowl, is down to it comming from the tank - get an inline petrol filter - the plastic car ones with crimped paper filter are best. Grit can also get in thru your air filter, so keep this cleaned and oiled regularly.
I would concentrate on cleaning up the carb internals if they are coated yellow, use carb cleaner and do everything - jets emulsifer tubes, inside of the float bowl, have a look at the clymer manual to see whats in there. Alternatively just get a good clean second hand carb, and put that on.

---rob

Hi, bolla,

Your problems sound to me like they carb are carb related. First the oily deposit sound like blowback thru the inlet valve, I wouldnt worry too much, its cured by regrinding the valves, and blowback can happen to some extent if the valves are OK. Any deposit in the float bowl is bad news, a yellow rubbery deposit is from evaporation of petrol, and gums up your jets and inlet stop valve (has the bike been standing unused for a long time?). Any grit in the float bowl, is down to it comming from the tank - get an inline petrol filter - the plastic car ones with crimped paper filter are best. Grit can also get in thru your air filter, so keep this cleaned and oiled regularly.
I would concentrate on cleaning up the carb internals if they are coated yellow, use carb cleaner and do everything - jets emulsifer tubes, inside of the float bowl, have a look at the clymer manual to see whats in there. Alternatively just get a good clean second hand carb, and put that on.

---rob

Thanks for reply
I am also thinking its the carb but have cleaned them twice ,so maybe something is worn.
I also own an XT 6003AJ and i think I will try swapping carbs over just to see if it cures the problem with the TTR as I really need the TTR running in 2 days time.
Also does any one know the easiest way to remove the carbs? on the TTR I have to unbolt the sub frame to disconet the air box from carb mouth then undo the inlet manifold from the cylinder is their an easier way thanks.