I installed a TM36 about a month ago. The install went really well but due to old man winter I've been unable to tune the accelerator pump.

A few days ago it started leaking out of one of the vents toward the rear of the carb. Pulled it yesterday and reset the float height to right at 19mm. That took care of the leaking out the vent hose but now it's leaking out the bowl drain hose.

Problem is - this bowl drain doesn't have a set screw to control the flow out of the hose like most carbs do. It seems to be just an open spigot.

First question - how do I turn the flow off?

2nd question - does this mean I still have a flow issue with the float system? Is the bowl drain simply another overflow?

TIA

 

dj, I'm not sure I'm understanding your question. Usually the spigot on carb bowls that have a plug screw is for draining the bowl. There is also a standpipe in the carb bowl that is not plugged with any screw, and it drains fuel from the carb when it rises above the "normal" level due to a stuck float, too high a float setting, and such. If that standpipe didn't drain that rising fuel, it would flow out the carb either into the airbox or into the head. You cannot...or at least should not...plug that standpipe. You'll just have to find why the fuel level is not stopping at the specified level.

 

Thanks TNC. I'm just surprised that the bowl drain isn't a simple set-screw arrangement like most carbs. Obviously it's an overflow. I didn't even look at it when I had the bowl off to reset the float height.

Bottom line - the float height is set correctly so any leakage is due to the needle not seating properly. I'll take it off again and blow it out and inspect. I neglected to do so when I had it apart because the pivot pin is in very tight so removal was not super-easy. At the time I was sure it was the float height itself because it was barely within specs.

Fortunately the TM36 goes in/out much easier than stock. I didn't even need to shim the tank or trim the cable wheel on my 300R. Has about 1/8" clearance above the top cover and the wheel with the stock tank.

 

dj, when you pull the carb again and blow it all out, I'd set it up level in a vise or similar manner. With the bowl off, use the tank or other fuel supply to the carb. Turn on the fuel delivery, and play with the float-needle-seat combo by pushing it up and down manually to see how/if it shuts the fuel supply off. When you find that exact point where it shuts the fuel off, measure it like you did when it was dry just to see if it's way off from the recommended 19mm. Sometimes (rarely) the float can lose its buoyancy quality...sometimes the float has a rough spot on the pivot pin from a crimp or twist. Your carb is new enough that the needle and float are probably fine, but it's not impossible for a manufacturer failure too.

 

I'll have to add my 2cents... take a picture and print it of the carb installed on the bike from the side. My suggestion is when you put it in the vice, tilt it to the same angle as on the bike. I do not believe the carb sits level in the bike. Maybe the main jet/floats/float fuel pin are in alignment, maybe they are not. But adjusting that way so that the fuel is over the main jet, but below the overflow may help.
If they are all in alignment (front to back), this would be unnecessary.

 

How did you not have to shim the tank and grind the wheel on your TM36 ? Do you have an aftermarket tank ? Was your bike a 250 bored to 300 ? I tried to install a Bill Blue tm34 and the amount of shimming required would not let the front tank bolts go back in. I then inquired about a tm36 and was told it was bigger than the tm 34. I ride a KLX300 bought new in 1999 and have been told that there have been some differences in the parts over the years. It is hard to imagine that much of a difference. Any ideas ?

 

Thanks guys. Should have blown it out when I had the chance. Truth is - it sat there for a month with no leak. I'm sure a piece of grit is preventing the needle from seating properly.

durielk -it's true the carb does not sit quite level.

kawboybill - it's a natural 300R with a stock tank. It's tight, but I have clearance all the way around. I haven't tried to put the tank bolts back in as it's sitting in my barn minimally torn down for tuning purposes. I'll check and see if they fit. They're actually not needed on the 300R but I'll give them a try and see - Maybe I have good clearance because the tank isn't fully seated.

The TM36 is obviously a larger carb, but I think the dimension to the top cover is less than the TM34.

 

I will be anxious to hear your results. The tank bolts on mine also have the aftermarket radiator brackets attaching at the same point so they are necessary. thanks for the reply.