Is there an easy way to do this?

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Hydro Junkie

Well-Known Member
Joined
Oct 2, 2006
Messages
5,714
Just a quick backstory first, before what might seem to be a stupid question:
Was at a race last weekend and had issues with the boat going dead after a three to five laps. When it was running, it ran well, then would just die. I tried the following to rectify the situation:
  1. reset the needle several times
  2. changed the carb
  3. replaced the coupler tube between the header and pipe
So, with all of that done, I've had some say it had to be a tank problem. I can't really agree with that since I didn't use enough fuel to empty the secondary tank so the primary tank (the one that directly feeds the carb) never was below full. In addition, when I drained the tanks after running my last heat, I was able to empty the tanks using a hand pump attached to the tube going to the carb so it seemed that the tanks are fine. Since I changed carbs, that kind of rules out a needle issue and, when the carb was changed, I set the needle with a flow meter, one I bought from Boris, to the same setting as the first carb. This leads me to the exhaust pressure and what I found in the coupler tube. The tube was lined with a layer of soot(or whatever you want to call it), and that has me thinking the pipe might be the same way. This brings up the question of "Is there an easy way to clean out the pipe so that I wouldn't have the possibility of the pressure fitting getting blocked by soot? Any other thoughts on how to remedy this would be great as well.
Thanks
 
Okay guys, I'll answer each of your questions separately:
  • Sam, the plugs looked fine and , with one exception, lit right up when an igniter was applied
  • Terry, it's never had one and never had an issue before though I do have one I will try this weekend
  • Don, the engine has only got maybe 15-20 engine starts on it total, including this past weekend so they "should" be still good. I'll be using a different engine this weekend as the one I ran last weekend had the upper carb screw break on me. Ended up borrowing a front plate to keep running that I have to return so, if the engine does the same thing, I can assume it has to be a fuel issue.
 
Does it occur regularly or just on that race meet?
Possibly just had a bad day ,,..

Weather.

If you use...dismantle your 3rd channel needle clean thoroughly.

Could be 3rd channel needle servo glitch or low battery.Causing too lean tune

Fuel line from needle to carby length .?

Are you using large fuel tubing for fuel and pipe pressure .?

Engine not overheating?

Pipe can be cleaned inside with hot soapy water and a small pipe cleaner..

Plug change hot or cold..

Can be many things
 
Something I probably should have mentioned(thanks David), that I ran it two weeks prior and actually got a 3rd in one heat with the same engine I was running last weekend so it's something that is on and off. Let me post the two differences between the two events and answer David:
  • temperature was 10 or so degrees cooler last weekend than the previous race
  • altitude was 1200 feet lower last weekend
  • I ran a needle setting of 50 on a Boris flow meter, at least when the engine was initially started
  • not using a third channel needle, just standard needle on an OS 9B carb
  • large lines used between tanks and to carb, would have to go back and look on the pressure line
  • engine is getting good cooling using large tubing and a Speedmaster rudder with single pick up
  • Plug is the same I've always used, an ODonnel blue
Now, to Allan:
  • using standard Sullivan 10 ounce slant tanks in series, not metal ones
  • I can pump the tanks dry using the pick up tube in the primary tank(the one that feeds the engine) with a standard manual fuel pump as I mentioned in the first post and, as also mentioned, the primary tank never went below full other than the consolation heat when I went several more laps than I did over the previous runs during the day
  • Here's what I have for a rudder assembly, pick up is on the other side
win_20220725_12_26_35_pro_c13ed04e58f19aaa60fa7e82f9d49c9add83d5d3.jpg
 
Frank, it's a CMB 67 greenhead. Gasket is like new, not even creased and the carbs got new O rings on installation.
Rinse with acetone......... I have some CRC Brake Clean that might work instead. I know the wife won't let me in the kitchen with a "crusty old pipe" so soap and water are out o_O
 
Brake clean works... denatured alcohol,
I flush my metal tanks with acetone too...
Especially if they have sat for any length of time...pump some in give em a good shake
and pump it back out...it's amazing what comes out some times...dissolves all of the old castor and junk from the pipe..

You can even use plain medical grade alcohol..70-91% ..works good !

I would check and make sure the crank pin hit the rotor hole when you put the plate on..
It can happen!
 
Heck, just flush everything with brakeclean..
Spraybar, needle valve, tanks, check all hoses for pinholes, bubble test your tanks..

Could just be a tiny piece of trash caught somewhere..

I'm wondering too, do you think there was enough of a change in altitude and air temp were you might need to take out a shim out of the head button ?
 
Good point Dave. If I still have issues this weekend, I'll change out the tanks(or, at least the rubber inserts) before going to the next race
 
Heck, just flush everything with brakeclean..
Spraybar, needle valve, tanks, check all hoses for pinholes, bubble test your tanks..

Could just be a tiny piece of trash caught somewhere..

I'm wondering too, do you think there was enough of a change in altitude and air temp were you might need to take out a shim out of the head button ?
Taking out a shim not necessary ,,Fairly certain HydroJ would have his engine squish already set and sorted.
However a 10degree cooler change in temp is a fair amount and can affect needle.
If weather is cooler then you would richen the needle ,, perhaps the engine did run lean ...
 
But he did run at a lower elevation (1200ft )
the week before. With the change in elevation, the air is thinner...
less volume of air.

Taking out a thin shim may be all it takes to compensate for the change.
Or prop down a little bit..
 
The way to check a tank is to:
Fill it up completely and DONT PUMP IT DRY, BUT let it siphon into a jug and watch for bubbles and it should siphon almost dry if not you may have a crack in a brass tube or rubber leaks with plastic tanks.

Also look for water leaks. Use a large syringe and push water in the water line at the disconnected water line with finger over the final exit tube. Push under pressure.

Had a somewhat a similar problem at the Cincinnati race recently and it was a water leak.
 
50 is pretty fat for a 67. Like Doc said look for those bubbles. You can still pump them dry and still have a leak. When the run came back, was the second tank full. I have also had water lines that got a small piece of tubing blocking the line. The chunk of tubing got cut off while pressing it on to the hard water line.
Mike
 
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