Subaru - driving me nuts !

[robin bird]

I have a Subaru robin 35cc with almost 200 hours on it. I thought i was getting carp in the carberetor so i put on a Dubro 1/8" line fuel filter. My mechanic disassembled it 3 times at 2 different times and it ran fine for about 10 hours then the same old problem- you can rev out to about 1/3 of its capacity only then if you dont back off on throttle it will die.I also tried another plug.
I moved away from this mechanic and so i bought another carb and poo the same problem. So then i thought maybe its the coil and a new one came today. It is set 100 mills above the flywheel and i also tried other settings- still carpy performance ! So now i dont know im not a mechanic but the service guide says adjust the valves every 200 hours - i need a mechanic to do that but do you guys need a valve setting every 200 hours? or do you have to clean the exhaust port ? would the 2 stroke Tanaka be less maintenance?

 

[Virginian]

I rode my Tanaka 32cc for 3800 miles and it has run beautifully, starts quickly, and has never left me stranded on the road. So I think it is a terrific reliable engine.

The only problems I had were:
1. Had to change the spark plug after about 2000 miles when it became difficult to start.
2. Had to replace the gas tank after original tank developed a hairline crack (possibly caused when a friend who tried the bike accidentally dropped it and the bike fell on the gas tank.)
3. Kill switch wire broke (but easily reconnected).

 

[professor]

Robin- it could be the valve adjustment. When I was on a tractor site I remembered about the valve adjustment on those engines could let the engine warm up and then die. Low and behold I got one that did that very thing. What happens is the exhaust valve warms up and grows longer - if the adjustment is too tight (no play) the valve growth puts a gap under the valve and you loose compression and power.
You have nothing to loose by trying to adjust the valves yourselves. Rotate the engine until one valve is fully open- adjust the other one. You only have 2. Go for it.

 

[robin bird]

Wow its now running smooth and powerful - got the valves done today and a new fuel tank scintered brass filter . Maybe it was the filter all along but the valves needed adjusting anyway as it actually has about 210 or more hours on the engine. . I may have wasted the money on the carb and coil but it would have cost me that much in labor locally as here it is a very expensive hourly rate. I took it to my original mechanic. Anyway im happy to be able to pull the hills and go fast again ! Well its a learning experience and thats what makes this hobby fun - go from frustration to exilleration

 

[HeadSmess]

your throwing your money away by seeing a mechanic at all. glad its going good, buuuut...

i dont trust anyone working on my stuff. gorillas, butchers, and plain moronic oafs do waaaaay tooo much damage. i did my apprenticeship and was disgusted by the idea that all mechanics should be a lil bit thick, cus its "easy". at least that was the criteria for 70% of the class...

anyways. simple things like checking valve clearances are twenty minute tasks, tops.

as the professor says....nothing to lose. a lil research on the topic, any lil engine will do, the basic concept is the same.

the net is full of info on engine maintenance. videos, pics, diagrams, text... save your money for parts and tools n hand cleaner

*likes teaching young ladies with flat tires how to change em cus theyre ever so grateful*

 

[lowracer]

Mine has a similar problem & it turned out to be the stock black fuel line was getting crimped going thru the grommet enough to cause bogging & the need to back off the throttle (once warm). Replaced the fule line with a firmer, slightly larger ID fuel hose from the local ACE hardware store & all is better.
-lowracer-