Engine Trouble Possibly carb issue but not sure

[dotcom]

seems like its the way you described but I still plan to test with different carb. I assume if the same thing happens with a different carb, there is another problem. I really don't feel or see any air leaks though and I cleaned the carb and blew through the jet to make sure it was clear. We'll see after testing with another carb and I will report it here.

 

[crassius]

I use a spray bottle to mist water in the area to find air leaks.

 

[HeadSmess]

and here we are with nomenclature difficulties... "bogging out"

some seem to think its when its too lean.

some seem to think the term applies better when its too rich.

i prefer

"it dies when given full throttle" for too lean.
" it runs but doesnt really rev" for too rich

if you need to tweak the choke whilst riding...it is lean. very lean.

what causes this? forget airleaks, they are only a concern at idle.

a blocked jet is likely.

a blocked fuel line/filter calls second place.

a blocked vent on the petrol tank takes third place.

you can eliminate the last two issues by seeing how fast/consistently it will flow from the (disconnected from carb) fuel line into a handy glass or similar vessel.


and lastly, very rarely...the clip comes of the needle and its no longer being lifted by the slide. idle is fine but it stalls as soon as the throttles opened.

 

[dotcom]

It was not the carb because I used another stock carb exactly like it and the same symptoms occured so I went on to check the crank seals and I thought one looked like it might needed to have been replaced so since i had an extra, I changed it but that appeared not it be it either. So now I think I will check my fuel flow from petcock and increase it if needed and see if that was it. I dont think it can be a blocked jet since I cleaned it and even tried with a working carb so it must be the fuel flow from petcock like headSmess suggests but I will check and report back.

 

[HeadSmess]

i forgot to mention base gasket between case and cylinder...thats an air leak that will affect everything. the evidence of a leak is fairly obvious though. a very rare one is the case gasket itself, where the two halves bolt together.
make sure headnuts are tight... worth popping the head off to check the gasket.

personally i use teflon tape rather than the lousy aluminium things they normally fit for a gasket. bit of fiddling and you figure out how to use it.

but it is sounding like fuel line issues here...

 

[dotcom]

Ive removed the gas line and checked the fuel flow from out of the petcock and seemed possible but unlikely to me but I also removed the petcock and cleaned it and put it back. Now I guess I will move on to the next possible culprit, the base gasket.

 

[crassius]

when checking fuel flow, I always pull the drain screw at bottom of bowl to see whole system at work

 

[dotcom]

I keep get new issues from leaking gas to an air leak near head somewhere but I have spent all day trying to fix it since this morning and just got these two new issues of leaking gas (AGAIN!) and air leak near head. I put my old gasket at the base and when I tried it out just now, I got a new leak at the top near head so I will continue it probably tomorrow

 

[crassius]

stick with it, you'll get better at it - once you've had some experience with these, you'll wonder why it seemed so hard earlier

 

[Deleted member 12676]

FYI the head from the factory is warped and needs to be planed flat. Use sandpaper on glass.
Make your own gasket from gasket material from the auto parts store. aluminum sucks