Backfire when blast of speed applied...

[crackshot]

1985 Honda 200s
I jam open the throttle for a few second blast of speed and let it snap back and get a "pop" like a backfire sound out of exhaust.
Plate and gasket on bottom of pipe are tight. Does not seem to be leaking out of connector to head pipe.
Removed valve covers and grabbed rocker while on TDC compression stroke, and exhaust valve seemed tight with a little movement. Intake seemed looser.
Now I dont mind having to check gap of the valves, but how the hell you supposed to get a feeler gauge down in there especially the intake valve access when the frame is so close to that som' *****?
Any info or diagrams would help also.

[mad_max]

Assuming the mechanicals are OK I'd say it was raw fuel exploding in the exhaust.... I call it back rap, kind of a brrrrraaaaappppp pop pop pop....

[mbubbac]

there could maby be a lil water in the gas if it wasnt changed for a while or the carb might be a lil too rich cuz when the engine is reving down its still drawing alot of fuel in and i would try to lean it up a lil

[200xkwit]

I heard somewhere that that kind of thing could be caused by excessive rod bearing clearence on the crank also. I think I read it in my 200x manual in the trouble shooting section

[crackshot]

there could maby be a lil water in the gas if it wasnt changed for a while or the carb might be a lil too rich cuz when the engine is reving down its still drawing alot of fuel in and i would try to lean it up a lil

The plug is a little black with no tan color at all.
Our altitude here is 5000 feet.
Rebuilt carb and has 98 main jet and 36 pilot.
Clip on needle is centered.

[jenndnn3]

When did this start? Just now, or after rebuild of carb? or has it always done this? Did you change anything? You may need to jet down.

[crackshot]

When did this start? Just now, or after rebuild of carb? or has it always done this? Did you change anything? You may need to jet down.

Did this when I bought it. had broken bolt on the cover on bottom of muffler so I drilled, re-tapped, put new bolt in and sealed it up.
This helped but still gat a "pop" as described above.

I think I will jet down to an 85 main. I hate to pull the carb apart again because it has new seals, etc. and is a PITA.

[bigredhead]

I'd like for someone to answer the " Intake Valve " access thing..... i've looked at it with itchy fingers a few times but left it alone... damn that's a tight squeeze.

[jenndnn3]

I adjust em, I have very small hands. Alot of folks bend the feelers to fit. Others have a tequinique where adjusting is not used by a feeler guage. Maybe one of them can pipe up.

Crackshot I feel your pain for getting to that carb, I have seen how tight it is in there. Usually there is a way to access the jets via the bottom. Does yours have this? That way you are not pulling the whole carb. It is not the actual bowl itself but rather a smaller area directly underneath the main jet at bottom of bowl.

[crackshot]

nope....gotta pull bowl apart...:( sucks nards having to pull the entire carb for a stinkin' dinky brass orifice.

[crackshot]

Well problem is solved and was the intake valve had way too much clearance.
Set to "T" mark in hole on case.
The exhaust valve was perfect clearance.
Intake was loose as a goose.
Now getting to the intake is a bear cat but can be done.
Clearances around valve access is tight.
You need 1/4 ratchet and stubby 10mm socket. You have to access on the exhaust side of engine.
Getting the feeler gauge in and keeping it in position is a PITA.
I snugged clearance, backed off 1/16 of a turn and tighted the locknut and re-gauged.
Had to do this twice and got a perfect clearance.
Put trike back together.
This is how my assesment of the situation went...
I think the intake valve was never adjusted when whoever had it took it in for tune up or did it themselves.
The exhaust valve adjustment is a piece of cake for access, the intake is not.

Took trike for a spin and made not a "pop" when I let off throttle now.