Old trx 300 missfire troubles

[lloydguy]

Crappy phone pic's ,I don't know if you can see it very well but there is a pretty good groove
wore into the cam bearing surface at the far right and for sure some wear in the tip of the intake
lobe.

 

[lloydguy]

Update on my old beast,It sat all winter and I just recently got new cam chain and front and rear cam chain
guides.Part's are in, start's and idles fine , just like before but it's still backfiring over 3000 rpm.(air filter and
box removed) I don't know what else to try on this old girl.I have 2 carb's,2 coil's and 2 cdi's. same backfire
after I exchange part's.
Could I be giving it too much air by doing my testing with the airfilter and box removed?
Thus leaning it out at higher rpm's and causing the backfire?

 

[tex78]

If it's a vacuum operating carb yes, needs filter and lid on to operate proper

Needs the back pressure persay to on either side of carb

 

[lloydguy]

OK, thank's TEX.I will try that tomorrow.Yes it's a vacuum pot type carb.I read a old thread on a honda
forum an backfiring issue another guy was having and responder's asked if the stock airbox or snorkel
had been altered from stock.They said the stock box and snorkel were designed to flow "X" volume
of air and if altered it can make these one lunger's run like crap.
FYI to anyone that might have any advise as to what to try next on this old POS I bought.
New part's are - Cam chain,both cam chain guides,all new gasket's,carb,coil,CDI,plug.
Fresh gas has been used for all test's,carb is 100% clean,timing is bang on and compression is 161 ish PSI.
Wiring was gone through end to end, stator and pulser coil test fine as per factory book.
I am 99% sure cam timing is correct,but I am going to pull the valve cover off again tomorrow just to double
check.
Valve lash is .006" for anyone that might ask again.
THIS THING IS DRIVING ME BONKER'S SOMEONE PLEASE TELL ME WTF IT'S PROBLEM IS.......................

 

[neilsleder]

I would buy a bigger and smaller pilot jet. Try the different sizes and see if it helps. My brute force ran the same way after I snorkelled it and the pilot jet fixed it.


Sent from my iPhone using Tapatalk

 

[gibsons]

There are no safety's built into the throttle are there?

 

[lloydguy]

There are no safety's built into the throttle are there?

No, there is not.
Farted around some more today.
removed carb,changed pilot and main with original's - no change
changed coil - no change
changed plug and CDI - no change
Anyone know what would happen if my pulser coil was loose? Am I grasping at straw's?

 

[lloydguy]

Update,I MIGHT have found the problem.I took the left hand crank case cover off lastnight
too see if the mounting bolt's were maybe loose on the pulse generator(pulser coil whatever)
They were not,but when I turned the cover upsidedown to start cleaning some of the shmag
out of it the blue/white signal wire (to tell the cdi where TDC is) fell off of the male spade that
it is supposed to be plugged into.There was hardly any connection there at all.
Being 2 AM ,when I finished last night I never test ran it yet but finger's crossed I will be firing it up
in afew hours.