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300ex only half rev..???

16477 Views 38 Replies 7 Participants Last post by  JERSYBOY73
i have a 1998 honda 300ex and just put in new rings. has a big bore kit in it. timing is right on and no odd noise when idle. fires right up and sounds great again but for some reason it will only rev half throttle and then revs out. all power is gone at that point. need some help i have tried going one tooth back on the timing and goin on tooth ahead and does not change,.any if would be great.
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Agree^^^^^ also the valve adjustment may be off maybe too tight? check your choke lever too
yeah clean the carb especially the jets and their seats
When you set the cam in how did you install it and what did you adjust the valves to?
You may have a ring that is not spaced properly, when you installed the piston kit did you check the end gap on the rings before you put them onto the piston? Also when the cam was installed after the top end was rebuilt, the Lobes should have been facing downward and the 2 "-" marks allign with the top of the head. The valves are set at .004 int and exh. I'm not trying to belittle your mechanical abilities I'm just trying to get all the facts form the time you removed the old piston to the time you re installed everything.
ok now that I am more clear on your install.... Lets get to the carb
1. these carbs are extremely sensative to minute specs of trash, when your son I believe is what you stated flooded the engine with water unless he jumped into a pool the water was dirty
2. the first passage the water will take is through the filter then the carb sucking into the engine choking it off the second passage is through the exhaust when it dies.
3. remove the carb completely dissassemble it remove all the o-rings and hoses. Remove the pilot (air) screw spring and o-ring there then the jets.
4. Thouroughly spray the ever loving piss out of the carb and all it's orfices the take your blow gun and blow it out real good.
5 grab a tiny single strand of wire like speaker wire and clean the slowjet the orfices are to tiny for torch tip cleaners, ust those for the main jet.
6. re install everything in reverse order, turn the pilot screw in until it seats and back it out 2 1/2 turns. install it and start her up and see how it goes
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Glad you got it fixed hang out we tend to be a fun bunch or people... lol
Thast what we are here for bro. good luck and be careful Post a few pics of the ol' beast
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