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Discussion Starter · #1 ·
crf 70 troubleshooting?

hello everyone!

i had just bought all new parts for my crf 70 which has been sitting for years and is finally ready to run well i hope ..i tried kicking it probably 50 times and alot of air comes out of the the airfilter.:confused:. i put new oil,gas,airfilter,spark plug and im wondering maybe another new carb like a mikuni.maybe i should try cleaning the carb??what would you say the problem is with this?...thank you very much..also does anyone know what size the stock intake is on a crf 70 or stock carb size i have new mikunis sitting in my garage that need to be used lol..thank you very much!
 

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Take the carb off and clean your jets and drain the bowl. Dont just spray them off with carb clean. Soak the jets in parts cleaner or carb clean, take a sewing needle and use it to clean in side the jets.Then take some compressed are and blow out all the jets and all the ports holes and so on. Also dran all that old moon shine out off your tank and replace it with (gas). P.S check your pet cock is on.
 

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Discussion Starter · #11 ·
Giffin774 said:
Take the carb off and clean your jets and drain the bowl. Dont just spray them off with carb clean. Soak the jets in parts cleaner or carb clean, take a sewing needle and use it to clean in side the jets.Then take some compressed are and blow out all the jets and all the ports holes and so on. Also dran all that old moon shine out off your tank and replace it with (gas). P.S check your pet cock is on.




thanks man! im gona try that.i was plannin on cleanin that carb but i have new mikunis in my garage i might try a new one!i did replace the gas and oil,and it has a new petcock i put on yesterday.i am gona print that off though and do what you said cause that all sounds good to me....i still dont get why its so easy to kick it though.could that be the problem right there?
 

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Discussion Starter · #12 ·
knucklehead459 said:
rings might be shot they are pretty easy to kick over stock


it hasnt been riden much. it was bought riden little and put in a barn for years.then given to me for free for a learning process..but you could be right.if its rings are those costly?...i now afically have 3 pit bikes to fix:cry: lol,but out of all them this poor lil 70 is bothering me the most, thanks for helpin me out with this man,i wana hear him run so bad lol
 

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Worn or collapsed rings are not the cause of your problem.



The only way for air to come back out of your air filter is:



The intake valve is open when it should be closed. This is confirmed by low compression (easy to kick over). I suspect you have a much more serious problem than carburetor.



Remove the crankcase timing cover and the head timing cover (the round one), remove spark plug.



Inside the head timing cover you'll note a notch on the left, on the camshaft sprocket you will find an "O" mark. Using the flywheel, rotate the "O" mark to the notch. Get as you can. Note the timing mark on the crankcase (smaller notch than in the head, but still readily identifiable). There are two markings on the radius of the flywheel, T & F. Is the T in line with the notch/timing mark?



If no, your timing chain may have skipped - possibly leading to bent valves (low compression, air through filter, easy to kick over). Let us know.
 

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Discussion Starter · #17 ·
LoudFastUgly said:
Worn or collapsed rings are not the cause of your problem.



The only way for air to come back out of your air filter is:



The intake valve is open when it should be closed. This is confirmed by low compression (easy to kick over). I suspect you have a much more serious problem than carburetor.



Remove the crankcase timing cover and the head timing cover (the round one), remove spark plug.



Inside the head timing cover you'll note a notch on the left, on the camshaft sprocket you will find an "O" mark. Using the flywheel, rotate the "O" mark to the notch. Get as you can. Note the timing mark on the crankcase (smaller notch than in the head, but still readily identifiable). There are two markings on the radius of the flywheel, T & F. Is the T in line with the notch/timing mark?



If no, your timing chain may have skipped - possibly leading to bent valves (low compression, air through filter, easy to kick over). Let us know.


thank you very much! im gona halft to tear this thing apart i quess and see what happends.i may have someone help me with this cause i dont have that much expierence yet with motors..should i get a manual before i do this are should i be fine
 

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Discussion Starter · #18 ·
Kurlon said:
Just for giggles check the valves for clearance. I've revived a couple 'dead' 70s in people's yards with a pair of pliars by getting a little clearance. All of a sudden the bike comes back to life.


okay. i will check that before i go and tear the whole motor apart.could have that possibly made it easy to turn over? thank you so much to everyone for helping me out!
 

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Kurlon said:
Just for giggles check the valves for clearance. I've revived a couple 'dead' 70s in people's yards with a pair of pliars by getting a little clearance. All of a sudden the bike comes back to life.




+1 Good point! Check this first. Clearance should be .002" to .004", set them to the loose side.
 

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Discussion Starter · #20 ·
LoudFastUgly said:
+1 Good point! Check this first. Clearance should be .002" to .004", set them to the loose side.


thankyou very very much i was just about to ask for the clearance because i have no manual.i think for down the road or if i gota split the case im gona order one off of ebay, i found a few on there
 
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