mk 2 carb

pirelli · Post by **pirelli** » 26 Nov 2006, 13:12

after having starting problems on my mk2 i bought a new pilot jet and cleaned out carb. the bike now starts easily but runs like the choke is on full. the only way it will run something like reasonably is if i switch off the petrol. then as it starts running out it will rev and run properly. stripped it and blown it out a few times since, checked float height, all ok. if any one has had a similar problem i would be glad to hear from them.
thanks.

shemston_crm · Post by **shemston_crm** » 26 Nov 2006, 20:23

got the identical problem on my mk3 any help would be appreciated no end.

CRMR · Post by **CRMR** » 26 Nov 2006, 21:49

i bet you have put it back together slightly wrong yet every time you strip it you make shure you put it back together the way it was , wich was wrong from the first time ,?????. It sounds like theres an o ring missing from one of the adjusters , , the emulsifier baffle is fitted wrong or the needle and sliders not fitted well ,

please read disclaimer in my sig ,,

shemston_crm · Post by **shemston_crm** » 26 Nov 2006, 23:42

thanks crmr gotta be worth a try.

by the way thats a very clever disclaimer you have there

pirelli · Post by **pirelli** » 28 Nov 2006, 17:40

dont think i put it back together wrong, fitted new o rings and pilot jet from leisure trail, but when i blew out carb after stripping it i thought some thing flew out , but cant see anything on diagram missing.

Post by **Jonorow** » 28 Nov 2006, 17:52

Check your idle screw is wound out and also check your fuel mix screw is set correctly. Then check your throttle cable is set corrctly and has not wound up pulling the slide with it. (easily don if you remove the carb top!!) Jon

pirelli · Post by **pirelli** » 28 Nov 2006, 18:01

thanks jonorow, checked those , but do think slide is to high but cant adjust it any lower.

Post by **Jonorow** » 28 Nov 2006, 18:05

check on the throttle end aswell. I only know to check all the cables as when i got my crm, the oil pump wouldn't line up and had to adjust all the cables properly. also has you oil feed come out? this would cause a massive air leak and also casuse a fast idle too. Jon

pirelli · Post by **pirelli** » 28 Nov 2006, 18:10

thanks, i will check that tonight

slider · Post by **slider** » 28 Nov 2006, 21:02

had a similar problem on my old kx250,that turned out to be the needle valve attached to the float wasn't seating right due to debris between it and the valve seat.with this problem though i had fuel peeing out of the over flow,turn the fuel off,the fuel level in the carb drops and it would run o.k for a while.if you havent got a puddle of fuel under the bike then this probably isnt the cause however i'd check the overflow hoses to make sure they arent blocked

shemston_crm · Post by **shemston_crm** » 28 Nov 2006, 22:44

thats what mine does slider pees out all over the shop runs fine with fuel off like you said

Post by **Jonorow** » 28 Nov 2006, 23:08

seems a common falt on crms at the mo ( yes mine does too sometimes!!!) but other times the bike runs great with no probs. stop it for half an hour then it pours fuel on your boots a bogs down when you ride on the flat........... CRF anyone? I am getting tempted, but cant be asred with the maintenace, so may look at an XR400....... or suffer for some great fun on the crm (when it runs) Jon

slider · Post by **slider** » 29 Nov 2006, 00:18

did any of you check the needle valves when you stripped the carbs?,if not then thats the first thing i'd go for.
take off the carb,remove the float bowl and hold the carb in its usual upright position.now blow down the petrol pipe while gently lifting the float,at first air should pass through the needle valve but the higher you lift the float the air should not be able to pass through it (you only have to apply light pressure to the floats to achieve this,so no vices,hammers,10 tonne presses etc

)
if you can still blow down the petrol pipe then its definetley the needle valve causing the problem
check the needle valve tip (pointy end)for any signs of wear eg pitting,marks or i have seen them with complete grooves all the way around,any noticeable damage replace immediately along with the brass seat that it fits into(normally screwed into the carb body)
if no damage is seen clean the valve tip,then check inside the valve seat for crap,clean the seat manually blowing them out isnt always 100% then rebuild and do the above test again.if the airflow stops your ok if it doesnt then get a new needle valve, remember check your float height again when youve sorted it
dont know if any of you have ever stripped your tanks down,i did mine when i painted it a while a go and the rusty s**t that came out of mine was unreal,when i stripped the carb down for inspection a few weeks later it was full of the same brown s**t,im beginning to wonder if theres a tank seal fault?any way i'm going to fit one of those clear plastic fuel filters in the fuel line when i put her back together to stop it happening again perhaps you guys should think about this aswell

let us know how you go on

shemston_crm · Post by **shemston_crm** » 29 Nov 2006, 00:56

thanks mate!

as for the tank i left an old crm tank (mk3) in the garden for about a year to discover there was no rust in there what so ever and that was with the cap off i came to the conclusion that it must be galved. what model is your crm?

slider · Post by **slider** » 29 Nov 2006, 01:16

its a 91 mk2,but it'd been badly treated before i got it.

it just struck me when reading yours and jonorow's posts that there may be a tank seal issue,dont know wether they use the same filler cap or not having never being up close and personal with a mk3
let me know wether this cures your fault shem