Jump to content
Sign in to follow this  

Crf250 starting problems

Recommended Posts

Hello, i just bought a 04crf250 that is awefull to start with the kickstart!

If i bump it as soon as i drop the clutch it goes straight away but from cold the thing just wont do anything! When its warm i can start it after 3 quick kicks with a little throttle!

I have been doing everything that is suggested on the interenet eg throttle pumps ans correct kicks.

I have taken the carb of and cleaned that out.

It has been suggested by a mate it could be my valves!

Can anyone help be most apreciated!

Share this post


Link to post
Share on other sites

Checked clearences all looks okay, i assume the best thing to do is strip the head of and have a look at valves

Share this post


Link to post
Share on other sites

Do a leak down test if you think they arent sealing with good clearances.

x2 

 

mine was the same with good clearance. it had me puzzled, long story short, i had a broken exhaust valve spring.  

Share this post


Link to post
Share on other sites

a leak down tester is probably the easiest, either that or take it apart and inspect it. Seeing as it runs fine bumpstarting it's probably low compression. 

 

you can inspect the piston and cylinder, measure ring end gap. check the valve seating by pouring some diesel or gas in the ports with the head upside down to get an idea if the are sealing ok.

 

like i said mine had a broken valve spring. i'd try to resist the temptation to bumpstart it and ride it anyway because it's telling you that there's a problem that could get very worse real fast. 

Share this post


Link to post
Share on other sites

Yeah i wont be carrying on till ive sorted it! Me an bro cleaned the carb other day and now we put it back from when i was having a play tonight quickly i noticed its shooting flames and back firing when i accelerate throttle and quickly shut it of so im not sure whats wrong there!

Share this post


Link to post
Share on other sites

Which valve is likely to have worn, could it just be carbon deposit around the valves causing them to no seat correctly? Or could it be piston rings?

Share this post


Link to post
Share on other sites

Just an update stripped the bike this afternoon, valves look imaculate and sat petrol on them level with the head and looks like they are all sealing perfectly, piston dosent loom very old and the cylinder wall looks imaculate so where do i go from here perhaos i measure the clearance wrong and they need shimming?

Share this post


Link to post
Share on other sites

Just an update stripped the bike this afternoon, valves look imaculate and sat petrol on them level with the head and looks like they are all sealing perfectly, piston dosent loom very old and the cylinder wall looks imaculate so where do i go from here perhaos i measure the clearance wrong and they need shimming?

sounds good. you can put the cam back in and remeasure it.

 

I usually fill the port. one side at a time, not the combustion chamber, but yea. at that point the valves are coming out for a closer inspection of the margins and seats anyway.

 

 take a close look at the ring end-gap. much over like what? .050 and it's going to be a problem. should be crap i forget, .015 ish. my old 04 quit starting and it was .054 i want to say. you want to measure it correctly in the right spot.

 

 

was your chain tensioner in good shape? 

Edited by over rev

Share this post


Link to post
Share on other sites

May habe found my problem looks like my valve clearance measing was a waste of time, re did it and one of the inlet valves is touching the cam it it that bad so going to take to motorbike ahop and get them to shim it will update you when i get it all back together thanks for help

  • Like 1

Share this post


Link to post
Share on other sites

Hate to break it to you, but you're likely going to need a valve job. Prepare for at least a $500 expense. This is if you pull the head yourself, ship it off, and reinstall it. Have someone else do it and it will easily be twice that. It's very simple to pull the head yourself. Get the service manual if you haven't already. It will pay for itself many times over.

Edited by mossman77

Share this post


Link to post
Share on other sites

If you do just get it shimmed ask what size they put in and measure the clearance again, then let us know what they are. Regardless of what that is though if the clearance starts closing again its time for new valves.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...