Jump to content

XR250 will not fire at all


Recommended Posts

Hi Guys

 

My friend has given me his bike (2004 Xr250e, black tank, no kickstarter) to try and get it to run.

 He broke the gear change shaft a while back and had this replaced by a bike mechanic (not me) and since then he has never been able to get it to run.

I have voluntered myself to help out and this is the symptoms and what up to yet I have checked

 

1/ The plug has a very healthy spark

2/ I took off the rocker cover and checked the timing wiith the TDC mark on the left side fly wheel All ok!

3/ Tappetts checked and adjusted to spec, all ok!

4/ I have checked to make sure the small pin and spring un der the decomp on the cam is in place and its all ok!

 

As the bike Does not have a kickstart, the only way of starting is via the electric start, this turns the motor fine but I get NO fire at all- not even a backfire.

 

The carb is a Keihin CV and I had a spare one which I fitted and this made no difference at all...

 

It does not appear to be getting gas from the carb, as the plug has NO petrol on it , even after turning over for 5-10 seconds ???

 

# Is it possible that there is not enough compression to pull a vacuum through the CV carb?? and if so what should I check #

 

I hope to resolve this , this week as we have a lond distance trail next Sunday..

 

Any ideas and help is greatly appretiated

Edited by mudflicker
Link to comment
Share on other sites

Clogged jet in the carb would be normal in this situation. How long did it sit?  Alcohol in the petrol over there?  We have problems in the US if they sit even a month or so with our 10% alcohol in gasoline.

Blow them out with compressed air or stick a fine wire through them to clear. Bet she starts right up. 🙂

Edited by MindBlower
Link to comment
Share on other sites

 If cleaning the jets gives no joy, Check compession! Had the piston rings stick in the piston grooves on mine earlier this year! , needed new rings, cleaning the old ones just made it smoke.

 Many thanks for your reply.

I have installed another carb (CV88) which is the same as the stock one fitted. I stripped this completey cleaned it before I fitted it and again NO fire up.

 

I have not done a compression test yet, but will do.

 

This model only has a auto de-comp and not a manual one, I have looked at this and it seems to be working. 

Link to comment
Share on other sites

You've determined that the cylinder is not getting fuel by reading the plug. Replaced carb. Silly question, is the CARB float bowl getting fuel? Time to look further upstream, fuel line, petcock, etc.

Compression test?

 

Yes, there is fuel in the float bowl, fuel through petcock.. I will be doing a compression tester later in week as I am waiting for the tester to arrive..

As this Keihin carb is a CV88 , I am having problems trying to find a dealer who can supply a repair kit/jets etc for it ( I live in UK)

 

 It does certainley look like it could be a fueling issue, combined maybe with a compression problem too.

 

Thanks for the help

Edited by mudflicker
Link to comment
Share on other sites

As this Keihin carb is a CV88 , I am having problems trying to find a dealer who can supply a repair kit/jets etc for it ( I live in UK)

Google on US sites for "Keihin carb CV 88" shows this carb is used on Harley's and many, many places sell rebuild kits.  Even Amazon.com....

 

Is there a different CV88 in UK/Europe?

 

 

The Google image search is interesting, also.

 

 

:ride:

Link to comment
Share on other sites

Look on ebay for a carb repair kit, i bought one from america for 50 dollars (oz) took about 2 weeks or so to get here.

If i was you id drop a very small amount of fuel down the plug hole and then see if it fires. If it does then you have a fuelling issue, if it dosnt then you have a compression or spark issue.

Id be surprised if its a compression issue, unless it was seriously down on compression. Mine has 80psi (should be 92-107 if i remember correctly) i could push the kick start down with one finger and mine starts first kick every morning, runs great.

Its probably something really simple that youre overlooking

Link to comment
Share on other sites

Make sure plunger and spring were put back in at last reassembly. Its small spring with pin above it,under cam lobe,on right side,runs decompression device. numbers 4 and 5 in attached page ,see this link

http://www.cheapcycleparts.com/oemparts/a/hon/5053dff4f870021c54bdfd57/cylinder-head

Edited by firstplacephoto
Link to comment
Share on other sites

Make sure plunger and spring were put back in at last reassembly. Its small spring with pin above it,under cam lobe,on right side,runs decompression device. numbers 4 and 5 in attached page ,see this link

http://www.cheapcycleparts.com/oemparts/a/hon/5053dff4f870021c54bdfd57/cylinder-head

 

Yep. the pin is in place and does spring move up and down when rotating the camshaft.. But how would I know if the mechanism is working or sticking, causing the ex valve to stay open ??

Link to comment
Share on other sites

Google on US sites for "Keihin carb CV 88" shows this carb is used on Harley's and many, many places sell rebuild kits.  Even Amazon.com....

 

Is there a different CV88 in UK/Europe?

 

 

The Google image search is interesting, also.

 

 

:ride:

 

The CV88 on my bike is a little different than the HD version, The bike was actually imported to UK from Japan in 2004 and it is Not a usual UK version..This is what has caused me problems getting info and spares etc..

Link to comment
Share on other sites

Update

today I put a small amount of fuel into the head via the sparkplug hole. try to start- expecting at least some kind of `fire up` and got nothing at all

 

I have an absoluetly brilliant spark and valves are adjusted perfectly.  I am beginning to think it could be one of the following:

 

1/ Bad compression due to stuck or broken rings

2/ Flywheel moved on crank ( henze valve timing out)

 

Any ideas out there befor I take the head off  ??

 

Oh just for clarity I slackened off the right hand Ex valve and it made no diference

Link to comment
Share on other sites

I'm gonna guess that you either put too much gas in and it flooded it, or not enough and it leaked past the rings by the time you got the plug back in. You've got to have REALLY low compression for an engine to not even pop a little (like a hole in the piston). Do you have access to a timing light? Shine the light in the timing mark peep hole while someone else kicks it. If it is firing at or near TDC, check <flywheel timing> off your list. Next do a compression test, or at least shoot some compressed air in the cylinder on the compression stroke. If it turns the engine backwards till an intake valve opens to release the pressure, your valves are closing well enough to fire - check that off your list.

I'd be willing to bet it is a fuel problem.

Edit: I just re-read your initial post and saw it was e-start only. Have you tried bump-starting it down a hill? Maybe the starter just isn't cranking fast enough to draw the right amount of fuel or create the right spark? Have a buddy tow you behind a car. If still no fire, imidiatelty pull the plug and see if it is wet.

Edited by ITLKSEZ
Link to comment
Share on other sites

I'm gonna guess that you either put too much gas in and it flooded it, or not enough and it leaked past the rings by the time you got the plug back in. You've got to have REALLY low compression for an engine to not even pop a little (like a hole in the piston). Do you have access to a timing light? Shine the light in the timing mark peep hole while someone else kicks it. If it is firing at or near TDC, check <flywheel timing> off your list. Next do a compression test, or at least shoot some compressed air in the cylinder on the compression stroke. If it turns the engine backwards till an intake valve opens to release the pressure, your valves are closing well enough to fire - check that off your list.

I'd be willing to bet it is a fuel problem.

Edit: I just re-read your initial post and saw it was e-start only. Have you tried bump-starting it down a hill? Maybe the starter just isn't cranking fast enough to draw the right amount of fuel or create the right spark? Have a buddy tow you behind a car. If still no fire, imidiatelty pull the plug and see if it is wet.

Thanks for the reply.

I have a `snap on` booster and the motor fly`s over super quick. with a brilliant spark,after turning over for 5-10 secs, the plug is completely dry,

maybe the timing is out  as you said above , I will try and get hold of a timing light and check the timing .

 

I have also swopped the cv carb for a spare I have and still a dry plug.

I bought a compression tester today so will carry out that test .

Edited by mudflicker
Link to comment
Share on other sites

Thanks for the reply.

I have a `snap on` booster and the motor fly`s over super quick. with a brilliant spark,after turning over for 5-10 secs, the plug is completely dry,

maybe the timing is out as you said above , I will try and get hold of a timing light and check the timing .

I have also swopped the cv carb for a spare I have and still a dry plug.

I bought a compression tester today so will carry out that test .

Is the other carb off of a running bike?

I'd keep adding fuel until the plug comes out at least damp. How about a squirt bottle of gas through the intake (take the rear boot off the carb)?

Link to comment
Share on other sites

Is the other carb off of a running bike?

I'd keep adding fuel until the plug comes out at least damp. How about a squirt bottle of gas through the intake (take the rear boot off the carb)?

 

Thats sounds like a plan,

as for the carb , it was not of a running bike, but I have stripped/cleaned/checked jets etc.

 

FYI.

This bike was `rebuilt` about 5 years ago and has NOT run since, this was befor I got it, this is why I am thinking that there could be a problem with piston/rings/sheared key etc..

I was thinking about taking the head and barrel off to check and see if it is actually at TDC with the marks..

Link to comment
Share on other sites

FYI.

This bike was `rebuilt` about 5 years ago and has NOT run since,

stop the show.

pull the valve cover, set the flywheel timing mark with piston at TDC (this can be verified with a straw or soft probe down the spark plug hole) and verify cam timing relative to correct TDC timing. Let me know what you find.

Link to comment
Share on other sites

stop the show.

pull the valve cover, set the flywheel timing mark with piston at TDC (this can be verified with a straw or soft probe down the spark plug hole) and verify cam timing relative to correct TDC timing. Let me know what you find.

 

Thanks Redhurricane, I will take some pictures and post back, is there any particular areas I should be looking at? I have looked at this the other day, and at TDC on flywheel the camshaft marks are level with the top of the head casing and the lobes on the cam are facing down.

 

*Update*

 

I have just spoken to the guy who rebuilt the engine 5 years ago!! Apparently the bike did run after the rebuild, but did seem a bit flat and loss of power etc. it was left and has`nt started since  ..

Edited by mudflicker
Link to comment
Share on other sites

Take out the air filter, put your hand over the inlet area, crank it. If not sucking you prob have compression issues! Might bump start!?

 

Ok, today I got hold of a compression tester and tested the compresion, which was 35psi  . well low, squirted a little oil in the cylinder and went up to 75psi.. I am assuming I have a piston or ring problem, so I have started to tear down,

This bike has a auto camchain tensioner , how do I get this out to release the camchain tension to allow me to take the cam out. I have read that you can rempove cam sprocket off the cam to release the tension, this seems odd to me..cam.jpg

 

*Edit*

 

I have managed to sort out the camchain tensioner and have removed the head, the head gasket looks suspitious , so maybe that was the issue, but I am going to take it down and remove the barrel too, might as well change the rings while I have it in `bits`

 

I would appretiate any feedback on spares and places to buy, I live on the Isle of Man in the Irish sea and my local Honda Dealer is not very helpful

Edited by mudflicker
Link to comment
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:

×
×
  • Create New...