• 2 Stroke Husqvarna Motorcycles Made In Italy - About 1989 to 2014
     WR = 2st Enduro & CR = 2st Cross

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250-500cc Wr 250 engine problems! Any ideas

Angles

Angles

Husqvarna
Gday guys I am new to the world of Husqvarna but have owned a few Jap bikes both dirt and road over the years. I fell in love with an 07 wr250 and it goes awesome as long as I can keep the water up to it on the first ride I noticed it was getting warm. On closer examination the coolant was low and the oil milky. So my first ride and first pull down. New water pump seals and a small shave of the head with new head gasket o-rings and all good I thought but it was still pressurising the radiator and pumping out coolant. next I have replaced the radiator cap (probably should have done this first) replaced the seals and bearings around the power valve and threw in a piston and ring kit while I was there since everything was within spec except the last owner must have been a bit rough in installing the rings and broke the edge off one.
I have also installed a trail Tech speedo and can confirm that it is getting to 75deg (measured on the head at the spark plug) and then it starts to pump out coolant out of the overflow. The oil isn't milky anymore a little greyish but I am told the clutch plates can do that. I am thinking maybe there could be a crack in the head or cylinder that is opening when it warms up? What do you husky blokes reckon is this a common problem? Is there something I am missing here? There is s 99 head on evil bay which according to the parts catalogue is the same (thanks you guys have helped already) I Am thinking of trying this to cheaply eliminate the head as an issue. Any thoughts ? Thanks in advance for any help. I am told you guys know your stuff and are happy to help a newby so thanks again any help or info would be very welcome
Angles
 
If you got a crack head or cylinder l can only suggest performing a leak down test.

Correct, greyish tranny oil is the result of clutch fibres and if you're a bit lazy in between the frequency of changinf tranny oil, the best sign is when you have a hard time finding neutral.

When you say "pump out coolant out of the overflow", is this stationary or after riding slow technical trails? You haven't filled it up to the brim? If so, you haven't allowed for expansion which will cause an overflow.
 
Fill the radiator just full enough to cover the cooling fin holes. If you fill it to the top it will puke out too much and you will be chasing your tail. If it still pukes out coolant when it's properly filled then you definitely have a problem and a pressure check should find it. There a hand pump that fits in place of the radiator cap, you pump it up to about 14 psi and look to see where the coolant is going.
 
Thanks for the response guys. Yeah I've been chasing my tail a bit for sure! I am filling it to 5mm above fins and it still does it. I am rocking it side to side to burp it when I've filled it and then topping again to get 5 mm above fins. Is this right?The coolant comes out of the overflow tube when the head temp gets to 75 deg Whether riding or stationary (not a drop before) and once started would continue to pump it dry if I let it I reckon. I will try to get hold of some pressure test gear and see. I'll get some gear and get back to you. Thanks
Angles
 
Angles said:
Thanks for the response guys. Yeah I've been chasing my tail a bit for sure! I am filling it to 5mm above fins and it still does it. I am rocking it side to side to burp it when I've filled it and then topping again to get 5 mm above fins. Is this right?The coolant comes out of the overflow tube when the head temp gets to 75 deg Whether riding or stationary (not a drop before) and once started would continue to pump it dry if I let it I reckon. I will try to get hold of some pressure test gear and see. I'll get some gear and get back to you. Thanks
Angles
Click to expand...
If the coolant is circulating like it's supposed to check to see if you're getting air bubbles passing by when you rev it up cold. Another test is to, upon 1st start up of the day, remove radiator cap to verify there is no pressure then replace cap and start the engine and snap throttle/rev it 3-4 times and immediately shut it off and then remove radiator cap and listen for pressure escaping. If there is pressure then it is combustion pressure since it can't be from expansion because the engine has only ran for 30 seconds or less and no heat exists. If pressure exists then pull the cylinder head and look at the top of the piston for signs that it has been steam cleaned from coolant getting past the "O" rings. If bubbles existed in the first check then this would reinforce your diagnosis and now would be a good time to check head and cyl for cracks, a cut or misplaced "O" ring or warpage. If in the 1st test the water was not circulating then look at your water pump for a slipping impeller or a drive not working.
 
Lankydoug by the same thinking cant you kick the engine over to see the bubbles in the system?
If your head is cracked i can arrange a replacment but i doubt its a cracked head over gaskets/improper torque of head bolts.
 
juicypips said:
Lankydoug by the same thinking cant you kick the engine over to see the bubbles in the system?
If your head is cracked i can arrange a replacment but i doubt its a cracked head over gaskets/impropet torque of head bolts.
Click to expand...
If it's really bad it will bypass combustion air while kicking but it usually takes a running snap throttle blip to build the pressure to show a minor leak. And yes it's usually "O" rings or gaskets but I try to include all the possibilities when typing so who ever is doing the work will look closely during disassembly and not miss anything.
 
lankydoug said:
If the coolant is circulating like it's supposed to check to see if you're getting air bubbles passing by when you rev it up cold. Another test is to, upon 1st start up of the day, remove radiator cap to verify there is no pressure then replace cap and start the engine and snap throttle/rev it 3-4 times and immediately shut it off and then remove radiator cap and listen for pressure escaping. If there is pressure then it is combustion pressure since it can't be from expansion because the engine has only ran for 30 seconds or less and no heat exists. If pressure exists then pull the cylinder head and look at the top of the piston for signs that it has been steam cleaned from coolant getting past the "O" rings. If bubbles existed in the first check then this would reinforce your diagnosis and now would be a good time to check head and cyl for cracks, a cut or misplaced "O" ring or warpage. If in the 1st test the water was not circulating then look at your water pump for a slipping impeller or a drive not working.
Click to expand...
LankyDoug thanks mate I will put it back together and try these checks. It has new o- rings that have only been in since run in but problem was there before that. There was no visible signs of the coolant breaching the o rings. I have been torquing down the head as per the manual so that should be good
 
juicypips said:
Lankydoug by the same thinking cant you kick the engine over to see the bubbles in the system?
If your head is cracked i can arrange a replacment but i doubt its a cracked head over gaskets/impropet torque of head bolts.
Click to expand...
Juicy pips thanks for the input mate. The bike has done the same thing for the six months I've owned it and I've pulled it down about 4 times now and each time I thought I had it :-) the head has been shaved so is flat and the o rings were new and only done the husky book run in procedure. Bolts were torqued down to spec and no evidence of coolant or exhaust gas breaching the head gasket o rings was seen on pull down. Last pull down some evidence of breaching was found under the power valve cover so I lapped both surfaces replaced the o rings and rebuilt it but bike still pumps out the coolant! That said there was no evidence of it leaking past here this time on pull down so that is an improvement! The joys of a second hand dirt bike I suppose! It is a 2 stroke so surely there can't be much left? I'm away this weekend but will try to get back to it early next week and let you guys know what I find. Maybe $60 for a second hand head isn't a bad idea. Local mob was going to charge me that to pressure test the head!
 
Could be your jug, barrel, cylinder has got the damage in it.
Thats an odd problem.
Good luck fixing the issue.
 
If memory serves me correct im sure there was a year where some of the cylinders wasn't machined correctly at the factory.
By not allowing the coolant flow properly and causing the motors to over heat. Might be worth having a search and see if its still on the forum some where.
 
To add to oneal's comment, I have seen on some engines where someone replaced the head bolts with longer head bolts that extended down into the cooling passages and restricted the coolant flow. Most cylinders don't have the head bolt holes tapped all the way through but it's another thing to look for.
 
Not sure on your issue but after 6 months and the bike still runs,....well that is a good sign so hang in there with your bike ...
 
Just lurking here in the wings hoping you find the problem. I've got a new to me 06 and it's been a solid performer since way before I got my hands on it. Always great to get a bike from someone who knows their stuff..

However knowing what happens is always good for future reference. Wish I had more experience with this motor or I'd have something more to add other than good luck!
 
oneal said:
If memory serves me correct im sure there was a year where some of the cylinders wasn't machined correctly at the factory.
By not allowing the coolant flow properly and causing the motors to over heat. Might be worth having a search and see if its still on the forum some where.
Click to expand...
Oneal thanks mate I'll check it out but I've only let the bike get hot on the first ride before I worked out it had a problem. On the upside I stop so regular to top up coolant that my mate's don't know how unfit I am :-) on the downside it drinks my camelback dry and I don't get a look in!
 
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