250-500cc 2009 Husqvarna WR 300 - Factory Air Leak, Engine Seizure & Fix

Hi All,

Posted this at Thumpertalk as well but wanted to make sure that the whole Husky community knows about it.

I purchased a ‘new’ 2009 Husqvarna WR 300 to replace my 2006 Husqvarna TE 510 in July 2009.

In early August, I was riding the bike briefly at ‘wide open throttle’ and experienced a complete seizure of the engine – the bike had approximately 4 to 5 hours of total time at that point. At this point, thinking that I was on my own, I ordered a piston kit & gasket kit from Tasky’s Metric Cycle in Everett, Washington, and dropped the cylinder off at Mongoose Machinery Port Coquitlam, BC, to repair and re-nickoseal the cylinder.

Given that no one had been able to tell me what had caused the engine failure, I took the further precaution of having a local machinist conduct ‘leak down’ test on the rebuilt engine. A serious leak was quite evident where the V-Force reed block meets the rubber boot from the carburetor - instead of merely bubbling the soapy water, the liquid was ‘blown’ right off and the applied pressure immediately bled away. The screw driver points to the location of the air leak at the top of where the boot and the reed block meet.

Upon closer inspection of the leak point, the V-Force reed block has a stamped 6 digit code right where the sealing O-ring from the ‘boot’ from the carburetor is therefore a tight seal is impossible (see attached images). The machinist attempted to use ‘3 Bond’ to seal the leak but it was unsuccessful. In the image below, the silver compound on the reed block is the 3 Bond and it clearly shows where the O-ring should seal and that the stamped digits make this seal impossible.


FIX ***

I used a piece of carburetor gasket between the carb boot and the reed block:
take the engine side carb boot off and trace the outside and inside edges of the boot on the gasket material
cut along the line outside and inside lines
the 'inside' line will likely not completely match thus additional work will be required to ensure complete airflow
This fix seems to have resolved the problem - now we'll see if I get any factory support on the engine seizure...

One cheap and quick way to find an air leak is to have your bike idling and then spray carb cleaner or starter fluid around any joint that could affect the fuel / air mixture; carb boot / reed block, base gasket, etc. If the engine rpm changes when the carb cleaner is applied then you have an air leak. The most definitive method though is to do a proper leak down test.

Given the number of WR 300 owners discussing the difficulties finding effective jetting combinations, this air leak is quite evidently a major contributor to this problem. This error is clearly a manufacturing oversight and needs to be remedied as soon as possible.

I am very interested to hear if anyone else has experienced this issue.

Cheers.

i have worked as a motorcycle mechanic for the better part of my working life, every bike i pull the reed block off of gets threebond 1104 to seal it. that boot from husky is one of.. nope sorry the worst production boots i have ever seen! good eye. also as quick precaution did u make sure your water jackets are actually connected in the cylinder? mine sure werent. surprised mine didnt seize.

heres the thread http://www.cafehusky.com/forums/showthread.php?t=3880&highlight=water jacket

id check yours if i were you.

Just wondering if anyone else had experienced a problem similar to this. I double-checked mine riding over the weekend, let it idle and squirted some carb cleaner around the reed block and the carb boot. Didn't seem to change anything or cause any odd behavior. I don't see any other posts about this, so i'm wondering if you just got unlucky, or what?

The reason I ask is I was contemplating taking off the carb boot and using some silicone sealer or something. otoh, if it ain't broke, why fix it? and it occurred to me that i might make it worse if there was silicone in there when i remove it again at some point in the future.

Do you know if the 2010 have this trouble ?

I have to say I switched my WR250 over to the V-3 reed block ( same version the newer bikes come with ) and ran into the problem. I caught mine on the first ride. It seemed fine until it got hot, then it would start high idling and surging. I could let it cool and ride it easy and it seemed fine, but if I really got after it then it would do it.

After cleaning it up I started looking for the leak and that's where it was. I installed another gasket between the manifold and the cage, which seems to have fixed it.

did you use the same gasket that goes between the reed cage and the motor? or cut a new one out of blank gasket paper? Just wondering if one of those methods would be better or worse than silicone or 3-bond gasket sealer

I did consider 3 Bond 1211 for the seal, but I had some old Honda intake gaskets and used one of those.

It seemed a little big if I remember right, so I went with the gasket.

I question V-Force's choice of compounds for the base plate material. It seems a little soft for that application and is another reason I went with the gasket.

well, i need to be able to sleep at night, and i need to be able to race this weekend. to help with both, i went to autozone and got $5 worth of gasket material (1/32", paper, suitable for gasoline and oil), and in 10 mins with an exacto knife and hole punch had myself a custom gasket to go between the carb boot and the reeed cage. I smeared a small fingerfull of 3-bond semi-drying gasket sealer on the side facing the reed cage. It's probably just my imagination, but it feels like it runs better, lol. at least I can wick it up w/o fearing disaster now. The whole operation only took 20-25 mins.

interesting topic.

never use silicone on an engine. fuel vapor, or anything that gets fuel contaminated, turns it into jelly and makes it useless. then there's the little balls that get everywhere. silicone is for fish tanks.

as stated use a gasket, and, make some load spreaders to go under the bolts. think those little tab's they made back in the day for SB Chevy valve covers.

i'm getting some 3bond today

based on the original poster's claim that even 3-bond didn't stop the air leak, i would recommend getting a paper gasket as well. I made mine (described above) and it worked awesome and only took a few minutes, and i'm a lazy and retarded mechanic.

I got curious and took my reed cage off yesterday. I could not see any evidence of a leak nor has my bike shown any symptoms, but I still went a step further and tried to remove the paper gasket to ensure it had a good, clean surface area for sealing. Of course, I tore the gasket and had no replacement

I had some Gasket-Cinch lying around and proceeded to use liberal doses on ALL mating surfaces. Went for a ride after work yesterday and everything feels good. No signs or hints of an air leak.

I'm wondering if the OP had a warped reed cage or boot. Or possibly some debris got between the mating surfaces during assembly. To be blowing water out of the leak vs. just bubbling is massive and this is the only instance I've heard of.