Rebuilding a1985 cr500... got some questions

It is bored to the max i believe. But im not worried like i said the top end looks like its in great shape. The guy was a bit weird but he knew his shit, he was just old probably coulnt type well. Its clean all over it just had some leaks but it was fullly rebuilt in 96 and barely ridden since. And yes if you are referring to the mud flap thing it was zip tied but i replaced it with a few new ones

I have bought things from that site already, I am truthfully fully content with the stock air boot and carb. I was worred my boot was cracked beyond repair but it wasnt cracked all the way thru so its fine and doesnt leak.

Update: Hi all. I bought my powerdynamo ignition and got it installed. Got her timed and running good. They sent me the AC version with just the regulator, but luckilly I still had my rectifier/regulator from my last attempt, so I was able to convert the AC to DC and my LED bar works great. I may even run a battery down the road and have the system charge it. I may also add more lights like brake lights or more headlights since I only used 30 of the 70 watts provided. The bike now is in a condition where it is reliable and runs good so I am very pleased.
I just had a few questions to make it even better.
Gearing: I bought the bike with 13-53 gearing which I thought was pretty low. With that gearing it still topped out right around 100. Next I tried extremely high gearing. I went with 14-48 and that made it wayyy faster. With that gearing fourth gear just pulled and pulled on top end and was already about 85-90 and 5 and 6th gear were unreachable on the length of road I had. The only problem with that gearing is low speed. It was just too much and would usually stall on steeps. Also my acceleration was drastically reduced. So I am now running 13-48 which I like since it increased my acceleration and gave me a top speed which I still have yet to reach, yet it still is a bit of a bear in slow speed trails. I have an 11,13,14 tooth front sporckets to play with and a 48 and 53 rear. What do you guys think is best all around?
Timing: I have it set to stock around 2.5 mm BTDC. The bike screams top end! And great throttle response all the way through. But I would like to experiment. The bike runs pretty hot and boils over unless you are getting airflow over the rads, (no detonation as far as I can tell though) as soon as you stop and are idling it boils. Could retarding the timimg slightly reduce this? As well as perhaps boost low end torque and maybe smooth out the power? I just want to experiment to find out where I like it before I red loctite everything!
Thanks for your help everyone!!

You should be able to set a combination of front sprockets that you can change depending on your riding spots. ie a12 for tight and a 13 for open country. the idea being that the chain has enough tensioning range to allow you to quickly c/o the sprocket and readjust the chain without having to change its length with an extra link or so. some times it works, sometimes it doesn't.

you have an issue if a swede 2 stroke is boiling over, i have never had that happen. im not graham jarvis by any means but i have put the bigger ones through some tougher paces and slow going and never lost coolant. its likely you have a bad cap, altho it could actually be overheating. i doubt it tho.
i like to run a 13 or 14 in the front on the 400 and up swedes, as the 12 tooth countershaft sprocket really gets hammered on a bike with torque. harder on the chain too making a sharper bend. im running a 14/52 on my 87 430 right now and it seems to be geared well all around. 1st and 2nd are working well in the woods and the rest of the gears are good, of course. i would kinda gear the bike by how the bottom gears work, as the upper gears always have enough in them when youre dealing with these swedes. i havent run my 500 for a few years but im pretty sure i ran similar gearing...i would have to check. the 14/48 you were running im sure would be too tall, as the 14/52 ive found is nice compromise. its really the same as 13/48, but i like to get the bigger sprocket up front as previously stated.the 500 should have plenty of power to have gearing that works well everywhere, its not a 250. if 1st and 2nd are working well for me with no clutch abuse im happy. ive found jt sprockets wear well are are good cheap steel. aluminum sucks especially on the 500.
if the bike is running well, and not kicking back when starting, you could leave the timing alone. if anything perhaps retard it abit closer to 2mm to start easier and be a little easier on the motor and its octane requirements.

It only boils over when I stop. The motor seems relatively cool running. To me the radiators seem to small and the cap Im running has this weird lever thing. The five gallon bucket of parts that came with it included a 1.1 cap but the seal was damaged. A friend of mine said to try a 1.6. The lever cap says 7 pounds but i dont know how to read rad caps. 14-48 gearing was very tall. I bet top speed was 120+. Fourth gear was so fast My helmet was getting pulled back and it has six gears. I know what u mean about judging the gearing by the first gears. I think ill try 14-53 because thats what I have to work with. Will retarding the timing take away that much top end? I dont think im having detonation im running 91 pump with castor 927 32:1 and good octane boost. Pretty easy starting especially wih the powerdynamo

retarding timing adds topend. advancing timing adds bottom end and response..
the motor should not boil over even sitting, the cap is wrong if it has a lever. you should really try running the correct pressure rated cap so the system works like it should...only "boiling over" when you stop is way messed up. i have been running waterless coolant lately from zip-ty and it builds pretty much zero pressure..really weird but im sure its easier on your seals and rads. the swedes hold quite a bit of coolant, more than a newer bike. part of this is likely from the large water jackets in the jug. the four strokes have even larger rads. but ive never seen one boil over, even idling for 60 secs in the middle of single track..im sure a real pro back in the day may be able to boil one but they are not weak in the cooling dept, thats for sure. its a racebike!
the castor and mix sound good, im a fan of castor myself.

that 1.1 and 1.6 are atmospheres which is 14.7 psi more or less 7 psi is one soft cap get a 1.1 you should be good to go

Yeah Im pretty sure the cap is the issue. I will try and get the proper one. Any leads on a good retailer for one? Or is husqvarna parts the way to go? As for timing, with the new ignition they recomend using a special kind of loctite on the crank due to the lack of a flywheel key. I did not do that since I wanted to be able to make adjustments and find out where I like the timing before I set it in stone. In the few rides I have done Im pretty sure the timing has slipped some because starting has gotten harder which is supposed to be the opposite with the powerdynamo. Its not bad but I think I will retard it back to 2mm and give it a shot then get the special loctite and call it good. Thanks for all your help guys. I will update when I fix timing.

You might want to go get a blue permanent sharpie.

Clean crank end and inside taper with acetone or thinner.

Then color crank end and flywheel taper with sharpie.

Use valve grinding compound to lap together for good fit. Means all the Sharpie blue is removed on both surfaces.

Think got mine at O Reilly Auto and came with light and heavy grit. I used the light grit.

When first started there were gaps in two surfaces upon checking.

Boiling over will happen if not enough air is being forced through the radiators. I have had boil over issues on that class (more or less) when arrowing or getting stuck waiting in line at a stopper at an event. The size of the impeller and radiators is small by even modern 125 class bikes, at least competition grade ones.

Yes the radiators are far smaller by 25% at least Id say than my honda 125.

my 95 360 has small rads as well then as they are the same size. the 95 has a larger impeller tho.

You can use the pwk39 with the stock intake.
Dvg needle 175-190 main and 45 pilot will be a good start.
Same top end but better mid and low.


It should never boil over with the stock rads.
Get a stock cap for it.

I just ordered a stock cap from husqvarna-parts. We will see how it performs when it arrives.

how long does the bike need to stop and idle before it starts to lose coolant?
will it lose any if you keep moving?

If I am riding even at one mile an hour it doesnt boil over. And sometimes it doesnt boil even when I do completely stop.
But 98% of the time, I come up to the spot to wait for my friends on their four strokes while they are riding through my dust cloud to catch me, and sitting there idling, the hose drips and turns to steam on the hot exhaust. My larger concern is that the drips are very close to my ignition gromet and my gromet is new but still doesnt seal very well so I may re route the boil over hose to the other side of the motor so I dont get moisture in my new ignition. By the way, I retarded my ignition back to 2mm and it seems pretty good, sometimes midrange there is a stutter if you will. To me it sounds like when my 125 is loaded up and just needs to be blown out. Can castor 927 plug up a motor this large after a bunch of single track then just needs to be blown out on the straights? Thanks guys

stutter in the mid range is possibly needle jet.

mark your throttle at 1/4 open 1/2 open and 3/4 open with a texta.

Drop the needle clip one notch and if its worse and dragging on the throttle at half way, go back to where it was then go 1more notch up and check if that improves it. check your plug color by riding at 1/2 throttle in 4th and jumping on the brakes and locking the wheel (don't back off as you hit the brakes, you have to catch the engine in operating condition), make sure its not too lean (very light color! you want choc brown). listen for engine knocking or pinging when you shut the throttle off. if this happens drop the clip down 1 notch to richen it up. that's the extent of my jetting knowledge!

no oil plugs up your exhaust really, its all about having it jetted right. that being said, a 500 isnt going to like being putted for extended periods of time. when jetted right they clear out quickly.
im betting your new cap fixes the issue. your current cap is likely weak and as soon as some pressure develops it just relieves itself. hopefully anyway! also maybe think about running zipty's waterless coolant..it builds no pressure, among other benefits.

Thanks for all the info guys. My cap is in the mail. The bike is jetted for reno nevada. And im in tahoe so if anything Im a little rich. The stutter is not bad and the reason I think it was just loaded up is because it doesnt really do it when its not being putted. Like you said it doesnt like to putt really. I dont think i have knocking or pinging but its hard to tell with all the engine vibration and noise. Im a farely decent two stroke mechanic and the motor sounds smooth and powerful as all hell when on the gas but I dont know if Im missing pinging. I think id be able to tell tho. Like you said the bike doesnt like putting at partial throttle openings. It just sounds happier with the throttle wide open. Is it bad for a big bore 2 stroke to drive "street style" where you are like half throttle third gear just cruising?