Husky_250
Husqvarna
B Class
Hi
I´m going to modify my TC 250 2018 motor to get more lowend and midrange power to smooth that violent hit it has originally. I still want it to rev more than std so all the mods must be done so it will still have some over rev, but smoother more "filled up" power curve. No FMF Gnarly for me as it cuts over rev too early.
So far airbox has some extra holes drilled to right hand side near the silencer as these Husky´s are known to have some asthmatic symptoms vs. KTM´s.
I have also done mods to original Mikuni TMX 38 carburetors slides intake side (notch) and fuel feeding improved for the mainjet (drilled four 1.5 mm holes to drain plug groove and opened up those plastic covers original small holes also to 1.5 mm size). It is already much better.
It got even better when I changed red power valve spring to green. Now that hit is not as violent as before. I have that power valve adjustment screw backed up level with the cover so it starts to open power valve early, but green heavier spring prevents power valve from opening fully too early. This way there is wider rev range when power valve adjusts power curve.
I have my ignition map at more agressive setting (connector plugs connected together) as I don´t like that soft map with less ignition advance.
I bought FMF Fatty exhaust pipe and Pro Circuit R304 shorty silencer. Also Boyesen Rad Valve intake reed valve. I have not installed these yet, but I assume these will have a good effect to smoothen out the power delivery and give good over rev.
I bought another used perfect condition TC 250 cylinder head and now I want to modify it to improve lowend and midrange power. These 2017 => cylinder heads don´t have same kind of squish band in their combustion chambers as earlier models for example 2014-2016 has. I measured with caliber what is the height of combustion chamber edge. It is 1.60 mm unmodified (0.063"). It´s a little too much IF piston top is level with the cylinder top at TDC (distance X= 0.00 mm). I was planning to cut that head -0.40 mm to 1.20 mm (0.047").
Is this a good squish band clearance 1.20 mm to this TC 250 2018 motor? I have understood that 1.60 mm is way too much and much less than 1.20 mm is not very practical.
I have in my other bike TE 250 2015 more mods done and it has RK-TEK head with only around 1.00 mm piston to head clearance, but I don´t want to go that far with this TC 250 2018 now. I want to try this time with modified std head instead to save some money and get maybe 70-80% of those benefits of RK-TEK head with these mods.
Next step is to add flywheel weight if it is still too agressive motor after these mods. Maybe 9 oz weight is ok. My TE 250 2015 has heavier flywheel from the factory as it is enduro bike so it has that starter gear in it which is heavier. These mx models have very light flywheels and I think with flywheel weight it is possible to easier get that power to the ground without getting tired so easy. Originally my TC 250 did wheelies everywhere unwanted. It´s nice to have power, but how that power comes out is more important.
I´m going to modify my TC 250 2018 motor to get more lowend and midrange power to smooth that violent hit it has originally. I still want it to rev more than std so all the mods must be done so it will still have some over rev, but smoother more "filled up" power curve. No FMF Gnarly for me as it cuts over rev too early.
So far airbox has some extra holes drilled to right hand side near the silencer as these Husky´s are known to have some asthmatic symptoms vs. KTM´s.
I have also done mods to original Mikuni TMX 38 carburetors slides intake side (notch) and fuel feeding improved for the mainjet (drilled four 1.5 mm holes to drain plug groove and opened up those plastic covers original small holes also to 1.5 mm size). It is already much better.
It got even better when I changed red power valve spring to green. Now that hit is not as violent as before. I have that power valve adjustment screw backed up level with the cover so it starts to open power valve early, but green heavier spring prevents power valve from opening fully too early. This way there is wider rev range when power valve adjusts power curve.
I have my ignition map at more agressive setting (connector plugs connected together) as I don´t like that soft map with less ignition advance.
I bought FMF Fatty exhaust pipe and Pro Circuit R304 shorty silencer. Also Boyesen Rad Valve intake reed valve. I have not installed these yet, but I assume these will have a good effect to smoothen out the power delivery and give good over rev.
I bought another used perfect condition TC 250 cylinder head and now I want to modify it to improve lowend and midrange power. These 2017 => cylinder heads don´t have same kind of squish band in their combustion chambers as earlier models for example 2014-2016 has. I measured with caliber what is the height of combustion chamber edge. It is 1.60 mm unmodified (0.063"). It´s a little too much IF piston top is level with the cylinder top at TDC (distance X= 0.00 mm). I was planning to cut that head -0.40 mm to 1.20 mm (0.047").
Is this a good squish band clearance 1.20 mm to this TC 250 2018 motor? I have understood that 1.60 mm is way too much and much less than 1.20 mm is not very practical.
I have in my other bike TE 250 2015 more mods done and it has RK-TEK head with only around 1.00 mm piston to head clearance, but I don´t want to go that far with this TC 250 2018 now. I want to try this time with modified std head instead to save some money and get maybe 70-80% of those benefits of RK-TEK head with these mods.
Next step is to add flywheel weight if it is still too agressive motor after these mods. Maybe 9 oz weight is ok. My TE 250 2015 has heavier flywheel from the factory as it is enduro bike so it has that starter gear in it which is heavier. These mx models have very light flywheels and I think with flywheel weight it is possible to easier get that power to the ground without getting tired so easy. Originally my TC 250 did wheelies everywhere unwanted. It´s nice to have power, but how that power comes out is more important.
I’m very glad I did these mods to it. First I was going to just leave it as stock, only GJ carb mods and red PW spring. But this head mod, Boyesen Rad valve and FMF Fatty + Pro Circuit R304 shorty were all quite inexpensive but still well working mods... and what a sound that exhaust has now!! 
