the differences between the 350/400 air cooled motors.

[duneracerweston]

I mainly want to make this thread as a answer to what interchanges, the differences, and such to hopefully answer some of the common asked questions on these parts. bare with me this will take a minute.

 

[duneracerweston]

as a bit of a introduction, I've been crawling all over these motors for about 14 years now, i have built more then a few record holding hp motors and am still steadily developing with these motors.



most of this will be referencing fit to the warrior 350 motor specifically. if you have questions of it switching the other way leave a comment.




the yfm350 motor is the Yamaha designation for their primarily air cooled 2 valve motors.

the yfm350 in particular has two variants, chain drive and shaft drive. they have more in common in name then the actual motors. some parts can be easily swapped over such as head, everything in the head, valvetrain, cam, timing chain, cylinder and piston. the rod is the same but the clutch side half of the crank is different and non swappable with out modification. the shift shaft is usable but must be cut in order to fit the warrior clutch cover. the oil cooler from the early 350 big bears with the 2 piece oil filter housing will cross over but causes interference and have become hard to find, however zoom zoom makes a oil cooler kit that is a replica of this setup with a draw back of shifter interference if you run a direct shifter. drw also makes a adapter that solves the size issue but is not a full kit and is a bit more costly.




the 400 shares even less with the warrior as far as direct fitment. the heads are identical even though the part numbers differ the design, ports, valve train and cam are all the same. the cylinder will fit but is taller then the warrior so the piston will never reach the top thus causing a lack of compression. it may fit but it wont just drop right on.

that is basically the conversion parts. the carbs are different, nothing jaw dropping performance change wise, the exhausts are completely different so that's a no go on those either.


now back to that cylinder, it is usable, although it takes a longer rod to do so. CP-Carrillo will make them and i have the specs on both the rod for a stock stoke motor or a stroker using the 4mm hot rods crank.



nothing that switches over from one to the other will make a warrior a "400" a 400 cylinder will not make it a 400 and the crank will most certainly not work with a warrior motor.






In short the heads swap, everything in the heads swap, the cylinders can but not a direct bolt on for the 400 cylinder. and they use the same pistons. that's about all that interchanges between these 3 motors.

before anyone asks the wolverine 350 has more in common with a big bear 350 then a warrior.

electronics do not swap over, and flywheels are timed and weigh different then the warrior.

any questions drop them down below.

 

[beastlywarrior228]

I’ll stick this for you.

 

[DANRULZ!]

as a bit of a introduction, I've been crawling all over these motors for about 14 years now, i have built more then a few record holding hp motors and am still steadily developing with these motors.



most of this will be referencing fit to the warrior 350 motor specifically. if you have questions of it switching the other way leave a comment.




the yfm350 motor is the Yamaha designation for their primarily air cooled 2 valve motors.

the yfm350 in particular has two variants, chain drive and shaft drive. they have more in common in name then the actual motors. some parts can be easily swapped over such as head, everything in the head, valvetrain, cam, timing chain, cylinder and piston. the rod is the same but the clutch side half of the crank is different and non swappable with out modification. the shift shaft is usable but must be cut in order to fit the warrior clutch cover. the oil cooler from the early 350 big bears with the 2 piece oil filter housing will cross over but causes interference and have become hard to find, however zoom zoom makes a oil cooler kit that is a replica of this setup with a draw back of shifter interference if you run a direct shifter. drw also makes a adapter that solves the size issue but is not a full kit and is a bit more costly.




the 400 shares even less with the warrior as far as direct fitment. the heads are identical even though the part numbers differ the design, ports, valve train and cam are all the same. the cylinder will fit but is taller then the warrior so the piston will never reach the top thus causing a lack of compression. it may fit but it wont just drop right on.

that is basically the conversion parts. the carbs are different, nothing jaw dropping performance change wise, the exhausts are completely different so that's a no go on those either.


now back to that cylinder, it is usable, although it takes a longer rod to do so. CP-Carrillo will make them and i have the specs on both the rod for a stock stoke motor or a stroker using the 4mm hot rods crank.



nothing that switches over from one to the other will make a warrior a "400" a 400 cylinder will not make it a 400 and the crank will most certainly not work with a warrior motor.






In short the heads swap, everything in the heads swap, the cylinders can but not a direct bolt on for the 400 cylinder. and they use the same pistons. that's about all that interchanges between these 3 motors.

before anyone asks the wolverine 350 has more in common with a big bear 350 then a warrior.

electronics do not swap over, and flywheels are timed and weigh different then the warrior.

any questions drop them down below.

as a bit of a introduction, I've been crawling all over these motors for about 14 years now, i have built more then a few record holding hp motors and am still steadily developing with these motors.



most of this will be referencing fit to the warrior 350 motor specifically. if you have questions of it switching the other way leave a comment.




the yfm350 motor is the Yamaha designation for their primarily air cooled 2 valve motors.

the yfm350 in particular has two variants, chain drive and shaft drive. they have more in common in name then the actual motors. some parts can be easily swapped over such as head, everything in the head, valvetrain, cam, timing chain, cylinder and piston. the rod is the same but the clutch side half of the crank is different and non swappable with out modification. the shift shaft is usable but must be cut in order to fit the warrior clutch cover. the oil cooler from the early 350 big bears with the 2 piece oil filter housing will cross over but causes interference and have become hard to find, however zoom zoom makes a oil cooler kit that is a replica of this setup with a draw back of shifter interference if you run a direct shifter. drw also makes a adapter that solves the size issue but is not a full kit and is a bit more costly.




the 400 shares even less with the warrior as far as direct fitment. the heads are identical even though the part numbers differ the design, ports, valve train and cam are all the same. the cylinder will fit but is taller then the warrior so the piston will never reach the top thus causing a lack of compression. it may fit but it wont just drop right on.

that is basically the conversion parts. the carbs are different, nothing jaw dropping performance change wise, the exhausts are completely different so that's a no go on those either.


now back to that cylinder, it is usable, although it takes a longer rod to do so. CP-Carrillo will make them and i have the specs on both the rod for a stock stoke motor or a stroker using the 4mm hot rods crank.



nothing that switches over from one to the other will make a warrior a "400" a 400 cylinder will not make it a 400 and the crank will most certainly not work with a warrior motor.






In short the heads swap, everything in the heads swap, the cylinders can but not a direct bolt on for the 400 cylinder. and they use the same pistons. that's about all that interchanges between these 3 motors.

before anyone asks the wolverine 350 has more in common with a big bear 350 then a warrior.

electronics do not swap over, and flywheels are timed and weigh different then the warrior.

any questions drop them down below.

This thread is 3 years old, but I still have questions!!!

My dad bought a Big Bear new in 96, and he just passed away in December. I plan to keep the machine, because it’s a sentimental piece for me. I helped him pick it out - we were familiar with Suzuki, but he wasn’t crazy about something on the King Quad, probably the price, so then we debated between Timberwolf and Big Bear. Again, it was a price thing…

I always thought the Big Bear could use just a smidge more power, so I bought a 98 Kodiak and drove that a few years. I liked it, but it wasn’t a huge power gain. Could’ve been a tired engine, since I bought it used, as a 15 year old machine.

This old Big Bear is tired and needs an injection of money - cv axles, brakes, inspection/tuneup and a smidge more power, if I can figure out how to get it. Information and parts are sparse if you’re like me, and don’t know where to look or who’s information to trust. Can you suggest anything?

I’m assuming a 400 Kodiak engine would be a direct swap?
If I wanted to keep the 350 engine and slap some upgrades in it, can you help me figure out what options I have? Is there a big bore kit out there? I’m a little confused about your post above, but it sounds like you can swap a Kodiak top end onto a Big Bear. Is that correct?

Thanks!!

 

[beastlywarrior228]

This thread is 3 years old, but I still have questions!!!

My dad bought a Big Bear new in 96, and he just passed away in December. I plan to keep the machine, because it’s a sentimental piece for me. I helped him pick it out - we were familiar with Suzuki, but he wasn’t crazy about something on the King Quad, probably the price, so then we debated between Timberwolf and Big Bear. Again, it was a price thing…

I always thought the Big Bear could use just a smidge more power, so I bought a 98 Kodiak and drove that a few years. I liked it, but it wasn’t a huge power gain. Could’ve been a tired engine, since I bought it used, as a 15 year old machine.

This old Big Bear is tired and needs an injection of money - cv axles, brakes, inspection/tuneup and a smidge more power, if I can figure out how to get it. Information and parts are sparse if you’re like me, and don’t know where to look or who’s information to trust. Can you suggest anything?

I’m assuming a 400 Kodiak engine would be a direct swap?
If I wanted to keep the 350 engine and slap some upgrades in it, can you help me figure out what options I have? Is there a big bore kit out there? I’m a little confused about your post above, but it sounds like you can swap a Kodiak top end onto a Big Bear. Is that correct?

Thanks!!

I would upgrade what's in it. Maybe start with a higher compression wiseco piston and maybe a warrior head and carb with stage 1 hotcam.

 

[DANRULZ!]

I would upgrade what's in it. Maybe start with a higher compression wiseco piston and maybe a warrior head and carb with stage 1 hotcam.

What advantages does a warrior head have vs a big Bear head?

In the 90’s, I used to use Dennis Kirk for ATV parts. What’s the best place these days to get parts like high compression pistons and cams and Warrior heads?

 

[beastlywarrior228]

What advantages does a warrior head have vs a big Bear head?

In the 90’s, I used to use Dennis Kirk for ATV parts. What’s the best place these days to get parts like high compression pistons and cams and Warrior heads?

Warrior head has bigger ports. You'll have to pick up and used one on eBay. Dennis Kirk is still good for new parts.