Big bear 350 shift issue - Yamaha ATV Forum
 
LinkBack Thread Tools Display Modes
post #1 of 2 Old 09-19-2019, 09:09 PM Thread Starter
Junior Member
 
Join Date: Oct 2018
Posts: 11
Big bear 350 shift issue

Ok i am not quick to jump on a forum and post a question without doing my own part and trying to research and solve the problem myself but I cannot find any definitive information anywhere about my problem. I have a Big Bear 350 that I picked up very cheap which had been sitting in a field for years. I am not new to building wheelers but this one has me beat. After rebuilding top end and replacing the carb it fires right up. The vin has some number worn off from being next to the shifter but from the parts in the clutch i assume it is early since 87 parts seem to be the only ones that match. Thats when the plot thickened.

Reverse works fine but when in the forward gears it would not go past 1st and was hard to get into neutral. ie. a it took a million clicks up to thump into 1 and as many down to find neutral. still never getting past 1st. within minutes i could hear metal screeching and whirling around in the clutch side of the motor. I took the cover off to find that 3 out of the 4 springs on the centrifugal clutch had broken and were shredded. Also the black mechanism that the pawl on shift shaft grabs moves was loose so it wasnt always grab to change the gear on the transmission. I tightened that mech, and replaced the springs assuming it would solve the problem since the gears were not actually changing from the lever and the carrier should obviously not only have 1 spring left.

After putting everything back together it did go into 1st fairly easy but then i again couldnt get it back to N without a million clicks down and couldnt get it to go past 1st. I did one time get it into a higher gear who knows what one but i gained some speed and dropped rpm.

If i jack both the front and the back wheels off the ground and run the motor it becomes much easier to shift and i can get it to run through the gears pretty well. Usually going into N without a huge fight. not perfect but it does hit neutral and roar while spinning the wheels instead of gain rpm and with the power.

I have tried every possible position on the clutch adjustment screw without any noticeable result. I think this could potentially be where my problem lies at this point.

does anyone know if the case is supposed to be threaded? because mine is not. obviously it seems as though it should be since every other bike ive touched has been. i even took the cover off my quadrunner to make sure it wasnt crazy.

when the screw is adjusted and the jam nut tightened the screw will just slide back out since there is no threading in the case. accomplishing nothing.



Does anyone have any insight on any of this? Are my plates stuck, Centrif clutch worn out, case stripped or something else crazy im over looking? And what made my springs break in the first place
Stavey22 is offline  
Sponsored Links
Advertisement
 
post #2 of 2 Old 09-20-2019, 11:51 AM
Senior Member
 
Join Date: Feb 2015
Location: southern oregon
Posts: 1,971
Garage
so i dont have hands on knowledge of your big bear but as i suspect you know if the bolt is not in a thread a jamb nut will not function. if you can post a picture but i would suspect the case is stripped. move your shifter up and down and i suspect you will see movement in the adjuster assembly.
in my opinion if its not simply the adjuster its not likely in the centrifugal set up, if it was the machine would not idle or would be lurching and jumping or not moving at all. i would look at the shift fork assembly and inspect your clutch pack with your symptoms i would suspect worn fibers or something worn in that shift assembly. in those duel clutch set ups you rely on that shifter for an awful lot and in general when its starts to get hard to shift the average guy just slams it harder instead of adjusting the clutch or in you case just strips it out. i looked at rocky mountains oem parts diagram but i was unable to find the bolt/adjuster you are looking at but you might give it a try since you know where the part is.
i just looked at ebay and found and 87 clutch cover for 25 bucks and i would say after looking at it your case is definitely stripped. the only way that adjuster could function is that center bolt threading into the case. my guess is that is a pretty rare piece pretty cheap.
cory52000 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Yamaha ATV Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome