Crank shaft bolt.

halfbreed4lyfe

halfbreed4lyfe

XS400 Addict
Messages
130
Reaction score
8
Points
18
Location
Rockford, Il
Hey guys got a question. I'm wanting to check valve clearance, and I've read up on it and went to attempt this task. I want to turn the crank for the compressino stroke, however I was under the impression I turn the 17mm bolt behind the left side cover (after letting the oil drain). When I turn this bolt as directed underneath it, ccw the bolt unscrews. Is there some thing I'm missing to turning the pistons to TDC? BTW I had bad compression both cylinders, about 80. Put in a little oil one went up slighlty the other did nothing. I cant change the piston rings at this time but if I find the valve clearance is the issue I'll be forever happy.
 
80 psi is pretty low It almost seems likeyou might have to remove the valve cover and take a look around.Check spring tension.Worst case burnt or valves that are sticking open.
 
It very could be possible the bore and cyclinders along with rings are causing your issue with the low compression.I beleive I read on here somebody similair problem.The tore the engine completely down and the sleave was very worn.
 
You must have your valves adjusted first. If they are not closing all the way your compression will be low. I would tighten the bolt off the crank to the spec lbs then you should have no problems rotating the engine. I think it is 25lbs
 
Ok let me research check the lash, no clue what you mean. Also if I torque er 25lbs wont i spin the crank the wrong direction? Is there a way to stop it from spinning in reverse while I tighten it. Maybe crank the engine while holding a socket on the bolt? Thanks for the feed back also guys.
 
Ok so lash is what I'm actually trying to set..the clearance between the valve stem tip, and the rocker arm. YEs this is just what I want to do I just cant rotate the engine with out the bolt unscrewing.
 
Lash is the gap inbetween rocker arms and push rods.Also how much pressure is on valves if thats a correct way of discribing it.The more space there is more clatter your going to hear.You dont want to over tighten too much though theres a spec sheet here in the manual section.This is the next maintanance to do on my bike also.You have the feeler guages that have angles at the ends in mm.
The intake and exhaust are set at 2 different specs.
 
i just bought feeler guage straight flags but i can bend them, I still however cannot turn to TDC to check clearances. Need to know how to turn the crank.
 
Last edited:
Put the bike in gear put the back tire on the ground then tighten the bolt. Put the bike back on its center stand and out of gear then move rotor to tdc:thumbsup:
 
Great I'll try this evening, BTW is a burnt or broken valve a large project or some thing that will require a new head? Or maybe there is just a way to replace the stuck valve I dont know I'll research it see if I can find the answer...Thanks guys.
 
XSChris that didnt work (putting the back wheel down to tighten, I spun the shaft backwards i bit so not sure if I threw off the timing. I did however brace my socket against the shifter and pushed on the kickstart that did the trick. Then onto the center stand and in neutral. So i adjusted to specs..Scorpio that link was great BTW, but I still am not getting her to run. Before she ran on one cylinder now none. however I got n awesom big puff of smoke back out the intake and now exhaust is coming from between the left engine cover and the block. This would seem like a bad gasket issue right? but why are the exhaust fumes making back down..bad rings then?
I dont know but tomorrow I'll take the head off maybe and give a look see.
 
So today she ran, but it was like before just on the right cylinder. The spark plug on the right is black dusty looking, know thats not good...too rich right? but I know its firing, the left is still just dirty covered in gas..smells like gas, but I can still see the white of the plug. I know it gets spark I tested for that. Will I have to open up the topend to source this issue..my compression is still low any way.
 
If the left plug is flooded with fuel, then it isn't sparking when in the engine. Swap the plugs and see if the problem follows the plugs. If you are using NGK plugs, get a new pair, the one that has been flooded is shot - and that is a statement of fact based on decades of experience with NGK plugs. Your choice if you want to believe me now or later...
 
:doh: Mind blown that worked, I switched sides and so did the heat! Gonna go grab a new pair now, thanks gonna see what condition she runs on both cylinders. She even stayed on idle with just that left cylinder the right always shut down after a few seconds.:thumbsup: Thanks 16VGTi.
 
Ok started her up with the new plugs and she fired right up and ran...and idled pretty good. One plug is black the other a dark tan. So tomorrow gonna build the bottle manometer and try to sync the carbs. Then find someone with a compression tester to see if there is fault in mine.
 
Look at my thread Frustrated and at my wits end.It describes how you can bench sync the carbs which get its real close.I just did mine again today this way.
 

Similar threads

CalgaryStreetBob
Cant turn engine HELP ME PLEASE
Replies
6
Views
972
CalgaryStreetBob
CalgaryStreetBob
B
XS rebuild back on track..maybe!
Replies
5
Views
822
JPaganel
JPaganel
R
Xs gx400sp S.A.
Replies
4
Views
866
ATXSOUTHAUSTIN
ATXSOUTHAUSTIN
P
Removing a rounded oil filter bolt
Replies
10
Views
3K
JWN
J
G
1982 XS400 SECA cam timing mark confusion
Replies
3
Views
2K
thomas2800
T
Back
Top