I've made a silly mistake with timing belt and cam positioning

Joined
Oct 7, 2010
Messages
8
Location
Salisbury, England
I've just replaced the water pump on my ST1100L and started the timing belt replacement when I was really too tired. I should have stopped earlier.
In my tiredness, I put the guide plate on the left hand pulley and torqued it up before fitting the belt (told you I was tired!). Of course, in torquing it I turned the pulley perhaps quarter of a turn, could be more or less). Now I don't know its original position. I felt some resistance but assumed that was the cams against the springs. I may even have turned the crank a bit too, mistaking that bolt for the tensioner bolt.
What do I do now? I can take the plugs out to see how close to tdc I was on the left cylinders, but how do I get everything back in alignment without risking bent valves?
Doh!
Thanks in advance for any sage advice that can get me out of this mess!
 
Joined
Jun 3, 2006
Messages
3,512
Location
British Columbia
Bike
2021 RE Meteor 350
I think you need to gat hold of the Honda Service Manual which will show you the proper position of all cam and crank marks with the engine no 1 cylinder at TDC on the compression stroke. Pull the plugs to make it all move easily.
 
OP
OP
Joined
Oct 7, 2010
Messages
8
Location
Salisbury, England
I think you need to gat hold of the Honda Service Manual which will show you the proper position of all cam and crank marks with the engine no 1 cylinder at TDC on the compression stroke. Pull the plugs to make it all move easily.
I have the manual, what I'm worried about is damaging the valves and pistons in getting everything back to the right position. The manual doesn't cover that (because it doesn't anticipate silly cock-ups).
 

ST1100Y

Site Supporter
Joined
Dec 4, 2012
Messages
4,981
Age
59
Location
Vienna, AuSTria
Bike
ST1100Y, ST1100R
STOC #
637
What do I do now?
Well, you only moved the pulley & reduction gear of the LHS head, right?
No big deal, remove the valve cover and check for the embossed/engraved lines on the front of the two cams... (as shown in the w/shop manual ;-) )
The two chinks must point outward, flush with the top edge of the head's bearing-bore (plus the punch-mark on the pulley match its counterpart on the belt-housing)

Since you haven't move the crank, nothing should be off, just gently rotate the pulley back c/clockwise till the markings are aligned.
 
Joined
Jun 3, 2006
Messages
3,512
Location
British Columbia
Bike
2021 RE Meteor 350
I have the manual, what I'm worried about is damaging the valves and pistons in getting everything back to the right position. The manual doesn't cover that (because it doesn't anticipate silly cock-ups).
You shouldn't damage anything just rotating by hand. As soon as you feel resistance, you will know you are contacting valves. Then it is a matter of rotating the cam, observing which valves are moving and get the timing lines lined up when the proper valves (#1) are closed.
 
Last edited:
Joined
Aug 8, 2015
Messages
3
Location
uk
I am sure you have got this fixed now but for future readers, I would say remove undo the cam bolt you have just torqued, then remove the belt guide, find the cam marking in tdc (top dead center) I assumed you had the engine in TDC for the water pump removal. Then fit the belt, only once the belt and tensionsers are tight and torqued up did I torque the cam bolts. Don't forget thread lock! I added a slightly modded Honda integra type r 1.8 tensioner when i did mine ?25 instead of Hondas ?75 unit.
 
Top Bottom