Jumped valve timing

I had recently had a thread about not being able to get my bike to run, I Got my new valve shims in and when i was rotating the crank i noticed that the cam timing cas off, i reset it, i was able to do this by loosening the tentioner and turning the crank clockwase i heard one click rotated the other way and that was not enough, after a second try i heard another click and the timing was dead on.

I then reinstalled the valve cover and the bike fired right up, I took her for a ride and it was all smoth till i gave it a good engine break and then it shut off as if i hit the kill switch, I still have spark and fuel getting to the cylendars and it is acting just as it did before i reset the timing. I will be getting a buddy to help move the thing back to my house tomorow.

The bike has 45,000 miles on it, I know that i should replace the tentioner, which i am looking to order, Is there anything else i should be looking at, Is it possible that i may be missing a tooth on the crank? Timing chain stretched to far?

Both of the later two ideas would require removal of the engine and complete dissasembely, so i am going to start with the tensioner, any other ideas would be a great help.

 

You don't need to remove the motor from the frame to replace the timing chain; nor does it require "complete disassembly." The timing chain can be replaced by removing only the valve cover if you're careful and follow the book.

Speaking of books, you do have a service manual by now, I hope?

Unless your tensioner is broken, it shouldn't need to be replaced; possibly cleaned up a bit.

 

I have an online copy, but it doesent show anything about replacing chain so i am begining to think it is not a complete copy.

I will take tensioner off and clean it. I feel like the bolt that is honling it in place is letting it slip.

From what i have read i need a chain breaker to replace the chain while the motor is still togeather, Does anyone have a good source for one?

What about the front and rear guides, What kind of dissasembely is required to replace these?

 

If you get a new timing chain, no need for a chain break, just grind the pins off a link on the old, fish through the new and peen over your pins with a ball peen hammer.

 

Well, I'd use a proper chain-staking tool but you don't actually need a chain breaker.

The reason for using a chain breaker vs. filing or grinding is to not be generating all those metal filings in such a sensitive area.

I got my chain breaker at Tractor Supply when my son got his minibike; it's the perfect size for cam chains too; cost all of about $15 or so and came with a staking tool.

 

Nice, my question is do you think that it is just a chain / tensioner that is creating this problem with the timing jumping off? The local yamaha dealer has a oem chain for 29 bucks, so i am thinking that is the way that i will go.

ANother thing that i noticed is that when i get the chain fully tight with the tensioner there is no play in it, meaning the tensioner has enough travel to fully take up the slack, regardless of direction i spin the engine there is no delay between cams and crank. Then once it has jumped time the tensioner lossens and there is slack. i believe that the tensioner is lossening, are there any tricks to keeping the tensoiner from sliding on the holding bolt, I will be taking apart today to get a better idea of what is going on in the tensioner. I may even take some pics and post them up here if i find anything strange inside.

 

PLEASE put your bike info in your signature so we have something to go by.

Which style tensioner are we talking about? (Manual or automatic?) If we knew what bike I wouldn't need to ask this one.

 

It is a manual tentioner

 

Ok got her home today, had to push her up a huge hill... not fun, anyway i have pinpointed my problem. I have added a picture of the cracked tensioner, on top of that there was no rubber boot at the end of it, does my model have one?



Finally what i noticed is that the chain has actuallly come off of the crank gear. it has eaten away some of the side of the chain so it looks like that is getting replaced too, i must have rode it with only engaging on the rivits on the outside of the chain. Thank god i only slipped 2 teeth... I hope that cranks alright, i am about to spin her arround and make sure all the teeth are there, How do i get the chain back on that gear? I am replacing chain but with the pull through method i need the chain back in place before i can replace it. I will also be purchasing a new tensioner housing.

 

STOP.

DO NOT "spin her over" this is an INTERFERENCE MOTOR the pistons will slam into any open valves.

I'll get you a picture of a cam chain tensioner from a 550.

As a matter of fact, when you discover that you CANNOT FIND a new tensioner, let me know. I might have one; if not Dave (Hogfiddles) is currently parting out TWO 550 Maxim motors.

You might talk to him about a replacement tensioner.

 

I am aware of the inerference engine, Is it possible to get the chain back onto the crank without splitting the case? I am lso aware of where the valves are and where i can and canot spin the engine.

Also xj forever has a case for the tensioner for 44 bucks, or i can go with an ebay one for 12 bucks plus shipping.

I really fought with the chain today to get it back on the crank for a few hours and i had no luck felt like i amonst got it once but no dice, any tips, ideas, or am i going to have to crack the case?

 

If you are sure the Chain is off the Crank Sprocket, ... don't try to force it back-on.

You can put the Chain back-on the Crank Sprocket by removing the Guides.

(Requires removal of the Cylinder Head).

::: Might be a good idea to see of they've been damaged. :::

 

Rick; it's a 550.

You MAY be able to get the chain back on the crank without popping the head off if you remove the sprockets from the cams so you can free the chain from the sprockets up top; and remove the front chain guide. It unbolts from the top, in that bulge at the front of the head.

With maximim slack introduced and the front guide removed, you may be able to finagle it back on.

Here's a pic of the guts of a complete 550 tensioner assembly, so you can see if you're missing anything.

The one bit you need to worry about is #16, "DAMPER" it has an arrow pointing to it in the pic. This is a metal/rubber composite washer (similar to a valve cover bolt donut) and the rubber has been known to disappear; or get hard as a rock and split/crumble.

Also note #14; there is (or should be) an o-ring mashed into the body where the adjuster bolt goes; you'll need to replace that if you're refurbishing a used part.