[Dave_C]

imported post

About 3 months ago I was given a GL1000. It was sitting in a garage for over a year. I had a shop take the carbs apart and clean then. The bike ran great. About 2 month ago I was riding and my left timing belt broke. After replacing the left timing belt (broke) and replacing both sets of points (Honda OEM Points) due to wear I can not get the timing dots to line up with the heel parts of the points per my tech manual. I have verified (several times) that the cam gear marks are lined up with their assocoated casing marks. I have adjusted and readjusted valves and have attempted to run the timing check without a strobe. It appears to be good. I would perfer to use my timing light but am unable to locate the special cover I need.The bike will run but the idle is very erratic and it backfires then sometimes dies. I believe if I can findout why the timing marks do not line up I can cure my problem. The bike was running great before the timing belt broke so I do not think it is a carb issue. Can anyone help with advice and things to check !!!

 

[Goldwinger1984]

imported post

Since the timing belt broke while the engine was running the first thing I would be checking is compression to see if any of the valves are bent. After you check the compression let us know and we'll see if wee can help you further.

Vic

 

[Dave Campbell]

imported post

The points are driven from one of the cams, right? Or am I suffering from Old Timers?

If so, one of the cams may have spun and sheared a key inside the pulley. If the cam stops because a valve tips a piston, it may have caused the cam to stop while the pulley keeps going. The cam marks would align OK but the misalignment beyond that would not be visible. Its not impossible to have sheared either or both keys.

In any case, remove the pulleys and replace the keys.. Be careful changing timing belts, it aint as simple as "throw them on."

 

[Dave_C]

imported post

Yes, the left belt which turns the left cam is the side that the points are running off of. I will chech this, also I will checkthe compression of the cylinders. If any other ideas come to mind please let me know. They would be greatly appreciated.

Also, the backfiring is coming from both exhaust and I can hear it in the air filter vellum shaft. Does this add any more light on my problem??

 

[Dave Campbell]

imported post

Thats gotta be it then, left side. Probably find the key sheared and pulley spun. Dont try to diagnose backfiring until thats fixed and compression is checked. If compis low on the left side, dont start the engine until the left head is pulled to inspect valves, a broken valve can do major cylinder damage!!! Head pull isnt too hard, but those valvetrains can be a nightmare to reassemble. NOT a budweiser job!!!:shock:

 

[Silicon Sam]

imported post

I worked on a bosses '71 Vette with a 454 that had stripped the timing gear. 8 bent intake valves, 8 bent pushrods, 8 cracked rocker arms. Some of the valves were so bad, they wouldn't even close anymore. It was a mess...

Raymond

 

[FitzAl]

imported post

Bear in mind that the GL1100 cam pulleys don't line up exactly with the marks on the casing. One of them is usually off by up to 1 tooth. That's just the way it is. Any more than one tooth and you have a problem though.

 

[wveith]

imported post

The timing by the marks are only right every 180 degrees. Same thing happened to me and I focued on what I did wrong on the left side. With the timing cover off the belts, rotate the engine and line up the RIGHT pully mark. do this again and see how the marks differ. Change the left to match and it will run good if no valve damage was done initally. I think the left belts are the ones to break. Has anyone heard of a right one breaking?? Good luck. Mine ran with the timing off.... But not good. Chased it for a month last summer. So much easier to do it before they break.



Bill

 

[Dave_C]

imported post

Okay, here we go. I hope someone can make sense of these numbers. They are totally wacko like I do not have something lined up right. Also, when the belt broke it was in a parking lot at idle so I do not think I have major engine damage What does anyone think.

Right Bank (Cylinders 1 and 3)

Number 1 - 150 psi, Number 3 - 110 psi (went up small increments)

Left Bank (Cylinders 2 and 4) Broken belt side

Number 2 - 30 psi (went up small increments), Number 4 - 0 psi

It looks to me that something in the cam alignment on the left side is wacko, either that or I have a engine that is jelley inside. I do not hear any wierd sounds like knocking etc.

Any tecnical advice would be grately appreciated !!!!!

 

[BRowan]

imported post

It really sounds like you have bent valves. If the timing is lined up on both belts (within a tooth) there is absolutely no way you would get 30 and 0 compression. A belt breaking at idle will hit valves, you might have tried starting the engine before realizing the belt had broken and that would have the pistons and valve making contact as well.

 

[Dave Campbell]

imported post

Time to pull the left head and cry. Parking lot doesnt matter, hit the piston oncce and theyre bent. Pistons may be damaged as well. BIG cry:crying::crying:

 

[wveith]

imported post

Brian; where are you located? This is not a big job and heads are cheap on ebay. I have an extra just in case. It looks like the heads are interchangable right to left. If the piston is damaged then cry..... On mine it damaged the valve bosses in the head only and that was running down the interstate. Sometimes you get lucky.

Bill

 

[wveith]

imported post

oops meant dave c

 

[wveith]

imported post

Anyone ever hear of a right belt breaking? Always seems to be a left.......

 

[englishted]

imported post

Either side can break. There isn't any difference in the right and left side belts so it's probably just coincidence that you only heard of one side breaking.

 

[Dave Campbell]

imported post

yes, both sides are designed the same, but there is a chance of one breaking over the other due to improper tensioning when installing new belts. With engine at TDC, one belt is tight (drivers right) and one loose. If the tight one is "too tight" it could fail early.

 

[Goldwinger1984]

imported post

Don't forget that the right cam operates the fuel pump and if there was an obstruction in the mechanical portion of the pump it could overload the right belt.

Vic

 

[wveith]

imported post

Vic; I thought that the right would be prone to fail but all the posts on the forums always reference the left as was my experiance. Mine just made a click sound and I pulled the clutch in. My valves still worked but I found a broken boss from the valve guides so I changed the head. Just funny that no one is saying they broke a right belt... I was lucky, no engine damage but went through hell getting it timed.

 

[Goldwinger1984]

imported post

It's one of those things that you want to kick yourself in the butt for because you didn't check it sooner. Were the old belts all cracked in the cog areas or did the belt fail due to oil contamination? Hopefully it's running fine for you now.

Vic

 

[Dave_C]

imported post

It failed due to cracking. It was dry as a bone (one of the few upsides of this). It has been raining here in N Cal for the past week so I have not pulled the heads off yet. Maybe tommorrow, it is suppose to be nice for 2 days then pour. I will put a good tarp over the bike to keep the moisture out. Tuesday is when the dry spell starts and it will take me at least that plus some to get some heads etc. I will keep everyone posted on what I find.