Actually, I've just checked an image of the 900 engine I've just put together, and both tensioners are in about the same position as the one shown in the original image. I'm sure the ones on my M900 were more like half way through the arc after adjustment when fitting new belts. It also shows the Flanged driven tensioner pulleys. Nasher
That black tubey thingy is the wrong way round / up side down. You can tell as you need to stand on yer head to read it.
Just a thought @Nasher . I don't suppose those are 70 tooth belts on an engine which is supposed to have the 68 tooth belts, by any chance?
I'll try counting them in the photo...................Oh, hold on........ .......apparently my dinner is ready.
It's Sad that I like looking at that picture so much. It's deffo got the right belts on, if you shortened them by two teeth the tensioner wouldn't be needed if you could stretch them enough. Plus I've turned the engine over loads of times and the marks always line up afterwards. Nasher
The number of teeth on the belt has nothing to do with the valve timing. That's purely controlled by the number of teeth on the driving and driven pulleys.
Yes, that's right. The length of the belt (i.e. the number of teeth) determines whether the belt can be adjusted to the correct tension within the range of adjustment permitted by the adjuster, not the timing. If the adjuster has to be moved to the maximum end of its range with a new belt, the implication is that a shorter belt would have allowed the adjuster to be set at the minimum end of its range. Of course belts are only available in a limited range of sizes, but it just happens that both 68 and 70 tooth sizes exist.
You are both of course perfectly right, not sure why I even typed it. Anyway - Look at my sexy engine. Oh, and I'm aware it needs some oil in it. Nasher.
When I did the belts on a friend's early 900 Monster it had the belt retaining lips on cam and crank pulleys. It was an absolute pain to get the belts on, needed a good push being careful not to damage the belt. Would that mean I'd got 68 tooth belts and they should have been 70? Should the belts just slide on even with the lips on both pulleys?
You almost certainly had the correct belts. They are an absolute pain to fit with lips top and bottom. If I'm working on an engine with top and bottom lips I pull them off the cam pulleys with a pair of pliers. They are not needed and weren't fitted to later engines.
I don't think belts with two teeth less would actually fit, and if you could get them on they would probably be stretched beyond the normal working tension already. The engine shown in my image currently has the old belts off my monster on it, the plan being to change them for a nice new set just before I run it up for the first time, and hence get the max life out of them. Bearing in mind it could be another year before I run it. When I do change them I'll cut two teeth out of one of the old ones and see if it will fit. Nasher
More patience than me then, I cut the bloody things to get them off. Then ended up using a 1/2" extension bar to push them on, as it had no sharp edges. Got there in the end but it did seem more difficult than it needed to be!
