| Author | Message | ||
     Jstfkndi |
I have a question for the motor people here. I have an 04 XB12R motor that I am rebuilding and we have gotten to the point where it is time to put the rocker boxes on. Everything was done the way it was supposed to be (or so thought) and as we started tightening the rocker boxes down, my freind decided that the motor should be able to turn over freely, but in forward rotation, it starts getting tight and won't turn. It seems like it might, but actually springs back when attempting to turn it with our hands. Is this normal or should the motor be able to turn rotations without that much effort? If so, then what could possibly be the cause for the stop of motion? It will turn just fine with out the rocker boxes on, but when we tighten them down, there appears to be an issue. The rods are in the correct place, the heads are located where they should be and everything was being put back together in the same spots that they had come out of, so what gives? Any help would be greatly appreciated! Thanks! He says that the lifters might not be good and I say I think the position of the pistons when we put the cams back in is not correct. The crank is different, so could the timing position be off? | ||
| Greg_e |
Are the plugs installed so that you are fighting compression? The valves also have a pretty good amount of spring on them that could be fighting you too. | ||
| Schmitty |
Do you have the spark pugs in the heads? If so the resistance you're feeling is the compression in the cylinders. Take the plugs out and you should be able to rotate the rear wheel in fifth gear with minor resistance. Schmitty | ||
| Jstfkndi |
The plugs are not in. We tried in fourth gear and then even put it in neutral to do it, but it just reaches a point after we install even only one of the rocker boxes that it makes a bunch resistance. We did it on both sides with only one installed on each cylinder thinking that it may have just been the front, but it happens on both. It feels like resistance rather than a mechanical blockage, meaning it seems like it should go, but takes a whole lot of effort. Don't want to try too hard for fear of breaking something. | ||
| Hughlysses |
I'd re-check the cam timing. It's fairly complicated to get right- 4 cams that all have to be synchronized with the crank. Get one wrong and they all could be wrong. That leads to valves contacting pistons at TDC. Definitely do NOT force it. |
