i'm surprise too ole, maybe couple more times out and then something might be knocking. my opinion if you are running a 27mm intake with a good ss narrow stem valve and good porting with a 275 lift your probably not going to gain anything more with a bigger valve. also probably not gaining anything by pulling 8700+ rpm's. cam is set up to pull max 8500. it takes a lot little mod's to get more out of that cam and you just don't have those.
New build, straight line speed attempt...
- Thread starter noseoil
- Start date
Yep, time to look at this motor again, but a bit more seriously now. Thinking I'll tear it down & at least replace the crank (have a new 60363 still in the box), that is, as long as the crank isn't egg-shaped like this one was at the main journal. Here was the original build if anyone's interested. Please remember, this is my first motor, so take it with a large pinch of salt...
https://www.oldminibikes.com/forum/index.php?threads/hemi-build-started.146490/
https://www.oldminibikes.com/forum/index.php?threads/hemi-build-started.146490/
"that scares me a bit." You & me both Ole, I just got lucky this time, but luck cuts both ways as you know.
I really need to stop at this point, take a step back & see what's happening inside the bottom end. Having a bad journal on the crank to start the build was something I should have thought more about. Now it seems like a minor miracle that I got away with what I did for this long. I guess I did things "mostly right" on the basics, but this can't last for ever. Sanding the journal to "mostly" round? Stock valves?
Will look into the new motor under the bench, unbox it & check the crank to see if this one is round & not an egg. I'll play with the new head I ordered that isn't here yet, get some better valves & keepers for it, then order some new rod bearings (maybe a new rod also?).
Need to look at the piston as well, to see what kind of ding the plug made in it & see if I floated the valves a little.
So, for now the red bike has done a pretty decent job. It does track really well at speed. Absoutely stable, steady & no sign of a wobble at all. I guess the geometry in the front end is good & was done right. The brakes are very solid, just about power brakes with the twin piston caliper setup. The total wet weight is a hefty 127#, but it's better than being too lite & bendy. The 1" DOM was a good choice for the frame & 7/8" for the front end is plenty strong.
I really need to stop at this point, take a step back & see what's happening inside the bottom end. Having a bad journal on the crank to start the build was something I should have thought more about. Now it seems like a minor miracle that I got away with what I did for this long. I guess I did things "mostly right" on the basics, but this can't last for ever. Sanding the journal to "mostly" round? Stock valves?
Will look into the new motor under the bench, unbox it & check the crank to see if this one is round & not an egg. I'll play with the new head I ordered that isn't here yet, get some better valves & keepers for it, then order some new rod bearings (maybe a new rod also?).
Need to look at the piston as well, to see what kind of ding the plug made in it & see if I floated the valves a little.
So, for now the red bike has done a pretty decent job. It does track really well at speed. Absoutely stable, steady & no sign of a wobble at all. I guess the geometry in the front end is good & was done right. The brakes are very solid, just about power brakes with the twin piston caliper setup. The total wet weight is a hefty 127#, but it's better than being too lite & bendy. The 1" DOM was a good choice for the frame & 7/8" for the front end is plenty strong.