my67xr
Miniriders Legend and Master Spanner Spinning Mode
The pressure inside the crankcase need's to go somewhere, if the brether is blocked it might be blowing out past your stem seal's.
Weird throttle issue
- Thread starter DHXrider
- Start date
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DHXrider
Well-Known Member
ah gotcha, I see what you mean now. I doubt it's that but I'll check it out. Thanks for the advice, would have never thought of that. I'll probably just pull the hose off completely. Will keep posted on the results...
DHXrider
Well-Known Member
Ok, so I'm back for a little update. The season is over here in Canada, well almost, and I've pulled the motor and I'm ready for yearly maintenance.
So I ended up riding the bike with it smoking a little bit, bike ran great aside from a little smoke and the throttle slide sticking, which was caused by oil or combustion residue getting into the intake. The smoke seemed to stop at certain point, I'm guessing it burnt through any excess transmission oil but the stickiness was always there. I've attached pictures of the intake manifold and the chamber, definitely something, either oil mist or combustion residue was getting through the intake valve and into the intake as you can see the oil res caked on the inner wall of the intake manifold and valve area. So I'm not sure if it's:
1. A leaky valve seal
2. A leaky valve seat
3. Worn piston rings (have about 3 seasons on that cylinder and piston)
Like I mentioned before, I had replaced the stock valves last year, lapped them, made sure they sealed perfectly. Thought everything looked good.
Now, with the engine apart, I tried testing them by pouring gas in the valve areas and I noticed the seep a little gas through but very slowly, I'm not sure if that's ok or if it should be PERFECTLY sealed 100%.
So what do you think the next course of action should be? I definitely will be replacing the piston and rings, the cylinder looks really good, just one very small scratch on one side down the entire length. More of a scratch then a gouge, I can feel it with my finger nail though. So I'm not sure if I should replace the cylinder also.....
And the head, well, not sure what to do....
So I ended up riding the bike with it smoking a little bit, bike ran great aside from a little smoke and the throttle slide sticking, which was caused by oil or combustion residue getting into the intake. The smoke seemed to stop at certain point, I'm guessing it burnt through any excess transmission oil but the stickiness was always there. I've attached pictures of the intake manifold and the chamber, definitely something, either oil mist or combustion residue was getting through the intake valve and into the intake as you can see the oil res caked on the inner wall of the intake manifold and valve area. So I'm not sure if it's:
1. A leaky valve seal
2. A leaky valve seat
3. Worn piston rings (have about 3 seasons on that cylinder and piston)
Like I mentioned before, I had replaced the stock valves last year, lapped them, made sure they sealed perfectly. Thought everything looked good.
Now, with the engine apart, I tried testing them by pouring gas in the valve areas and I noticed the seep a little gas through but very slowly, I'm not sure if that's ok or if it should be PERFECTLY sealed 100%.
So what do you think the next course of action should be? I definitely will be replacing the piston and rings, the cylinder looks really good, just one very small scratch on one side down the entire length. More of a scratch then a gouge, I can feel it with my finger nail though. So I'm not sure if I should replace the cylinder also.....
And the head, well, not sure what to do....
DHXrider
Well-Known Member
Hmmmm.... just realized maybe the timing caused that build up in the intake, if the exhaust valve closed to early and the intake valve opened too early on the exhaust stroke, then you would get exhaust going up the intake end.... that would make a lot of sense. But I lined up the timing marks fine....