De-Tuning My Dyna...
#1
De-Tuning My Dyna...
Initially I didn't think this thread was going to be this long but I didn't really want to start posting anything until I got into the meat of my problems..
After drag racing the bike and then riding it home 220 mi, I heard a little top end noise but didn't pay a lot of attention to it but after doing a couple test hits again on the street when I got back home, I had a engine failure... The top end was very noisy and the motor wouldn't idle properly.. It sounded like I had a dead cylinder.. The AFRs on the rear cylinder were jumping from 12.5 to 17 consistently but once I got it up to 2000 RPM the AFR started smooth out a little bit.. The thing is I forgot to turn my rev limiter back down after my dyno tune, I had it up to 6,700 rpm and when I raced it I did hit it the Rev limiter a couple times.. Stupid Mistake..
So before I did any more damage to it, I got it home and just started tearing it apart.. I wasn't sure if I had crank issues or possible wrist pin clip or whatever, so the tear down started..
It didn't take too long to see what the issue was once I got the front rocker cover off..
Never seen that before.. Infact I never even heard of it happening..
The 2 main rocker support plate bolts on the spark plug side loosened up allowing the rocker plate to flex and brake.. But that wasn't the only damage.. I proceeded to check the push rods to see if I possibly bent one.. luckily none of them were bent, Thank God... It also sounded as if their might have been a collapsed lifter and again luckily they were all solid.. So with valve train disassembled I decided to do a leak down test knowing both valves are totally closed It would be easy at this point.. The front had 38% leakage coming right out the intake valve back through the intake and throttle plate.. When I opened up the throttle plate you could really hear the air escaping.. The rear cylinder was good., only 7% leakage.. At that point I removed the head to check for possible valve to piston and again luckily there was no indication of any contact..
So with that I took the stage four heads off and pulled out my stage two heads that have about 5,000 mi on them, cleaned up the chambers a little bit threw them on.. I the redid the leak down test and everything seemed good, only 6% leakage.. I was very happy with that..
However by going to the stage two heads because I can't afford to get the other heads fixed right now, I also have to pull the T-Man 660 PS-2 cam because of stage two heads won't handle the lift.. There springs are only good to .600" lift... But I'm ok With that.. I always liked the way the Woods 888 cams ran in that build anyways.. At 11.2:1 compression, they really did a nice job..
I also decided while I had that apart time for new tensioners, I have about 12,000 on the ones in there.. It's not that they're terribly worn but I got it apart so might as well do it.. I also rechecked the run out on the crank and must say that these wheels can take more punishment and power than a lot of people out there claim.. When I initially built this motor and checked the run out about 12,000 miles ago I had .0055" run out on the pinion shaft which I didn't think was terribly bad and to my amazement with the way I ride that bike drag race it you name it, whatever, it's still at .0055".. Maybe even a tad less..
Sorry I probably would have helped if I showed the pinion shaft in the video but I wasn't really too concerned about that.. What I'm impressed with is that it hasn't gone anywhere and in all honesty I think some of that is because of the S&S cam plate helping to keep it in place..I don't know but it must be better than the OEm garbage..
So I ordered a new rocker support plate $83, not bad and when that and the tensioners get here I'll get it all back together..
While I was at it I decided to measure the inside of my exhaust pipes.. The old Hooker tunable 2-1 and to my surprise the inside ID is only 1.485" .. I wonder if that could be the reason as to why I couldn't get my horsepower numbers up there.. My torque was a flat beautiful curve with lots of area below the curve.. However the horsepower just didn't seem to get to where I thought it would.. The only thing I could blame for that at this point is the pipe, too small...
So then I measured the stock head pipes and they are much larger at 1.610" I'd But that's only at the mouth as soon as you get past that they open right up to 1 7/8".. That's a lot more area to help get rid of the exhaust.. I know they're just 2-3 but ****, I think I'm going to go back to them.. They have the rush 2 1/4" louvered baffles.. The only thing I'm going to need to do is drill and re-tap the O2 sensors to 18 mm.. Currently they're the 12 mm narrow band bungs.. The nice thing about the stock head pipes is that the plate that's welded into the pipe, I'm pretty sure is drillable and tappable, we'll see..
So that's why I'm currently at Maybe one of these days I'll learn to stop writing so hard cuz no honestly I'm tired of fixing what normally shouldn't be fixed..
Phew, I'm tired going to bed..
After drag racing the bike and then riding it home 220 mi, I heard a little top end noise but didn't pay a lot of attention to it but after doing a couple test hits again on the street when I got back home, I had a engine failure... The top end was very noisy and the motor wouldn't idle properly.. It sounded like I had a dead cylinder.. The AFRs on the rear cylinder were jumping from 12.5 to 17 consistently but once I got it up to 2000 RPM the AFR started smooth out a little bit.. The thing is I forgot to turn my rev limiter back down after my dyno tune, I had it up to 6,700 rpm and when I raced it I did hit it the Rev limiter a couple times.. Stupid Mistake..
So before I did any more damage to it, I got it home and just started tearing it apart.. I wasn't sure if I had crank issues or possible wrist pin clip or whatever, so the tear down started..
It didn't take too long to see what the issue was once I got the front rocker cover off..
Never seen that before.. Infact I never even heard of it happening..
The 2 main rocker support plate bolts on the spark plug side loosened up allowing the rocker plate to flex and brake.. But that wasn't the only damage.. I proceeded to check the push rods to see if I possibly bent one.. luckily none of them were bent, Thank God... It also sounded as if their might have been a collapsed lifter and again luckily they were all solid.. So with valve train disassembled I decided to do a leak down test knowing both valves are totally closed It would be easy at this point.. The front had 38% leakage coming right out the intake valve back through the intake and throttle plate.. When I opened up the throttle plate you could really hear the air escaping.. The rear cylinder was good., only 7% leakage.. At that point I removed the head to check for possible valve to piston and again luckily there was no indication of any contact..
So with that I took the stage four heads off and pulled out my stage two heads that have about 5,000 mi on them, cleaned up the chambers a little bit threw them on.. I the redid the leak down test and everything seemed good, only 6% leakage.. I was very happy with that..
However by going to the stage two heads because I can't afford to get the other heads fixed right now, I also have to pull the T-Man 660 PS-2 cam because of stage two heads won't handle the lift.. There springs are only good to .600" lift... But I'm ok With that.. I always liked the way the Woods 888 cams ran in that build anyways.. At 11.2:1 compression, they really did a nice job..
I also decided while I had that apart time for new tensioners, I have about 12,000 on the ones in there.. It's not that they're terribly worn but I got it apart so might as well do it.. I also rechecked the run out on the crank and must say that these wheels can take more punishment and power than a lot of people out there claim.. When I initially built this motor and checked the run out about 12,000 miles ago I had .0055" run out on the pinion shaft which I didn't think was terribly bad and to my amazement with the way I ride that bike drag race it you name it, whatever, it's still at .0055".. Maybe even a tad less..
Sorry I probably would have helped if I showed the pinion shaft in the video but I wasn't really too concerned about that.. What I'm impressed with is that it hasn't gone anywhere and in all honesty I think some of that is because of the S&S cam plate helping to keep it in place..I don't know but it must be better than the OEm garbage..
So I ordered a new rocker support plate $83, not bad and when that and the tensioners get here I'll get it all back together..
While I was at it I decided to measure the inside of my exhaust pipes.. The old Hooker tunable 2-1 and to my surprise the inside ID is only 1.485" .. I wonder if that could be the reason as to why I couldn't get my horsepower numbers up there.. My torque was a flat beautiful curve with lots of area below the curve.. However the horsepower just didn't seem to get to where I thought it would.. The only thing I could blame for that at this point is the pipe, too small...
So then I measured the stock head pipes and they are much larger at 1.610" I'd But that's only at the mouth as soon as you get past that they open right up to 1 7/8".. That's a lot more area to help get rid of the exhaust.. I know they're just 2-3 but ****, I think I'm going to go back to them.. They have the rush 2 1/4" louvered baffles.. The only thing I'm going to need to do is drill and re-tap the O2 sensors to 18 mm.. Currently they're the 12 mm narrow band bungs.. The nice thing about the stock head pipes is that the plate that's welded into the pipe, I'm pretty sure is drillable and tappable, we'll see..
So that's why I'm currently at Maybe one of these days I'll learn to stop writing so hard cuz no honestly I'm tired of fixing what normally shouldn't be fixed..
Phew, I'm tired going to bed..
Last edited by 98hotrodfatboy; 09-04-2024 at 08:35 PM.
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14GuineaPig (09-05-2024),
Architect (09-05-2024)
#2
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98hotrodfatboy (09-04-2024)
#3
I commented several months ago that the pipe looks like 1.5” in the picture you posted but you blew me off. You have a good first swing on a potent combo, I imagine it should be making about 15 more hp with the right pipe. Hope you take another swing at it when things turn around for you. I’d use a Supermeg.
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Max Headflow (09-04-2024)
#4
I commented several months ago that the pipe looks like 1.5” in the picture you posted but you blew me off. You have a good first swing on a potent combo, I imagine it should be making about 15 more hp with the right pipe. Hope you take another swing at it when things turn around for you. I’d use a Supermeg.
But I don't think I'm going to chase the Rabbit anymore..
Last edited by 98hotrodfatboy; 09-05-2024 at 01:28 AM.
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harpwrench (09-04-2024)
#5
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98hotrodfatboy (09-05-2024)
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#10
[QUOTE][After drag racing the bike and then riding it home 220 mi/QUOTE]
The best advice I ever received in this situation was. “Madnss, you either build a street bike or a race bike, can’t have both with the same bike.”
This doesn’t help your situation, just passing on some advice! Good luck! I’m not a big twin guy.
The best advice I ever received in this situation was. “Madnss, you either build a street bike or a race bike, can’t have both with the same bike.”
This doesn’t help your situation, just passing on some advice! Good luck! I’m not a big twin guy.
The following users liked this post:
98hotrodfatboy (09-05-2024)