I have a 1997 Venture 600 twin that lost the mag side piston last week when the skirt broke. I tore the engine down and inspected the crank and all seemed fine.
I replaced both pistons. I spoke to some sledheads at work and they told me the sled was lean as there was no piston wash but I always heard these sleds were pig rich.
I increased the main jet from 160 to 170 and raised the needle 1/2 a notch.
Low end and mid range are perfect, 3/4 throttle and above is dirty- wont rev up right and runs like crap. Mid range sled runs great sled will do 70 mph at 3/4 throttle.
When I did the engine rebuild I did pull the carbs and cleaned the heck out of them.
My understanding is that 3/4 throttle and above is all the main jet. Should I return them to the stock 160?
I replaced both pistons. I spoke to some sledheads at work and they told me the sled was lean as there was no piston wash but I always heard these sleds were pig rich.
I increased the main jet from 160 to 170 and raised the needle 1/2 a notch.
Low end and mid range are perfect, 3/4 throttle and above is dirty- wont rev up right and runs like crap. Mid range sled runs great sled will do 70 mph at 3/4 throttle.
When I did the engine rebuild I did pull the carbs and cleaned the heck out of them.
My understanding is that 3/4 throttle and above is all the main jet. Should I return them to the stock 160?
I will also add that this sled was known for bad factory pistons so I believe that was the reason for the broken skirt. The sled only has 2,000 miles on it.
I changed the mains back to stock. No change.
Can anyone comment as to the piston wash?
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drew24
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How did the crank seals look?
The crank seals looked good.
I put about 150 miles on this since rebuilding it last week, here's what I noticed:
No change in performance with the original 160 main jets vs the 170 main jets. I re-installed the 170's.
Anything over 3/4 throttle results in a drop in RPM and it will not build back up.
Performance is great anywhere below 3/4 throttle.
I can build to 7,000 rpms eventually, if I go full throttle it will drop, and eventually settle at 6,000 rpms.
Any advice would be really appriciated guys. I will say that, my fuel mpg went from 7 mpg to 10 mpg after the rebuild even with the larger main and the increase in needle jet height.
I put about 150 miles on this since rebuilding it last week, here's what I noticed:
No change in performance with the original 160 main jets vs the 170 main jets. I re-installed the 170's.
Anything over 3/4 throttle results in a drop in RPM and it will not build back up.
Performance is great anywhere below 3/4 throttle.
I can build to 7,000 rpms eventually, if I go full throttle it will drop, and eventually settle at 6,000 rpms.
Any advice would be really appriciated guys. I will say that, my fuel mpg went from 7 mpg to 10 mpg after the rebuild even with the larger main and the increase in needle jet height.
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Just spitballing here......if the top of your air box comes off, see if running w/o it changes anything. There is nothing blocking up the exhaust?
Good idea- but no change (tried it out a couple days back during tuning). The exhaust seems clear, when I did the rebuild I shook it out and nothing was loose.
I need to throw this out there as I failed to do so earlier- when I did the rebuild I installed a thinner head gasket (took 3 layers out leaving 2) and did the reed notch. I thought I had stated this, not sure if any of it makes a difference as to this problem.
I need to throw this out there as I failed to do so earlier- when I did the rebuild I installed a thinner head gasket (took 3 layers out leaving 2) and did the reed notch. I thought I had stated this, not sure if any of it makes a difference as to this problem.
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Blip the choke up around 6-7000.
I will do that and report back. Are you thinking that with the head gasket mod and reed notch it is lean at WOT?
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drew24
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How does the float adjustment look? When was the fuel filter last changed?
I'm not sure what to look for in float adjustment to be honest. I know before the rebuild I never had this issue.
I pulled the carbs off again for another look. I found nothing abnormal, and they are spotless.
One thing that I did realize, is that the impluse line going to the fuel pump was replaced at time of engine rebuild. I used standard blue fuel line. I have replaced it with rubber hose. I dont think this was a problem but maybe it was collapsing during high RPM.
One thing that I did realize, is that the impluse line going to the fuel pump was replaced at time of engine rebuild. I used standard blue fuel line. I have replaced it with rubber hose. I dont think this was a problem but maybe it was collapsing during high RPM.
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The reason he mentioned float adjustment is that it sounds like it might be starving above 3/4 throttle.
drew24
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Did you get the motor properly aligned with the proper specs for clutch distance and offset. Possible it is a binding problem. I'm also just throwing stuff out there as I think of it.
Before I pulled the motor I made alignment marks on all 4 motor mounts, when reinstalling I matched them up. Not perfect but it has to be very, very close.
I did check the floats in the carbs, very limited range of movement. I tweaked the tabs a bit allowing the needles to drop more, I am leary of fuel seeping by but so far so good.
I also replaced the impluse line with a hard rubber that can't collapse.
Sled is warming up now and I will report back in a few minutes.
I did check the floats in the carbs, very limited range of movement. I tweaked the tabs a bit allowing the needles to drop more, I am leary of fuel seeping by but so far so good.
I also replaced the impluse line with a hard rubber that can't collapse.
Sled is warming up now and I will report back in a few minutes.
ls No change. Sled falls on it's face if you go wide open at anypoint- from idle, from a cruise speed, or from 3/4 throttle.
This has smart carbs, I think I am going to disconnect some of the sensors and see what happens- unless someone thinks that's a bad idea.
This has smart carbs, I think I am going to disconnect some of the sensors and see what happens- unless someone thinks that's a bad idea.
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Make sure the rubber impulse line you used is reinforced w/ ply. If not, it could collapse under load. I usually use the Dayco stuff because that's readily available.