Power Loss
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Novice
Joined: May 2013
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From: Minnesota
Thread Starter
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Novice
Joined: May 2013
Posts: 15
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From: Minnesota
A littlee more info
i wouldnt take it apart just yet-- 125/90 it will still run and run good -- check the timing like said-- mufflers or baffles in a 80" 68 main jet -- open pipes 70 main jet
how do the plugs look? clean? kinda gray/white? (unleaded fuel) -- best plugs i found are the autolite XS-65 gap to .040
gas cap vent -- see if it runs better with the cap off -- whats the inside of the pipes look like? black?? really black and sooty? both? just the rear?
does it smoke? blow a puff when you revv it?
and andrews cam if its like a "J" "A" small cams -- the jet is stock like --
does it start easy?? idle? or sound labored? pop ? spit?
i had one the dude put his own ignition in and turned it in retarts -- super slug -- i turned the breaker plate the opposit way and it cam to life -- before that it was a real dog -- nooooooo power --
how do the plugs look? clean? kinda gray/white? (unleaded fuel) -- best plugs i found are the autolite XS-65 gap to .040
gas cap vent -- see if it runs better with the cap off -- whats the inside of the pipes look like? black?? really black and sooty? both? just the rear?
does it smoke? blow a puff when you revv it?
and andrews cam if its like a "J" "A" small cams -- the jet is stock like --
does it start easy?? idle? or sound labored? pop ? spit?
i had one the dude put his own ignition in and turned it in retarts -- super slug -- i turned the breaker plate the opposit way and it cam to life -- before that it was a real dog -- nooooooo power --
Plugs were normal: front was nice & white rear was a little black
It smoked a little but not enough to be noticed if you weren't looking for it.
The cam is a Andrews 2 grind jets are stock as far as I know
Started great idled great. Didn't pop or spit sounded slightly labored if you took the time to listen.
No power at low rpm but improved with higher rpms
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Novice
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From: Minnesota
Condition of Heads
I took the rear head off, she was pretty carbines up but there was no obvious issues. I would think if it was a valve issue you would be able to tell rather easy, am I wrong in this line of thinking?
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Joined: Apr 2012
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From: new orleans,la
i wouldnt have taken it apart-- i would have filled the cylinders with sea foam and let it sit -- 90lbs isnt low -- its apart now --
turn the head over --- fill the combustion chamber with a light fluid like diesl,mineral spirits -- see where it leaks and how bad -- if any thing take the valves and hand lap them and check again --
i still think ya need to check the timing -- JMO
turn the head over --- fill the combustion chamber with a light fluid like diesl,mineral spirits -- see where it leaks and how bad -- if any thing take the valves and hand lap them and check again --
i still think ya need to check the timing -- JMO
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Novice
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From: Minnesota
I filled the chamber with white gas, I'll let them sit over night and take a look in the morning. I'm starting to feel like you might of been right. Why would I be getting air out both the exhaust & the intake. 90psi is the minimum for a stock 74 CI motor & 110 for a stock 80". If the front is 125 and the spec call for no more than a variance of 10 psi (29 for a 74") so under these parametersit seems low.
Seasoned HDF Member
Joined: Nov 2006
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From: la la land jerzey
take the head to a motorcycle machine shop - have them take it apart and check it - in the 45 years i have been doing this that ( filling the chamber with a liquid ) only works around 10 percent of the time - you already know the bike is down on power dont put it back together again before having it checked - jz
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Road Master
Joined: Apr 2012
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From: new orleans,la
take them apart -- check for carbon around the valve to guide -- clean the valve stems and guides -- check for wear how loose the valve is in the guide -- exhaust are gonna be more loose -- if not exsessive clean everything -- lap the valves -- assemble WITH seals -- IMO i still think your timing is in retard -- compression ISNT the final word -- i always tried to find why its low -- i had a bike where he was running rich -- corrected the jets -- compression was low after a week of riding with the correct jet both cylinders came up --- he rode that bike for 2 more years before doing a for real rebuild -- its a harley -- a tractor not a space shuttle --
i use cast iron guides and ferrea valves 505 and 506 im going on my 5th year with a Leinweber L3S cam -- leinwebers as they say wear out the valve train fast -- 5 years?? ooooooooook.. noisy?? you bet -- tic-tic loud also -- loud loud -- the L3S is THE best cam for a 74/80 but its NOISY --
after your done if you decide to lap-- gas check them again - no leaks at the seat your good to go -- they WILL leak around the guides -- use VITON seals NOT teflon
also look at the bore -- see a ridge near the top?? any scoring in the bore?
fill the cylinder about 1" above the piston with transmission fluid wait an hour -- see if it leaked down -- if the fluid is still there like if it leaked that 1" its good to go -- if it is all gone PISTON time --
i use cast iron guides and ferrea valves 505 and 506 im going on my 5th year with a Leinweber L3S cam -- leinwebers as they say wear out the valve train fast -- 5 years?? ooooooooook.. noisy?? you bet -- tic-tic loud also -- loud loud -- the L3S is THE best cam for a 74/80 but its NOISY --
after your done if you decide to lap-- gas check them again - no leaks at the seat your good to go -- they WILL leak around the guides -- use VITON seals NOT teflon
also look at the bore -- see a ridge near the top?? any scoring in the bore?
fill the cylinder about 1" above the piston with transmission fluid wait an hour -- see if it leaked down -- if the fluid is still there like if it leaked that 1" its good to go -- if it is all gone PISTON time --
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From: Near Frankenmuth, MI
I've had second thoughts about both valves being open at the same time.
I believe there is a point where on the intake or exhaust stroke you have both valves open in a short overlap. If this is true (?) then your observation of both being open at the same time COULD BE normal.
Here's an article about the overlap.
Here's a motor animation.
I believe there is a point where on the intake or exhaust stroke you have both valves open in a short overlap. If this is true (?) then your observation of both being open at the same time COULD BE normal.
Here's an article about the overlap.
Here's a motor animation.