Tec H50 with Oval Bore Mikuni problem ... pics and Videos ...
The Motor is New Old Stock ... I bought it a few months ago ... The motor came as assembled from the factory "AS FAR AS I KNOW"
It came with the cam and springs installed.
I had to put the rod, rod bearings, valve keepers and valve retainers in when I got the motor as they came in separate factory Tecumseh boxes with corresponding part numbers on the boxes.
This is where I bought it from ...
Tecumseh 5.0HP shortblock (994k) | eBay
At the time I bought it, it was the last one of 4 listed.
After I bought it 4 more were listed by the seller.
2 are left ...
In short ... Factory cam and springs are in my motor that hasent ever been started until a month ago by me.
It came with the cam and springs installed.
I had to put the rod, rod bearings, valve keepers and valve retainers in when I got the motor as they came in separate factory Tecumseh boxes with corresponding part numbers on the boxes.
This is where I bought it from ...
Tecumseh 5.0HP shortblock (994k) | eBay
At the time I bought it, it was the last one of 4 listed.
After I bought it 4 more were listed by the seller.
2 are left ...
In short ... Factory cam and springs are in my motor that hasent ever been started until a month ago by me.
I am mostly certain the Tiny Tach is correct but not 100% sure .... I will look into that ... I will hook it up to one of my Hilltoppers ... 3500 is about max on those ....
They are adjustable from 1 to 8 cylinders ... 360 degrees is the one cyl setting and I know I set it to that .... is it still there?
They are adjustable from 1 to 8 cylinders ... 360 degrees is the one cyl setting and I know I set it to that .... is it still there?
Too bad to hear that about Mike Clements! It sounds like yet another (superior knowledge) icon is leaving the business. To be clear, with all of the work and persistence (refer to my last post) you have ALREADY put into this engine you are FAR from "giving up easily" my friend by seeking the assistance of a professional/specialist at this point, if it can get you out riding that bike sooner. Personally, I certainly would not settle for only 5,000 rpm with THIS engine when it is capable of so much more. I am not sold that when installing a TAV it will limit you to that rpm...
Michael
Michael
Your comment has me wondering about a couple things here. Kevin's comment in post #41 states "This bike is for trails, dirt, sand, hills, etc .. not balls to the wall street riding". I'm wondering what trail can be ridden with a TAV at 5000 RPM's on a mini bike? Depending on gearing, wouldn't that be more than 50 mph?
Another member just reported 45 mph with a 212 and a TAV at around 3700 rpm's, and governed. Do you really need 5000 rpm's on a trail bike with a TAV?
I do understand that he wants the engine to run well in the rpm range the engine was built for. I would do the same.
Another member just reported 45 mph with a 212 and a TAV at around 3700 rpm's, and governed. Do you really need 5000 rpm's on a trail bike with a TAV?
I do understand that he wants the engine to run well in the rpm range the engine was built for. I would do the same.
The project started out as a chain drive with a manual 3D clutch ... with its current gearing it will hit 6500 if the tach is right.
The project requires some things to be done first ... the motor/carb set up needs to be finalized ... the TAV wont go on till the motors done ... and as you can see the motor has been a major stumbling block.
But I gotta admit ... this is fun for me ... we are all going to learn something from this weather its my stupidity (very possible) or the factory used a substandard part ... etc ... I'm in no hurry to get this bike on the road ... so lets figure this out!!
The project requires some things to be done first ... the motor/carb set up needs to be finalized ... the TAV wont go on till the motors done ... and as you can see the motor has been a major stumbling block.
But I gotta admit ... this is fun for me ... we are all going to learn something from this weather its my stupidity (very possible) or the factory used a substandard part ... etc ... I'm in no hurry to get this bike on the road ... so lets figure this out!!
Can you explain that please ... I know what compression release is but not sure how it applies ... teach me!!
Not sure if this makes since but it's the best way I can explain it .
I'am pretty sure your motor will rev more than what it's doing . Those springs in the look twice as big as my stock HS springs .
+1 on that.
But wait if that would be a fix it would be just for this engine, think about it, by now it would be known that this engines had a flaw and milling for valve clearance was the fix. On top of that, the procedure for small that it maybe it will lower compression.
I am starting to think that some one pulled a fast one and did the old parts switcheroo on the motor before it went out the door.
Jaime
PS This guys here are talking about sort of the same problem observed on the intake of the carb yet with a BS motor.
OT briggs and stratton valve problem - Yesterday's Tractors
But wait if that would be a fix it would be just for this engine, think about it, by now it would be known that this engines had a flaw and milling for valve clearance was the fix. On top of that, the procedure for small that it maybe it will lower compression.
I am starting to think that some one pulled a fast one and did the old parts switcheroo on the motor before it went out the door.
Jaime
PS This guys here are talking about sort of the same problem observed on the intake of the carb yet with a BS motor.
OT briggs and stratton valve problem - Yesterday's Tractors
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Yes, I know what he meant ...
But with .100 clearance between the valve and the head when the valve is fully open how is the valve even touching the head?
Maybe its not a valve train issue ...
I just got in from assembling the motor with .070 preloading the valve springs.
If it is a valve train issue something different will happen ... if not its back to the drawing board.
But with .100 clearance between the valve and the head when the valve is fully open how is the valve even touching the head?
Maybe its not a valve train issue ...
I just got in from assembling the motor with .070 preloading the valve springs.
If it is a valve train issue something different will happen ... if not its back to the drawing board.
Lest's say the valve springs are too strongh
If so the exhaust valve would close too fast to let out all the burnt stuff and the intake valve would close too fast to let as much air fuel in. All of this dependent on the cam lobe separation and lobe profile cut.
What if we leave the intake spring alone and just slightly lower the pressure on the exhaust valve spring. I am thinking that the exhaust pressure is actually venting out the intake and causing the observed intake reversion.
Jaime
PS What if you try installing a stock exhaust spring and leave the intake alone.
To say the least this is fun, we, you or someone here is going to figure it out but we are going to :thumbsup: .
If so the exhaust valve would close too fast to let out all the burnt stuff and the intake valve would close too fast to let as much air fuel in. All of this dependent on the cam lobe separation and lobe profile cut.
What if we leave the intake spring alone and just slightly lower the pressure on the exhaust valve spring. I am thinking that the exhaust pressure is actually venting out the intake and causing the observed intake reversion.
Jaime
PS What if you try installing a stock exhaust spring and leave the intake alone.
To say the least this is fun, we, you or someone here is going to figure it out but we are going to :thumbsup: .
Here is what Ole said earlier: "It is a Tecumseh motorsports cam with associated ss valves alloy retainers and keepers. It is a stock lift long duration cam. It is not a fast ramp cam."
Is a valve striking the head? I cant see how springs have anything to do with that. I could see them causing float at high RPM. Without knowing the specifications on compression and length with them, it's a guess, but since they're both identical I wouldn't suspect them.
Wulf speaks about achieving higher RPM. If I recall, he had a specially ground Isky cam on stock springs?
Could it be that 6200 RPM is all you're going to get out of a stock lift cam? Ole's comment on stock lift and longer ramping would make this a lower RPM torque motor, would it not? And if that were true, it would be a better engine for the TAV type of transmission.
Is a valve striking the head? I cant see how springs have anything to do with that. I could see them causing float at high RPM. Without knowing the specifications on compression and length with them, it's a guess, but since they're both identical I wouldn't suspect them.
Wulf speaks about achieving higher RPM. If I recall, he had a specially ground Isky cam on stock springs?
Could it be that 6200 RPM is all you're going to get out of a stock lift cam? Ole's comment on stock lift and longer ramping would make this a lower RPM torque motor, would it not? And if that were true, it would be a better engine for the TAV type of transmission.
Morning Dave!
After I get some coffee in me I'm gonna go out and see what an additional .070 added to the springs does, if any.
This pic
.
and the unexplained angry can of bees sound are enough to make me question "is the valve hitting"?
Right now I'm in "process of elimination mode.
With the additional preload, if the valve train is involved something will change.
I'm just going to bolt the motor down, use the tilly and the spare tank mounted above it.
I'm not going to ride it.
The .070 is diagnostic only, they are not staying in there.
After I get some coffee in me I'm gonna go out and see what an additional .070 added to the springs does, if any.
This pic
and the unexplained angry can of bees sound are enough to make me question "is the valve hitting"?
Right now I'm in "process of elimination mode.
With the additional preload, if the valve train is involved something will change.
I'm just going to bolt the motor down, use the tilly and the spare tank mounted above it.
I'm not going to ride it.
The .070 is diagnostic only, they are not staying in there.