Tec H50 with Oval Bore Mikuni problem ... pics and Videos ...

Sixpac440

Sixpac440

#61
#61
Yes it did but it wouldn't work with the stack down on the Tilly ...

With the Mikuni the choke is on the same side as the exhaust I didn't check but thought it would interfere. It came with a intake that is similar to what I made ... I tried it with that intake and it ran better but still had reversion.

Tomorrow I will see what can be done to get the Mikuni on with just the adapter ...

Thanks amigo!!
 
ole4

ole4

#62
#62
looking at the picture of your manifold it looks pretty short already but if you have the one that comes on the motor can you try that one? Did your motor come with a carb in the box?
 
danford1

danford1

#63
#63
That spring in the pipe very effective !
Where did you hear about that idea? It is brilliant.
It still looks like a straight pipe yet is pretty quiet.
Where did you get the spring?

Danford1
 
Sixpac440

Sixpac440

#65
#65
ole4

ole4

#66
#66
Run it with the tilly and the stock manifold. The stack up just causes problems with idle and gas running out into the air cleaner when you stop it. But for running at 6000 rpm it will make no difference. See if the reversion stops. I thought you had already tried the tilly but maybe it was on you manifold. does the stuttering start when you first start seeing the cloud of fuel?
 
Sixpac440

Sixpac440

#67
#67
I did try it stack up but it was on my manifold .. that was done because the Nelson exhaust was in the way of the adjustment screws and to more easily jury rig string for a temp throttle.

If I can get the Mikuni on there I want to try that first, I would rather use that carb because I am quickly understanding it and because the throttle linkage is easy.
If I have problems with it I will try the tilly ..

I will spend some time out there tomorrow ...


ole4 said:
Run it with the tilly and the stock manifold. The stack up just causes problems with idle and gas running out into the air cleaner when you stop it. But for running at 6000 rpm it will make no difference. See if the reversion stops. I thought you had already tried the tilly but maybe it was on you manifold. does the stuttering start when you first start seeing the cloud of fuel?
Click to expand...
 
Sixpac440

Sixpac440

#68
#68
Got out there today to see what's what ...

Tried getting the Mikuni to work .. I cut the intake to make it a bit straighter and shorter ...


Grabbed the duct tape to seal it ...


No difference.

I put the tilly on with the 3/8" spacer provided.
I went on you tube for the Cliffs Notes version of how a tilly works ..
Adjusted the low speed pretty good but never really could get the high speed adjusted.
Stuttering and backfiring ... maybe lack of exhaust is part of the problem.
I had to run the tilly stack up and the exhaust completely off the motor as they both needed the same space.
The following video is the result ...

[video=youtube;6RDBkV-Izhc]https://www.youtube.com/watch?v=6RDBkV-Izhc&feature=youtu.be[/video]

My video is clearer than the you tube version ..
It stuttered anyway, you can see the cloud at the mouth of the carb and well as raw gas dripping because the stack is up.
The tank was placed above the carb but no pump was used.
If you want to see the original video PM me your email address and I will send it.
 
David wulf

David wulf

#69
#69
That manifold you cut was not to long ! And it's not causing the problem . I can't tell you what is ,but I run manifolds just like yours and their longer with no problems .
 
jaimenv

jaimenv

New Member
#70
#70
Turn the lights off

Literally turn the lights off, butt first set the bike up on the stand and start it, have someone turn the lights off and run the bike as usual.
This time look closely at the sparkplug wire and observe for fireworks between the wire and the engine body/fins, try and see if you can sneak a look at the coil area again looking for fireworks.

This is a old school way of checking for bad sparkplug wires/distributor.
Sometimes a small mist of water magnify a small problem.

Jaime


PS Just when you think your bag of tricks is empty, out of the blue comes this old ideas.
Let it not be for lack of trying, this came to mind when I saw the intake manifold cut in two O.O .
 
Last edited:
Sixpac440

Sixpac440

#71
#71
First thanks to David Wulf, Jaimenv, ole4 and others for following this thread and putting input into this frustrating issue.

I don't believe its the intake either ... I can make another easily so I didn't feel bad about hacking it up.

I mounted up the tilly in the 1st video without an exhaust because the pin for the butterfly sticks out in the path of the screw in pipe nipple that goes in the exhaust port, so I was unable to screw it in. I don't have a flange muffler made up yet as I need to get the carb and jackshaft set up before the exhaust gets made.

In this next video I cut the excess off the butterfly pin, went to Home depot and bought a 3-1/2" pipe nipple and put the exhaust on.
[video=youtube;hq-OEkVrc6E]https://www.youtube.com/watch?v=hq-OEkVrc6E&feature=youtu.be[/video]

As you can clearly see it's blowing a gas cloud out the back of the tilly and its still bumping and stuttering up against 6500 RPM.
I was able to hold the butterfly with one hand and adjust the hi speed jet with the other until it leaned out and stalled. I backed it out and did it a couple more times adjusting the low speed too ...
I put some effort into dialing in the low and hi screws and this was the best it ever got.

Just got back in from checking for spark in the dark with some help from my wife... I didn't see anything ... (she puts up with so much!)

Like I said in an earlier post (and it got no response) Between 62-ish and 6500 a sound builds and sounds like a coffee can full of angry bees ... ?
 
ole4

ole4

#72
#72
The cloud does not look that bad in this video If it is a reversion issue you would lean carb and it should clean up but then die once you lower rpm beyond the reversion rpm as it would go way lean. I can't tell from the sound what is happening as my sound is not clear. Did the stuttering ever stop at 6500 rpm before it died?
 
jaimenv

jaimenv

New Member
#73
#73
You have a keeper (wife)

I am inclined to go this route, either the intake valve spring is weak or if they are different from the exhaust ones they got switch around.

Your fuel is there
spark is there

And it all works great till it hits a rpm spot. Sounds mechanical to me.

PS I used to have a keeper wife, if I needed help of any kind she was there, rain, mud.
In short, what she does not know is your fault and given the wrong conditions she can be a life saver with what she learns from you. Exploit that disposition to assist/learn.
 
Sixpac440

Sixpac440

#74
#74
At no point did the motor ever run smooth .. the shaking in the video is the motor missing/stuttering ...
I held the butterfly open and adjusted the hi speed jet in till it cut out then it was backed off ... it never ran smooth ...

ole4 said:
The cloud does not look that bad in this video If it is a reversion issue you would lean carb and it should clean up but then die once you lower rpm beyond the reversion rpm as it would go way lean. I can't tell from the sound what is happening as my sound is not clear. Did the stuttering ever stop at 6500 rpm before it died?
Click to expand...
 
Sixpac440

Sixpac440

#75
#75
The motor was made in 1994 and was NOS when I got it.
It came with aluminum valve keepers in a box.
I bought a valve compression tool to safely get the metal keepers out and the aluminum ones in.
They were done one at a time so I did not switch the springs.
Being 23 year old springs could they be sacked out from being loaded all these years?
It is possible one was compressed for all those years in storage.

The breather cover was pulled and here is what it looks like in there right now.






My new magneto should be here today.

Should I consider new springs?
Floating valves were mentioned but someone said my symptoms did sound like floating valves. I don't know what it would do if they were floating.

jaimenv said:
I am inclined to go this route, either the intake valve spring is weak or if they are different from the exhaust ones they got switch around.

Your fuel is there
spark is there

And it all works great till it hits a rpm spot. Sounds mechanical to me.
Click to expand...
 
ole4

ole4

#76
#76
I think you have ruled out reversion. I would not rule out valve float but they came with special springs that were very stiff with alloy retainers. Could cam timing be off?
 
danford1

danford1

#77
#77
The sounds of angry bees could be pre-ignition, detonation or spark knock. Your timing could be getting way to far advanced at higher rpm.
Lets hope your new ignition fixes your problem.

Danford1
 
Sixpac440

Sixpac440

#78
#78
Ok kids lets tear it apart ... all bolts were tight ...

Head and Deck ...


Head and Deck, bigger view ...


Valve clearance as taken with 2 part epoxy, the head was snugged down while it cured ... .100 on the schnoz ...


Blower housing has been rubbing on the mounting plate ...


Magneto air gap is .004 on the left and .019 on the right ...
Magneto looks beat up, I don't know if it came that way or it happened after I got it ... nothing ever got in there that I know of and I don't remember hitting it ...


This is the kill wire routing ... a small tube was placed around the wire where it goes through the sheet metal, it was gently zip tied to it ...


Pulled the side cover, used a puller on the bearing, cam never came out ... here's the line up ...


I'm gonna need a new head gasket ... who sells the thin motorsports one ... maybe get some new valve springs too?
 
ole4

ole4

#80
#80
I am not understanding valve clearance are you measuring to the head? What is the clearance between tappet and valve stem Is it correct?
 
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