Topic: Weber + ARD Mag setup no start issue

[valt]

As a quick aside I would really like to say a huge thank you to everyone who took the time to respond and help me try and figure this out. I super appreciate it, for the most part its just me trying to figure this stuff out and its definitely good to hear from people who have way more experience with non stock setups like this.

I will be honest I'm at least slightly nervous about this bike now lol. The other motor was well worn so it was certainly down on power. I'm imagining going to the larger pistons is going to make the motor pick up power in the lower rpm range and its already handful there. I have found that with the webers it is very snappy down low as well, where it certainly was not with stock carbs.

[754]

Its gonna be so worth it, way more fun, maybe better gas mileage. .  Enjoy it.l

[BPellerine]

glad you had success!yes it will be snappy,but mostly after 3000 rpm at least thats what I found.bill

[scottly]

I have found that with the webers it is very snappy down low as well, where it certainly was not with stock carbs.

The first 1/8 turn of the throttle makes a big difference with Webers, and the last 1/8 has almost no effect. I re-shaped the part of the throttle tube where the cable rides to slow the initial amount of throttle opening, which helped a little.

[valt]

Well I have had it going for a bit now. I have found that its kind of scary to start when cold, since its full advance all the time. I have had it kick back with a vengeance several times. But it seems to run really good power is smooth across the board. One thing I noticed is that I'm getting a bit of smoke from the breather at idle. I was kind of attributing that to valve guides being worn. But That vent is the crank case vent is it not? It should be noted that I have a filter on it so its not just venting to nothing.

Also the modified scooter throttle cable I was using broke. I ordered a much nicer one from mikesxs.com, but for some reason it binds and causes the throttle pull to be very heavy and not return. I did some little tweaks to it and made it be better but I'm still having to use a 1.5 lbs spring to make it return correctly. This obviously makes the throttle pull be exceedingly heavy.

[Don R]

 I made a deal on a 900cc sohc motor but can't seem to complete it so I'm moving on and will put my ard and webers on a different engine. You can bet I'll refer to this thread many times. My plan is get it running well and swap one item at a time.

[BPellerine]

mine does not kick back valt,maybe retard it just a touch,the cable must really be binding,webers have a real light throttle,I dont know what linkage you have but I just made up a bracket so I could use a stock honda cable with the carb end ball cut off.bill

[754]

And figure out how much to prime.lt maybe only needs part squirt and 2 might be too much...

[scottly]

Well I have had it going for a bit now. I have found that its kind of scary to start when cold, since its full advance all the time. I have had it kick back with a vengeance several times.

Some kicking back is normal with full advance, but you may be a bit more than the normal 35* full advance?

[valt]

mine does not kick back valt,maybe retard it just a touch,the cable must really be binding,webers have a real light throttle,I dont know what linkage you have but I just made up a bracket so I could use a stock honda cable with the carb end ball cut off.bill

Yeah I ended up getting a cable from mikesxs.com which works pretty well. I had to use a different throttle tube and had to message it a bit as it was binding in my throttle housing. But now its nice and light and it fires right up usually. I had to end up putting some loctite on the carb support bolts as they kept wanting to back out and that would cause the carb to flop around and for what ever reason make it VERY difficult to start. I'm still waiting on getting the head back with the stainless valves, but once I get it back I'm going to order a new cycle x cam.

[754]

Remind me again why the carbs are at such a steep angle ? Can't be helping any.. they are usually level..
 How's gas mileage when not twisting on it all  the time. ..?

[valt]

Remind me again why the carbs are at such a steep angle ? Can't be helping any.. they are usually level..
 How's gas mileage when not twisting on it all  the time. ..?

Thats how they mount when using the stock carb boots and in a lot of car setups its not uncommon for them to be at a bit of an angle. When the mounts are tight it starts and runs without issue.

[Tintop]

Keep in mind that ALL Weber books recommend that the carbs not be more than 5* +/- from horizontal. More than this will affect the float level and cause issues.

[754]

Yours is the only one I have seen at that angle in 45 years..
 And EVERY RC manifold I have seen,sat near level. .... make that all manifolds.
 Only exception, drag bikes with 2 or more motors , or raised ports.

[valt]

Yours is the only one I have seen at that angle in 45 years..
 And EVERY RC manifold I have seen,sat near level. .... make that all manifolds.
 Only exception, drag bikes with 2 or more motors , or raised ports.

It should be noted that my motor is in a hand made frame and is entirely likely that its laid forward a bit more then a normal frame.

[754]

Your motor is pretty much level ....

[valt]

Well just to go back to this I think I discovered why the motor was so tight. I noticed that the bike was seeming skipping gears in first it only did it a couple of times then it started doing it all the time. I decided to pull the motor to see what was going on. Upon pulling the oil pan I found parts of a piston ring. So I took the top off and found that one of the pistons had lost a oil control ring and destroyed the piston and bore. I was looking at the jugs and noticed something off. The bores are literally off center by .5mm, I don't know how I never noticed this. I'm not sure thats what caused the ring to fail but I can't imagine having the bore center or possibly the bore not being straight .5mm is ever going to work.

At least I had a complete 78k motor, so I ordered 836 J&E pistons for it. I also pulled the clutch out of the motor since when it was in the bike it was slipping. Of course the clutch was all messed up, so I had to piece a working one together and got barnett clutch plates for it.

[754]

How did you determine bores were off center? how could you tell ?

[valt]

You can visibly see it plus I measured with digital calipers. fyi I took my measure farther up in the bore and not just at the very lip where you could have a chamfer. Plus the machinist I took the 836 stuff too agreed it was wrong. he is going to measure the bore for straightness once he pulls the liners out, since I wanted to use those jugs since they were already blasted and painted.

[754]

It sounds like bore size is not consistent , and varies from top to bottom or in the middle..is that what you mean ?
 Bore off  center , you would have to dial in onooe bore , then go to next  and dial in , while measuring the distance in between , that would be off center. ..if the centers were off spec..if you even know the  bore center spec.
 If your bore is not same size top to bottom , it will never live very long.. hard on parts..

[valt]

It sounds like bore size is not consistent , and varies from top to bottom or in the middle..is that what you mean ?
 Bore off  center , you would have to dial in onooe bore , then go to next  and dial in , while measuring the distance in between , that would be off center. ..if the centers were off spec..if you even know the  bore center spec.
 If your bore is not same size top to bottom , it will never live very long.. hard on parts..

All I know right now is that all of the bores were not centered as far as the bottom is concerned, all of them were thin on the same side. I didn't pull the liners out so I can't measure the tops, but the machinist I brought the 836 kit too thinks that the bores might not be straight and he was going to measure it when he pulled the liners.

[754]

I see now you mean the bottom of the sleeves., , yes off to one side. May have been honed all the way, take a loooonnnnggg time..  yes bore geing perpendicular should be better ..

[PeWe]

That does not explain broken oil rail.
Pistons are JE?
They use thin oil rails that demand really careful assembly of cylinder, if not rail WILL fail.

Is the bore really displaced, not only the beginning of bore?

You need new sleeves or another cylinder plus another shop that can do it properly.

[754]

I was going to mention, cant see much chamfer.....harder to get rings in...

[MRieck]

I was going to mention, cant see much chamfer.....harder to get rings in...

I'll say.